New Zealand Society for Earthquake
-
Upload
m-refaat-fath -
Category
Documents
-
view
130 -
download
9
description
Transcript of New Zealand Society for Earthquake
New Zealand SocietyFor Earthquake
Engineering
Assessment and Improvementof the Structural Performance
of Buildings in Earthquakes
Section 10 RevisionSeismic Assessment of
Unreinforced Masonry Buildings
Recommendations of a NZSEE Project Technical GroupIn collaboration with SESOC and NZGS
Supported by MBIE and EQCJune 2006
Issued as part of Corrigendum No. 4ISBN 978-0-473-32278-6 (pdf version)
This document represents the current status of a review of the original Section 10 of the NZSEE Guidelines which was published in 2006. Any comments will be gratefully received. Please forward any comments to NZSEE Executive Officer at [email protected]. April 2015
SeUpd
S
ection 10 - Seismdated 22 April 2015
Section Maso
10.1 Ge
10.
10.
10.
10.
10.
10.
10.2 Typ
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.3 Ob
10.
10.
10.
10.
10.
10.
10.
10.
10.
10.4 Fac
10.
10.
10.5 As
10.
10.
10.
10.
10.6 On
10.
10.
10.
mic Assessmen
10 - Seinry Bui
eneral ..........
.1.1 Backg
.1.2 Scope
.1.3 Basis
.1.4 How t
.1.5 Notat
.1.6 Defin
pical URM B
.2.1 Gene
.2.2 Buildi
.2.3 Found
.2.4 Wall c
.2.5 Const
.2.6 Floor/
.2.7 Diaph
.2.8 Wall t
.2.9 Damp
.2.10 Built-i
.2.11 Bond
.2.12 Bed-j
.2.13 Lintel
.2.14 Secon
.2.15 Seism
bserved Seis
.3.1 Gene
.3.2 Buildi
.3.3 Diaph
.3.4 Conn
.3.5 Walls
.3.6 Walls
.3.7 Secon
.3.8 Poun
.3.9 Found
ctors Affect
.4.1 Numb
.4.2 Other
sessment A
.5.1 Gene
.5.2 Asses
.5.3 Asses
.5.4 Asses
n-site Invest
.6.1 Gene
.6.2 Form
.6.3 Diaph
t of Unreinforce
ismic Aildings .
....................
ground .........
e ..................
s of this secti
to use this se
tion ..............
itions ...........
Building Pra
eral ...............
ng forms .....
dations ........
construction .
tituent mater
/roof diaphra
hragm seatin
to wall conne
p-proof cours
in timber ......
beams ........
oint reinforce
s ..................
ndary compo
mic strengthe
smic Behav
eral ...............
ng configura
hragms .........
ections ........
s subjected to
s subjected to
ndary compo
ding .............
dations and
ting Seismic
ber of cycles
r key factors .
Approach ....
eral ...............
ssment proce
ssment of str
ssment of row
igations ......
eral ...............
and configu
hragm and co
ed Masonry Buil
Assessm.............
....................
....................
....................
on ...............
ection ..........
....................
....................
actices in Ne
....................
....................
....................
....................
rials .............
agms ............
ng and conne
ections.........
se (DPC) .....
....................
....................
ement ..........
....................
onents .........
ening method
iour of URM
....................
ation .............
....................
....................
o face loads
o in-plane loa
onents/eleme
....................
geotechnica
c Performan
and duration
....................
....................
....................
ess ..............
rengthened b
w buildings .
....................
....................
ration ..........
onnections ..
Seismic As
ldings
ment of .............
....................
...................
...................
...................
...................
...................
...................
ew Zealand .
...................
...................
...................
...................
...................
...................
ections ........
...................
...................
...................
...................
...................
...................
...................
ds used to da
M Buildings .
...................
...................
...................
...................
...................
ads .............
ents ............
...................
l failure .......
nce of URM
n of shaking
...................
....................
...................
...................
buildings .....
...................
....................
...................
...................
...................
ssessment of U
IS
Unreinf............
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
ate ...............
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
Buildings ...
...................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
Unreinforced Ma
SBN 978-0-4
forced ............
....................
...................
...................
...................
...................
...................
...................
....................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
...................
....................
...................
...................
...................
...................
...................
...................
...................
...................
...................
....................
...................
...................
....................
...................
...................
...................
...................
....................
...................
...................
...................
asonry Buildings
10-i473-26634-9
. 10-1
....... 10-1
....... 10-1
....... 10-2
....... 10-3
....... 10-4
....... 10-4
..... 10-11
..... 10-14
..... 10-14
..... 10-14
..... 10-18
..... 10-19
..... 10-25
..... 10-25
..... 10-28
..... 10-30
..... 10-30
..... 10-31
..... 10-32
..... 10-33
..... 10-34
..... 10-34
..... 10-35
..... 10-39
..... 10-39
..... 10-41
..... 10-42
..... 10-42
..... 10-45
..... 10-48
..... 10-52
..... 10-53
..... 10-54
..... 10-54
..... 10-54
..... 10-55
..... 10-58
..... 10-58
..... 10-60
..... 10-64
..... 10-66
..... 10-68
..... 10-68
..... 10-68
..... 10-68
s
i 9
Section 10 - SeUpdated 22 April 20
1
1
1
1
1
1
1
1
10.7 M
1
1
1
1
1
1
1
1
10.8 A
1
1
1
1
1
1
1
10.9 A
1
1
1
1
10.10 A
1
1
1
1
1
1
1
1
10.11 A
10.12 I
Refere
Sugge
eismic Assessm015
10.6.4 Loa
10.6.5 No
10.6.6 Co
10.6.7 Fou
10.6.8 Ge
10.6.9 Se
10.6.10 Se
10.6.11 Pre
Material Pro
10.7.1 Ge
10.7.2 Cla
10.7.3 Co
10.7.4 Dir
10.7.5 Dia
10.7.6 Mo
10.7.7 Tim
10.7.8 Ma
Assessmen
10.8.1 Ge
10.8.2 Str
10.8.3 Dia
10.8.4 Co
10.8.5 Wa
10.8.6 Wa
10.8.7 Oth
Assessmen
10.9.1 Ge
10.9.2 Glo
10.9.3 Glo
10.9.4 Glo
Assessmen
10.10.1 Ge
10.10.2 Pri
10.10.3 Pa
10.10.4 Ve
10.10.5 Fle
10.10.6 Rig
10.10.7 Co
10.10.8 Co
Assessmen
Improving S
ences ...........
ested Refere
ment of Unreinfo
ad-bearing w
on load-beari
oncrete .........
undations ....
eotechnical a
condary elem
ismic separa
evious streng
operties and
eneral ...........
ay bricks and
ompressive s
rect tensile st
agonal tensile
odulus of elas
mber diaphra
aterial unit we
nt of Compo
eneral ...........
rength reduct
aphragms ....
onnections ...
all elements
alls under in-
her items of a
nt of Global C
eneral ...........
obal capacity
obal capacity
obal analysis
nt of Earthqu
eneral ...........
mary structu
rts and comp
rtical deman
exible diaphra
gid diaphragm
onnections pr
onnections tra
nt of %NBS .
Seismic Perf
....................
ences for Fu
orced Masonry B
walls .............
ng walls .......
....................
....................
nd geologica
ments ...........
ation .............
gthening.......
d Weights ....
....................
d mortars......
trength of ma
trength of ma
e strength of
sticity and sh
agm material
eights ...........
nent/Elemen
....................
tion factors ..
....................
....................
under face lo
-plane load ...
a secondary
Capacity .....
....................
y of basic bu
y of complex
s ...................
uake Force a
....................
ure ................
ponents .......
ds ................
agms ...........
ms ...............
roviding supp
ansferring dia
....................
formance of
....................
urther Readi
Seismic
Buildings
....................
....................
....................
....................
al hazards ...
....................
....................
....................
....................
....................
....................
asonry ........
asonry .........
f masonry ....
hear modulus
properties ..
....................
nt Capacity
....................
....................
....................
....................
oad ..............
....................
y nature ........
....................
....................
ildings .........
buildings ....
....................
and Displac
....................
....................
....................
....................
....................
....................
port to face-l
aphragm she
....................
f URM Build
....................
ing ..............
c Assessment o
...................
...................
...................
...................
...................
...................
...................
...................
....................
...................
...................
...................
...................
...................
s of masonry
...................
...................
....................
...................
...................
...................
...................
...................
...................
...................
....................
...................
...................
...................
...................
cement Dem
...................
...................
...................
...................
...................
...................
oaded walls
ear loads ....
....................
dings ...........
....................
....................
of Unreinforced
ISBN 978-
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
y ..................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
mands ..........
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
....................
Masonry Buildi
1-0-473-26634
......... 10-69
......... 10-70
......... 10-70
......... 10-70
......... 10-70
......... 10-70
......... 10-71
......... 10-71
.......... 10-77
......... 10-77
......... 10-77
......... 10-78
......... 10-79
......... 10-79
......... 10-79
......... 10-79
......... 10-79
.......... 10-80
......... 10-80
......... 10-80
......... 10-80
......... 10-86
......... 10-89
....... 10-104
....... 10-119
........ 10-120
....... 10-120
....... 10-123
....... 10-125
....... 10-125
........ 10-128
....... 10-128
....... 10-128
....... 10-130
....... 10-130
....... 10-130
....... 10-132
....... 10-132
....... 10-132
........ 10-132
........ 10-133
........ 10-133
........ 10-137
ngs
0-ii 4-9
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-iii Updated 22 April 2015 ISBN 978-0-473-26634-9
Appendix 10A: On-site Testing
Appendix 10B: Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10C: Charts for Assessment of Out-of-Plane Walls
SeUpd
S
1
1
ThIm20onAinapin Uoffechdipe Amtoatidto Thre
Upe19coanre
ection 10 - Seismdated 22 April 2015
SectionM
G0.1
B0.1.1
his sectionmprovement006. It drawn the signi
Auckland, Unformation opproach to ntroduction
URM construf integrity beatures of Uhimneys, paiaphragms aeople within
Assessing thmechanisms o be limitedttached to fdealisation oo assess thes
he seismic esult in marg
URM watheir conmodes.
They rely
They ofte
Their streof inelastespecially
Unlike otherermitted to 964. Therefompare to tnd %NBS aequirements
mic Assessmen
n 10 - SMason
General
Backgrou
n replaces tt of the Str
ws on key obficant quan
University oon materialthe treatm
of spandrel
uction can bbetween com
URM buildinarapets andand return wn a relativel
he performare differend to out-offlexible diapof a buildingse structures
capacity ofgins against
alls and piernfiguration,
y on friction
en have high
ength and sttic responsey in larger-m
r constructicontribute tfore, there the standardas it relatess set out in t
t of Unreinforce
Seismicry Buil
l
und
the unreinfructural Perbservations
ntity of resof Canterbus characteri
ment of in-pmodels.
be vulnerabmponents angs are inadd gable-endwalls. Thesly wide zone
mance of thnt from thosf-plane walphragms, ang acting as s reliably.
f URM beart collapse th
s may havematerial c
n and overbu
hly variable
tiffness dege to shakingmagnitude,
ion materiato the buildis no stand
d achieved s to URM this section.
ed Masonry Buil
c Asseldings
forced masrformance
s from the 2earch condury and fuisation, a neplane pier
ble to earthqand lack of dequately red walls), fase can presee from the b
hese buildise occurringll behaviournd tying ofone unified
ring wall buhat are smal
e limited noncharacterist
urden from
e material pr
grade with eg. Thereforelonger-dura
als coveredding lateral dard for nefor an exisbuildings
Seismic As
ldings
essmen
sonry (URMof Building
2010/11 Canducted in reurther afieldew method capacity b
quake shakideformation
estrained eleace-loaded ent a signifibuilding.
ings can bg in other br, relative f parts. Thid mass, but
uildings is all for the fol
n-linear deftics, vertica
supported l
roperties.
each additioe, they are vation earthq
d by these load resisti
ew URM buting buildinis therefore
ssessment of U
IS
nt of U
M) section gs in Earthnterbury earecent yearsd. New secfor diaphraased on fa
ing becausen capabilityements at hewalls, and
icant risk to
be complexbuilding typmovement s conflicts is essential
also difficulllowing reas
formation caal stresses
loads and w
onal cycle ovulnerable touakes with
guidelinesng system iuildings whng. New bue assumed
Unreinforced Ma
SBN 978-0-4
Unreinf
in “Asseshquakes”, purthquake ses at the Unctions incluagm assessmailure mode
e of its highy. The mosteight (such
d their conno occupants
x as potenpes. Perform
of differenwith the mto understa
lt to quantisons:
apability deand poten
wall weights
of greater dio incrementmultiple af
s URM hasin new builhich could uilding stan
to be defin
asonry Buildings
10-1473-26634-9
forced
ssment andublished inquence and
niversity ofude revisedment, a newes, and the
h mass, lackt hazardousas façades,
nections tos as well as
ntial failuremance tendsnt elements
more typicaland in order
fy and may
epending onntial failure
.
isplacementtal damage,
ftershocks.
s not beenldings sincebe used todard (NBS)ned by the
s
9
d n d f d w e
k s ,
o s
e s s l r
y
n e
t ,
n e o ) e
Section 10 - SeUpdated 22 April 20
If buildinghave alreaearthquakesignificantrationale foas an impo(rather thanrelieve stre Note:
We recommbefore proImprovemerequired toprovide alm
Using sounyou may emay appea
Figure
10.1.2
This sectio
unreinmortar,bond, E
eismic Assessm015
gs have undady been ue should conly lower th
for interim sortant part n strengthe
esses at area
mend that yoceeding tent of diapo provide thmost no sup
nd engineerend up with ar to be the o
e 10.1: Temp
Scope
on sets out g
nforced soli, laid in sinEnglish bon
ment of Unreinfo
dergone damused by thensider this dhan in theshoring for of building
ening) to preas of high co
you consideo a detail
phragm to whe building pport.
ring judgeman econom
only option
porary secu(Dunning
guidelines fo
id clay bricngle or mu
nd, running b
orced Masonry B
mage in an e main evdamaged stair undamagURM build
g conservatevent furtheoncentration
er selective led assessmwall connewith any m
ment when mically non-
.
uring of a mig Thornton/H
or assessing
ck masonryulti-wythe wbond and F
Seismic
Buildings
earthquakeent. Assessate. As a reged or repdings (Figution. These er dilation n.
strengtheniment, partiections, for meaningful
assessing U-viable solu
ildly damagHeartwood C
g:
y buildingswalls, and iFlemish bon
c Assessment o
e, much of sment of t
esult, their spaired stateure 10.1) to
techniquesof rocking
ing of URMcularly in example, wcapacity as
URM buildiution, with t
ed solid maCommunity
; constructein forms ofnd.
of Unreinforced
ISBN 978-
the cyclic hese buildieismic capa. This is tmitigate fu
s typically por sliding p
M buildings high seism
will almosts the as-bui
ings is alsothe result th
asonry URM)
ed of rectanf bond such
Masonry Buildi
1-0-473-26634
capacity mings after acity could the importaurther damaprovide tyiplanes, and
as a first stmicity aret certainly ilt details w
o important hat demoliti
M building
ngular units h as comm
ngs
0-2
4-9
may an be
ant age ing
to
tep as. be
will
or ion
in mon
SeUpd
Th
Th
N
Th
N
Aco
1
ThthreA Mofin PronbeanexhaFaCre
ection 10 - Seismdated 22 April 2015
hese guidel
walls in settlemen
walls und
brick ven
stone ma
hey can also
unreinfor
hollow clbrick or b
rubble stocovered h
cobble stguideline
ot in scop
his section d
earthquak
reinforced
Note:
Although theomments on
B0.1.3
his sectionhe Universitesearch unde
ASCE, 2013.
Most of the df Auckland ncluding FE
rocedures fon displacemeen verifiednalyses andxtended the as been conattal, 1976;onsultants,
ecent researc
mic Assessmen
ines are val
good connt or similar
der face loa
neers under
asonry whe
o be applied
rced stone m
lay brick ablock infill m
one masonrhere, includ
tone masones.
pe
does not co
ke-damaged
d partially f
e strengthenn this topic h
Basis of
n is largelyty of Auckertaken by .
default stres(Lumantarn
EMA, 1998;
for assessingment responsd by researcd by labora
preliminarynducted else; Hendry, 1981; Karich has been
t of Unreinforce
lid for:
ndition; wir factors.
ad attached
r face loadi
re the ston
d, with som
masonry that
nd concretemasonry wa
ry: the failuing the poss
nry: assessm
ver:
d masonry b
filled and fu
ning of URhave been in
this sec
y based okland, UnivMagenes et
ss values hana et al., 20ASCE, 201
g face-loadse that incluch (Blaikie,
atory testingy conclusioewhere, som1973, 198otis, 1986;
n conducted
ed Masonry Buil
ith negligib
d to rigid o
ing
nes are laye
me additional
at is well cou
e block maalls in frame
ure modessibility of d
ment of fac
buildings
ully filled bl
RM buildingncluded in
ction
on experimversity of t al. (1997)
ave been ado014a; Luma13; Kitching
ded walls spudes strong, 2001, 200g that incluons reached me of which1; HaseltinDrysdale, 1
d by Derakh
Seismic As
ldings
ble mortar
r flexible d
red.
l requireme
ursed and la
asonry (refeed construc
of these strdelamination
ce-loaded c
lock masonr
gs is outsidSection 10.
mental and Canterbury
) and Blaiki
opted from antarna et alg, 1999; and
panning vergly non-line02) using nuded testing
in Blaikie h is listed i
ne, 1977; W1988; Lam,shan et al.,
ssessment of U
IS
joint crac
diaphragms
nts, to:
aid in runnin
er to Sectiontion)
ructures man
capacity is
ry
e the scope12.
analytic sy and in Aie (1999, 20
tests undertl., 2014b) ad Foss, 2001
tically in onar effects. Tumerical ing on shake and Spurr (
in studies inWest, 1977
1995; and 2014.
Unreinforced Ma
SBN 978-0-4
cking, brick
s
ng bond
on 9 for ass
ay be other
not covere
e of this se
studies undAustralia, a002). It als
taken at theand from ot1.
one directionThese procentegration tie tables. Th(1993). Othncluding Y7; Sinha, 1
Mendola, 1
asonry Buildings
10-3473-26634-9
k splitting,
sessment of
than those
ed by these
ection, brief
dertaken atand on theo draws on
e Universityher sources
n are basededures haveime history
his researchher researchokel, 1971;
1978; ABK1995. More
s
3
9
,
f
e
e
f
t e n
y s
d e y h h ;
K e
Section 10 - SeUpdated 22 April 20
Other usef(1998) and
10.1.4
This sectio
Understa
These sectbuilding prnon-engineit is sugges
Assessin
These sectasked and and the nuinvestigatiowell as pro
Improvin
Although fon improvito a broad
10.1.5
Symbol
A
Agross
Ämax
An
An
An
Anet
a
B
b
BCA
eismic Assessm015
ful informatd ASCE, 20
How to
on is set out
anding UR
tions providractices in Neered constrsted you rev
ng URM bu
ions explainthe type of
umber of pon is particu
obable mate
g URM bu
formally ouing seismic field of tech
Notatio
Mea
Angubottoline tradia
Gros
Max
Areathe w
Net p
Net p
Net ppene
Para
Dept
Para
Build
ment of Unreinfo
tion on mat13.
use this
as follows.
RM buildin
de importanNew Zealanruction, andview this inf
uildings (S
n how to apf building yprevious strularly impo
erial propert
uildings (S
utside the scperformanc
hniques wh
on
ning
ular deflectionom parts of a wthrough the toan
ss plan area of
acceleration
a of net mortarwall web, mm2
plan are of wa
plan area of m
plan area of detration, m2
ameter given b
th of diaphrag
ameter given b
ding Consentin
orced Masonry B
terials, insp
s section
gs (Sectio
t context onnd, and obsd given the rformation c
Sections 1
pproach youyou are asserengthening
ortant. We pties, before s
Section 10
ope of the sce of existinich is under
(rotation) of twall panel relap and bottom
f diaphragm
red/grouted se2
all, mm2
masonry, mm2
iaphragm exc
by equation
m, m
by equation
ng Authority
Seismic
Buildings
pection and
n
ons 10.2 to
n the characserved beharecent learn
carefully bef
10.5 to 10.
ur assessmeessing. Givg techniqueprovide a chsetting out t
0.12)
section, we ng URM bur continual d
the top and ative to a restraints,
ection of
cluding any
c Assessment o
assessment
o 10.4)
cteristics ofaviour in eanings about fore proceed
11)
nt dependinven the natues used on hecklist of wthe detailed
have includuildings. Thdevelopmen
Comments
The angle is there were no
Eqs 10B.5, 1
Eq 10.6
Eqs 10B.19,
Eq 10.30
Eq 10.51
Eq 10.9
Eq 10.6
Eqs 10.13, 1010.31, 10.32,
Eqs 10.8, 10.
Section 10.8.Table 10.12,
of Unreinforced
ISBN 978-
ts is contain
f URM builarthquakes. A
its seismic ding to the a
ng on what yure of URM
these buildwhat to look d assessment
ded some bris is an intront and resea
in radians. It iso inter-storey d
0B.13, 10B.14
10B.26
0.14, Table 10 10B.2, 10B.2
54, 10.55
5.1, Eqs 10.12Eqs 10B.3, 10
Masonry Buildi
1-0-473-26634
ned in FEM
ldings, typicAs URM isperformancassessment
you are beiM constructi
dings, on-sk for on-site nt methods.
rief commenoduction on
arch.
s measured adeflection.
4
0.12, Eqs 10.223, 10B.27
2, 10.21, 0B.28
ngs
0-4
4-9
MA
cal s a ce, .
ing ion ite as
nts nly
s if
28,
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-5
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
bsp Width of spandrel Eqs 10.35, 10.37, 10.39, 10.40, 10.41, 10.42, 10.43, 10.46, 10.47, 10.48, 10.49
c Masonry bed-joint cohesion, N/mm2 The ability of the mortar to work in conjunction with the bricks.
This is related to moisture absorption in the bricks. It depends less on the absorption qualities of individual brick types and is not greatly influenced by keying of the brick surface (e.g. holes, lattices or patterning).
Cohesion is relevant to the primary decision of whether to use cracked or un-cracked masonry properties for the analyses.
Eqs 10.3, 10.33, 10.39, 10.47 10.36
c Probable cohesion, MPa Table 10.4
C(0) Section 10.10.5.1, Figure 10.78
C(T1) Elastic site hazard spectrum for horizontal loading
Eq 10.53
C(Td) Seismic coefficient at required height at period Td
Eq 10.54
Ch(0) Spectral shape factor for relevant soil determined from Clause 3.1.1, NZS 1170.5, g
Appendix 10C
Ch(T1) Spectral shape factor for relevant site subsoil type and period T1 as determined from Section 3, NZS 1170.5, g
Eq 10.53
Chc(Tp) Spectral shape factor for site subsoil type C and period Tp as determined from Section 3, NZS 1170.5, g
Eq 10.16
CHi Floor height coefficient for level i as defined in NZS 1170.5
Appendix 10C
Ci(Tp) Eq 10.16, Section 10.10.3
Cm Value of the seismic coefficient that would cause a mechanism to just form, g
Uniform acceleration to the entire panel is assumed in finding Cm
Eq 10.21, Section 10.8.5.2 Step 15 Note, Table 10.12, 10.27, 10B.20
Cp(0.75) Seismic coefficient for parts at 0.75 sec. Value of the seismic coefficient that would cause a mechanism to just form, g
Section 10.8.5.2 Step 13 & Step 15 Note
Cp(Tp) Design response coefficient for parts as defined by Section 8, NZS 1170.5, g
Section 18.8.5.2 Step 8, Eqs 10.18, 10.19, Section 10.8.5.2 Step 13
CSW Critical structural weakness
D Table 10.14
Dph Displacement response (demand) for a wall panel subject to an earthquake shaking as specified by Equation 10.18, mm
Eqs 10.18, 10.20
e Table 10.14
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-6
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
Em Young’s modulus of masonry, MPa, kN/m2 Eqs 10.4, 10.8, 10.51, 10.52
eb Eccentricity of the pivot at the bottom of the panel measured from the centroid of Wb, mm
Eq 10.12, Table 10.12, 10.15, Section 10.8.5.2 Step 4, Figure 10B.1
eo Eccentricity of the mid-height pivot measured from the centroid of Wb, mm
Eq 10.12, 10.15, Section 10.8.5.2 Step 4, Figure 10B.1
ep Eccentricity of P measured from the centroid of Wt, mm
Eq 10.12, 10.15, Table 10.12, Section 10.8.5.2 Step 4, Figure 10B.1
et Eccentricity of the mid-height pivot measured from the centroid of Wt, mm
Eqs 10.12, 10.15, Section 10.8.5.2 Step 4, Figure 10B.1
F Applied load on timber lintel Eq 10.42
Fi Equivalent static horizontal force at the level of the diaphragm (level i)
Section 10.10.5.1, Figure 10.78
f’b Compressive strength of bricks, N/mm2 Measured on the flat side
Section 10A.3.2
f’b Probable brick compressive strength, MPa Table 10.3, 10.5, Eqs 10.1, 10.2
f’j Normalised mortar compressive strength, N/mm2
Eq 10A.1
f’j Probable mortar compressive strength, MPa
Table 10.4, Eq 10.2, Table 10.5
f’ji Measured irregular mortar compressive strength, MPa
Eq 10A.1
f’m Compressive strength of masonry, MPa Eq 10.31
f’m Probable masonry compressive strength, MPa
Eq 10.2, Table 10.5, Eq 10.4
f'r Modulus of rupture of bricks, MPa Eq 10.1, Section 10.8.5.1
f't Equivalent tensile strength of masonry spandrel, MPa
Eqs 10.9, 10.35, 10.36
fa Axial compression stress on masonry due to gravity load, MPa
Eqs 10.3, 10.30, 10.31
fbt Probable brick tensile strength, MPa May be taken as 85% of the stress derived from splitting tests or as 50% of stress derived from bending tests
Table 10.3
fdt Diagonal tensile strength of masonry, MPa Eqs 10.3, 10.30, 10.38, 10.40, 10.48
fhm Compression strength of the masonry in the horizontal direction (0.5f’m), MPa
Eqs 10.37, 10.46
g Acceleration due to gravity, m/sec2 Eqs 10.15, 10.17, 10.18, 10.29
G’d Reduced diaphragm shear stiffness, kN/m Eqs 10.6, 10.7, 10.8
G’d,eff Effective diaphragm shear stiffness, kN/m Eqs 10.7, 10.54
Gd Shear stiffness of straight sheathed diaphragm, kN/m
Table 10.8, Eq 10.6
Gm Shear modulus of masonry, MPa Eqs 10.5, 10.51, 10.52
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-7
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
h Free height of a cantilever wall from its point of restraint or height of wall in between restraints in case of simply-supported face-loaded wall
The clear height can be taken at the centre-to-centre height between lines of horizontal restraint. In the case of concrete floors, the clear distance between floors will apply.
Eqs 10.13, 10.17
hi Average of the heights of point of support Section 10.8.5.2 Step 8
hi Height of attachment of the part Figure 10.78
Hl Height of wall below diaphragm, m Eq 10.8
heff Height of wall or pier between resultant forces
Table 10.13, Eqs 10.31, 10.32, Figures 10.65, 10.74, Table 10.14, Eq 10.51
hi Average of the heights of points of support Section 10.8.5.2 Step 8
hn Figure 10.78
hsp Height of spandrel excluding depth of timber lintel if present
Eqs 10.35, 10.37, 10.38, 10.39, 10.40, 10.41, 10.42, 10.43, 10.46, 10.47, 10.48, 10.49
htot Eq 10.46, Figure 10.69
Hu Heigh of wlall above diaphragm, m Eq 10.8
Ig Moment of inertia for the gross section representing uncracked behaviour
Eq 10.51
Ixx Mass moment of inertia about x-x axis, kgm2
Eq 10B.9
Iyy Mass moment of inertia about y-y axis, kgm2
Eq 10B.10
J Rotational inertia of the wall panel and attached masses, kgm2
Eqs 10.14, 10.15, 10.17, Table 10.12, Eqs 10.29, 10B.8, 10B.30
Janc Rotational inertia of ancillary masses, kgm2
Eqs 10.15, 10B.8
Jbo Rotational inertia of the bottom part of the panel about its centroid, kgm2
Eqs 10.15, 10B.11
Jbo Polar moment of inertia about centroid, kgm2
Eqs 10B.8, 10B.11
Jto Rotational inertia of the top part of the panel about its centroid
Eqs 10.15, 10B.8
k In-plane stiffness of walls and piers, N/mm Eqs 10.51, 10.52
KA Section 10.9.2
KR Seismic force reduction factor for in-plane seismic force
Coefficient proposed in lieu of Sp and K
Eq 10.53, Table 10.15
L Span of diaphragm, m Eq 10.8, 10.54, 10.55
l Length of header Section 10.8.5.1
lsp Clear length of spandrel between adjacent wall piers
Eqs 10.35, 10.37, 10.38, 10.40, 10.41, 10.42, 10.43, 10.44, 10.46, 10.48
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-8
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
Lw Length of wall Eqs 10.31, 10.33
M Moment capacity of the panel Eq 10.9
M.F Eq 10A.4
M1, Mi, Mn Moment imposed on wall/pier elements Figure 10.72
m Mass, kg Eq 10B.11
mi Seismic mass at the level of the diaphragm (level i)
Section 10.10.5.1, Figure 10.78
N(T1,D) Near fault factor determined from Clause 3.1.6, NZS 1170.5
Eq 10.53
n Number of recesses Eq 10.10
N1, Ni, Nn Axial loads on pier elements Figure 10.72
P Superimposed and dead load at top of wall/pier
Eqs 10.31, 10.32, 10.33, 10.34
P Load applied to the top of panel P is assumed to act through the pivot at the top of the wall
Section 10.8.5.1, 10.8.5.2 Step 2, 3 & 4, Eqs 10.9, 10.12, 10.13, 10.15, 10.28
p Depth of mortar recess, mm Eq 10.10, Figure 10.62
P-∆ P- delta Section 10.8
pp Mean axial stress due to superimposed and dead load in the adjacent wall piers
Eq 10.36
psp Axial stress in the spandrel Eqs 10.35, 10.37, 10.38, 10.39, 10.40, 10.41, 10.42, 10.43, 10.46, 10.47, 10.48, 10.49
Pw Self-weight of wall and pier Eqs 10.31, 10.32, 10.33, Figure 10.65, EQ 10.34
Q Live load Section 10.10.5.2
Q1, Qi, Qn Shear in pier element Figure 10.72
R Return period factor, Ru determined from Clause 3.1.5, NZS 1170.5
Eq 10.16
ra Eq 10.44, Figure 10.69
ri Eqs 10.44, 10.45, Figure 10.69
ro Eq 10.45, Figure 10.69
RP Risk factor for parts as defined in NZS 1170.5
Eq 10.18, Section 10.8.5.2 Step 13
Ru Return period factor for ultimate limit state as defined in NZS 1170.5
Eq 10.53
Si Sway potential index Eq 10.50
Sp Structural performance factor in accordance with NZS 1170.5
Section 10.8.5.2, 10.10.2.1, 10.10.5.1, 10.10.8
SW Structural weakness
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-9
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
t Depth of header Section 10.8.5.1
t Effective thickness, mm Varies with position
Section 10.8.5.2 Step 2, 3 & 4, Eq 10B.22
T1 Fundamental period of the building, sec. Eq 10.53
Td Fundamental period of diaphragm, sec. Eqs 10.54, 10.55
tgross Overall thickness of wall, mm Varies with position
Eq 10.10
tl Effective thickness of walls below the diaphragm, m
Eq 10.8, Figure 10.59
tnom Nominal thickness of wall excluding pointing, mm
Varies with position
Eqs 10.9, 10.10, Section 10.8.5.2 Step 2 & 3, Eqs 10.33, 10B.22
Tp Effective period of parts, sec. Eqs 10.14, 10.16, 10.18, 10.19, 10.23, 10.24, 10B.15, 10B.16, 10B.17, 10B.18, 10B.24, 10B.25, 10B.31
tu Effective thickness of walls above the diaphragm, m
Eq 10.8, Figure 10.59
V Probable shear strength capacity
Vdpc Capacity of a slip plane for no slip Eq 10.34
Vdt In-plane diagonal tensile strength capacity of pier and wall
Eq 10.30
Vfl Peak flexural capacity of spandrel Figure 10.68, Eqs 10.35, 10.43
Vfl,r Residual flexural strength capacity Figure 10.68, Eqs 10.37, 10.46
(Vprob)global, base Figure 10.75
(Vprob)line, i Section 10.9.2
(Vprob)wall1,wall2 Figure 10.77
Vr In-plane rocking strength capacity of pier and wall
Eq 10.32, Figure 10.66
Vs In-plane bed-joint shear strength capacity of pier and wall
Eq 10.33, Figures 10.66, 10.68
Vs1 Eqs 10.39, 10.47
Vs2 Eqs 10.40, 10.48
Vs,r Residual spandrel shear strength capacity or residual wall sliding shear strength capacity
Eq 10.33, Figure 10.68, Eqs 10.41, 10.49
Vtc In-plane toe-crushing strength capacity of pier and wall
Eq 10.31
Vtc,r Figure 10.66
W Weight of the wall and pier Section 10.8.5.2 Step 3, Eqs 10.28, 10B.11
Wb Weight of the bottom part of the panel Section 10.8.5.1, 10.8.5.2 Step 2 & 14, Eqs 10.12, 10.13, 10.15, 10.17, 10.21
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-10
Updated 22 April 2015 ISBN 978-0-473-26634-9
Symbol Meaning Comments
Wt Weight of the top part of the panel Section 10.8.5.1, 10.8.5.2 Step 2 & 14, Eqs 10.12, 10.13, 10.15, 10.17, 10.21
Wtrib Uniformly distributed tributary weight Eqs 10.54, 10.55
yb Height of the centroid of Wb from the pivot at the bottom of the panel
Eqs 10.12, 10.13, 10.15, 10.17, 10.21, Sections 10B.2.6, 10B.2.7, 10B.2.8, 10B.3.2, 10B.3.3
yt Height from the centroid of Wt to the pivot at the top of the panel
Eqs 10.12, 10.13, 10.15, 10.17, 10.21
Z Hazard factor as defined in NZS 1170.5 Eq 10.53
αa Arch half angle of embrace Eqs 10.43, 10.44, 10.45, 10.47, 10.48, 10.49
αht t/l ratio correction factor Eqs 10A.1, 10A.3
αtl t/l ratio correction factor Eqs 10A.1, 10A.2
αw Diaphragm stiffness modification factor taking into account boundary walls
Eqs 10.7, 10.8
β Factor to correct nonlinear stress distribution
Eq 10.30, Table 10.13
β1 Section 10.9.2
βs Spandrel aspect ratio Eq 10.38
Participation factor for rocking system This factor relates the deflection at the mid-height hinge to that obtained from the spectrum for a simple oscillator of the same effective period and damping
Eqs 10.17, 10.18, 10.25, 10B.21, 10B.32
Horizontal displacement, mm Eq 10B.16
d Horizontal displacement of diaphragm Eq 10.54
i Deflection that would cause instability of a face-loaded wall
Wb, Wt and P are the only forces applying for this calculation
Eqs 10.11, Table 10.12, Eqs 10B.6, 10B.16, 10B.30, Section 18.8.5.2 Step 6, Eq 10.20
m An assumed maximum useful deflection = 0.6 ∆i and 0.3∆i for simply-supported and cantilever walls respectively
Used for calculating deflection response capacity
Section 18.8.5.2 Step 6, Eqs 10.20, 10B.6
t An assumed maximum useful deflection = 0.6Δm and 0.8Δm for simply-supported and cantilever walls respectively
Used for calculating fundamental period of face-loaded rocking wall
Eq 10B.16
tc.r Deformation at the onset of toe crushing Section 10.8.6.2, Figure 10.66
y Yield displacement Section 10.8.6.2, Figure 10.66
y Yield rotation fo the spandrel Figure 10.68, Table 10.14
Structural ductility factor in accordance with NZS 1170.5
Sections 10.8.5.2, 10.10.2.1, 10.10.5.1, 10.10.8
dpc DPC coefficient of friction Eq 10.34
SeUpd
Sy
f
f
p
ρ
V
V
V
V
ϕ
ϕ
1
Ac
Ad
Be
Be
Be
Bo
Br
Ca
Co
Co
ection 10 - Seismdated 22 April 2015
ymbol
p
V*u,Pier
Vn,Pier
V*u,Spandrel
Vn,Pier
D0.1.6
ction
dhesion
eam
earing wall
ed joint
ond
rittle
avity wall
ohesion
ollar joint
mic Assessmen
Meanin
Masonr
Probab
Ductility
Density
Equival
Sum of demandthe join
Sum of below th
Sum of demandright of
Sum of and righ
Strengt
Capacit
Inter-sto
Definitio
Sedefterm
Bo
An
A w
The
A b
A bbendeffail
A careconwa
Bo
A can to buns
t of Unreinforce
ng
ry coefficient o
le coefficient o
y of part (wall)
y (mass per un
ent viscous da
the 100%NBSds on the pierst calculated us
the piers’ caphe joint
the 100%NBSds on the spanthe joint calcu
the spandrel ht of the joint
h reduction fa
ty reduction fa
orey slope, rad
ns
t of concentraformation impom ‘load’ is also
nd between m
element subje
wall that carrie
e horizontal la
bond is the pa
brittle material nding, swayingform before it ure is initiated
cavity wall cone commonly boncrete. The call.
nd between m
collar joint is aouter masonrbe filled solid wspecified.
ed Masonry Buil
of friction
of friction
)
nit volume)
amping
S shear force s above and bsing KR = 1.0
pacities above
S shear force ndrels to the leulated using K
capacities to t
actor
actor…
dian
ated or distribuosed on a struo often used t
masonry unit a
ected primaril
es (vertical) gr
ayer of mortar
attern in which
or structure isg or deformatfails and it ve
d.
nsists of two 'soth masonry, avity is constru
mortar and bric
a vertical longitry wythe and awith mortar or
Seismic As
ldings
Co
EqSe
Ta
Se
Eq
Se
below
e and
eft and KR = 1.0
the left
Se
Ta
Inthe
Eq
uted forces actucture or consto describe dir
and mortar.
y to loads pro
ravity loads du
on which a br
masonry unit
s one that failsion. A brittle sry quickly lose
skins' separatesuch as brick ucted to provid
ck.
tudinal space another backur grout, but so
ssessment of U
IS
omments
qs 10.3, 10.33ection 10A.2.4
able 10.4
ection 10.8.5.2
qs 10B.9, 10B.
ection 10.10.2.
ection 10.8.2
able 10.6, Tab
ter-storey defleight
q 10.12
ting on a strucstrained withinrect actions.
ducing flexure
ue to floor and
rick or stone is
s are laid.
s or breaks sutructure has v
es lateral load
ed by a hollowor concrete b
de ventilation a
between wythp system. Thimetimes colla
Unreinforced Ma
SBN 978-0-4
, 10.36, 10.394
2 Step 13
.10
.1
le 10.7
ection divided
cture (direct acn it (indirect ac
e and shear.
roof weight.
s laid.
uddenly when very little tende
carrying capa
w space (cavitylock, or one cand moisture
hes of masonris space is ofte
ar-joint treatme
asonry Buildings
10-11473-26634-9
9, 10.47,
d by the storey
ction), or ction). The
subjected to ency to acity once
y). The skins ould be control in the
ry or between en specified ent is left
s
9
y
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-12
Updated 22 April 2015 ISBN 978-0-473-26634-9
Course A course refers to a row of units stacked on top of one another.
Cross wall An interior wall that extends from the floor to the underside of the floor above or to the ceiling, securely fastened to each and capable of resisting lateral forces.
Dead load The weight of the building materials that make up a building, including its structure, enclosure and architectural finishes. The dead load is supported by the structure (walls, floors and roof).
Diaphragm A horizontal structural element (usually suspended floor or ceiling or a braced roof structure) that is strongly connected to the walls around it and distributes earthquake lateral forces to vertical elements, such as walls, of the lateral force resisting system. Diaphragms can be classified as flexible or rigid.
Dimension When used alone to describe masonry units, means nominal dimension.
Ductility The ability of a structure to sustain its load-carrying capacity and dissipate energy when it is subjected to cyclic inelastic displacements during an earthquake.
Earthquake-Prone Building (EQP)
A legally defined category which describes a building that has been assessed as likely to have its ultimate limit state capacity exceeded in moderate earthquake shaking (which is defined in the regulations as being one third of the size of the shaking that a new building would be designed for on that site). A building having seismic capacity less than 34%NBS.
Earthquake Risk Building (ERB)
A building having seismic capacity less than 67%NBS.
Face-loaded walls Walls subjected to out-of-plane shaking. Also see Out-of-plane load.
Flexible diaphragm A diaphragm which for practical purposes is considered so flexible that it is unable to transfer the earthquake loads to shear walls even if the floors/roof are well connected to the walls. Floors and roofs constructed of timber, steel, or precast concrete without reinforced concrete topping fall in this category.
Gravity load The load applied in a vertical direction, including the weight of building materials (dead load), environmental loads such as snow, and moveable building contents (live load).
Gross area The total cross-sectional area of a section through an element bounded by its external perimeter faces without reduction for the area of cells and re-entrant spaces.
In-plane load Seismic load acting along the wall length.
In-plane walls Walls loaded along its length. Also referred as in-plane loaded wall.
Irregular building A building that has a sudden change in the shape of plan is considered to have a horizontal irregularity. A building that changes shape up its height (such as setbacks or overhangs) or is missing significant load-bearing walls is considered to have a vertical irregularity. In general, irregular buildings do not perform as well as regular buildings perform in earthquakes.
Lateral load Load acting in the horizontal direction, which can be due to wind or earthquake effects.
Leaf See Wythe.
Load path A path through which vertical or seismic forces travel from the point of their origin to the foundation and, ultimately, to the supporting soil.
Load See Action.
Low-strength masonry Masonry laid in weak mortar; such as weak cement/sand or lime/sand mortar.
Masonry unit A preformed component intended for use in masonry construction.
Masonry Any construction in units of clay, stone or concrete laid to a bond and joined together with mortar.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-13
Updated 22 April 2015 ISBN 978-0-473-26634-9
Mortar The cement/lime/sand mix in which masonry units are bedded.
Mullion A vertical member, as of stone or wood, between the lights of a window, the panels in wainscoting, or the like.
Net area The gross cross-sectional area of the wall less the area of un-grouted areas or penetrations.
Out-of-plane load Seismic load (earthquake shaking) acting normally (perpendicular) or at right angles to the wall surface. Walls subjected to out-of-plane shaking are also known as face-loaded walls. Walls are weaker and less stable under out-of-plane than under in-plane seismic loads.
Partition A non-load-bearing wall which is separated so as not to be part of the seismic resisting structure.
Party wall A party wall (occasionally party-wall or parting wall) is a dividing partition between two adjoining buildings or units that is shared by the tenants of each residence or business.
Pier A portion of wall between doors, windows or similar structures.
Pointing (masonry) Troweling mortar into a masonry joint after the masonry units have been laid. Higher quality mortar is used than for the brickwork.
Primary element An element which is relied on as part of the seismic force resisting system.
Regular building see Irregular building.
Return wall A short wall usually perpendicular to, and at the end of, a freestanding wall to increase its structural stability.
Rigid diaphragm A suspended floor, roof or ceiling structure that is able to transfer lateral loads to the walls with negligible horizontal deformation of the diaphragm. Floors or roofs made from reinforced concrete, such as reinforced concrete slabs, fall into this category.
Running or stretcher bond
The unit set out when the units of each course overlap the units in the preceding course by between 25% and 75% of the length of the units.
Seismic hazard The potential for damage caused by earthquakes. The level of hazard depends on the magnitude of probable earthquakes, the type of fault, the distance from faults associated with those earthquakes, and the type of soil at the site.
Seismic system That portion of the structure which is considered to provide the earthquake resistance to the entire structure.
Shear wall A wall which is subjected to lateral loads due to wind or earthquakes acting parallel to the direction of an earthquake load being considered (also known as an in-plane wall). Walls are stronger and stiffer in plane than out of plane.
Special study A procedure for justifying a departure from these guidelines or determining information not covered by them. Special studies are outside the scope of these guidelines.
Stack bond The unit set out when the units of each course do not overlap the units of the preceding course by the amount specified for running or stretcher bond.
Strength, design The nominal strength multiplied by the appropriate strength reduction factor.
Strength, probable The theoretical strength of a component section, calculated using the section dimensions as detailed and the theoretical characteristic material strengths as defined in these guidelines.
Strength, required The strength of a component section required to resist combinations of actions for ultimate limit states as specified in AS/NZS 1170 Part 0.
Structural element Component of a building that provides gravity and lateral load resistance and is part of a continuous load path. Walls are key structural elements in all masonry buildings.
Section 10 - SeUpdated 22 April 20
Through ston
Transom
Transverse w
Unreinforced(URM) wall
Veneer
Wall tie
Wall
Wythe
10.2
10.2.1
Most of Ntime; betwmethods astonemasonHowever, t
10.2.2
The range characteris
Most otimber
Many level an
Larger where f
Large, shakingpartitio
In these guand halls buildings. property anthe approp
eismic Assessm015
ne
wall
d masonry
Typica
Genera
New Zealandween the lateare relativelns and the these buildi
Buildin
of typical Ustics for eac
of the smalwalls with
smaller comnd high bott
buildings tfloors and r
complex bg as they tons and man
uidelines smare catego Simplifie
nd analysisriate section
ment of Unreinfo
A long stone (wall. It is also be a concreteconcrete that
See Mullion.
See Cross wa
A masonry waunreinforced wmasonry mate
See Wythe.
The tie in a caconstructed o
A vertical elemand strength o
A continuous independent oreferred to as
al URM
al
d’s URM be 1870s andly uniform customary
ings vary su
ng forms
URM buildh type. Not
ller buildingthe perimet
mmercial Utom storeys
tend to havroofs are sup
buildings sutend to havny windows
maller buildrised as baed approac, are possibns below.
orced Masonry B
(header unit) tknown as bon
e block, a woodperform the s
all.
all containing nwall resists graerials.
avity wall usef wires, steel b
ment which beof a structure.
vertical sectioof, or interlocka veneer or le
Buildin
uildings wed 1940 (Rus
with only stones (“ha
ubstantially
dings is set oe that:
gs are celluter masonry
URM buildis.
e punched wpported by t
uch as churve irregulars.
dings (ie lesasic buildinches, particble when as
Seismic
Buildings
that connects nd stone. Cond element, or ame function.
no steel, timbeavity and later
d to tie the intbars or straps
ecause of its p
on of masonryked with, the aeaf.
ng Prac
ere built dusell & Ingha few vari
ard rock” oin their stru
out in Tabl
ular in natuy façade to p
ings have f
wall framestimber, cast
rches are par plans, tal
ss than twongs to distcularly assossessing bas
c Assessment o
two wythes tontrary to its nasteel bars wit
er, cane or othral loads solel
ternal and extes.
position and sh
one unit in thadjoining wythe
tices in
uring a relatham, 2010). ations refle
or “soft rockuctural conf
le 10.1 toge
ure, combinprovide an o
fairly open
s (Figure 10t iron or ste
articularly vll storey he
o storeys), itinguish theociated witsic building
of Unreinforced
ISBN 978-
ogether in a stome, a throughh hooked end
her reinforcemy through the
ernal walls (or
hape contribut
ickness. A wye(s). A single
n New Z
tively narroAs a result
ecting the ok”) they usefiguration an
ether with so
ning internaoverall rigid
street façad
0.2) and opel posts.
vulnerable teights, offs
ncluding smem from mth determings. These a
Masonry Buildi
10-0-473-26634
tone masonry h stone can alsds embedded i
ment. An strength of th
r wythes)
tes to the rigid
ythe may be wythe is also
Zealand
ow window t, constructiorigins of ted for layinnd layout.
ome comm
al masonry d unit.
des at grou
pen plan are
to earthquaet roofs, fe
mall churchmore complning materare covered
ngs
0-14
4-9
so in
e
dity
of ion the ng.
mon
or
und
eas
ake ew
hes lex rial
in
SeUpd
Thin
Ta
Fo
1 S
Ma
Brfrocagr
1 S
Ti
Brfroplagr
ection 10 - Seismdated 22 April 2015
he interaction more detai
able 10.1: B
orm
Storey cellula
asonry Intern
racing predomom in-plane waantilevering froround level
Storey cellula
mber Interna
racing predomom walls loadeane cantileverround level
mic Assessmen
on of buildiil in Section
F
uilding form
Ill
ar:
nal Walls
minantly walls om
ar:
al Walls
minantly ed in-ring from
t of Unreinforce
ings construn 10.5.4.
Figure 10.2:
ms
lustration
ed Masonry Buil
ucted with c
URM buildi
Seismic As
ldings
common bou
ing with pun
ssessment of U
IS
undary or p
nched wall
Partic
Bo
Pladem
Refrom
Sufixit
Grodia
Cointe
Stifma
Stifma(pla
Flewit
Timbra
Unreinforced Ma
SBN 978-0-4
party walls i
ular issues
onding at wall i
an regularity –mand if irregu
elative stiffnessm varying wal
bfloor height aty
ound floor aphragm/braci
onnection to mersections
ffness compatasonry – wall g
ffness compatasonry – mateaster/lath, fibr
exibility of strath respect to m
mber wall founacing capacity
asonry Buildings
10-15473-26634-9
is discussed
intersections
– diaphragm lar
s/strength ll lengths
and level of
ng
masonry at
tibility with geometry
tibility with riality
rous plaster)
pping/lining masonry
ndation y
s
5
9
d
Section 10 - SeUpdated 22 April 20
Form
>1 Storey Ce
Masonry Inte
Bracing predfrom walls loaplane with intover doorwaybetween floo
>1 Storey Ce
Timber Inter
Bracing predfrom walls loaplane with intover doorwaybetween floo
1 Storey Ope
Bracing predfrom walls loaplane cantileground level
>1 Storey O
Bracing predfrom walls loaplane cantileground level,contributionswalls
Most commocentre commstructures
eismic Assessm015
ellular:
ernal Walls
dominantly aded in-teraction ys and
ors
ellular:
rnal Walls
dominantly aded in-teraction ys and
ors
en:
dominantly aded out-of-vering from
pen:
dominantly aded out-of-vering from with
s from end
on town mercial
ment of Unreinfo
Illustration
orced Masonry B
Seismic
Buildings
c Assessment o
Par
As
As
of Unreinforced
ISBN 978-
rticular issues
1 Storey plus:
Wall coupling
Change in wafirst floor
1 Storey plus:
Hold-down of lower walls
Hold-down anlower walls to
End walls andstiffness
Ground condifoundations c
Wall connectiofloor slab if pr
Diaphragm st
Diaphragm st
Ancillary strucbracing
Contribution obeams/frame
Plan regularity
Masonry Buildi
10-0-473-26634
s
over doorway
all thickness at
f upper walls to
nd bracing of o piles
d differential
itions and critical
on with grounresent
tiffness
trength
ctures forming
of shop front
y
ngs
0-16
4-9
ys
t
o
d
g
SeUpd
Fo
Mu
Brfroloa
MuInt
Brcowawa
MuFr
Brcowawa
MoFo
Brfrosinfre
Stch
ection 10 - Seismdated 22 April 2015
orm
ulti-storey Op
racing predomom perimeter waded in-plane
ulti-storey witernal Structu
racing from ombination of ialls and perimalls loaded in-
ulti-storey rame/Wall
racing from ombination of ialls and perimalls loaded in-
onumental – orm
racing predomom cantilever angle degree ofeedom
tatues, towershimneys and th
mic Assessmen
Ill
pen
minantly walls
ith ures
internal meter -plane
internal meter -plane
Single
minantly action, f
, he like
t of Unreinforce
lustration
ed Masonry Buil
Seismic As
ldings
ssessment of U
IS
Partic
Waconout
Diaimpana
Diaofte
Ho
Puana
Wacon
Cointestru
Puana
Oftbutasc
Inteperstif
Higplaele
Oftbe
Fou
Coform
Da
Unreinforced Ma
SBN 978-0-4
ular issues
all-to-diaphragnnection demat-of-plane wal
aphragm stiffnportant for outalysis
aphragm strenen high
oles in diaphra
nched walls inalysis can be
all-to-diaphragnnection dema
ompatibility beternal and stiff uctures
nched walls inalysis can be
ten heavyweigt strength difficertain
ernal frame strimeter punchffness
gh shear demaane connectionements
ten rocking gobeneficial
undation stab
ombination of mrming masonry
amping
asonry Buildings
10-17473-26634-9
gm ands high for l loads
ness t-of-plane wall
ngth demands
agms
n-plane complex
gm ands high
tween flexibleexternal
n-plane complex
ght floors: stiff cult to
tiffness vs. ed wall
ands on in-n to perimeter
overned – can
ility critical
materials y unit
s
7
9
l
f
r
Section 10 - SeUpdated 22 April 20
Form
MonumentaForms
Multiple degrfreedom withstiffnesses/pe
Most churchelarger civic st
10.2.3
Foundationincluding transverse thickeningcontact witand unrein Deeper coreinforced where the fspanned bewas often regardless As the widpoorer grooften be “b Larger indlarge, isolaso are an e
eismic Assessm015
l – Multiple
rees of h different eriods
es and tructures
Founda
ns for URMunder opento the wall s were usedth the groun
nforced.
oncrete striwith plain rfoundation etween drivrudimentar
of reinforce
dening of tound either built in” so w
dustrial builated pads. Axcellent ind
ment of Unreinfo
Illustration
ations
M buildingsnings in puto give a h
d in large snd with a l
ips (Figurereinforcing formed a se
ven timber ry, with thement.
he foundatiduring or
would not b
ldings withAs these werdicator of se
orced Masonry B
s were typiunched wa
half-to-one btructures. Tayer of con
e 10.3(b)) bars, flats,
ea wall or wor sometim
he depth of
ion was oftafter const
be visible.
h timber, stere sized for ettlement.
Seismic
Buildings
ically shallalls or facabrick-thicke
The bricks wncrete. In sm
for largeror train/tram
wharf, thesemes betweenf the concr
ten nominatruction. Se
eel or cast the “live” a
c Assessment o
Par
ow strip foades. Bricksening, althowere typicamaller build
r buildings m rails. In e
e reinforced n steel or prete at leas
l, some setettlement du
iron posts actions, they
of Unreinforced
ISBN 978-
rticular issues
Highly complebetween elem
Special study
Peer review re
ootings (Figs were typugh larger mlly protecte
dings, this w
were ofteextremely poconcrete str
precast pilesst half that
tlement wauring constr
were ofteny are often l
Masonry Buildi
10-0-473-26634
s
ex interaction ments
y
ecommended
gure 10.3(apically placmulti-stepp
ed from direwas often th
en nominaoor ground
trips generas. The desit of the sp
as common truction cou
n founded lightly load
ngs
0-18
4-9
a)), ced ped ect hin
lly or lly ign pan
in uld
on ded
SeUpd
1
So
ection 10 - Seismdated 22 April 2015
W0.2.4
olid and cav
Solid walof town, a
Cavity wuse of hiexterior.
mic Assessmen
(b
Wall con
vity walls w
lls were genand for part
walls were uigher qualit
t of Unreinforce
(a)
b) A cross s
Figure 10
structio
were commo
nerally usedty walls and
used in builty bricks w
ed Masonry Buil
) Typical fo
ection of UR
0.3: URM bu
n
on types of c
d for industd walls eithe
ldings to cowhere a bett
Seismic As
ldings
undation de
RM building
uilding found
construction
trial buildiner not visibl
ontrol moistter architec
ssessment of U
IS
etails
g foundation
dations
n:
ngs and buille or in lowe
ture ingressctural finish
Unreinforced Ma
SBN 978-0-4
n
ldings on ther storeys.
s. They alsoh was requi
asonry Buildings
10-19473-26634-9
he outskirts
o allow theired on the
s
9
9
s
e e
Section 10 - SeUpdated 22 April 20
In cavity wmisleadingan outer wthick wythConstructioor at the re
Fig Often a cainterior wathat is not a
10.2.4.1
The commtwo wytheaddition to
10.2.4.2
In cavity wwith #8 tiespacings oCast steel,
eismic Assessm015
walls, the exg impression
wythe that whe for the toon quality w
ear of buildi
ure 10.4: Ch
avity wall, wall followinga wythe mu
Wall thi
monly used nes), 350 mmo any outer v
Cavity t
walls, outer es, sometim
of 900 mm wrought ste
ment of Unreinfo
xterior mason of these w
was continuoop storey awas usuallyings.
hange in cro
which was g subsequen
ultiple.
ckness
nominal thim (14”, thrveneer of 11
ties
wythes wemes with a k
horizontallyeel or mild
orced Masonry B
onry wytheswalls’ structous over theand two or y better for
oss-section
originally ont alteration
icknesses ofree wythes)10 mm (4½
ere usually tkink in the y and everysteel toggle
Seismic
Buildings
s act as an atural thicknee full height
more wythvisible wal
of brick wa
on the extern. This will
f brick wall) and 450 m
½”, one wyth
tied to the middle, or
y fifth or sies were som
c Assessment o
architecturaless). It was t of the wallhes for lowells and vene
ll (Holmes C
rior of the bbe recognis
ls in New Zmm (18”, f
he).
inner wyther with flat pixth course
metimes used
of Unreinforced
ISBN 978-
l finish (whialso comm
l plus an inner storeys (eers than in
Consulting G
building, hasable by a w
Zealand are four wythe
e or main spieces of tin
vertically (d at similar
Masonry Buildi
10-0-473-26634
ich can givemon to proviner one-bric(Figure 10.4
n hidden are
Group)
as become wall thickne
230 mm (9s). This is
structural wn generally (Figure 10.spacings.
ngs
0-20
4-9
e a ide ck-4). eas
an ess
9”, in
wall at
5).
SeUpd
10
Abeman Sthe Inshin Nadvo
C
Mthbo Chahesagr
ection 10 - Seismdated 22 April 2015
(a
M0.2.4.3
A number oelow. The b
masonry unitnd how its c
tretcher unieaders are b
n cross sectihould be antervals.
Note that sodjoining wyoid between
lay brick m
Most New Zhe most freqottom (grou
ommon bonas layers ofeaders can ame buildinround storey
mic Assessmen
a) Common
(c) B
Figure 1
Masonry
f different bond patternts in a wall components
its, or stretbricks laid a
ion, a wall adequately
metimes faythes. Thesen the inner a
masonry
Zealand URMquently occund) storey.
nd is sometf stretchersbe at differ
ng. For examy but every
t of Unreinforce
wire ties
Butterfly ties
10.5: Comm
bond and
bond patten is an impoare connect act togethe
tchers, are cross the w
three units connected
ake headerse can disguiand outer wy
M buildingurring bond
imes referre, and headerent levels
mple, the hefourth cour
ed Masonry Buil
s
monly observ
d cross s
erns have bortant featuted and has er as a comp
bricks laid wall joining t
thick is a tto the adj
s are incorpise the presythes.
s were cond pattern, o
ed to as Amers every tin differen
eaders may rse near the
Seismic As
ldings
ved wall ties
sections
been used fure of URM
a significanplete structu
in the plathe masonry
three wytheoining wyt
porated intoence of a c
structed witr English b
merican bonthree to sixt buildings,be every se
e top of the
ssessment of U
IS
(b) Double
(d) V-drip
s (Dymtro D
for URM buM buildings:
nt effect on ural element
ne of the wy wythes tog
e wall. To athe with h
o a wythe tavity wall w
th either cobond, which
nd or Englisx courses (F, and someecond coursthird storey
Unreinforced Ma
SBN 978-0-4
e hook ties
flat fishtaile
Dizhur)
buildings, asit determin
n both the wt.
wall. Headegether.
act as one, headers at
that do notwhere there
ommon bonh is often fo
sh garden wFigure 10.6etimes evense at the boy. Header c
asonry Buildings
10-21473-26634-9
ed wall ties
s describednes how the
wall strength
er units, or
each wytheappropriate
t cover twoe is a cavity
nd, which isound on the
wall bond. It6(a)). Thesen within theottom of theourses may
s
9
d e h
r
e e
o y
s e
t e e e y
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-22
Updated 22 April 2015 ISBN 978-0-473-26634-9
be irregular and made to fit in at ends of walls and around drainpipes with half widths and other cut bricks. English bond has alternating header and stretcher courses (Figure 10.6(c)).
(a) Common bond (b) Running bond
(c) English bond (d) Flemish bond
Figure 10.6: Different types of brick masonry bonds
Other bond patterns used in New Zealand include Running bond (Figure 10.6(b)) and Flemish bond (Figure 10.6(d)). Running bond (stretcher courses only) often indicates the presence of a cavity wall. Flemish bond (alternating headers and stretchers in every course) is the least common bond pattern and is generally found between openings on an upper storey; for example, on piers between windows.
Stone masonry
Stone masonry buildings in New Zealand are mainly built with igneous rocks such as basalt and scoria, or sedimentary rocks such as limestone. Greywacke, which is closely related to schist, is also used in some parts of the country. Trachyte, dolerite, and combinations of these are also used.
Wall texture
Wall texture describes the disposition of the stone courses and vertical joints. There are three different categories (Figure 10.7): ashlar (squared stone); rubble (broken stone); and cobble stones (field stone), which is less common.
SeUpd
Awcoblde(F Akebe
Rrigasst
ection 10 - Seismdated 22 April 2015
(a) Ashla
Ashlar (dreswill be at rioursed ashllock-in-courescribes theFigure 10.8(
All ashlar shept plumb. e considered
(c) R
Fig
Rubble stoneght angles (s foundationone.
mic Assessmen
ar (squared
Figure
ssed or undight angles ar, which irse ashlar
e broken con(c)), or brok
hould have sThis type od as a hybri
(a) Coursed
Random-cou
ure 10.8: Sc
ework cons(Figure 10.7ns and bac
t of Unreinforce
stone) (
10.7: Classi
ressed) is sto each ot
is in regula(Figure 10ntinuity of t
ken ashlar (F
straight andof stone cand between r
d ashlar
urse ashlar
chematic of
ists of ston7(b)). This
cking, and
ed Masonry Buil
(b) Rubble (
ification of s
stonework cther (Figurar courses .8(b)). It mthe bed andFigure 10.8
d horizontaln also be forubble and a
different fo
es in whichform of mafrequently
Seismic As
ldings
broken ston
stone units
cut on four re 10.7(a)). with contin
may also apd head joint(d)).
l bed joints,und in courashlar stone
(b
rms of Ashl
h the adjoiniasonry is ofconsists of
ssessment of U
IS
ne)
(Marta Giare
sides so thAshlar is
nuous jointppear as brts) of either
, and the versed rubble;ework.
b) Block-in-c
(d) Broke
ar bond (Lo
ing sides arften used fof common,
Unreinforced Ma
SBN 978-0-4
(c) Cobble s(field sto
etton)
hat the adjousually lai
ts (Figure 1roken cour
r random-co
ertical joint; in which c
course ashla
en ashlar
owndes 1994
re not requior rough ma
roughly dr
asonry Buildings
10-23473-26634-9
stones one)
oining sidesid as either10.8(a)), orrses (whichourse ashlar
s should becase it may
ar
4)
red to be atasonry suchressed field
s
3
9
s r r h r
e y
t h d
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-24
Updated 22 April 2015 ISBN 978-0-473-26634-9
Wall cross section
It is usually not possible to establish the cross section characteristics of a stone masonry wall from the bond pattern. More detailed inspection is required to identify any connections between the wythes; determine what material the core is composed of; and locate any voids, a cavity, or the presence of other elements such as steel ties. All of these contribute to determining the wall’s structural properties.
(a) Dressed stone in outer
leaves and “rubble” fill (b) Stone facing and brickwork backing
(c) Stone facing and concrete core
Figure 10.9: Stone masonry cross sections in New Zealand. Representative cases observed in Christchurch after the Canterbury earthquakes (Marta Giaretton)
Concrete block masonry
Although solid concrete masonry was used in New Zealand from the 1880s, hollow concrete block masonry was not used widely until the late 1950s. Masonry was usually constructed in running bond, but stacked bond was sometimes used for architectural effect. From the 1960s onwards, masonry was usually constructed with one wythe 190 mm thick, although this was sometimes 140 mm thick. Cavity construction, involving two wythes with a cavity between, was mostly used for residential or commercial office construction but occasionally for industrial buildings. The external wythe was usually 90 mm thick and the interior wythe was either 90 mm or 140 mm. Cavity construction was often used for infills, with a bounding frame of either concrete or encased steelwork. To begin with, reinforcement in concrete masonry was usually quite sparse, with vertical bars tending to be placed at window and door openings and wall ends, corners and intersections, and horizontal bars at sill and heads and the tops of walls or at floor levels. Early on, it was common to fill just the reinforced cells. Later, when the depressed web open-ended bond beam blocks became more available, more closely spaced vertical reinforcement became more practicable. When the depressed web open-ended bond beam blocks (style 20.16) became available without excessive distortion from drying shrinkage, these tended to replace the standard hollow blocks for construction of the whole wall (with specials at ends, lintels and the like). Wire reinforcement formed into a ladder structure (“Bloklok” or a similar proprietary product) was common in cavity construction. Two wires ran in the mortar in bed joints, joined across the cavity by another wire at regular centres and acting as cavity ties.
SeUpd
1
10
Ncl
10
Mwcom N
Ww
10
Totim
10
Frww
1
Flco
ection 10 - Seismdated 22 April 2015
C0.2.5
B0.2.5.1
New Zealandlay bricks us
M0.2.5.2
Mortar is uweathering aonstituents v
mortar was c
Note:
While the limwill leach lea
Figure 10.
T0.2.5.3
otara, rimu,mber specie
C0.2.5.4
rom the bewhere lean mwas usually 3
F0.2.6
loors of URoncrete slab
mic Assessmen
Constitu
Bricks
d brick sizesed in maso
Mortar
sually soft and leachinvaried signiommon but
me in lime ading to dete
.10: Soft mo
Timber
, matai (blaes in URM b
Concrete
ginning, homix concret30 MPa or g
Floor/roo
RM buildingbs.
t of Unreinforce
ent mate
es are basedonry buildin
due to fang (Figureificantly thrt cement-lim
mortars wilerioration o
ortar. Note th(Ing
ck pine) anbuildings.
block
ollow concrte was comgreater.
of diaphr
gs were usu
ed Masonry Buil
erials
d on imperings is 230 m
actors inclue 10.10). Broughout thme-sand mo
ll continue of the morta
he delaminagham and G
nd kahikatea
rete blocks mpacted into
ragms
ually made
Seismic As
ldings
ial size. Thmm x 110 m
uding inferBoth the tye country. U
ortar and cem
to absorb mar.
ated mortar Griffith, 2011
a (white pin
were manuo moulds u
from timbe
ssessment of U
IS
he most commm x 70mm
rior initial ype and pUntil early lment-sand m
moisture an
from bricks1)
ne) were the
ufactured bsing vibrati
er and some
Unreinforced Ma
SBN 978-0-4
mmon nomi(9”x 4½”x
constructioproportions last centurymortar were
nd “reset”, o
s in the back
e most comm
by the Bession. Concre
etimes from
asonry Buildings
10-25473-26634-9
inal size of3½’).
on, ageing,of mortar
y, lime-sande also used.
over time it
kground
monly used
ser process,ete strength
m reinforced
s
5
9
f
, r d
t
d
, h
d
Section 10 - SeUpdated 22 April 20
10.2.6.1
Timber flo(T&G) meMatai, rimtimbers maThe diaphringress. Asearthquakenails in usprimarily fpairs of nais differendirections. earthquake
10.2.6.2
Reinforceddiaphragmmodern cosignificant(such as hocapacity. Oeven train r
Figure 10fro
Portland cthe late 19concretes (of lime proas concreteformed in s
eismic Assessm015
Timber
oor diaphragembrane na
mu and oregay have harragm may as well as the is dictatedse a centurfrom frictionails in a boant for each
Hence die loading or
Reinfor
d concrete m. While theonstruction, ly less bondooks, thickOther typesrails.
0.11: Concrem carbonat
ement grad920s, which(often calledoducts) are e was a relaslabs using
ment of Unreinfo
floors
gms are usailed to timgon were cordened fromalso have behe timber chd by the behry ago weren between t
ard. A furthh direction,iaphragm inriented both
ced conc
slabs wereey may hav
these bars d than expeenings, thre of reinforc
ete slab withtion of the c
dually becamh was the d “Clinker”significantl
atively expehollow cera
orced Masonry B
ually constmber joists tommonly usm a centuryeen damageharacteristichaviour of te much softhe boards, er complica, recognisinn-plane stiparallel and
crete slab
e usually me been reinwere often cted today. eads/nuts) wcement incl
h expanded oncrete ove
me availabltime of mu concretes aly weaker ansive materamic tiles.
Seismic
Buildings
tructed of 1that are sused for the
y of drying ed by insectcs, the respothe nail joinfter than thcomplemenation is thatng that joiiffness andd perpendic
bs
monolithic nforced withn round or o
As a resultwill have a luded expan
metal lath rer time has c
le throughouch URM as they werand should brial during t
c Assessment o
19-25 mm tupported by
floor diaphand be “loc
t infestationonse of thents. It shoulhose used tnted by “viet the responists and bo
d strength cular to the
to brick wh bars, as isof a roughnt, the presenmarked eff
nded metal
reinforcemecaused the
ut New Zeconstructioe produced be assessedthese times,
of Unreinforced
ISBN 978-
thick tonguy timber or hragm memcked up” fr
n or decay fse diaphragld be recogtoday. Resierendeel” acnse of timbeoards spanshould be orientation
walls and s commonlyess pattern
nce of termifect on the
lath (Figur
nt. Corrosioconcrete to
aland from n. Non-Porfrom only a
d with cautio, voids or ri
Masonry Buildi
10-0-473-26634
ue and groosteel beam
mbrane. Therom long ufrom moistugms during gnised that tstance comction from ter diaphragmn in differe
assessed fof the joists
form a rigy the case fthat provid
ination detaload carryire 10.11) a
on of the lato spall.
m the 1890s rtland cemea single firion. Similaribs were oft
ngs
0-26
4-9
ove ms. ese se. ure an
the mes the ms ent for s.
gid for des ails ing and
h
to ent ing rly, ten
SeUpd
N
Tainco
10
Thsasimannadididi N
Rm
ection 10 - Seismdated 22 April 2015
Note:
ake care wnvestigation onstituents p
R0.2.6.3
he roof struarking (Figumilar actionnd strengthaturally stifiagonal “truisplacementirect shearin
Note:
efer to Sectmore detail in
(a) Typ
mic Assessmen
when mak is essentialproperly if f
Roofs
ucture is uure 10.13) nn to floorin
h of the hiffer and struss” membt capacity wng of the fix
tion 10.8.3 n Section 1
pical horizon
Figure 1
t of Unreinforce
king assuml to understforces great
sually provnailed to pung, but boargh-friction ronger than
bers betweewill be less xings along
for the capa1.
ntal roof sar
10.12: Typic
ed Masonry Buil
mptions relatand the mater than nom
vided with urlins suppords are oftetongue an
n rectangulen the rafte
than for rethe lines of
acities of th
rking
cal timber di
Seismic As
ldings
ating to thkeup of the
minal are to
straight sarorted by timen square ednd groove ar sarking
ers and purectangular sf the boards
hese types o
(b) Roof
iaphragms –
ssessment of U
IS
he concrete original sla
be transferr
rking (Figumber trussesdges so do connection.because th
rlins. Howesarking as m.
of systems. T
f diaphragm
– straight sa
Unreinforced Ma
SBN 978-0-4
te strengthab construcred.
ure 10.12) os. Straight not have th
. Diagonal he boards pever, its dumovements
This is also
m with vertic
arking
asonry Buildings
10-27473-26634-9
h. Intrusivection and its
or diagonalsarking hashe stiffnesssarking is
provide theuctility ands will cause
o covered in
cal sarking
s
7
9
e s
l s s s e d e
n
Section 10 - SeUpdated 22 April 20
The strengmaterial. Cplaster, fibplywood b
10.2.7
URM buildcomponent Often, wal(Figure 10anchor pladiaphragmbuilding, thas a remed
Figure 10.
eismic Assessm015
Figur
gth of both Common tybrous plasteroards and p
Diaphra
dings are chts.
lls parallel t0.14), excepates, someti
ms to walls hey may ha
diation meas
.14: A lack oand re
ment of Unreinfo
re 10.13: Typ
floor and roypes of ceilr, steel lath-
plasterboard
agm sea
haracterised
to the joists pt in a few imes referrsince the la
ave been inssure.
of connectioeturn walls
orced Masonry B
pical timber
oof diaphraings that pr-and-plaster
d may have
ating and
d by absent o
and rafterscases depened to as roate 19th censtalled durin
on of the waleading to c
Seismic
Buildings
r diaphragm
agms is comrovide strucr, and pressalso occurre
d connec
or weak con
s are not tiending on thosettes or wntury (Figung the origin
alls parallel tcollapse of w
c Assessment o
s - diagonal
mplemented ctural capaced metal. Med over tim
ctions
nnections be
d to the floohe design arwashers, ha
ure 10.15). Inal construc
to joist and wall under f
of Unreinforced
ISBN 978-
l sarking
by the ceilcity are tim
More moderne.
etween vari
ors and roorchitect. Waave been usIf these arection or at a
rafters withace load
Masonry Buildi
10-0-473-26634
ling sheathimber lath-anrn additions
ious structu
of respectiveall-diaphragsed to secue present inany time sin
h diaphragm
ngs
0-28
4-9
ing nd-
of
ral
ely gm ure n a nce
ms
SeUpd
Evelbepo Amcath
(
ection 10 - Seismdated 22 April 2015
Figure 1
ven where wlements. Coeen observeockets.
Another commoisture tranannot be trahey can be e
a) Steel bea
(c) Flo
mic Assessmen
0.15: 1896 ico
walls are caonnections med (Figures
mmon featurnsfer from nsferred fro
effective in h
am to wall p
oor seating
Figure 10.1
t of Unreinforce
mage showonstruction
arrying beammade of ste 10.16 and
re is a gap brickwork
om walls to horizontal s
ocketed con
arrangemen
6: Typical c
ed Masonry Buil
wing anchor (National L
ms, joists oreel straps tyd 10.17), so
on either sk to timber
joists. Howshear transfe
nnection
nt
connection b
Seismic As
ldings
plate conneLibrary of Ne
r rafters, theing the bea
ometimes w
side of the tr. With sucwever, if thefer between
(b) Floopresenc
(d) Fish
between ma
ssessment of U
IS
ections instaew Zealand)
ey are not ams, joists o
with a fish-t
timber joistch connecti joists are sthe wall and
or joist to wace of steel s
h-tail conneand
asonry walls
Unreinforced Ma
SBN 978-0-4
alled in earl
always securor rafters to tail cast in
ts and beamions, horizoset tightly ind floor struc
all connectiostrap (Matt W
ection betwejoist
s and joist
asonry Buildings
10-29473-26634-9
y URM
red to thesewalls have
to concrete
ms to avoidontal shearn the pocketcture.
on. Note Williams)
een wall
s
9
9
e e e
d r t
Section 10 - SeUpdated 22 April 20
(a
(c) W
10.2.8
In most ctogether. Cpossible thmay just bhave very l
10.2.9
Most traditfoundationthick bitum The DPC surroundinbond for fahas been re
eismic Assessm015
a) Wall to ro(Miyamo
Wall to roof t
Wall to
ases, there Concrete bahat they webe with intelittle tie or s
Damp-p
tional buildns and grounmen or bitum
layer usualng masonry ace loading ecorded, as
ment of Unreinfo
oof truss conoto Internatio
truss conne
Figure 10.
wall con
are no mands may beere built by ermittent steshear capac
proof co
dings incorpnd floor lev
men fabric.
lly forms afor slidingor hold-dowshown in F
orced Masonry B
nnection onal)
ection. Note (Miyamoto I
17: Typical
nnection
mechanical ce provided bdifferent te
eel ties, or ity.
ourse (DP
porate a damvel. This ca
a slip plane. It also forwn of wallsigure 10.18
Seismic
Buildings
(
truss is seaInternationa
wall to roof
ns
connectionsbut may noeams at difbricks pock
PC)
mp-proof coan be made
e (Figure 1rms a horizos for in-plan8(b).
c Assessment o
(b) Roof seaparapet w
ated on a coal)
f connection
s provided ot be tied tofferent stageketed into t
ourse (DPC)e from galva
0.18(a)) whontal disconne loading. S
of Unreinforced
ISBN 978-
ating arrangewall (Dymtro
oncrete pad
ns
to tie orthogether at coes. If they athe abutting
) in the masanised meta
hich is weantinuity whiSliding on t
Masonry Buildi
10-0-473-26634
ement and
o Dizhur)
stone
hogonal waorners as itare jointed,g walls whi
sonry betweal, lead, sla
aker than thich can affethe DPC lay
ngs
0-30
4-9
alls t is , it ich
een ate,
the ect yer
SeUpd
Cw
1
M
ection 10 - Seismdated 22 April 2015
onsiderationwall: refer to
(a) DPC be
B0.2.10
Most traditio
fixing of
plates sup
forming h
top plates
Figu
mic Assessmen
n of the DP Section 10
elow timber Welling
Built-in t
nal URM b
linings, skir
pporting int
header conn
s for affixin
ure 10.19: 12
t of Unreinforce
PC layer is.8.6 for deta
– Chest Hogton
Figure 1
imber
uildings inc
rting, cornic
ermediate f
nections betw
ng rafters or
2 mm timbe
ed Masonry Buil
s an importails.
ospital,
0.18: Comm
corporate bu
ces and dad
floor joists
tween wall l
trusses.
r built into e
Seismic As
ldings
tant part of
(b) BitumC
mon DPC ma
uilt-in timbe
do/picture ra
layers, and
every eighth
ssessment of U
IS
f establishin
en DPC andCook Strait e
aterials
ers (Figure
ails
h course for
Unreinforced Ma
SBN 978-0-4
ng the capa
d sliding eviearthquakes
10.19) for:
r fixing linin
asonry Buildings
10-31473-26634-9
acity of the
dent after s
gs
s
9
e
Section 10 - SeUpdated 22 April 20
DegradatioThis will tyTimber alsin full conengagemenwalls.
10.2.11
Bond beamconcrete, performanc
providiprovidi
distribu
tying wbeam is
providi
providi
providi Dependingreinforced should be a– so care sh
(a)
eismic Assessm015
on of these iypically be so shrinks, pntact with tnt with the
Bond b
ms or perimplain concce of mason
ing a largering better lo
uting diaphr
wythes toges laid over b
ing coupling
ing longitud
ing out-of-p
g on the ageconcrete bo
avoided. Stihould be tak
) Bond beam
ment of Unreinfo
items is commore sever
particularly the surrounmasonry is
beams
eter tie beamcrete or tinry building
r, often strooad distribu
ragm loads
ether in cavboth wythes
g between w
dinal tying t
plane stabili
e of the struond beams,irrup reinfoken when sh
m in cavity w
orced Masonry B
mmon, whicre on the sou
perpendicunding masos often limit
ms (Figure imber. Thegs, including
onger substrtion
along the le
vity construs
wall panels
to spandrel b
ity to face-lo
ucture, there, so concentorcement in hear loads a
wall also for(Dunning
Seismic
Buildings
ch causes louth side of bular to the gonry. In theted to local
10.20) wereey can prog:
trate for the
ength of a w
uction (Figu
for in-plane
beams, and
oaded walls
e may be potrated loadsthese beam
are being ap
rming lintel –g Thornton)
c Assessment o
ocalised strebuildings or
grain, and sue case of colised timber
e typically covide sign
e attachmen
wall
ure 10.20),
e loads
d
s.
oor/no hooks near the e
ms is often npplied to the
– Chest Hos)
of Unreinforced
ISBN 978-
esses or bowr nearer the uch timbersontinuous tr blocks not
constructednificant ben
nt of fixings
provided t
k or terminatends of suchnominal – ifese element
spital, Wellin
Masonry Buildi
10-0-473-26634
wing of wal ground lev
s are often ntimber plattched into t
d of reinforcnefits to t
s and there
that the bo
ation detailsh bond beamf present at ts.
ngton
ngs
0-32
4-9
lls. vel. not es, the
ced the
eby
ond
in ms all
SeUpd
ThFi ThcaW
1
Bin
ection 10 - Seismdated 22 April 2015
he presencigure 10.21
he reinforcarbonation/c
When severe
Figure 10
B0.2.12
ed-joint reinclude:
single wir
single wicourses
prefabrica
mic Assessmen
ce of a coshows a co
cement in chloride att, this will sp
0.21: The wi
Bed-joint
inforcement
res or pairs
ires or pairs
ated/welded
t of Unreinforce
(b) Ty
Fig
ncrete banoncrete capp
the beam ack has penplit the conc
ide cracks t
t reinfor
t (course r
of wires lai
s of wires l
d lattices lai
ed Masonry Buil
ypical lintel
gure 10.20: B
nd providesping beam th
may also netrated intcrete.
hrough bonin the beam
rcement
reinforceme
id in mortar
laid in mort
id in multi-w
Seismic As
ldings
detail (Dizh
Bond beams
s no suretyhat is obvio
have degrto the conc
nd beams inm (Dizhur)
ent) varies
r courses to
tar courses
wythe walls
ssessment of U
IS
hur)
s
y that reinously not rei
raded or mrete to the
dicate a lac
in type an
augment in
to act as li
s to ensure b
Unreinforced Ma
SBN 978-0-4
nforcement inforced.
may soon depth of re
ck of reinforc
nd applicat
n-plane perf
intels or tie
bond
asonry Buildings
10-33473-26634-9
is present.
degrade ifeinforcing).
cement
ion. It can
formance
s to soldier
s
3
9
.
f .
n
r
Section 10 - SeUpdated 22 April 20
prefabr
cast iro
chicken Bed-joint rrobustness This type orequiremenspecificatio
10.2.13
Lintels com
reinfor
reinforsupport
steel an
steel fla
timber
soldier
stone li Arches or walls in plbuilding. Reinforcedeffectivelysupports anare also usufficiently
10.2.14
Parapets aroff centre attached toexternal farocking can Note:
Parapets, cpresent a Employmethese must Partition wdiaphragm
eismic Assessm015
ricated/weld
on oversize
n mesh.
reinforcemebut usually
of reinforcent for bedons.
Lintels
mmonly com
ced concret
ced concretted on cavit
ngles
ats (shorter
piece
course arch
intels.
flat arches lane. This t
d concrete y reinforce nd, if such
useful compy high) as th
Second
re commonfrom the wo the streetace just abon occur.
chimneys, psignificant
ent has issuet be included
walls are otm and can po
ment of Unreinfo
ded lattices
cavity ties l
ent is ofteny does not a
ement is nod joint rein
mprise:
te beams the
te beams bety ties or a s
spans)
hes or flat a
add a permthrust along
beams cathe spandframes dila
ponents forhey provide
dary com
nly placed oall beneath,t side. Roo
ove roof lev
pediments, hazard to
ed a determd in the seis
ther secondose a serious
orced Masonry B
laid across
laid in mult
n small in sdd significa
t usually apnforcement
e full width
ehind a decsteel angle
arches, and
manent outwg with any
an contribudrel. Howevate, can be r attachmene a robust, b
mponent
on top of th, and cappinof flashingsvel, creating
cornices anthe public
mination (20smic assessm
dary elemens threat to li
Seismic
Buildings
cavity wall
ti-wythe wa
size relativant structura
pparent fromwas often
h of the wall
corative fac
ward thrust other force
ute to in-pver, they cpoints of o
nts for diapblocky elem
ts
he perimeterng stones os are often g a potentia
nd signage c. The Min12/043) clament rating
nts which ife safety.
c Assessment o
ls to form ca
alls to ensure
ve to a fairlal strength.
m a visual in noted in
l
cing course,
to a buildines should b
plane pier/wconcentrate overloadingphragms (ifent to conne
r walls. Ther other ornachased int
al weak poin
(Figure 10nistry of Barifying thatg of a buildin
are usually
of Unreinforced
ISBN 978-
avity ties
e bond, and
ly massive
inspection. n the origi
, with this
ng which cabe resisted b
wall behavbearing loor destabil
f the windoect to.
ey are usualamental featto the bricknt in the m
0.22) on strusiness, Inexternal ha
ng.
y not tied t
Masonry Buildi
10-0-473-26634
d
wall. It ad
However, tinal mason
facing cour
an destabiliby ties in t
viour as thoads at thlisation. Thow heads a
lly positionatures are thkwork on t
masonry whe
reet frontagnnovation aazards such
to the ceili
ngs
0-34
4-9
dds
the nry
rse
ise the
hey eir
hey are
ned hen the ere
ges and
as
ing
SeUpd
1
Mre(e Awbeglbe N
Badanas Amth Te
ection 10 - Seismdated 22 April 2015
S0.2.15
Many URM equirementse.g. followin
A number ofwere to tie u
earing struclobally as a e fully mobi
Note:
efore 2004ddition, in mnchors werssurance pro
Assessment measures thahe seismic p
echniques u
chimneysexternal s
parapets: bonded re
face-loadtensioninstrips, rehorizonta
mic Assessmen
Figure 1
Seismic
buildings hs (e.g. earthqng the 1942
f strengthenunrestrainedcture and to
box with thilised even
, seismic stmost strengtre mostly uocedures.
of previousat historicallperformance
used historic
s: internal strapping an
vertical steeinforcemen
ded walls: g, internal einforced
al and vertic
t of Unreinforce
10.22: Secon
strength
have been stquake-proneWairarapa
ing techniqd componentie various
he intentionthough it m
trengtheninthening projuntested, a
sly retrofittly have bee
e.
cally for str
post-tensiond bracing, r
eel mullionsnt, near surf
vertical stbonded reiconcrete o
cal reinforce
ed Masonry Buil
ndary eleme
hening m
trengthenede building learthquake
ques have bents, such asbuilding co
n that the avmay not alwa
ng requiremjects the ma
and they w
ted buildingen carried o
rengthening
oning and removal an
s, raking brface mounte
teel or timinforcementor cementied concrete
Seismic As
ldings
ents (Miyam
methods
d over the ylegislation) e).
een used (Iss chimneysomponents vailable lateays have be
ments for URaterial propewere install
gs requires out and the
different st
steel tube d replaceme
races, steel ed (NSM) c
mber mulliot, composititious overbands.
ssessment of U
IS
moto Internat
used to
years either or post-eart
smail, 2012and parap
together so eral capacityen increase
RM buildinerties were nled without
an understlikely effec
tructural me
reinforcement
capping, pocomposite st
ons, horizoe fibre overlay, grout
Unreinforced Ma
SBN 978-0-4
tional)
o date
because ofthquake rec
2). The mainets, to the the buildiny of the buied.
ngs were venot verifiedt document
tanding of ct these wou
echanisms in
ment, concr
ost-tensionintrips
ontal transerlay, NSMt saturatio
asonry Buildings
10-35473-26634-9
f legislativeconstruction
n principlesmain load-
ng could actlding could
ery low. Ind by testing,ted quality
the retrofituld have on
nclude:
rete filling,
ng, internal
oms, post-M compositeon/injection,
s
5
9
e n
s -t d
n ,
y
t n
,
l
-e ,
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-36
Updated 22 April 2015 ISBN 978-0-473-26634-9
wall-diaphragm connections: steel angle or timber joist/ribbon plate with either grouted bars or bolts/external plate, blocking between joists notched into masonry, external pinning to timber beam end or to concrete beam or floor, through rods with external plates, new isolated padstones, new bond beams
diaphragm strengthening: plywood overlay floor or roof sarking, plywood ceiling, plywood/light gauge steel composite, plasterboard ceiling, thin concrete overlay/topping, elastic cross bracing, semi-ductile cross bracing (e.g. Proving ring), replacement floor over/below with new diaphragm
in-plane wall strengthening/ new primary strengthening elements: sprayed concrete overlay, vertical post-tensioning, internal horizontal reinforcement or external horizontal post-tensioning, bed-joint reinforcement, composite reinforced concrete boundary or local reinforcement elements, composite FRP boundary or local reinforcement elements, nominally ductile concrete walls or punched wall/frame or reinforced concrete masonry walls, nominally ductile steel concentric or cross bracing, limited ductility steel moment frame or concrete frame or concrete walls or timber walls, ductile eccentrically braced frame/K-frames, ductile concrete coupled or rocking walls, or tie to new adjacent (new) structure
reinforcement at wall intersections in plan: removal and rebuilding of bricks with inter-bonding, bed-joint ties, drilled and grouted ties, metalwork reinforcing internal corner, grouting of crack
foundation strengthening: mass underpinning, grout injection, concentric/balanced re-piling, eccentric re-piling with foundation beams, mini piling/ground anchors
façade wythe ties: helical steel mechanical engagement – small diameter, steel mechanical engagement – medium diameter, epoxied steel rods/gauze sleeve, epoxied composite/non-metallic rods, brick header strengthening
canopies: reinforce or recast existing hanger embedment, new steel/cast iron posts, new cantilevered beams, deck reinforcement to mitigate overhead hazard, conversion to accessible balcony, base isolation.
Figures 10.23 to 10.27 illustrate some of these techniques. A detailed table (Table 10.2) is included in Section 10.6.11. This table lists common strengthening techniques and particular features or issues to check for each method.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-37
Updated 22 April 2015 ISBN 978-0-473-26634-9
Figure 10.23: Bracing of wall against face load (Dunning Thornton)
(a) Bent adhesive anchor
(b) Through anchor with end plate (plate anchor)
Figure 10.24: Wall-diaphragm connections (Ismail, 2012)
Section 10 - SeUpdated 22 April 20
(a) C
eismic Assessm015
Figure 10
Concentric s
(c) FR
Figu
ment of Unreinfo
0.25: New pl
steel frame
P overlay
ure 10.26: Im
orced Masonry B
ywood diap
(Beca)
mproving in
Seismic
Buildings
phragm (Hol
(d) S
n-plane capa
c Assessment o
mes Consu
(b) Steel
Steel frame
acity of URM
of Unreinforced
ISBN 978-
lting Group
frame (Dizh
(Dunning T
M walls
Masonry Buildi
10-0-473-26634
p)
hur)
Thornton)
ngs
0-38
4-9
SeUpd
Sttimlash N
Wbepa
1
1
Wpoco Thheenpe Thanco Hprla
ection 10 - Seismdated 22 April 2015
trengtheningmber roof s
ack of vertihaking, or th
Note:
When strengtelow and barapet still f
O0.3
G0.3.1
When assessotential seiomponents.
he most haeight, such and walls. Teople in a zo
he next mond return wollapse, they
However, whrevented, thateral force a
mic Assessmen
g of parapestructure (reical tie-dowhe flexibility
thening parback into thfails, but co
Figure 1
Observe
General
ing and retrismic defic
zardous of as street-fachese are usone extendi
st critical ewalls. Even y could pos
hen buildinghe building waction.
t of Unreinforce
ets is oftenefer to Figu
wn to county of the roo
rapets, it is he structurellapses in la
10.27: Parapof the
ed Seis
rofitting exciencies an
these deficcing façadessually the fiing well out
lements arethough the
e a severe th
g componenwill act as a
ed Masonry Buil
n done usinure 10.27). ter the vert
of amplifyin
essential toe. The dangarger, more
pet bracing.e parapet (D
smic Be
xisting URMnd failure
ciencies ares, unrestrain
first elementside the bui
e face-loadeeir failure mhreat to life
nts are tied a complete e
Seismic As
ldings
ng racking bHowever, itical force ng shaking o
o make a robger of nondangerous
Note a lackDmytro Dizh
ehaviou
M buildingshierarchy
inadequatened parapet
nts to fail inilding perim
ed walls andmay not lee safety.
together anentity and in
ssessment of U
IS
braces, withissues with component
of the parap
bust connec-robust strepieces.
k of vertical hur)
r of UR
it is imporof these
ely restraines, chimneys
n an earthqumeter.
d their connad to the b
nd out-of-pln-plane elem
Unreinforced Ma
SBN 978-0-4
th one end this metho
t of brace apet.
ction down engthening
.
tie-up
RM Build
rtant to undbuildings
ed elementss, ornamentuake and ar
nections to dbuilding’s c
lane failurements will c
asonry Buildings
10-39473-26634-9
tied to thed include aand ground
to the wallis that the
dings
derstand theand their
s located atts and gablere a risk to
diaphragmscatastrophic
of walls iscome under
s
9
9
e a d
l e
e r
t e o
s c
s r
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-40
Updated 22 April 2015 ISBN 978-0-473-26634-9
Failures of URM buildings (summarised in Figure 10.28) can be broadly categorised as:
local failures – these include the toppling of parapets, walls not carrying joists or beams under face load, and materials falling from damaged in-plane walls. These local failures could cause significant life-safety hazards, although buildings may still survive these failures.
global failures – these include failure modes leading to total collapse of a building due to such factors as loss of load path and deficient configuration.
Figure 10.28: Failure modes of URM buildings
In URM buildings, in-plane demands on walls decrease up the height of the walls. In-plane capacity also decreases with height as the vertical load decreases. In contrast, out-of-plane demands are greatest at the upper level of walls (Figure 10.29), but out-of plane capacity is lowest in these areas due to a lack of vertical load on them. Hence, the toppling of walls starts from the top unless these are tied to the diaphragm.
Figure 10.29: Out-of-plane vibration of masonry walls are most pronounced at the top floor
level (adapted from Tomazevic, 1999)
SeUpd
1
Buacthbede Buthinac TathIn(Ftra Ais onou“birrsh
ection 10 - Seismdated 22 April 2015
B0.3.2
uilding conct as stiff stheir parts. Cetween flooepending on
uildings whhan the wallnitiates fromccelerations
aller buildinhe confinemn larger buiFigure 10.46ansmit forc
As with all sgenerally m
n street cornuter points. buttressing”regularity inhop front.
Figure 10
mic Assessmen
Building
nfiguration ttructures, at
Collapse of wors and abun the angle o
here the spals tend to ham the mids are necessa
ngs exhibit ment of theildings, the 6). This resues up the bu
structures, thmore predicners (especi
Shop front” from adjacn which stif
0.30: Reduc
t of Unreinforce
configu
tends to dicttracting higwalls under utting wallsof loading a
an or flexibave more did-span of arily as high
less damage masonry
weaker elults in periouilding.
he behaviouctable. Builially with ants similarlycent buildinff façades t
tion of dam
ed Masonry Buil
uration
ctate the natgh acceleratr face load as respectivand the wall
bility of theisplacementthe diaphrh).
ge at low levfrom the w
lements (usod lengthen
ur of URM ldings with n acute ang
y experiencengs in a “rowtend to mov
age towards(Dunning T
Seismic As
ldings
ure of URMtions and thas they try tely tends tl configurat
e diaphragmt-related fai
ragm where
vels than shweight abovsually spaning of the s
buildings wirregular p
le corner), se high driftw” effect. Tve as a solid
s base of buThornton)
ssessment of U
IS
M failures. Cherefore forto span vertito be indeption.
m is an ordilures. Walle movemen
horter buildive providesdrels) fail tructure and
with a moreplan configusuffer high s, but these
This effect ald element ab
uilding as ax
Unreinforced Ma
SBN 978-0-4
Cellular typrce-governetically and hpendent for
der of magnls and parapnts are gr
ings (Figures significanfirst from
d reduces th
e regular courations, sudisplacemee are often
also disguisebove the fle
xial load inc
asonry Buildings
10-41473-26634-9
pe buildingsd failure of
horizontallyr each cell,
nitude morepet collapsereatest (but
e 10.30), asnt strength.bottom up
he ability to
onfigurationch as those
ents on theirmasked by
es a verticalexible open
creases
s
9
s f y ,
e e t
s .
p o
n e r y l n
Section 10 - SeUpdated 22 April 20
10.3.3
The timbermay resultlarge displfail (Figure
Figure
Figure 10.wall and ce
Figure 10
In some cathe diaphra
10.3.4
10.3.4.1
The follow(Campbell Canterbury
punchin
yield o
rupture
eismic Assessm015
Diaphra
r diaphragmt in large dlacement dee 10.31).
e 10.31: Out
32 shows aeiling due to
0.32: Lath anthe wall h
ases, diaphragm (Tena-C
Connec
General
wing types et al, 20
y earthquak
ng shear fai
r rupture of
e at join betw
ment of Unreinfo
agms
ms commondiaphragm emand on th
t-of-plane w
a photograpo shear tran
nd plaster chave caused
ragm and shColunga &
ctions
l
of damag12) – the e sequence:
ilure of mas
f connector
ween conne
orced Masonry B
nly used in displacemehe adjoining
wall failure d(Dizhur
ph of delamnsfer.
eiling. Noted the plaster
hear-wall acAbrams, 19
e to wall-dfirst four
:
sonry
rod
ector rod an
Seismic
Buildings
URM builents during g face-load
ue to exceset al, 2011)
mination of
e that stressr to delamin
ccelerations996).
diaphragm were actua
nd joist plate
c Assessment o
ldings are gan earthqu
ded walls, w
ssive roof di
f plaster due
es where shate from the
s can increa
connectionally observ
e
of Unreinforced
ISBN 978-
generally fleuake. Thesewhich could
aphragm m
e to interac
hears are trae timber lath
ase with the
ns have beeved during
Masonry Buildi
10-0-473-26634
exible, whie will impod lead them
ovement
ction betwe
ansmitted toh.
e flexibility
en postulatthe 2010/
ngs
0-42
4-9
ich ose
to
een
o
of
ted /11
SeUpd
10
Cseinofsopibo Wnehadi
10
Faw(Fjo
ection 10 - Seismdated 22 April 2015
splitting o
failure of
splitting o
yield or ru
W0.3.4.2
onnections eparation) ancompatibilif a wall anoftening of tiers. The inonding betw
While return ecessarily cave adequaiaphragm tie
(a) Vertic
W0.3.4.3
ailure of rwas commonFigure 10.34oints in a ma
mic Assessmen
of joist or st
f fixing at jo
or fracture o
upture at th
Wall to wa
between thafter a fewity between
nd pier assethe buildingntegrity of
ween orthog
wall separaconstitute siate out-of-pes.
cal cracks (D
Figure 10.3
Wall to flo
rosettes, rupnly observe4). This faianner that tr
t of Unreinforce
tringer
oist
of anchor pl
hreaded nut.
all conne
he face-loadw initial cyn stiff in-plaembly workg, resulting
connectiongonal walls.
ation can caignificant splane capa
Dmytro Dizh
33: Damage
oor/wall t
pture of aed followiilure mode races a failu
ed Masonry Buil
late
ections
ded and retuycles of shane and flexking in plain a change
n between
ause significstructural dacity to sp
hur) (b
e to in-plane
to roof c
anchor barsing the 2is characte
ure surface
Seismic As
ldings
urn walls whaking (Figxible face-loane. This lee in dynamwall at jun
cant damagedamage. Thipan vertical
b) Corner ve
e and face-lo
onnectio
s and punc2010/11 Carised by faaround the
ssessment of U
IS
will open (i.gure 10.33) oaded wallseads to lossic characternctions and
e to the builis is providlly and the
ertical splittkeyed in t
oaded wall ju
ons
ching shearanterbury ilure of theperimeter o
Unreinforced Ma
SBN 978-0-4
.e. there is ) because os and a natus of flange ristics of thd corners d
lding fabricded the wa
here are en
ting where wtogether
unctions
r failure oearthquake
e mortar beof the ancho
asonry Buildings
10-43473-26634-9
return wallof stiffnessural dilation
effect ande walls anddepends on
c it does notall elementsnough wall
walls poorly
of the walle sequenced and head
or plate. For
s
3
9
l s n d d n
t s l
y
l e d r
Section 10 - SeUpdated 22 April 20
multi-wythshear failucover a bro
Figur
Testing at may exhibexamples)
(a
Figu
(a) Samwhere pr
eismic Assessm015
he walls theure, it is posoader area.
re 10.34: Pla
the Universbit a varietyso their con
a) Location
ure 10.35: W
ple 1-02: Fareviously ne
ment of Unreinfo
e head jointssible that t
ate anchor o
sity of Aucky of differendition shou
of failure m
Wall-diaphrag
ailure ecked
orced Masonry B
s will not bthe failure s
on verge of
kland (Cament failure uld be consi
modes
gm anchor p
(b) Samplfailure of
Seismic
Buildings
be in alignmsurface on t
punching s
mpbell et al.,modes (ref
idered caref
(b
plate failure
le 2-01: Brittanchor plat
c Assessment o
ment and, asthe interior
hear failure
2012) has fer to Figufully.
b) Componea
modes (Ca
tle te
(fail
w
of Unreinforced
ISBN 978-
s for a concrsurface of
(Dizhur et a
shown that ures 10.35 a
ents of the cassembly
mpbell et al
c) Sample 2ure where cwas fixed to
Masonry Buildi
10-0-473-26634
rete punchithe wall m
al, 2011)
anchor platand 10.36 f
connection
l., 2012)
2-02: Brittle connector roo joist plate
ngs
0-44
4-9
ing may
tes for
od
SeUpd
(
ATheiof(F
1
OmThpe
ection 10 - Seismdated 22 April 2015
(d) Sample 3previou
Figure 10
Adhesive anhese typicalither grout of failed adhFigure 10.37
Their use(such as obrick woreven if th
Incorrect where theoperationanchorag
Anchors joint sheconnected
W0.3.5
ut-of-plane masonry buil
he seismic performance
mic Assessmen
3: Failure whusly necked
0.36: Observ
nchorages lly involve or epoxy a
hesive anch7). Reasons
e in regionson the rear rk was likel
he adhesive
installatione drilled ho
n so there we was of ins
that were aear around d to the anc
Figure 10.
Walls su
wall collapldings, partiperformancof wall-dia
t of Unreinforce
here (
ved failure m
have beena threaded
adhesive. Uhorages foll
for this inc
s expected surface of a
ly to crack ihad been pl
n – exampole had not bwas inadequsufficient le
adequately sits perimehorage, wh
37: Failed a
bjected
pse under ficularly whe of the URaphragm co
ed Masonry Buil
(e) Sample 4threaded
modes from
n a populd rod bein
Unfortunatellowing the
clude:
to be loadea parapet thin the vicinlaced effect
les includebeen suffic
quate bond ength.
set into a breter. As a hile the rema
adhesive bri
to face l
face load isen a timber
RM face-loaonnections
Seismic As
ldings
4: Failure at d region
m tensile test
ar form og chemically, there hae 2010/11 C
ed in flexuhat may topnity of the atively.
ed cases of iently clearto the bric
rick but theresult, only
ainder of the
ck anchors
loads
s one of thr floor and raded walls dand the wa
ssessment of U
IS
(f) S
t series (Cam
of anchorally set intoave been nCanterbury
ral tension pple forwardnchorages a
f insufficienred of brick k surface,
e secured bry the indive brickwork
(Dizhur et a
he major cauroof are supdepends on tall-wall con
Unreinforced Ma
SBN 978-0-4
Sample 6: Fthreaded re
mpbell et al
age for mo a drilled numerous o
earthquake
during an d onto the sand cause th
nt or absenk dust from
or where t
rick had faividual brick had failed
al., 2013)
auses of despported by tthe type of
nnection. Fi
asonry Buildings
10-45473-26634-9
Failure at egion
., 2012)
any years.hole usingbservationse sequence
earthquakestreet) – thehem to fail,
nt adhesive,the drilling
the inserted
iled in bed-ck was left.
struction ofthese walls.diaphragm,igure 10.38
s
5
9
. g s e
e e ,
, g d
-t
f . , 8
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-46
Updated 22 April 2015 ISBN 978-0-473-26634-9
illustrates the response of face-loaded walls to the type of diaphragm and wall-diaphragm connections.
Figure 10.38: Effect of types of diaphragm on face-loaded walls – a) inferior wall-to-wall
connection and no diaphragm, b) good wall-to-wall connection and ring beam with flexible diaphragm, c) good wall-to-wall connection and rigid diaphragm
Figures 10.39 and 10.40 show images of damage to masonry buildings due to collapse of walls under face load.
Figure 10.39: Out-of-plane instability of wall under face load due to a lack of ties between
the face-loaded wall and rest of the structure (Richard Sharpe)
Gable end walls sit at the top of walls at the end of buildings with pitched roofs. If this triangular portion of the wall is not adequately attached to the roof or ceiling, it will rock as a free cantilever (similar to a chimney or parapet) so is vulnerable to collapse. This is one of the common types of out-of-plane failure of gable walls (Figure 10.40).
SeUpd
Cdadupefo
Thshdejo Infloea
ection 10 - Seismdated 22 April 2015
Figure 10.4loading and
avity wall camage and muring the erformance orces.
he veneers haking (Figueteriorated coints due to
n multi-storeoor level. Tarthquake sh
mic Assessmen
40: Collapsed a compan
constructionmajor colla2010/2011 was signifi
Fig
of cavity wure 10.41). condition oweak morta
ey buildingThis is due thaking there
t of Unreinforce
e of gable waion failed ga
n can be paapse of URM
Canterburicantly wor
gure 10.41: F
wall construcToppling isf the ties, o
ar, or a total
gs the out-ofto the lack oe (Figure 10
ed Masonry Buil
all. Note a sable end tha
articularly vM buildingsry earthquarse than soli
Failure of UR
ction also hs typically aoverly flexibl absence of
f-plane collof overburd0.29).
Seismic As
ldings
secured gabat was not s
vulnerable ts with this take inspectid URM co
RM cavity w
ave the poteattributed toble ties, pulf ties.
lapse of waden load on
ssessment of U
IS
ble end that ssecured (Ing
to face-loadype of constions (Figunstruction i
walls (Dizhur
ential to topo the walls’ ll-out of tie
lls is more the walls an
Unreinforced Ma
SBN 978-0-4
survived ea
gham & Griff
ding. Severstruction waure 10.41) in resisting
r)
pple during high slende
es from the
pronouncednd amplific
asonry Buildings
10-47473-26634-9
arthquake fith, 2011)
re structuralas observed
and theirearthquake
earthquakeerness ratio,mortar bed
d at the topation of the
s
7
9
l d r e
e ,
d
p e
Section 10 - SeUpdated 22 April 20
10.3.6
Damage tois less signelements inof distress principallydimensions In general,These modstraining. Fthe wall is Masonry wbetween o(spandrel mpiers may combinatiounit crackiunpenetrat
eismic Assessm015
Walls s
o URM walnificant thann URM (wain individu
y, because s. Neverthe
, the preferrdes have thFor exampleunlikely to
walls are eiopenings plmasonry). Wdemonstraton of these.ing or jointed and pene
Figure
ment of Unreinfo
subjected
ls due to inn damage dalls, piers anual elements
the spectrless, some f
red failure mhe capacity e, sliding dibecome un
ther unpenelus a portioWhen subjee diagonal t Similarly, t sliding. Fetrated wall
10.42: In-pla
orced Masonry B
d to in-p
n-plane seismdue to out-ond spandrelss than the sral displacefailure mod
modes are rto sustain hisplacement
nstable due t
etrated or pon below oected to in-tension cracthe spandre
Figure 10.42ls.
ane failure m
Seismic
Buildings
plane loa
mic effects of-plane seiss) usually mskeletal struements are des are less a
rocking or high levels ts at the basto the shear
penetrated. openings (s-plane earthcking, rockiels may dem2 shows th
modes of UR
c Assessment o
ads
(in the diresmic effects
make these suctures of m
small comacceptable t
sliding of wof resistan
se of a wall r displaceme
A penetratesill masonrhquake shaking, toe cru
monstrate dihe potential
RM wall (FE
of Unreinforced
ISBN 978-
ection of thes. In additiostructures m
modern frammpared to than others.
walls or indnce during l
can be toleents.
ed wall conry) and aboking, masonushing, slidiniagonal tens
failure me
EMA, 1998)
Masonry Buildi
10-0-473-26634
e wall lengton, the stoc
more forgivimed building
the memb
dividual pielarge inelaserated becau
nsists of pieove openinnry walls aing shear, orsion crackinechanisms f
ngs
0-48
4-9
th) ky
ing gs; ber
ers. stic use
ers ngs and r a ng, for
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-49
Updated 22 April 2015 ISBN 978-0-473-26634-9
Rocking of URM piers may result in the crushing of pier end zones and, under sustained cyclic loading, bricks could delaminate if the mortar is weak. An example of this is shown in Figure 10.43, where the damage to the building is characterised by the rotation of entire piers.
Figure 10.43: Rocking and delamination of bricks of a one-storey unreinforced brick
masonry building with reinforced concrete roof slab (Bothara & Hiçyılmaz, 2008)
Sliding shear can occur along a distinctly defined mortar course (Figure 10.44(a)) or over a limited length of several adjacent courses, with the length that slides increasing with height (Figure 10.44(b)). This can often be mistaken for diagonal tension failure, which is less common in walls with moderate to low axial forces.
(a) Sliding shear failure along a defined plane at first floor level (Dunning Thornton)
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-50
Updated 22 April 2015 ISBN 978-0-473-26634-9
(b) Stair-step crack sliding, in walls with low axial loads (Bothara)
Figure 10.44: Sliding shear failure in a brick masonry building
Alternatively, masonry piers subjected to shear forces can experience diagonal tension cracking, also known as X-cracking (Figure 10.45). Diagonal cracks develop when tensile stresses in the pier exceed the masonry tensile strength, which is inherently very low. This type of damage is typically observed in long and squat piers and on the bottom storey of buildings, where gravity loads are relatively large and the mortar is excessively strong.
(a) Diagonal tension cracks to a brick pier. Note splitting of bricks (Dizhur)
SeUpd
(
Incaa indesp A(F
ection 10 - Seismdated 22 April 2015
(b) Diagona
n the penetratastrophic dreduction
ncrease in demands whipandrels, an
As noted inFigure 10.18
Figure 10.4
mic Assessmen
al tension cr
rated walls,damage (Fiin the over
deflection wich may be
nd the result
n Section 8).
46: Failure o
t of Unreinforce
racks to bricstronge
Figure 10
, where spaigure 10.46)rall wall c
will increasea mitigatin
ting effect o
10.2.9, sl
of spandrelsof the
ed Masonry Buil
ck masonry.er than bric
0.45: Diagon
andrels are ). This coulapacity and
e the fundamng effect. In on life safety
liding on
s. Also note e parapet (D
Seismic As
ldings
. Note splittiks (Russell
nal tension c
weaker thald turn squad an increamental perioany event t
y needs to b
the DPC
rocking of uDmytro Dizh
ssessment of U
IS
ing of bricks2010)
cracking
an piers, theat piers intoase in expeod of the buthe consequ
be considere
layer has
upper piers hur)
Unreinforced Ma
SBN 978-0-4
s, indicative
he spandrel o tall piers, ected deflecuilding anduences of faed.
also been
and corner
asonry Buildings
10-51473-26634-9
e of mortar
may sufferresulting inctions. The
d reduce theailure of the
n observed
r cracking
s
9
r n e e e
d
Section 10 - SeUpdated 22 April 20
10.3.7
The instabcantileverschimneys (Ismail, 20
Bracingwhere t
Ties tydeficien
Strengtstrength
Spacin
High v
Lack o
(a) Out-of
Canopies c
They aedge ddiagonconnec
Howevproppefalling
eismic Assessm015
Second
bility of pars. which c
and para012). Possib
g to the roothe roof stru
ying the parnt.
thening stahen URM b
g between l
vertical acce
f deformati
f-plane insta
can be both
are often hudo not obstral hangers
ction point.
ver, if they ed, they can
objects.
ment of Unreinfo
dary com
rapets and can topple apets also ble reasons i
of caused coucture was f
rapets to th
andards webuildings to
lateral supp
elerations.
on compatib
ability of par
Figure 10.4
beneficial a
ung off the ruct the fooact to pry th
are sufficiprovide ov
orced Masonry B
mponent
chimneys iwhen sufffailed du
include:
oupling withflexible.
he wall belo
ere low (utwo thirds
ort points to
bility betwe
rapet (Beca)
47: Seconda
and detrime
face of theotpath or rohe outer lay
iently robusverhead prot
Seismic
Buildings
ts/eleme
is caused bfficiently acuring the
h the vertica
ow the diap
until 2004 of NZSS 19
oo large.
een support
) (b) C
ary compone
ental in relat
e buildingsoadway. Wyers of bric
st in their tection by ta
c Assessment o
nts
y these eleccelerated Canterbury
al response m
phragm lev
the gener900 (Chapte
points (Fig
himney at o
ents/elemen
tion to life s
s so columnhen subject
ck off the fa
decking anaking at lea
of Unreinforced
ISBN 978-
ments actin(Figure 10
y earthqua
modes of th
vel did not
ral requiremer 8), 1965)
gure 10.47(b
onset of falli
nts
safety (Figu
ns supportint to verticalace of the b
nd fixings oast the first i
Masonry Buildi
10-0-473-26634
ng as rocki0.47). Bracake sequen
he roof truss
exist or we
ment was ).
b)).
ng ( Dizhur)
ure 10.48):
ng their oual loads, thebuilding at t
or if they aimpact of a
ngs
0-52
4-9
ing ced nce
ses
ere
to
)
ter ese the
are any
SeUpd
1
ThwwU(F
Ththcl
ection 10 - Seismdated 22 April 2015
Figure 10downw
P0.3.8
his failure where there iwhen vibratiURM buildinFigure 10.49
he magnitudhe differenclearance of s
mic Assessmen
0.48: Face-loward force on
Pounding
mechanismis insufficieing laterallyngs were o9).
de of pounde in stiffnesstructural se
t of Unreinforce
oad failure on canopy. N
g
m only occuent space bey during anobserved fo
Figure 1
ding dependss between eparation be
ed Masonry Buil
of URM façaNote the adja
(Dunning T
urs in row-etween adjan earthquakollowing the
10.49: Pound
ds upon thethe buildin
etween adja
Seismic As
ldings
de exacerbaacent proppThornton)
-type constacent buildinke. Many exe 2010/11
ding failure
floor alignngs, the pouacent buildin
ssessment of U
IS
ated by outwped canopy
ruction (refngs so they xamples ofCanterbury
(Cole)
nment betweunding surfangs if separ
Unreinforced Ma
SBN 978-0-4
ward loadindid not coll
fer to Sectpound into
f pounding y earthquak
een adjacenace, floor wration is pro
asonry Buildings
10-53473-26634-9
gs from apse.
ion 10.5.4)o each other
damage toke sequence
nt buildings,weights, andovided.
s
3
9
) r o e
, d
Section 10 - SeUpdated 22 April 20
10.3.9
Foundationdifferentialso they spdisplacemespreading, reached.
(a) L
Figure 10.5
10.4
10.4.1
The strengand the dumoderate building tSimilarly,
eismic Assessm015
Founda
n damage thl settlementplit at the went (Figure
this is les
Large diago
50: Earthqu
FactorBuildin
Numbe
gth and stiffuration of gaccelerationo withstandamage fro
ment of Unreinfo
ations an
hat can be st. URM builweakest po10.50). Ho
ss likely to
onal cracks a
(b) Settlem
ake-induced
rs Affecngs
er of cycl
fness of URground shan sustainedd than a om higher a
orced Masonry B
nd geote
een by inspldings typic
oint along aowever, giv
induce act
and lateral mground
ment and late
d geotechni
cting Se
les and d
RM degradeaking (Figurd over timesingle, muacceleration
Seismic
Buildings
echnical
pection is cocally have na wall. “Fa
ven the slowtual collaps
movement omovement
eral spread
ical damage
eismic P
duration
es rapidly wure 10.51). e can be m
uch larger n, shorter p
c Assessment o
failure
ommonly frno tying capailure” is ower and nonse until ext
of the acces
towards riv
e to URM bu
Perform
n of shak
with an incrIn general,much morepeak acceleriod groun
of Unreinforced
ISBN 978-
rom lateral sacity at fou
often an extn-cyclic nattreme displ
ss ramp cau
ver
ildings (Nei
mance o
king
reasing num a number
e difficult leration (FEnd shaking
Masonry Buildi
10-0-473-26634
spreading aundation levtremely larture of latelacements a
used by
ill et al., 201
of URM
mber of cyclr of cycles for an UREMA, 200from shallo
ngs
0-54
4-9
and vel, rge ral are
4)
les of
RM 6). ow
SeUpd
east
N
Thththev
1
10
O
ection 10 - Seismdated 22 April 2015
arthquakes iffer URM b
(a) Po
Figure 10.5
Note:
he assessmherefore prohe building wvent.
O0.4.2
G0.4.2.1
ther key fac
building f
unrestrain
connectio
wall slend
diaphragm
in-plane w
foundatio
redundan
quality of
maintenan
mic Assessmen
could be cobuildings fa
ost-Septembvisib
51: Progres
ment of damgressive dewill have be
Other key
General
ctors affecti
form
ned compon
ons
derness
m deficienc
walls
ons
ncy
f constructio
nce.
t of Unreinforce
onsiderably ar more than
ber 2010 eveble damage
(c) Pos
sive damagearthqua
maged builterioration aeen appropr
y factors
ing the seism
nents
y
on and alter
ed Masonry Buil
y greater than flexible fr
ent – minor
st-June 2011
ge and effecake sequenc
ldings is ouafter the mariately stabi
s
mic perform
rations, and
Seismic As
ldings
an from deerame and tim
(b) P
1 event – wa
t of shakingce (Dmytro D
utside the ain event is ilised if this
mance of UR
ssessment of U
IS
ep earthquamber structu
Post-Februasection on
all collapse
g duration – Dizhur)
scope of tnot conside
s had been r
RM building
Unreinforced Ma
SBN 978-0-4
akes. This cures.
ary 2011 eveverge of fai
2010/11 Ca
these Guidered. It is asrequired aft
gs include:
asonry Buildings
10-55473-26634-9
could affect
nt – wall lure
anterbury
delines, andssumed thatter the main
s
5
9
t
d t n
Section 10 - SeUpdated 22 April 20
10.4.2.2
A structurathe concenexample ofhighly pencould be tosoft/weak lead to coll
10.4.2.3
Instability imposed acroof line an
10.4.2.4
URM buildand its coreduce the together asdeficiencieparticularly
10.4.2.5
Unreinforcsusceptibleplane bendto span ofexterior wy
10.4.2.6
Diaphragmthat lateralflexible, thimposes lacould resul
10.4.2.7
These walperformanclocation ofof bond be
10.4.2.8
FoundationURM builbuilding fabuilding linteraction
eismic Assessm015
Building
ally irregulantration of f this is bui
netrated, wiotally openstorey meclapse.
Unrestr
of parapetccelerationsnd can topp
Connec
dings can somponents c
vertical sles a whole, res in URMy those betw
Wall sle
ced face-loe to out-of-pding is predf wall). Cavythes to the
Diaphra
ms act as a ll loads are trheir abilityarge displaclt in wall co
In-plane
ls provide ce is definf penetrationeams, built-i
Founda
n flexibilityldings. Howailure is rarliquefies orn tend to red
ment of Unreinfo
g form
ar building both force
ildings alonth relatively
n. This confhanism. Th
rained co
ts and chims. When sub
ple over whe
ctions
how significan maintaenderness oather than a
M buildings ween walls
endernes
oaded masoplane failurdominantly vity walls abacking wa
agm defic
id to a box ransferred t
y to do thicement demollapse.
e walls
global strenned by: the ns; relative in timber an
tions
y and deformwever, founrely causedr suffers l
duce the for
orced Masonry B
suffers moand displa
ng urban stry narrow pfiguration chis can resu
omponent
mneys is cabject to seisen sufficien
icant resiliein their int
of a wall anas independ
in New Zand diaphra
ss
onry walls es. The eartdictated byare especialall can be w
ciency
and are essto the laterais is comp
mand on w
ngth and stslendernesstrength be
nd DPC.
mation affendations te
d by groundlateral sprece demand
Seismic
Buildings
ore damage acement dereets where piers betweecould imposult in increa
ts
aused by thsmic action
ntly accelera
ence to seismtegrity. Thend also to mdent parts. HZealand is agms.
are weakthquake vul
y its slenderlly vulnerab
weakened by
sential for tyal load-resispromised. E
walls, particu
tiffness agass of walls etween mort
ect the localend to be qd settlementeading. Fouon the prim
c Assessment o
than a regmands on the façades
en openingsse significanased displac
heir low benns, they rockated by an e
mic shakinge wall-diap
make the buHowever, on
the lack o
k in out-oflnerability orness (the rable as the sy corrosion.
ying the wating elemenExcessive dularly on fa
inst earthquand piers;
tar and mas
l and globaquite tolerat unless theundation e
mary lateral-
of Unreinforced
ISBN 978-
ular buildincertain coms facing thes, and the bnt torsional
cement dem
nding strenk on their suarthquake.
g as long ashragm anch
uilding compne of the mof adequate
f-plane benof a URM watio betweesteel ties co
alls togethernts. If diaphdiaphragm face-loaded
uake load. T vertical lo
sonry units;
l earthquakant to defoe ground unffects or s-force-resist
Masonry Buildi
10-0-473-26634
ng because mponents. Ae street can bottom storl demand a
mand and m
ngth and hiupports at t
s the buildihors serve
mponents woost significa
connection
nding so awall to out-oen thicknessonnecting t
r and ensurihragms are t
displacemewalls, whi
Their seismoad; size a and presen
ke response ormations anderneath tsoil structuting elemen
ngs
0-56
4-9
of An be
rey and
may
igh the
ing to
ork ant ns;
are of-ses the
ing too ent ich
mic and nce
of and the ure nts,
SeUpd
suadthacalin Exliqcopipeplthgr
10
Rabcoon
10
Ummneco
10
Ostrofreto
ection 10 - Seismdated 22 April 2015
uch as stiff dditional rothe wall needccumulated lteration of nduced lique
xisting highquefaction-ionsiderationin connecterpendiculalane actionshe footings (round lurch
R0.4.2.9
edundancy bility to ronsiderationnly one of it
Q0.4.2.10
URM buildinmany changemodifications
ew penetratomponents.
M0.4.2.11
lder buildirength due f timber aneinforced coo leaching o
Figu
mic Assessmen
f in-plane lotational demds to be coover the buthe surroun
efaction.
h bearing induced setn for a URMions. Howr/abutting w
s may be a (or ground s, so vulnera
Redundan
of a buildinredistribute n, as a builts structural
Quality of
ngs in Newes of occups at differentions in walSuch altera
Maintena
ngs that hto weather
nd other prooncrete memf lime from
re 10.52: Se
t of Unreinforce
oaded wallsmand on thensidered ca
uilding’s lifnding soil o
pressures rttlements. SM building
wever, carewalls is esseconsideratioslabs if presability to the
ncy
ng refers to demands
ding with ll elements f
f constru
w Zealand repancy. As nt times whils and diaph
ations will a
nce
have been ing (Figureocesses tha
mbers. Similm the mortar
everely degr(In
ed Masonry Buil
s. At the sae bottom stoarefully as dfe (such as uor levels), a
require careSettlement as the upp
eful considential. For on (refer Sesent), there ese induced
the alternathrough a
low redundfails.
uction an
epresent ana result, thich may nothragms, remaffect seism
insufficiente 10.52), coat weaken mlarly, water
r.
raded bricksngham & Gr
Seismic As
ldings
ame time, orey wall udo the condundermininand if these
eful considof long soer floors an
deration of taller wallsection 14). Wwill be little
d displaceme
ative load paa secondar
dancy will b
d alterat
n old buildinhere may hat have been
moving exismic performa
tly maintainorrosion of cmasonry, cr penetration
s and mortariffith, 2011)
ssessment of U
IS
ground defnder face loditions at thg by brokene have chan
deration witolid walls ind roof framf the indu, ratchetingWith little oe resistanceents should
aths able to ry load pabe susceptib
ions
ng stock whave been a
n well considsting compoance.
ned will hcavity ties (onnection cn in lime-ba
ar due to mo
Unreinforced Ma
SBN 978-0-4
formation coad. The bahe wall basn drains, clanged with e
th respect is often nome into theuced damagg down withor no reinfo
e to lateral sbe assessed
add to resiath is an ble to total
hich has goa number odered, suchonents and a
have reduce(Figure 10.capability, ased mason
oisture ingre
asonry Buildings
10-57473-26634-9
an pose anase fixity ofe that haveay heave orearthquake-
to possibleot a critical
walls withge to anyh cyclic in-orcement inpreading ord.
stance. Theimportant
collapse if
one throughf structural as openingadding new
ed material53), rottingtimber andry will lead
ess
s
7
9
n f e r -
e l h y -n r
e t f
h l g w
l g d d
Section 10 - SeUpdated 22 April 20
The metallhave no co
10.5
10.5.1
The assessnumber of The natureterms of co It is, thereappreciatiobehaviour likely to Sections 10progressing It is a geneconsideredplaced on ino differenprocesses o Past obserparticularlyidentified capacity “from left toof the weacapacity wthe chain. from left to
eismic Assessm015
lic cavity tiorrosion pro
Figure 10.
Asses
Genera
sment of URf building co
e of the consonstruction,
efore, conson of how thof similar baffect the
0.2, 10.3 ag through th
eral recommd independeit, bringing nt for URMoutlined bel
rvations in y vulnerablthat can bechain” for o right on thakest link in
will typicallyThis sugge
o right in Fi
ment of Unreinfo
ies used in otection so a
53: Metal ca
sment A
al
RM buildinomponents a
struction of quality of t
sidered imphese buildinbuildings inir seismic and 10.4 whe assessme
mendation oently from both togeth
M buildingslow.
earthquakele to earthqe useful in a typical U
he chain. Tn the chainy be dependests that theigure 10.54.
orced Masonry B
the originaare prone to
avity ties in
Approa
ngs requiresand how the
f this type ofthe original
portant thatngs were con previous
performanwhich are ent processe
f these guidthe demand
her only in ts and is th
s indicate tquake shak
guiding thURM buildhe capacity
n, and the adent on the
assessment.
Seismic
Buildings
al constructsevere dete
rusted cond
ach
s an understese are likel
f building ml workmansh
t assessors onstructed, tearthquake
nce. Theseconsidered
es outlined i
delines that ds (imposedthe final ste
he basis beh
that some cking and a he assessmeding with cy of the builability of eaperformanc
nt of compo
c Assessment o
tion of URMerioration (F
dition (Dizhu
tanding of tly to interac
means that ehip and curr
of this typtheir currens and a hol
e issues had to be essin this secti
the capacityd inertial loep of the asshind the re
componentshierarchy
ent processcomponent lding will bach componce of component capaci
of Unreinforced
ISBN 978-
M cavity wFigure 10.53
ur et al, 201
the likely bct with each
each buildinrent conditi
pe of buildt condition,listic view ave been sential readon.
y of a buildoads and disessment precommende
s of URM in vulnera
s. Figure 10vulnerabilite limited bynent to fullonents to thities should
Masonry Buildi
10-0-473-26634
walls typica3).
1)
behaviour ofh other.
ng is uniqueion.
ding have , the observof the factodiscussed
ding prior
ding should displacemenrocess. Thised assessme
buildings aability can 0.54 showsty decreasiy the capacly develop he left of it d also proce
ngs
0-58
4-9
lly
f a
in
an ved ors in to
be nts) s is ent
are be
s a ng ity its on
eed
SeUpd
F
W(etore Ubuanstrso Inpathstr(S
ection 10 - Seismdated 22 April 2015
Figure 10.54
While the crie.g. lack of ao evaluate thequire retrof
URM buildinuildings mand internal ructures. G
olutions for
n Section 10articular emhe buildingrengthening
Section 10.5
mic Assessmen
4: The capac
itical structuany positivehe capacityfit and the li
ngs come iay require a
actions wGuidance is
common si
0.5.2 the assmphasis on hg. The assg (Section 5.4)).
t of Unreinforce
city “chain”
ural weaknee ties from
y of each linikely cost o
in different first-princi
within comps provided imple buildi
sessment prhow the appsessment ap10.5.3), an
ed Masonry Buil
and hierarc
ess in a strubrick wallsnk in the ch
of this.
configuratiples approaponents, si
for both ings.
rocess, as it proach migh
approach wnd its locat
Seismic As
ldings
chy of URM
uctural syst to floors/rohain to full
ions, sizes ach to the amplificationthe detailed
applies to Uht be varied
will also btion (includ
ssessment of U
IS
building co
em will oftoof) it will gy inform on
and complssessment ons are posd complete
URM buildd dependingbe influencding when
Unreinforced Ma
SBN 978-0-4
omponent vu
ten be readigenerally bn the comp
lexity. Whiof componessible for me solutions
dings, is discg on the comced by any
it is a ro
asonry Buildings
10-59473-26634-9
ulnerability
ily apparente necessary
ponents that
le complexent capacitymore basic
and basic
cussed withmplexity ofy previousw building
s
9
9
t y t
x y c c
h f s g
Section 10 - SeUpdated 22 April 20
10.5.2
Key steps described b
eismic Assessm015
Assess
involved inbelow.
Fig
STEP 1
STEP 2
STEP 3
STEP 4
STEP 5
STEP 6
STEP 7
STEP 8
STEP 9
STEP 10
ment of Unreinfo
sment pr
n the assess
gure 10.55: A
Ga
On
Asse
Iden
Orde
As
D
Dec
Arelat
a
orced Masonry B
rocess
sment of U
Assessmen
ather docu
n-site inves
ess materia
ntify potent
er potentiavulnerab
Assess co(S
ssess globa
Determine d
cide on levebuild
Analyse thetionship beand global
De
Seismic
Buildings
URM buildin
nt process fo
mentation
stigations
al propertie
tial structur(SWs)
al SWs in tebility (Sectio
omponent Section 10.
al capacity
demands (S
Reporting
el of assessding compl
e structure tetween comcapacity (S
termine %N
c Assessment o
ngs are sho
or URM buil
(Section 10
(Section 10
es (Section
ral weakne
rms of expon 10.5.1)
capacities .8)
(Section 1
Section 10.1
g
sment baselexity
to determinmponent acSection 10.9
NBS
of Unreinforced
ISBN 978-
own in Figu
dings
0.6)
0.6)
n 10.7)
esses
pected
0.9)
10)
ed on
nections 9)
Masonry Buildi
10-0-473-26634
ure 10.55 a
ngs
0-60
4-9
and
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-61
Updated 22 April 2015 ISBN 978-0-473-26634-9
Step 1 Gather documentation
Collect relevant information and documents about the building including drawings, design feature reports, calculations and specifications, and any historical material test results and inspection reports (if available).
If the building has been previously altered or strengthened, collect all available drawings, calculations and specifications of this work.
Study this information before proceeding with the on-site investigation.
Step 2 Consider building complexity
Determine an assessment strategy based on an initial appraisal of the complexity of the building. This can be reviewed as the assessment progresses.
Although all aspects will need to be considered for all buildings, simplifications can be made for basic buildings e.g. one or two storey commercial, rectangular in plan. For these buildings the default material strengths are expected to be adequate without further consideration so that on-site testing, other than scratch testing of the bed joints to ascertain mortar type and quality, is not considered necessary. Foundation rotations are also not expected to have a significant effect so can be ignored.
Concentration of effort should be on assessing the score for face-loaded walls, connections from the walls to the diaphragms and the diaphragms (lateral deflection between supported walls). The score for the walls in plane will depend on the ability (stiffness) of the diaphragm to transfer the shears but the calculations required are likely to be simple irrespective of whether the diaphragms are rigid (concrete) or flexible (timber, steel braced). Behaviour can be assumed to be linear-elastic (ie ignore any non-linear behaviour).
Complexity is likely to be increased if a building has previously been retrofitted. Not all issues with the building will necessarily have been addressed in historical retrofits. Stiffness compatibility issues will often not have been considered or fully addressed.
Step 3 Investigate on-site
Refer Section 10.6.
Evaluate how well the documentation describes the “as constructed” and, where appropriate, the “as strengthened” building.
Carry out a condition assessment of the existing building.
Complete any on-site retrieval of samples and test these.
Identify any site conditions that could potentially affect the building performance. (Refer Section 14).
Step 4 Assign material properties
Start by using the probable material properties that are provided in Section 10.8, or establish actual probable values through intrusive testing (this may be a step you come back to depending on the outcome of your assessment).
Recognise that for basic buildings obtaining building-specific material strengths through testing may not be necessary to complete an assessment.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-62
Updated 22 April 2015 ISBN 978-0-473-26634-9
Step 5 Identify potential structural weaknesses and relative vulnerability
The first step is to identify all of the various components in the building and then to identify potential SWs related to these.
The identification of potential SWs in this type of building requires a good understanding of the issues discussed in Sections 10.2, 10.3 and 10.4.
Early recognition of SWs and their relative vulnerability and interdependence is likely to reduce assessment costs and focus the assessment effort.
Prior experience is considered essential when identifying the SWs in complex buildings.
Separate the various components into those that are part of the primary lateral load resisting system and those that are not (secondary components). Some components may be categorised as having both a primary lateral load resisting function (e.g. in-plane walls and shear connections to diaphragms) and a secondary function (e.g. face-loaded walls and supporting connections).
The relative vulnerability of various components in typical URM buildings is likely to be (refer also Figure 10.54):
- Inadequately restrained elements located at height; such as street-facing façades, unrestrained parapets, chimneys, ornaments and gable end walls. Collapse of these components may not lead to building collapse but they are potential life-safety hazards and therefore their performance must be reflected in the overall building score.
- Inadequate connection between face-loaded walls and floors/roof; little or no connection capacity will mean that the walls will not be laterally supported when the inertial wall forces are in a direction away from the building and then it can be easily concluded that the walls and/or connections will be unlikely to score above 34%NBS, except perhaps in low-seismic regions. If observations indicate reasonable diaphragm action from the floors and/or roof, adequate connections will mean that the out-of-plane capacity of the face-loaded walls may now become the limiting aspect.
- Out-of-plane instability of face-loaded walls. If the wall capacity is sufficient to meet the requirements set out for face-loaded walls, then the capacity of the diaphragms becomes important as the diaphragms are required to transfer the seismic loads from the face-loaded walls into the in-plane walls.
- The in-plane capacity of walls: these are usually the least vulnerable components.
Step 6 Assess component capacities
Calculate the seismic capacities from the most to the least vulnerable component, in turn. There may be little point in expending effort on refining existing capacities only to find that the capacity is significantly influenced by a more vulnerable item that will require addressing to meet earthquake-prone requirements or target performance levels. Connections from brick walls to floors/roof diaphragms are an example of this. Lack of ties in moderate to high seismic areas will invariably result in an earthquake-prone status for the masonry wall and therefore it may be more appropriate and useful to assess the wall as < 34%NBS and also calculate a capacity assuming ties are in place. This will inform on the likely effect of retrofit measures.
A component may consist of a number of individual elements. For example, the capacity of a penetrated wall (a component) loaded in-plane will need to consider the
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-63
Updated 22 April 2015 ISBN 978-0-473-26634-9
likely behaviour of each of the piers and the spandrel regions between and above and below the openings respectively (the elements). For some components the capacity will be a function of the capacity of individual elements and the way in which the elements act together. To establish the capacity of a component may therefore require structural analysis of the component to determine the manner in which actions in the elements develop.
For each component assess whether or not exceeding its capacity (this may be more easily conceptualised as failure for these purposes) would lead to a life safety issue. If it is determined that it will not, then that component can be neglected in the assessment of the expected seismic performance of the structure. The same decisions may need to be made regarding the performance of elements within a component.
Step 7 Analyse the global structure
In general, the complexity and extent of the analysis should reflect the complexity of the building.
Start with analyses of low sophistication, progressing to greater sophistication only as necessary.
An analysis of the primary lateral load resisting structure will be required to determine the relationship between the global capacity and the individual component actions.
The analysis undertaken will need to recognise that the capacity of components will not be limited to consideration of elastic behaviour. Elastic linear analysis will likely be the easiest to carry out but the assessor must recognise that restricting to elastic behaviour will likely lead to a conservatively low assessment score.
The analysis will need to consider the likely impacts of plan eccentricities (mass, stiffness and/or strength).
Step 8 Assess global capacity
From the structural analyses determine the global capacity of the building. This will be the capacity of the building as a whole determined at the point that the most critical component of the primary lateral load resisting system reaches its determined capacity.
It may also be useful to determine the global capacity assuming successive critical components are addressed (retrofitted). This will inform on the extent of retrofit that would be required to achieve a target score.
Step 9 Determine the demands and %NBS
Determine the global demand for the building from Section 5 and assess the global %NBS (global capacity/ global demand x 100).
Assess the demands on secondary components and parts of the building and assess %NBS for each (capacity/demand x 100).
List the %NBS values in a table.
The CSW will be the item in the table with the lowest %NBS score and that %NBS becomes the score for the building.
Review the items in the %NBS table to confirm that all relate to elements, the failure of which would lead to a life safety issue. If not, revise the assessment to remove the non-life safety element from consideration.
Section 10 - SeUpdated 22 April 20
Step 10
Refer S
10.5.3
Seismic asthat undertinstalled sSection 10and associa Issues requcontinuity,elements.
10.5.3.1
The effectipoorly perprojects inc
Shallow(i.e. les(Moon
Groutewith th
MechanURM dthat can
The defauldiaphragmtested in ac Existing naccordance Existing heor if anchrequired. Existing wboundary jwhen facewall anchobending canecessary sthe ribbon to a boundbe checked
eismic Assessm015
Reportin
Section 12.
Assess
ssessment oftaken for ustrengthenin.6 providesated feature
uiring cons, and deform
Wall-to-
iveness of erforming anclude:
w embedmess than half et al. 2011)
ed plain rounhreaded bar
nical expandue to the n be achiev
lt connectorm anchors th
ccordance w
non-headed e with the te
eaded wall hor capaciti
wall-to-diapjoists shoul-loaded waor brackets apacity andseismic loaboard or so
dary joist, pd, with adeq
ment of Unreinfo
ng
sment of
f URM builun-strengtheng compons a detailedes.)
sideration inmation com
-diaphrag
existing walnchors that
ent groutedthe wall thi).
nd bar anchor deformed
nsion ancholow tensileed with ava
r strengths dhat are in gwith the requ
wall anchoest procedur
anchors shoies greater
phragm ancd be review
alls pull aware not pro
d, in many ds in past eolid blockinresence of
quate conne
orced Masonry B
f strengt
ldings that pned structu
nents has list of stre
nclude the mpatibility b
gm ancho
ll-to-diaphraare known
d anchors. Aickness) we
hors. Plain rd reinforcin
ors. Mechan capacity o
ailable mech
detailed in good conditiuirements o
ors of unknres detailed
ould be testthan the d
chor connewed. Cross-
way from suovided (refinstances, h
earthquakes ng is well-cosolid blockiction to the
Seismic
Buildings
thened b
previously hures except
to be takengthening
capacity ofetween the
ors
agm anchorn to have b
Anchors insere observed
round bars ng bar ancho
nical anchorof masonry hanical anch
Section 10.ion and are
of Appendix
nown consd in Append
ted if there default valu
ections that-grain bendiupporting flfer Figure 1has been fo(ICBO, 20
onnected toing between
e joists.
c Assessment o
buildings
have been sthat the peen into actechniques
f the installoriginal an
rs needs to een used in
stalled withd to perform
have a low ors.
rs do not gand the lim
hors.
.8.4 can be e known to x 10A.
truction shix 10A.
is evidenceues detailed
t rely on ing will occloor diaphr10.56). Timound to be 00). Capaci
o the joists. n one or mo
of Unreinforced
ISBN 978-
s
strengthenederformance ccount. (Taused in UR
led elementnd installed
be verified.n previous
h low embem poorly und
bond streng
enerally permited embe
used for exhave been
ould be pr
e of significd in Sectio
cross-graincur in the bagms for th
mber has lowinadequate
ity is greatlyWhere the
ore pairs of
Masonry Buildi
10-0-473-26634
d is similar of previousable 10.2 RM buildin
ts, diaphragstrengtheni
. Examples strengtheni
edment deptder face loa
ngth compar
erform well edment dept
xisting wall installed a
roof tested
cant corrosion 10.8.4 a
n bending boundary johe case whw cross-grae to resist tly improvedconnection
f joists shou
ngs
0-64
4-9
to sly in
ngs
gm ing
of ing
ths ads
red
in ths
to and
in
ion are
of oist hen ain the d if n is uld
SeUpd
10
Dloof Exfodicodiro
10
Flm Wcosy Astrrebe Ocoif (am
ection 10 - Seismdated 22 April 2015
Figure 10.5
D0.5.3.2
etailing of oad paths exf the diaphra
xisting nailorces unlessiaphragm dontinuity (Oiaphragms tole of structu
D0.5.3.3
lexible latemoment resis
When assesompatibilityystem needs
An understarengthening
elationships e present.
ften it willomponent bf this foundassuming th
masonry) and
mic Assessmen
56: Out-of-p
Diaphrag
existing strxist to transfagm.
led plywoos adequate ddesign methOliver, 201that arise wural diaphra
Deformat
eral load resting frames
ssing the y between ths to be consi
anding of g compone
determined
l not be pobefore the ded will be t
here is confid reassess th
t of Unreinforce
lane loading
m contin
rengthened fer the inert
d sheathingdetailing is hodology ca10), with c
when continagms, even
ion comp
esisting syss, have been
effect of he stiff URidered.
f the nonent will bed for the UR
ossible to meformation to delete thidence that he capacity.
ed Masonry Buil
g cross grai
nuity
diaphragmtia loads fro
g joints shoprovided a
an be used checks the
nuity is not if not origin
patibility
stems, suchn used to str
strengtheniRM structure
n-linear stre required
URM compo
mobilise thcapacity of
the URM fa life safety.
Seismic As
ldings
in bending f
s should beom the face
ould not bet the joint lto assess e
en made torealized or
nally intend
h as structurengthen UR
ing measue and the m
rength-deforso that th
onents and o
he full capaf the URM from the py issue doe
ssessment of U
IS
failure mech
e reviewed -loaded UR
e relied upolocations (ICexisting diao assess ifr is lost canded to be dis
ural steel oRM building
res such more flexibl
rmation rehis can beother struct
acity of a is exceeded
primary seiss not arise f
Unreinforced Ma
SBN 978-0-4
hanism (Oliv
to ensure tRM walls in
on to transCBO, 2000aphragm strf those disn continue tscontinuous
or reinforcengs (Figure 1
as this, dle lateral loa
elationship e comparedtural system
flexible strd. An optiosmic resistfrom the fa
asonry Buildings
10-65473-26634-9
ver, 2010)
that reliablento the body
sfer tension0). The sub-rengtheningscontinuousto fulfil thes.
ed concrete10.26(a)).
deformationad resisting
for eachd with the
ms that may
rengtheningon availableing system
ailure of the
s
5
9
e y
n -g s e
e
n g
h e y
g e
m e
Section 10 - SeUpdated 22 April 20
10.5.4
Row buildtheir neighbetween thconsideredas one buil Note:
The guidan
The effectresearchedoutside the The effectsbuilding wof these eperformancadjacent bu Favourableunit and shrow or an i Unfavouraelements; t Buildings abe subjectaccumulatialmost uniparticularlymore quickstandard pwith care a Note:
These guidstructure armay be beipoint of vibrought to or retrofit hazard in tdue to the row buildiassessment
eismic Assessm015
Assess
ings are simhbours, ofthe individu
d in isolatiolding for the
nce below h
t of seismicd topics, pae scope of th
s of seismicwithin the ro
ffects shouce. The buuildings are
e effects inchare seismicisolated bui
able effects the loss of w
at the ends t to the ineion of effecidirectionaly detrimentkly than wh
procedures fand consider
delines recore describeding assessediew may exthe Buildinconsent pro
that section,capacities iings shouldt process.
ment of Unreinfo
sment of
milar buildinen with coual buildingon. Buildinge purposes o
has been inf
c shaking articularly fhese guideli
c shaking duow) and unfuld be accouilding or se demolished
clude the poc loads, andlding.
include powhich could
of rows sufertia/poundcts along th, pushing tal to masonhen elemenfor the asseration for th
ommend thad as part of d as if it is oxtend for thng Consent ocess. Stren, but the seiin the remaid be discus
orced Masonry B
f row bui
ngs arrangeommon bougs during ags interconnof assessme
ferred from
on row bufor URM bines.
ue to a lackfavourable (unted for wtructure wid.
otential for d buttressing
unding (knd potentially
ffer from twing effects he row. Secthe end bunry structurets are able
essment of hese effects
at all row eff its analysison one title,he whole bAuthority’
ngthening oismic capacinder of thessed and ag
Seismic
Buildings
ildings
ed side by siundary (para seismic nected acrosent.
observed bu
uildings is cbuildings. It
k of seismic (for the builwhen assesithin a row
the whole bg of central
nee effect any lead to los
wo significaof not ju
cond and muildings off es where strto completbuildings a.
ffects on a s and the vu, but the bu
block. The cs (BCA’s)
one “buildincity of the oe structure. greed with
c Assessment o
ide with insrty) walls: shaking suss boundari
uilding dam
complex but requires a
gap can beldings on thsing the bu
w could bec
block of rowbuildings b
nd impact) ss of the gra
ant additionst the adja
more importthe row. T
rains/crack e a full retuat the ends
particular bulnerabilitieilding fromconnectivityattention th
ng” as part verall buildThe legal aowners an
of Unreinforced
ISBN 978-
sufficient sei.e. there
uch that theies should b
mage only.
ut also onea special stu
e both favouhe ends of thuilding’s ovcome an en
w buildingsby adjacent b
on verticalavity load pa
al effects. Facent builditantly, forcThis ratchewidths accuurn cycle. Tof rows sh
building froes recorded.
a structuray of the pa
hroughout thof a row w
ding may stind compliad BCAs as
Masonry Buildi
10-0-473-26634
eismic gaps is interactiey cannot be consider
e of the leatudy which
urable (for the row). Boverall seismnd building
s to act as obuildings in
l load-beariath.
First, they cing but somces tend to eting effect umulate muTherefore, thould be us
om the over A “buildin
al connectivarts should he assessme
will reduce till remain loance effects s part of a
ngs
0-66
4-9
to ion be
red
ast is
the oth mic
if
one n a
ing
can me be is
uch the sed
rall ng” ity be
ent the ow of
any
SeUpd
10
Th
Thcoth OUno Thrigofwsapopu Incalais lo
10
If agw If buundithinelbeel
ection 10 - Seismdated 22 April 2015
G0.5.4.1
he performa
floor diap
façades,
primary t
common
he extent oommon to bhe floor, she
ften, even iURM buildin
ot participat
he effect ofgid diaphraften low he
with small diame alignmeounding eneunching.
n addition toause poundiarger displac
sensitive tooss of signif
B0.5.4.2
f row buildgainst the le
wall.
f they are tuildings (annbonded, aissipation ohe relative mnterrupt eaclements retueams. Whelement whic
mic Assessmen
General p
ance of row
phragms
transverse b
walls
of misalignmboth buildinear failure ca
if floors arengs). As a lte in the pou
f pounding gm building
eight of thesisplacementent pound inergy is disp
o the aboveing. Similarcement. Howo impact. Thficant vertic
Building i
dings are nength of de
tied, note thnd similarlyand ductilef energy. F
movement oh other’s re
urn togetherre floors mch will (elas
t of Unreinforce
performa
w buildings d
bracing elem
ment of flongs. When tan also be in
e misalignedarge proporunding actio
damage to g as it tendsse buildingts, and thern their stronpersed over
, most URMrly, with flewever, it is herefore, yoal load-carr
interconn
not tied togependable s
hat the pery retrofit t. Rigid anor elastic u
of the two stesonances. r. Where flo
misalign, thstically) tran
ed Masonry Buil
nce
depends pri
ments, when
oors increasthe extent onduced.
d, the façadrtion of the on between
masonry bus to be mores, the imparefore carryng directionr a large ar
M buildingsexible diaphimportant t
ou should asrying eleme
nection
gether, theirseating of t
rformance oties) can bnd elastic uunbonded eltructures thSome force
oors align, hese rods/bensfer the flo
Seismic As
ldings
marily on th
n situated ag
ses the bendof misalign
des are in thmass of ththe misalig
uildings is ge localised.
act forces ary less energyn. Poundingrea will hav
s have timbehragms the to consider ssess if the
ents.
r relative dthe floors, o
of elementse classifiedunbonded lements, if their differene will also the ties mayeams will boor force acr
ssessment of U
IS
he alignmen
gainst the bo
ding effect ment is gre
he same plae building i
gned floors.
generally leBecause of
re high freqy. Façades
g between pave a smaller
er floors whimpact enerthat URM idamage cau
displacemenor roof elem
s that provid into threeelements trthere is suff
nt stiffnessesbe lost thr
y take the fbe coupled ross the offs
Unreinforced Ma
SBN 978-0-4
nt (or otherw
oundary, an
on structureater than th
ane (this is is in the faç
ess than forf the high stquency andand other warallel wall
er effect tha
hich have lirgy is absoris a brittle mused is likel
nt should bments on th
ide tying be types: riransfer for
fficient strets will interarough pounform of sim
to a verticfset.
asonry Buildings
10-67473-26634-9
wise) of:
nd
res that arehe depth of
common inçade, it will
r a frame ortiffness and
d associatedwalls in thes where the
an localised
ttle mass torbed over a
material andly to lead to
be assessedhe common
between thegid, elastic
rce withouttch to allowact and willding as the
mple rods orcal column
s
7
9
e f
n l
r d d e e d
o a d o
d n
e c t
w l e r n
Section 10 - SeUpdated 22 April 20
10.6
10.6.1
You will nstrength an Your on-sithe rear offollowing a
10.6.2
Verify includimay hbetwee
Note thof builshould
Note thresistin
Also nounrestr
Note adto Sect
10.6.3
Note thbeam s
Note ththese e
Examinplate) tinvestigconnecalterati
Note:
If adhesiveinspection
A dribble However, ilength of th
For pomasonr
eismic Assessm015
On-sit
Genera
need to condnd before pr
ite investigaf the buildinaspects.
Form a
or establiing load pathave had men available
he number olding dimenidentify an
he structurang system, b
ote any archrained comp
djacent builtion 10.5.4 f
Diaphra
he diaphragmspacing, and
he presencelements.
ne wall-diapto identify dgate conne
ctions, any ions or deter
e anchors awill not be
of epoxy oit may also he anchor; o
ocket type cry on both s
ment of Unreinfo
e Inves
al
duct a detailreparing any
ation shouldng and any
nd confi
sh the formths between
many changdocumenta
of storeys, bnsions shouy discontinu
al system abasement an
hitectural feponents/elem
ldings and afor specific
agm and
m types. Fod their conn
e of floor a
phragm condetails and cections an
variation rioration.
are used, thesufficient a
on the walindicate th
or that the a
connectionssides or if th
orced Masonry B
stigation
led buildingy strengthen
d cover thehidden area
iguration
m and conn componenges of occuation and the
building dimuld include uities in the
and materiand foundatio
eatures that ments such
any potentiaimplication
d connec
or timber diaections, me
and roof dia
nnections ancondition. Yd anchoragin connec
ese warrantand an on-si
l can indicat there are
anchor was i
s, check if here is a gap
Seismic
Buildings
ns
g inspectionning propos
e whole buias. It should
n
nfiguration nts, elementupancy, thee actual bui
mensions aopening lo
e structural s
al descriptioon system.
t may affectas parapets
al for poundns for row b
ctions
aphragms, iembrane and
agonal brac
nd anchoraYou may nege types.
ction types
t careful invite testing p
cate that th voids betwinserted, tak
the joists/rp on both si
c Assessment o
n in order toal.
lding, payind include, b
of the buts, and systere may beilding. Reco
nd year of ocations ansystem.
on, includin
t earthquakeor chimney
ding and falbuildings.)
investigate td cladding t
cing system
ge types (med to removRecord thand other
vestigation.programme s
he anchor hween segmenken out and
rafters/beamdes of the jo
of Unreinforced
ISBN 978-
o assess exis
ng particulabut not be l
ilding and ems. As URe significanord this if so
constructionnd their dim
ng vertical
e performanys.
lling hazard
the timber type.
s and the d
mechanical, ve floor or che conditior features
In some cshould be co
hole was filnts of adhes
d reinserted.
ms are tightoists/rafters
Masonry Buildi
10-0-473-26634
sting buildi
ar attention limited to, t
componenRM buildinnt differenco.
n. Your notmensions, a
lateral forc
nce, includi
ds. (Also ref
type, joist a
dimensions
adhesive aceiling tileson of thesuch as a
cases, a visuonsidered.
lled propersive along t
tly packed s/beams.
ngs
0-68
4-9
ing
to the
nts, ngs ces
tes and
ce-
ing
fer
and
of
and to
ese any
ual
rly. the
by
SeUpd
1
N
Vinin
Nm
Thonas
ection 10 - Seismdated 22 April 2015
When inaccommoless than stiffness larger diainfluence
Note if thnails plac
Your assethe suppoPlaster, enails and of a sarkrusting or
L0.6.4
Record thfrom pasperforman
For multwythes, pNote that
Record theaders. Ithan one
Check anpatterns.
Record thweatherinrepointingstrength rInvestigaDamage t
Note:
Visual inspenvestigate tnspection sh
Note that themortar, so scr
he extent on the imporssessment re
Check andeteriorat
mic Assessmen
nspecting thodating stair
10% of thand strengtaphragm pee on diaphra
he diaphragced by a nai
essment shoorting strucespecially if
screws canking board or signs of le
Load-bea
he walls’ gst earthquance.
ti-wythe coplacement ot cavity wall
the bond tyIf possible, wythe. Che
ny unusual
he type anng, erosion g, includingrelative to ttion of existo bricks ind
ction and sthe quality hould includ
e mortar userape the poi
f to which tance of theesult.
ny damp aretion of the m
t of Unreinforce
he diaphrar or elevatorhe diaphragth in proporenetrations aagm respons
gm has prevl gun or if i
ould also coture to tranf cementition cause splitof the suppeaks, especia
aring wa
eneral condakes, or alt
onstruction, of inter-wyls will appe
ype of the confirm tha
eck if the co
characteris
nd conditionor hardnes
g cracks anthe bricks asting damagdicates a str
simple scraof mason
de both face
ed for pointiint to full de
detailed tese building a
eas and themasonry and
ed Masonry Buil
agm, note r access. St
gm area it irtion to thea special stse.
viously beeit has been v
onsider the nsfer the loaous, will actting of timb
porting framally in roof
alls
dition incluterations an
record theythe ties, anear thicker th
masonry, at the bond
ollar joint is
stics, such a
n of the mss of the mnd internal vas stronger ge to masoronger mort
atching of tnry constitues of the ma
ing is usualepth so you
sting of the and the likel
e rear part od its constit
Seismic As
ldings
the locatiotudies have is appropriae reduction tudy should
n re-nailed varnished.
quality of tads and pret to protectber which c
ming. We encavities if t
ding any dnd addition
e number ond the condhan the actu
including tbricks (heafilled.
as a mix o
mortar and mortar) and
voids. It is mortar can
onry walls ctar and weak
the bricks auents. To sonry.
ly far betteru can investi
materials sly sensitivit
of the buildtuents.
ssessment of U
IS
on and sizshown that
ate to reducin diaphrag
d be underta
at every na
the fixings event bucklt the fixingscan drasticancourage cathese are acc
eteriorationns that cou
of wythes, dition and aual structura
the presencaders) are no
f walling u
mortar jointhe conditiimportant tlead to a b
can reveal tker brick.
and mortar be fully e
r than the acigate this.
should be cty of the ma
ing to inves
Unreinforced Ma
SBN 978-0-4
ze of the t when penece in-plane gm area. Hoaken to est
ail joint usi
from any sling of the s. However
ally reduce tareful examcessible.
n of materiauld affect
the distancattachment al wall.
ce and distot fake and
units or unu
nts (for exion of any to establishbrittle modetheir relativ
r may be sueffective, y
ctual main b
considered waterial prope
stigate the
asonry Buildings
10-69473-26634-9
penetrationetrations are
diaphragmowever, forablish their
ing modern
sheathing todiaphragm.
r, rusting ofthe strength
mination for
als, damageearthquake
ce betweenof wythes.
tribution ofcover more
usual crack
ample, anypointing orthe mortar
e of failure.ve strength.
ufficient toyour visual
body of the
will dependerties to the
quality and
s
9
9
n e
m r r
n
o . f h r
e e
n .
f e
k
y r r . .
o l
e
d e
d
Section 10 - SeUpdated 22 April 20
Note aunits, o
Recordcrackintesting.
Examincontact
Record
Identifyshould leaningwhethe
If opeSectionallow fspecificverticacapacit
10.6.5
Recordmay stibe a sig
Check
10.6.6
Take cIntrusivconstrutransfer
10.6.7
Note th
Check extent damp.
10.6.8
Carefulparticu
Note afor slop
10.6.9
Recordlift wel
eismic Assessm015
any horizonor diagonal
d the presenng or decay. Refer to S
ne and recot with maso
d the presen
fy any verticbe observe
g parapets oer these are
ening up in 10.2.10) sfor the bricc investigatl load pathty.
Non loa
d the materiiffen the flognificant co
any unusua
Concre
care when mve investiguction and irred.
Founda
he type, mat
if the brickto which th
Geotec
lly investigular, check a
any geologicpe failure an
Second
d the detailslls, heavy eq
ment of Unreinfo
ntal cracks icracks near
nce of bondy should beection 7 for
ord any rottonry, particu
nce of any D
cal componed. Note anor chimneystied to the s
is permitteso allowancck capacity tions can ph where tim
ad-beari
al and consoor diaphra
omponent in
al wall plast
ete
making assugation is its constitue
ations
terial and st
s are in conhe bricks w
chnical a
gate any fouaround drain
cal site haznd surface f
dary elem
s of secondaquipment, c
orced Masonry B
in bed jointr openings.
d beams ane investigatr further info
ing and insularly in dam
DPC layers.
nents that arny separatios. Check Ustructural sy
d, include ce can be m
only, with prove otherwmber plates
ng walls
struction detgm and bra
n the total w
ter construct
umptions reessential toents properl
tructure of t
ntact with thwere fired w
and geolo
undation sens and slope
zards such afault rupture
ments
ary elementcanopies and
Seismic
Buildings
ts, vertical
nd their located and, w
formation on
sect infestatmp areas.
re not straigon of exteri
URM party wystem.
areas witmade during
no beneficwise. Existis have shru
s
tails of the nace the main
weight.
tion.
elating to to understaly if any gr
the foundati
he soil. Degrwhen origin
ogical h
ettlement ores.
as susceptibe. Look for
ts such as pd chimneys
c Assessment o
cracks in h
ations, and where appro
n concrete t
tion of timb
ght. Bulgingor wythes, walls and p
th built-in g the analyscial supporting bowingunk can sev
non-load ben loading w
the concreteand the mreater than n
ion system.
radation cannally produc
azards
r deteriorati
bility to liqupast signs o
arapets, orns. Include de
of Unreinforced
ISBN 978-
head joints
covered wpriate, inclutesting.
ber. Investig
g or undulaout-of-plum
partitions an
timbers (sis. This ant from the tg of walls averely redu
earing wallswalls. Their
e strength amakeup of
nominal for
n occur depced, and/or
on due to v
uefaction anof ground m
namentationetails of the
Masonry Buildi
10-0-473-26634
and mason
walls. Signs lude chemic
gate timber
ations in wamb walls, and investiga
(described nalysis shoutimber unleand a lack uce face lo
s. These waweight cou
and detailinthe origin
rces are to
pending on tr if the soil
vegetation.
and conditiomovement.
n, gable waleir dimensio
ngs
0-70
4-9
nry
of cal
in
alls and ate
in uld ess of
oad
alls uld
ng. nal be
the is
In
ons
lls, ons
SeUpd
1
Instrenet
1
Vdoanpaobbustr Ta
StMe
Ch
Pa
(dwepa
ection 10 - Seismdated 22 April 2015
and locatfeatures a
In particuparapets t
S0.6.10
nvestigate seructural sepntire length t al., 2011).
P0.6.11
Verify any socumentationd note thearticular issbservations.uildings, inrengthening
able 10.2: H
tructural echanism
himneys
arapets
urability and eathering of articular conce
mic Assessmen
tion. Also as these crea
ular, check to estimate
Seismic
eismic sepaparation is nof the sepa
Previous
strengtheninon. Record type of anues that can. Also referncluding dg elements.
istorical tec
Techni
Interna
Interna
Concre
Externa
Externa
Removlightwe
ern)
Vertica
Raking
t of Unreinforce
check for ate addition
if parapetsthe location
separati
aration with not necessararation is cle
s strengt
ng systems any variatio
nchors usedn arise withr to Section
deformation
chniques us
que
l post-tensioni
l steel tube re
ete filling
al strapping
al bracing
al and replaceight
l steel mullion
Braces
ed Masonry Buil
the presennal mass and
s are position of the rock
ion
adjacent burily an indicear of any o
thening
that have ons and detd, their sizeh different sn 10.5.3 fo
n compatib
sed for URM
ing
inforcement
ement with
ns
Seismic As
ldings
nce of cappd eccentricit
oned off-ceking pivot.
uildings. (Ncation that pobstructions
been usederioration o
e and locatistrengtheninr additiona
bility betwe
buildings a
Comme
Requiredegrade
Wrap-artube imp
Adds m
Adhesioto tie
Inward cif morta
Geometoutwardnot to a
Raking compon
Compatflexible
Heritage
Robust little wa
Weathe
Robust little wa
Interact
Vertical
ssessment of U
IS
ping stonesty.
entre to the
Note that an pounding wis between th
d against avobserved. Chion. Use Tang techniquel consideraeen the o
and common
ents/Issues
es well-mappeed vertical load
round/tie reinfportant
ass
on to surround
collapse needr degraded on
try often meand: changes in apply stress co
braces shouldnents of load re
tibility of stiff bdiaphragm mu
e and weather
attachment toll/weight abov
ring through r
attachment toll/weight abov
ion with roof m
tie-down requ
Unreinforced Ma
SBN 978-0-4
s or other
wall benea
apparent prill not occuhe two build
vailable draCheck as-buiable 10.2 toes: record a
ations for storiginal and
n features
ed, understoodd-path
forcement to c
ding brick often
ds to be checkn inside
ns external fraangle need fu
oncentrations t
d have all vertresolved at ea
braced chimneust be checke
ring implicatio
o upper levels ve critical
roof
o upper levels ve critical
modes can de
uired to raking
asonry Buildings
10-71473-26634-9
ornamental
ath. Inspect
resence of aur unless thedings (Cole
awings andilt accuracyo check forany relevanttrengthenedd installed
d and not
connect to
n insufficient
ked, especially
ames step ll resolution to masonry
ical ch end
ey with a ed
ns
of brick with
of brick with
stabilise
g braces
s
9
l
t
a e e
d y r t d d
y
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-72
Updated 22 April 2015 ISBN 978-0-473-26634-9
Structural Mechanism
Technique Comments/Issues
Steel capping spanning between abutting frames or walls
Anchorage depth down into mass of parapet to clamp down loose upper bricks
Internal Post-tensioning Anchorage depth down into mass of parapet to clamp down loose upper bricks
External post-tensioning Anchorage depth down into mass of parapet to clamp down loose upper bricks
Internal bonded reinforcement Anchorage depth down into mass of parapet to clamp down loose upper bricks
Near Surface Mounted (NSM) composite strips
Parapet responds differently to different directions of load
UV degradation
Face-loaded walls
Vertical steel mullions (Figure 10.23) Stiffness vs out-of-plane rocking/displacement capability important
Regularity/robustness of attachment to wall is important
Vertical timber mullions Stiffness vs out-of-plane rocking/displacement capability important
Regularity/robustness of attachment to wall is important
Horizontal transoms spanning between abutting frames or walls
Stiffness and attachment requirements need to consider wall above which gives clamping action to masonry at level of attachment
Internal post-tensioning Durability
Anchorage level and fixity
Level of pre-stress to allow rocking without brittle crushing
External post-tensioning As above
Internal bonded reinforcement Maximum quantity to ensure ductile failure
Anchorage beyond cracking points, and consider short un-bonded lengths
Composite fibre overlay Preparation to give planar surface very involved
Near Surface Mounted (NSM) composite strips
Wall responds differently to different directions of load
Bond important if in-plane capacity is not to be weakened
Reinforced concrete overlay Wall responds differently to different directions of load
Reinforced cementitious overlay Wall responds differently to different directions of load
Ductility of reinforcement important for deflection capacity
Grout saturation/injection Elastic improvement only: more suitable for low seismic zones and very weak materials
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-73
Updated 22 April 2015 ISBN 978-0-473-26634-9
Structural Mechanism
Technique Comments/Issues
Connection of walls to diaphragms
Steel angle with grouted bars (Figure 10.24(a))
Bar anchorage
Diaphragm/bar eccentricity must be resolved
Steel angle with bolts/external plate (Figure 10.24(b))
Diaphragm/bar eccentricity must be resolved
Timber joist/ribbon plate with grouted bars
Bar anchorage
Diaphragm/bolt eccentricity causes bending of timber across grain - a potential point of weakness
Timber joist/ribbon plate with bolts/external plate
Diaphragm/bolt eccentricity causes bending of timber across grain - a potential point of weakness
Blocking between joists notched into masonry
Joist weak axis bending must be checked
Tightness of fit of joists into pockets
Degradation of joists
External pinning to timber beam end Quality assurance/buildability of epoxy in timber
Concentrated localised load
Development in masonry (external plate preferred for high loads)
External pinning to concrete beam or floor
Development in masonry (external plate preferred for high loads)
Concrete floor type (hollow pots, clinker concrete)
Through rods with external plates Elastic elongation
Concentrated localised load
New isolated padstones Tightness of fit
Resolution of eccentricity between masonry bearing and diaphragm connection
New bond beams High degree of intervention
Diaphragm strengthening
Plywood overlay floor or roof sparking (Figure 10.25)
Flexibility
Requires continuous chord members and primary resistance elements
Plywood ceiling As above, plus existing ceiling battening/fixings may not be robust or may be decayed
Plywood/light gauge steel composite Stiffer but less ductile than ply-only
Eccentricities between thin plate and connections must be resolved
Plasterboard ceiling As ply ceiling but less ductile
Prevention of future modification/removal
Thin concrete overlay/topping Thickness for adequate reinforcement Additional mass
Ductility capacity of non-traditional reinforcement
Buckling restraint/bond to existing structure
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-74
Updated 22 April 2015 ISBN 978-0-473-26634-9
Structural Mechanism
Technique Comments/Issues
Elastic cross bracing Stiffness relative to wall out-of-plane capacity
Edge distribution members and chords critical
Concentration of loads at connections
Semi-ductile cross bracing (e.g. Proving ring)
As elastic
Energy absorption benefit not easily quantified without sophisticated analysis
Replacement floor over/below with new diaphragm
Design as new structure
In-plane wall strengthening
New primary strengthening elements (Figure 10.26)
Sprayed concrete overlay Restraint to existing floor/ roof structure
Out-of-plane capacity of wall
Ductility capacity if used very dependent on aspect ratio
Chords
Foundation capacity needs to be checked (uplift/rocking)
Internal vertical post-tensioning Ensure pre-stress limited to ensure no brittle failure
See out-of-plane issues also
External vertical post-tensioning Ensure pre-stress limited to ensure no brittle failure
See out-of-plane issues also
Internal horizontal reinforcement Coring/drilling difficult
Stressing horizontally requires good vertical (perpendicular) mortar placement and quality
External horizontal post-tensioning Stressing horizontally requires good vertical (perpendicular) mortar placement and quality
Bed-joint reinforcement Workmanship critical
Low quantities of reinforcement only possible
Composite reinforced concrete boundary or local reinforcement elements
Development at ends/nodes
Bond to existing
Composite FRP boundary or local reinforcement elements
As above plus stiffness compatibility with existing
Nominally ductile concrete walls or punched wall/frame
High foundation loads result
Nominally ductile reinforced concrete masonry walls
Stiffness compatibility considering geometry (including foundation movement) important
Nominally ductile steel concentric or cross bracing
Stiffness compatibility assessment critical considering element flexibility, plan position and diaphragm stiffness
Drag beams usually required
Limited ductility steel moment Frame Flexibility/stiffness compatibility very important
Limited ductility concrete frame Flexibility/stiffness compatibility important
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-75
Updated 22 April 2015 ISBN 978-0-473-26634-9
Structural Mechanism
Technique Comments/Issues
Limited ductility concrete walls Assess effectiveness of ductility, including foundation movements
Ensure compatibility with any elements cast against
Drag beams often required
Limited ductility timber walls Flexibility/stiffness compatibility very important
Drag beams often required
Ductile EBF/K-frames Element ductility demand vs building ductility assessment important
Drag beams usually required
Ductile concrete coupled or rocking walls
Element ductility demand vs building ductility assessment important
Ensure compatibility with any elements cast against drag beams often required
Tie to new adjacent (new) structure Elastic elongation and robustness of ties to be considered
Higher level of strengthening likely to be required
Reinforcement at wall intersections in plan
Removal and rebuilding of bricks with inter-bonding
Shear connection only with capacity reduced considering adhesion and tightness of fit
Disturbance of bond to adjacent bricks
Bed joint ties Small reinforcement only practical but can be well distributed
Care with resolving resultant thrust at any bends
Drilled and grouted ties Tension only: consider shear capacity
Depth to develop capacity typically large
Compatibility with face-load spanning of wall
Metalwork reinforcing internal corner Attachment to masonry
Small end-distance in abutting wall can mean negligible tension capacity
Grouting of crack Shear friction only: tension mechanism also required
Stabilises any dilation but does not allow recovery
Foundation strengthening
Mass underpinning Creates hard point in softer/swellable soils
Even support critical
Grout injection Creates hard point in softer/swellable soils
Difficult to quantify accurately
Concentric/balanced re-piling Localised “needles” through walls must provide sufficient bearing for masonry
Eccentric re-piling with foundation beams
Stiffness of found beams important to not rotate walls out-of-plane
Mini piling/ground anchors Cyclic bond less than static bond
Testing – only static practical
Vulnerable to bucking if liquefaction
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-76
Updated 22 April 2015 ISBN 978-0-473-26634-9
Structural Mechanism
Technique Comments/Issues
Pile type: vertical stiffness and pre-loading
Pre-loading dictates load position
Pre-loading important if new foundations less stiff than existing
Dynamic distribution between new and old likely different than static
Effects of liquefaction must be considered: may create limiting upper bound to strengthening level
Façade wythe ties
Helical steel mechanical engagement – small diameter
Low tension capacity, especially if cracked
Steel mechanical engagement – medium diameter
Some vierendeel action between wythes
Durability
Epoxied steel rods/gauze sleeve Some vierendeel action between wythes
Epoxied composite/non-metallic rods Stiffness
Brick header strengthening Additional new headers still brittle; can become overstressed under thermal/seasonal or foundation loadings in combination
Canopies Reinforce or recast existing hanger embedment
Degradation of steel
Depth of embedment to ensure sufficient mass of bricks to prevent pull-out
New steel/cast iron posts Propping of canopy can mitigate hazard from masonry falling to pavement
Props in addition to hangars are not so critical with regard to traffic damage
New cantilevered beams Co-ordination with clerestory/bressumer beam
Backspan reaction on floor
Deck reinforcement to mitigate overhead hazard
Sacrificial/crushable layer to mitigate pavement hazard
Conversion to accessible balcony Likely to achieves all of the above objectives for canopies and also has natural robustness as designed for additional live load. Hazard still exists for balcony occupants
Base isolation A lack of sufficient gap around the building
Vertically re-founding the building
SeUpd
1
1
Thas Thcoatse N
Binvabeanva
Wenasag
1
Rmthsim Toanchprmwjoth Ta
Br
So
Me
Ha
ection 10 - Seismdated 22 April 2015
M0.7
G0.7.1
his section pssociated m
hese valueomprehensivt any reliablection is rec
Note:
efore procenformation walue the infoe used to dend, thereforalues given
When assessnsure that tssign differege, weathere
C0.7.2
ecommendemortars, corrhese tables ample on-sit
o ensure thany weatherharacteristicroperties wh
may not be rewhether the moint and inshrough the jo
able 10.3: Pr
rick hardness
oft
edium
ard
mic Assessmen
Material
General
provides deaterials.
s can be ve testing ple judgemen
commended
eeding to onwill be col
formation wetermine thre, and whein this secti
ing the mathe adoptedent materiaed condition
Clay bric
ed probablrelated againare based onte tests you
at the test isred or recs. This reqhere the surepresentativmortar condspect the coint.
robable stre
s Brick des
Scratches
Scratches
Does not s
t of Unreinforce
l Prope
efault proba
used for aprogramme nt, some on.
n-site intruslected from
will add to thhe influenceether testingion is warra
terial charad material pl propertiesn or other a
cks and m
e default mnst hardnessn the use ofcan use.
s representaemediated quirement isrface mortarve of the modition is uniondition of
ength param
scription
s with aluminiu
s with 10 cent
scratch with a
ed Masonry Buil
erties an
able materia
assessment (refer to Ap
n-site testing
sive testing,m any inveshe reliabilitye of any mag to refine anted.
acteristics oproperties as to differenspects.
mortars
material prs, are givenf a simple s
ative of the surface m
s particularlr may be eiortar at depiform acrossf the extrac
meters for cl
um pick
copper coin
above tools
Seismic As
ldings
nd Weig
al properties
of URM ppendix 10Ag such as sc
, it is imporstigation, hoy of the ass
aterial paramthat materi
of the buildiare represennt masonry
roperties fon in Tables 1scratch test
structural cmaterial prily importanther weathe
pth. One recs the wall thcted mortar
lay bricks (A
st
ssessment of U
IS
ghts
s for clay br
buildings A for detailcratching, et
rtant to senow that wosessment. Semeter on thial paramet
ing, survey ntative. It mwalls depe
or clay bri10.3 and 10but there ar
apability ofior to asst for establi
ered or prevcommendedhickness is r dust as th
Almesfer et a
Probable bricompressiv
trength, f’b (M
14
26
35
Unreinforced Ma
SBN 978-0-4
rick masonr
in the absls). Howeve
etc. as discu
nsibly underould be usedensitivity an
he assessmeter beyond
the entire may be appending on v
icks and li0.4. The desare a variety
f the materisessing thelishing mortviously remd technique
to drill intohe drill bit
al, 2014)
ick ve MPa)
Protens
f
asonry Buildings
10-77473-26634-9
ry and other
sence of aer, to arrive
ussed in this
rstand whatd and whatnalyses cannt outcomethe default
building topropriate to
variations in
ime/cementcriptions in
y of similar,
als, removee hardnesstar materialediated andto establish
o the mortarprogresses
bable brick ile strength, fbt (MPa)
1.7
3.1
4.2
s
7
9
r
a e s
t t n e t
o o n
t n ,
e s l d h r s
Section 10 - SeUpdated 22 April 20
Table 10.4:
Mortar hardness
Very soft
Soft
Medium
Hard
Very hard†
Note: † When very
shear will head and b
Values higmaterial an
Values for In cases wtesting, the
10.7.3
In cases whof extracteestablishedcompressivand mortar
Table 10.5:
Mortar stren
eismic Assessm015
Probable s
Mortar des
Raked out
Scratches
Scratches w
Scratches
Does not s
y hard mortar form diagonal
bed joints. Suchgher than 0.6 mnd the thicknes
adhesion m
where the pre following
′ MPa
Compre
here the comed masonryd using Equve strength r probable c
MPa
Probable c
ngth, f’j (MPa)
0
1
2
5
8
ment of Unreinfo
strength par
scription
by finger pres
easily with fing
with finger na
using aluminiu
scratch with ab
is present it cacracks passing
h a failure modemay be considers of the mortar
may be taken
obable modvalue may b
0.12
essive s
mpressive sy prisms, thuation 10.2 values of c
compressive
0.75
0.75
compressive
)
orced Masonry B
rameters for
ssure
ger nails
ils
um pick
bove tools
an be expected through the bri
e is non-ductilered with care/inwith respect to
n as half the
dulus of rupbe used (Al
strength
strength of mhe probable(Lumantarn
clay brick me strength va
. x . .
e strength o
Probable m
Probable b
1
5
5
6
8
10
Seismic
Buildings
r lime/cemen
Probable mcompressstrength
(MPa)
0-1
1-2
2-5
To be estabfrom testing
To be estab
that walls subjicks rather than
e. Very hard monvestigation de
o the brick rough
e cohesion v
pture of claylmesfer et a
of maso
masonry cae masonry na et al, 20
masonry basalues from T
for 1
for 1
of clay brick
masonry com
brick compre
14
5.4
5.4
6.7
8.8
0.1
c Assessment o
nt mortar (A
mortar sive
h, f’j )
PCo
lished
lished from te
jected to in-plan a stair-steppedortar typically copending upon thness.
values prov
y bricks canal, 2014):
onry
annot be estcompressiv
014b). Tablesed on this Tables 10.3
MPa
MPa
masonry
mpressive str
essive streng
26
8.6
8.6
10.6
14.0
16.1
of Unreinforced
ISBN 978-
Almesfer et a
robable hesion, c (MPa)
0.1
0.3
0.5
0.7
sting
ane loads and fd crack pattern tontains cementthe nature/roug
ided in Tab
nnot be esta
ablished frove strengthe 10.5 presequation us and 10.4.
rength, f’m (M
th, f’b (MPa)
Masonry Buildi
10-0-473-26634
al, 2014)
Probable coefficient oFriction, µf
0.3
0.6
0.8
failing in diagothrough the mot. ghness of the br
ble 10.4.
ablished fro
…10.
om the testih, f’m, can sents probabsing the bri
…10.2
Pa)
35
10.8
10.8
13.3
17.5
20.1
ngs
0-78
4-9
of
onal rtar
rick
om
1
ing be
ble ick
2
SeUpd
1
Thbean
1
Wte
w
1
Thcothelup Y
Sh
1
R
1
Yre Ta
Ma
Br
Oa
Tim
ection 10 - Seismdated 22 April 2015
D0.7.4
he direct tene assumed tnalysis are s
D0.7.5
Where specifension streng
where: cµfa
M0.7.6
he masonryompressive hat this vallasticity betp to maximu
Young’s mod
hear modulu
T0.7.7
efer to Sect
M0.7.8
You can useeliable meas
able 10.6: U
aterial
rick masonry
amaru stone m
mber
mic Assessmen
Direct te
nsile strengto be zero, satisfied for
Diagonal
fic materialgth, this ma
MPa
= mµf = mfa = a
Modulus
y modulus ostrength in
lue of modtween 0.05um strength
dulus of clay
us of clay b
Timber d
tion 11 for t
Material
e the unit wsurements.
nit weights
masonry
t of Unreinforce
nsile str
gth of masonexcept whe
r vertical spa
l tensile
testing is nay be taken
0.5
masonry bedmasonry co-axial compr
of elast
of elasticityn accordancdulus of ela
and 0.7h.
y brick mas
300
brick masonr
0.4
diaphrag
timber diaph
unit wei
weights in T
ed Masonry Buil
rength o
nry, includien the requianning face
strength
not undertakas:
d-joint cohe-efficient ofression stres
ticity and
y, Em, can bce with Equasticity has
in order
sonry can be
nry can be ta
m mater
hragm mate
ghts
Table 10.6
Seismic As
ldings
f mason
ing any cemrements giv
e-loaded wa
h of mas
ken to deter
esion f friction ss due to gra
d shear
be calculateuation 10.4s been estato represen
e taken as:
aken as (AS
rial prop
erial propert
as default
ssessment of U
IS
ry
ment renderiven in Sectialls.
sonry
rmine proba
avity loads.
modulus
d by using (Lumantarn
ablished as nt the elasti
CE 41-13):
perties
ties.
values if y
Unit weig
1
1
5-
Unreinforced Ma
SBN 978-0-4
ing and plaion 10.8.5.2
able mason
s of mas
the masonrna et al, 20 a chord mic stiffness
:
you do not
ght (kN/m3)
18
16
-6
asonry Buildings
10-79473-26634-9
ster, should2 for elastic
ry diagonal
…10.3
sonry
ry probable014b). Notemodulus ofappropriate
…10.4
…10.5
have more
s
9
9
d c
l
e e f e
e
Section 10 - SeUpdated 22 April 20
10.8
10.8.1
This sectiothat make u In the dispof the dem
10.8.2
The assesstherefore, tequations 1.0.
10.8.3
10.8.3.1
Diaphragmwalls orienthe potentistorey shea The relativoften quitconstructed Flexibility walls and shears to mappropriatediaphragmplane respo When assestrength an The probabin these gu The deform The deformdetrimenta The diaphdeflections2.5%.
eismic Assessm015
Asses
Genera
on covers thup a mason
lacement bamand is an in
Strengt
sment procthe strengthand recomm
Diaphra
General
ms in URM nted perpenial to allowar and the to
ve lateral ste low dued of timber
in a diaphrthus affect
minimal levely allowed
m flexibility onse of the
essing the cnd deformat
ble strengthuidelines tha
mation capa
mation capal behaviour
hragm defos for check
ment of Unreinfo
sment
al
he assessmenry building
ased procedntegral part
th reduc
cedures in h reduction fmended def
agms
l
buildings fdicular to th
w shears to orsion due t
tiffness of e to the hior steel bra
ragm, if too the respon
vels, althoud for in the is, thereforewalls.
apacity of dtion capaciti
h capacity sat relate to t
acity will be
pacity is alr of supporte
ormations sking overall
orced Masonry B
of Com
nt of the ca.
dure for faceof the proce
ction fact
these guidfactor, , shfault probab
fulfil two prhe directionbe transfer
to any plan e
the diaphraigh stiffnesacing.
high, can rnse of theseugh this wilglobal analye, essential
diaphragmsies.
hould be dethe particula
e that for wh
lso limited ed walls or
should be l building d
Seismic
Buildings
mponent
apacity of th
e-loaded waedure.
tors
delines are hould be setble capaciti
rincipal funn of loadingrred betweeeccentricitie
agms to thess of the w
reduce its abe walls, or ll not generysis of the for proper u
s it is neces
etermined iar construct
hich the stre
to that wof the build
included wdeformation
c Assessment o
t/Eleme
he various c
alls that is p
based on t equal to 1.ies in this s
nctions. Theg and, if stifen walls ines.
e walls prowalls, parti
bility to prorender its arally be an building. Cunderstandi
sary to con
n accordanction materia
ength capac
which it is ding as a wh
when deterns against t
of Unreinforced
ISBN 978-
ent Cap
omponents
presented, th
probable s.0. The probsection assu
ey provide sff enough, thn any level,
viding latericularly for
ovide adequability to trissue if re
Considering ing of both i
sider both t
ce with the al of the diap
ity can be su
expected whole.
rmining thethe NZS 11
Masonry Buildi
10-0-473-26634
pacity
and elemen
he assessme
strengths anbable strengume equa
support to tthey also ha, to resist t
ral support r diaphragm
uate supportransfer storecognised a
the effects in and out-o
their probab
requiremenphragm.
sustained.
will result
e inter-stor170.5 limit
ngs
0-80
4-9
nts
ent
nd, gth als
the ave the
is ms
to rey and
of of-
ble
nts
in
rey of
SeUpd
InenRine
10
Indish(Fmmin
10
G
MThnaredi20cedaIf floredi
ection 10 - Seismdated 22 April 2015
n the sectionnsure adequigid diaphrecessary rel
D0.8.3.2to
n order to iaphragm inhould not Figure 10.5
masonry wymaximum acnner wythe.
Figur
T0.8.3.3
General
Most URM bheir in-planail connectieplicated asirections eit013c), refereiling overlaamage, and f the diaphraooring, thi
ecommend iaphragm st
mic Assessmen
ns below reuate supportragms woulative stiffne
Diaphrago face-lo
ensure thatn-plane disp
exceed 557). For caythe is usuacceptable di
re 10.57: Mid
Timber di
buildings inne deformatons (Wilsos a shear bther paraller Figure 10.ay, the degrany prior r
agms have his has beethat you u
tiffness coul
t of Unreinforce
ecommendat for face-lold typicallyess with the
m deformoaded wa
t the face-lplacement m0% of th
avity constrally the loaphragm di
d-span diap
iaphragm
n New Zealtion respon
on et al., 2beam (Wilsel or perpen58, and are radation of remediationhad epoxy cn observedundertake ald be more t
ed Masonry Buil
ations are proaded wallsy need to e walls.
mation limalls
loaded wallmeasured w
he thicknesruction withoad-bearing isplacement
hragm dispflexible fou
ms
land have flnse is stron2013a) andson et al., ndicular to
significantthe diaphra
n such as re-coatings thad to resulta sensitivitthan given h
Seismic As
ldings
rovided fors and flexibbe constru
mits to p
ls are adeqwith respectss of the h adequatewythe and
t to be limit
lacement limundation
flexible timbngly influend their glob
2013b). Rthe orientaly influence
agm due to a-nailing or at have penet in substaty analysishere by an o
ssessment of U
IS
diaphragmle (timber) cted of con
rovide ad
quately suppt to the dia
supported e cavity tied this criteted to 50%
mit for URM
ber floor annced by the bal responsResponses c
tion of the ed by the praspects suchvarnishing etrated into antial stiffe, recognisinorder of ma
Unreinforced Ma
SBN 978-0-4
m deformatioand rigid dncrete to a
dequate s
pported, theaphragm supd (face-loades installederion will of the thick
M building on
nd ceiling de characterisse is most can be sep
joists (Wilresence of ah as moistu(Giongo, etthe joints b
fening. Theing that thagnitude or g
asonry Buildings
10-81473-26634-9
on limits todiaphragms.achieve the
support
e maximumpport wallsded) walls, the innerrequire the
kness of the
n a
diaphragms.stics of theadequately
parated intolson, et al.,any floor orure or insectt al., 2013).between theerefore, wehe effectivegreater.
s
9
o . e
m s s r e e
. e y o , r t . e e e
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-82
Updated 22 April 2015 ISBN 978-0-473-26634-9
Figure 10.58: Orthogonal diaphragm response due to joist orientation
It is assumed here that the diaphragm is adequately secured to all perimeter walls via pocketing and/or anchorages to ensure that diaphragm deformation occurs rather than global sliding of the diaphragm on a ledge. It is also assumed that the URM boundary walls deform out-of-plane in collaboration with deformation of the flexible timber diaphragm. For non-rectangular diaphragms, use the mean dimensions of the two opposing edges of the diaphragm to establish the appropriate dimensions of an equivalent rectangular diaphragm. Note:
Timber roofs of unreinforced masonry buildings were often built with both a roof and ceiling lining. As a result, roof diaphragms are likely to be significantly stiffer than the mid-height floor diaphragms if there are no ceilings on the mid-floors. Diagonal sarking in the roof diaphragm will also further increase its relative stiffness compared to the floor diaphragms. If the diaphragm you are assessing has an overlay or underlay (e.g. of plywood or pressed metal sheeting), consult the stiffness and strength criteria for improved diaphragms. You will still need to consider stiffness and ductility compatibility between the two. For example, it is likely that a stiff, brittle timber lath-and-plaster ceiling will delaminate before any straight sarking in the roof above can be fully mobilised. While the flooring, sarking and sheathing provide a shear load path across the diaphragm, it is necessary to consider the connections to the surrounding walls (refer to Section 10.8.4) and any drag or chord members. A solid URM wall may be able to act as a chord as it has sufficient in-plane capacity to transfer the chord loads directly to the ground. However, a punched URM wall with lintels only over the openings will have little tension capacity and may be the critical element in the assessment. Timber trusses and purlins, by their nature, only occur in finite lengths: their connections/splices designed for gravity loads may have little tie capacity.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-83
Updated 22 April 2015 ISBN 978-0-473-26634-9
Probable strength capacity
The probable strength capacity of a timber diaphragm should be assessed in accordance with Section 11 of these guidelines.
Probable deformation capacity
Deformations in timber diaphragms should be assessed using the effective diaphragm stiffness defined below. The probable deformation capacity should be taken as the lower of the following, assessed for each direction:
L/33 for loading oriented perpendicular to the joists or L/53 for loading oriented parallel to the joists
Deformation limit to provide adequate support to face-loaded walls. Refer Section 10.8.3.2.
Deformation required to meet global inter-storey drift limit of 2.5% in accordance with NZS 1170.5. Refer Section 10.8.3.1.
Effective diaphragm stiffness
To determine the effective stiffness of a timber diaphragm, first assess the condition of the diaphragm using the information in Table 10.7. Table 10.7: Diaphragm condition assessment criteria (Giongo et al., 2014)
Condition rating Condition description
Poor Considerable borer; floorboard separation greater than 3 mm; water damage evident; nail rust extensive; significant timber degradation surrounding nails; floorboard joist connection appears loose and able to wobble
Fair Little or no borer; less than 3 mm of floorboard separation; little or no signs of past water damage; some nail rust but integrity still fair; floorboard-to-joist connection has some but little movement; small degree of timber wear surrounding nails
Good Timber free of borer; little separation of floorboards; no signs of past water damage; little or no nail rust; floorboard-to-joist connection tight, coherent and unable to wobble
Next, select the diaphragm stiffness using Table 10.8 and accounting for both loading orientations. Note:
While other diaphragm characteristics such as timber species, floor board width and thickness, and joist spacing and depth are known to influence diaphragm stiffness, their effects on stiffness can be neglected for the purposes of this assessment.
Pretesting has indicated that re-nailing vintage timber floors using modern nail guns can provide a 20% increase in stiffness.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-84
Updated 22 April 2015 ISBN 978-0-473-26634-9
Table 10.8: Shear stiffness values† for straight sheathed vintage flexible timber floor diaphragms (Giongo et al., 2014)
Direction of loading Joist continuity Condition rating Shear stiffness†, Gd (kN/m)
Parallel to joists Continuous or discontinuous joists Good 350
Fair 285
Poor 225
Perpendicular to joists††
Continuous joist, or discontinuous joist with reliable mechanical anchorage
Good 265
Fair 215
Poor 170
Discontinuous joist without reliable mechanical anchorage
Good 210
Fair 170
Poor 135
Note: † Values may be amplified by 20% when the diaphragm has been renailed using modern nails and nail guns †† Values should be interpolated when there is mixed continuity of joists or to account for continuous sheathing at joist
splice
For diaphragms constructed using other than straight sheathing, multiply the diaphragm stiffness by the values given in Table 10.9. If roof linings and ceiling linings are both assumed to be effective in providing stiffness, add their contributions. Table 10.9: Stiffness multipliers for other forms of flexible timber diaphragms (derived from ASCE, 2013)
Type of diaphragm sheathing Multipliers to account for other sheathing types
Single straight sheathing x 1.0
Double straight sheathing
Chorded x 7.5
Unchorded x 3.5
Single diagonal sheathing Chorded x 4.0
Unchorded x 2.0
Double diagonal sheathing or straight sheathing above diagonal sheathing
Chorded x 9.0
Unchorded x 4.5
For typically-sized diaphragm penetrations (usually less than 10% of gross area) the reduced diaphragm shear stiffness, G’d, is given by Equation 10.6:
/ …10.6
where Anet and Agross refer to the net and the gross diaphragm plan area (in square metres). For non-typical sizes of diaphragm penetration, a special study should be undertaken to determine the influence of diaphragm penetration on diaphragm stiffness and strength. The
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-85
Updated 22 April 2015 ISBN 978-0-473-26634-9
effective diaphragm stiffness must be modified further to account for stiffness of the URM boundary walls deforming in collaboration with the flexible timber diaphragm. Hence:
, kN/m …10.7
where αw may be determined using any rational procedure to account for the stiffness and incompatibility of deformation modes arising from collaborative deformation of the URM walls displacing out-of-plane as fixed end flexure beams and the diaphragm deforming as a shear beam. In lieu of a special study, prior elastic analysis has suggested that Equation 10.8 provides adequate values for αw:
α ≅ 1 ℓ
ℓ …10.8
where
ℓ = effective thickness of walls below the diaphragm, m = effective l thickness of walls above the diaphragm, m ℓ = height of wall below diaphragm, m = height of wall above diaphragm, m
Em = Young’s modulus of masonry, MPa = depth of diaphragm, m. = span of diaphragm perpendicular to loading, m.
Refer to Figure 10.59 for definition of the above terms. For scenarios where the URM end walls are likely to provide no supplementary stiffness to the diaphragm, αw = 1.0 should be adopted.
Figure 10.59: Schematics showing dimensions of diaphragm
B
Direction of loading
Ltu or tl (as appropriate)
tu or tl (as appropriate)Face‐loaded wall
Wall loaded in‐plane
Section 10 - SeUpdated 22 April 20
10.8.3.4
When assinvestigateas their abdiaphragm Rigid diapwalls.
10.8.4
10.8.4.1
The probabcapacity of
punchin
yield o
rupture
splittin
failure
splittin
yield o Suggested provided b
10.8.4.2
You can ustesting pro
The caitself o
When strength
The m12 diam
Shear staken a
Linear inte(ASCE, 20 Simultaneovalues from
eismic Assessm015
Rigid di
essing rigie the presenbility to tra
m capacity.
phragms can
Connec
General
ble capacityf the failure
ng shear fai
r rupture of
e at join betw
ng of joist or
of fixing at
ng or fractur
r rupture at
default prbelow togeth
Embedd
se the probavided that:
apacity shour the anchor
the embedmh should be
minimum edmeters.
strength of as zero.
erpolation o013).
ous applicatm Tables 10
ment of Unreinfo
iaphragm
d diaphragnce of termiansfer the
n be assume
ctions
l
y of diaphre modes liste
ilure of mas
f connector
ween conne
r stringer
t joist
re of anchor
threaded nu
robable capher. Guidan
ded anch
able capacit
uld not be r to grout or
ment lengthe taken as ze
dge distance
anchors wi
of shear stre
tion of shea0.10 and 10.
orced Masonry B
ms
gms, you cination detaloads at th
ed to have m
ragm to waed below:
sonry
rod in tensi
ector rod an
r plate
ut.
pacities fornce on speci
hors
ties provide
taken greatr grout to br
h is less thaero.
e to allow
ith edge dis
ngth for edg
ar and tensio.11.
Seismic
Buildings
can use a ails (hooks, he strut-and
minimal eff
all connectio
ion or shear
nd joist plate
r embeddefic assessm
ed in Tables
ter than therick bond.
an four bol
full shear
stances equ
ge distance
on loads nee
c Assessment o
“strut-and-thickening
d-tie nodes
fect on the
ons is taken
r
e
ed and plament of capac
s 10.10 and
e probable
t diameters
strength to
al to or les
s between t
ed not be co
of Unreinforced
ISBN 978-
-tie” methos, threads/nis likely t
response of
n as the low
ate bearing cities is also
d 10.11 in li
capacities o
or 50 mm
o be assum
s than 25 m
hese bound
onsidered w
Masonry Buildi
10-0-473-26634
od. Howevnuts) carefuto govern t
f out-of-pla
west probab
anchors ao provided.
ieu of speci
of the anch
m, the pull-o
med should
mm should
ds is permitt
when using t
ngs
0-86
4-9
er, lly the
ane
ble
are
fic
hor
out
be
be
ted
the
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-87
Updated 22 April 2015 ISBN 978-0-473-26634-9
Table 10.10: Default anchor probable shear strength capacities for anchors into masonry units only1.
Anchorage type Rod size Probable shear strength
capacity2,
(kN)
Bolts/steel rods fixed through and bearing against a timber member1,2
M12 8.5
M16 15
M20 18.5
Bolts/steel rods fixed through a steel member (washer) having a thickness of 6 mm or greater
M16 20
Note: 1. Anchors into mortar bed joints will have significantly lower shear capacities 2. Timber member to be at least 50 mm thick and MSG8 grade or better 3. For adhesive connectors embedment should be at least 200 mm into solid masonry
Table 10.11: Default anchor probable tension pull-out capacities for 0m, >0.3m and > 3m of wall above the embedment)
Mortar hardness Single-wythe wall
(kN)
Embedment 160 mm1 into two-wythe wall
(kN)
Embedment 250 mm1 into three-wythe wall
(kN)
0 >0.3 m(3) >3 m 0 >0.3 m(3) >3 m 0 >0.3 m(3) >3 m
Very soft 0.3 0.5 1 1 1.5 4 1.5 3 8
Soft 1 1.5 3 2.5 4 9 5 8 18
Medium 1.5 2.5 6 4 6.5 15 8 14 31
Hard 2.5 3.5 8 6 9 21 11 19 43
Very hard >2.5(4) >4(4) >8(4) >6(4) >10(4) >21 >11(4) >20(4) >43(4)
Notes: 1. Representative value only: assumes drilling within 50 mm of far face of wall 2. Simultaneous application of tension and shear loading need not be considered 3. These values are intended to be used until there is >3 m of wall above the embedment. 4. Values for very hard mortar may be substantiated by calculation but can be assumed to be at least those shown.
The values in Table 10.11 are based on the pull-out of a region of brick, assuming cohesion or adhesion strength of the mortar on the faces of the bricks perpendicular to the application of the load factored by 0.5 and friction on the top and/or bottom faces (refer Figure 10.60), depending on the height of wall above the embedment as follows:
0 m (ie at the top of the wall) - adhesion only on the bottom and side faces
>0.3 m but < 3 m – adhesion on the top, bottom and side faces, friction on the top and bottom faces
>3 m – cohesion on the top, bottom and side faces, friction on the top and bottom faces. A factor of 0.5 has been included in these values to reflect the general reliability of mechanisms involving cohesion/adhesion and friction.
Section 10 - SeUpdated 22 April 20
The designrequired bomortars cangrouting an For coarseaccount ofrather than When assespecificatio For inclinehorizontal componentinsignifican
10.8.4.3
For plate a A wall pun
eismic Assessm015
Figure
ner should ond directlyn be used bnd cleanout
thread scref the brick cn mortar cou
essing the con and the m
ed embeddevector com
t. If the incnt and the f
Plate an
anchors, pos
nching shear
ment of Unreinfo
10.60: Basi
select a bary to the bricut the capac
t methodolo
ews, use thecompressiveurses.
capacity ofmethodolog
ed anchors,mponent, anclination is
full capacity
nchors
stulate the p
r model is s
Figure 10.6
orced Masonry B
is for embed
r diameter acks and groucity should
ogy propose
e manufactue strength a
f straight orgy prescribe
, the horizond checks ms less than y of the anch
potential fail
shown in Fi
61: Failure s
Seismic
Buildings
dded ancho
and tested ut system abe substantd by relevan
urer’s data and ensurin
r bent adheed by the an
ontal force made for an
22.5 degrehor can be a
lure surface
gure 10.61.
surfaces for
c Assessment o
or capacity e
epoxy systeas appropriatiated by sitnt standards
for the direng that fixin
esive anchochor manuf
capacity sh adequate l
ees these efassumed.
e to estimate
plate ancho
of Unreinforced
ISBN 978-
estimation
em that wilte. Alternate pull-out tes/specificati
ect bond to bngs are into
ors, refer tofacturer.
hould be reoad-path fo
ffects can b
e its capacit
ors
Masonry Buildi
10-0-473-26634
ll develop ttively, cemeests, using tions.
bricks, takiwhole bric
o the produ
educed to tor the verticbe consider
ty.
ngs
0-88
4-9
the ent the
ing cks
uct
the cal red
SeUpd
10
Wthoflamco Foa rosi
1
10
ThbathSe N
Ththpohapoth(h
ThthUetthso
Prwefrigve
Fuco Foorflopr
ection 10 - Seismdated 22 April 2015
C0.8.4.4
Where the lahan four timf wall spannateral force
masonry; foronical “yield
or most appcylinder wi
ound by haldes of this c
W0.8.5
G0.8.5.1
his section ased inelasthe direct tenection 10.8.
Note:
he procedurhat were basotential enerave since beotentially unhey are supphigh modulu
his update uhe more sign
University oft al, 2013b, he detailed ome simplif
rocedures gway horizonffects (i.e. agorous reseertically. Ca
urther reseomprehensiv
or walls spar as verticaloors and thresented her
mic Assessmen
Capacity
ateral spacinmes the wall ning betwee(FEMA, 20
r example, d line” patte
plications inith a cross lf the thickncylinder.
Wall elem
General
provides bic methods
nsile capacit.5.2 – Gener
res in somesed on the crgy due to seen shown nsafe; particported on a us of elastic
uses the samnificant recf Auckland Derakhsha
procedures fying assum
given for astally and vassumption earch and aution is the
arch has bve procedur
anning vertilly cantilevehe roof for re for one-w
t of Unreinforce
of wall b
ng of connethickness, m
en the ancho009). This cthrough th
ern develop
nvolving beasection the ness of the
ments un
both force-bfor assessinty of the maral are met.
e earlier verconcept of eshifts of weto be deficicularly whetorsionally ity) masonr
me formulatcent researc
and Univeran et al, 201
set out in mptions that
ssessing facvertically, a
of elastic oare not as
erefore requ
been carriedres in the ne
ically in oneered (as in p
all such wway vertica
ed Masonry Buil
between c
ections usedmeasured aors to resist check migh
he compressps in the bric
aring platessame shapewall. Cohe
nder face
based (assung face-loadasonry are o
rsions of thequating toteights) of thient. These ere walls arflexible bea
ry.
tions as thech findings. rsity of Ad14a and 20this researcmade these
ce-loaded ware based oor nominalls well dev
uired when u
d out in text update.
e direction bpartitions anwalls. If thially spannin
Seismic As
ldings
connectio
d to resist thlong the lenthe local ou
ht be undertsive membrck around th
s, it should be as the beaesion may b
e load
uming elastded walls. Tonly approp
his documental energy (
he rocking wprocedures
e physicallyam with no
2006 guideThese are
elaide (Der14b). Howech (Derakh
e procedures
walls spanninn response
ly elastic reveloped as using these
this area a
between a fnd parapets)is restraint ng walls ca
ssessment of U
IS
ons
he wall anchngth of the wut-of-plane taken allowrane forces he anchor.
be sufficienaring plate bbe considere
tic behaviouThe force-bpriate if all
nt (such as strain energ
wall to that fs give incony hinged at wall undern
elines but abased on w
rakhshan et ever, we ha
hshan et al, s less suitab
ng one-wayassuming
esponse). Thprocedures
recommend
and we exp
floor and an), assure thecannot be
annot be use
Unreinforced Ma
SBN 978-0-4
horage forcwall, checkbending ca
wing for arcs that devel
ntly accuratebut lying o
red to be ac
ur) and disbased methoof the crite
the 1995 “gy of deformfor an elastinsistent resufloor levels
rneath) or m
accommodatwork carried
al 2013a, Dave not incl
2014a) as ble for thick
y horizontalonly weak
hese are bas for walldations.
pect to inc
nother floor e lateral rest
assured, thed. Howeve
asonry Buildings
10-89473-26634-9
ce is greaterk the sectionaused by theching in thelop when a
e to assumeutside it all
cting on the
splacement-ods utilisingria listed in
“Red Book)mation plusic oscillatorults and ares (i.e. when
made of stiff
tes some ofd out at theDerakhshanluded all ofthere were
ker walls.
lly, or two-k non-linearased on lesss spanning
clude more
or the roof,traint of thehe methodser, it might
s
9
9
r n e e a
e l e
-g n
) s r e n f
f e n f e
-r s g
e
, e s t
Section 10 - SeUpdated 22 April 20
still be posother walls Multi-wyth
all wytregular
testing units.
Otherwise, Header cowould normThese headthe interiorwill be eitlapping ov If the abovby assumin0.5Wb. Thipurpose, yob, t and l abrick in be If a wythe the backingtheir own l Non-structshould be evaluated. Internal wachecks on required. Walls shououtwards).either direc
10.8.5.2
General
When usintensile stre
the dem
an insp
the in-p
eismic Assessm015
ssible to asss, columns o
he walls can
thes are intrly along the
or special
, consider e
urses are tymally sufficder courses r as requirether one bri
ver the centr
ve criterion ng a verticais shear neeou can assu
are the breadending.
is not integg wall. If bload indepen
tural masonconsidered
alls with flothe diaphra
uld be asses Set the ratiction of load
Vertical
ng an elasticength of the
mands are c
pection of th
plane calcul
ment of Unreinfo
sess such wor other elem
n be conside
terconnectee length of t
study has c
ach wythe a
ypically proce for wallswould norm
ed. For examick higher ral wythe.
is not met,al shear actieds to be r
ume each hedth, depth a
gral with thoth wythes ndently for
nry (usuallyd as a mass
oors on bothagms (streng
ssed in evering of the wding will le
l spannin
c analysis tomasonry un
alculated as
he wall reve
lations indic
orced Masonry B
walls by anaments, or as
ered as one
ed with heathe wall, or
onfirmed th
as acting ind
ovided evers loaded oumally pass mple, in tripor lower th
investigateing on the cesisted by header brick and length o
e main struare one briout-of-plan
y single-wyt within the
h sides can gth and def
ry storey anwall at the le
ad to progre
ng walls
o determine nless:
ssuming =
eals no signs
cate crackin
Seismic
Buildings
alysing thems two-way a
integral uni
ader course
hat the wyth
dependently
ry four to ut-of-plane (through theple brick whan the hea
e the sufficicentreline oheader briccontributes
of the heade
uctural wall,ick (110 mmne checks.
the partitioe building a
be assumedformation) a
nd for both east value foessive failur
the capacit
= 1 and Sp =
s of crackin
ng of the bri
c Assessment o
m as spanniassemblages
it for face-l
es at least e
hes are capa
y.
six courses(but note the whole wal
walls the heaader course
iency of theof the lowercks crossings a shear reser and fr is i
, assume them) thick, yo
ons, acousticand the risk
d to be suppand perpend
directions oound, as failre of the wh
ty of a wall
= 2, and
ng at that sec
ickwork is n
of Unreinforced
ISBN 978-
ing horizons.
oading if:
every fourt
able of actin
in commohe caution rll, with bricader course
on the out
e available hr wall equag the centresistance of 2its modulus
e wythe waou can assum
c linings orks for face-
ported at flodicular wall
of response lure in any ohole wall.
section, ign
ction, and
not expected
Masonry Buildi
10-0-473-26634
ntally betwe
th course a
ing as integr
on bond. Thraised abovcks lapping on the insi
tside to allo
header coural to P + Wt
eline. For th2frbt2/l, whes of rupture
all piggybacme they car
r fire lining-load collap
oor levels bls will still
(inwards aone storey f
nore the dire
d.
ngs
0-90
4-9
een
and
ral
his e). in
ide ow
rse Wt +
his ere of
cks rry
gs) pse
but be
and for
ect
SeUpd
If sh0. Inmguisotpo
E
Awm
w
w
n If
Than
ection 10 - Seismdated 22 April 2015
f you adopthould be lim3 times the
n the case omeet minimu
uidelines, lisue and arether supportortal or stee
lastic ana
A simple benwalls using Emet. Equation
where: PAMtn
where: ptg
n
=2 if recessf the recess i
he imposednd bottom, o
mic Assessmen
t a displacemited to 0.6
instability
of walls supum requireimits on the defined ints to face-lo
el bracing re
alysis
nding analyEquation 10n 10.9 is ap
P = LoAn = NeM = Mnom = No
p = degross = ov
n = nu
ses are provis less than
d moment mor critical at
t of Unreinforce
ement base6 times the idisplacemen
pported agaements to he deflectionn Section 10oaded walls,etrofits.
ysis may be0.9 providedpplicable for
oad applied et plan area
Moment capaominal thick
epth of mortverall thicknumber of rec
vided on bot6 mm, it ca
Figure
may be assut the base o
ed Masonry Buil
ed approachinstability dnt for cantil
ainst face loensure the n of diaphr
0.8.3.2. The, for examp
e performedd that the crr a unit wall
d to top of paa of masonryacity of the kness of wa
tar recess (iness of wallcesses.
th sides; n=an be ignore
10.62: Poin
umed criticaf cantilever
Seismic As
ldings
h, the maxdisplacemenlever walls,
oad, deflecwalls can
ragms are cese deflectiople, the supp
d for the seriteria givenl length.
anel (N) y (mm2) panel (Nmm
all excludin
in mm) as shl (in mm)
1 otherwiseed.
nting with re
al at mid-her walls.
ssessment of U
IS
imum out-ont for simpl e.g. parape
tion of the n respond aconsidered on limits shoport that ma
eismic assen in Section
m) g pointing (
hown in Fig
e.
ecess
ight of wall
Recess
Unreinforced Ma
SBN 978-0-4
of-plane dily supportedets.
supports was assumeda diaphrag
hould also apay be provid
essment of f10.8.5.2 - G
(mm)
gure 10.62
ls restrained
asonry Buildings
10-91473-26634-9
isplacementd walls and
will need tod. In thesegm capacitypply to anyded by steel
face-loadedGeneral are
…10.9
…10.10
d at the top
s
9
t d
o e y y l
d e
p
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-92
Updated 22 April 2015 ISBN 978-0-473-26634-9
The direct tensile strength, f’t, should be ignored in capacity calculations unless there is no sign of pre-cracking in the wall at the section being considered and the demand is assessed assuming fully elastic behaviour and taking Sp =2 (synonymous with applying a 0.5 factor to the capacity) and cracking of the brickwork in the region of the section is not expected for loading in-plane.
Inelastic displacement-based analysis for walls spanning vertically between supports
Follow the steps below to assess the displacement response capability and displacement demand in order to determine the adequacy of the walls. Note:
Appendix 10B provides some guidance on methods for determining key parameters. Refer to Figure 10B.1 for the notation employed.
We have also provided some approximations you can use (listed after these steps) if wall panels are uniform within a storey (approximately rectangular in vertical and horizontal section and without openings).
Charts are provided in Appendix 10C that allow assessment of %NBS for regular walls (vertically spanning and vertical cantilever) in terms of height to thickness ratio of the wall, gravity load on the wall and parameters defining the demand on the wall. The wall panel is assumed to form hinge lines at the points where effective horizontal restraint is assumed to be applied. The centre of compression on each of these hinge lines is assumed to form a pivot point. The height between these pivot points is the effective panel height h (in mm). At mid-height between these pivots, height h/2 from either, a third pivot point is assumed to form. The recommended Steps for assessment of walls following the displacement-based method are discussed below:
Step1
Divide the wall panel into two parts: a top part bounded by the upper pivot and the mid height between the top and bottom pivots; and a bottom part bounded by the mid-height pivot and the bottom pivot.
Note:
This division into two parts is based on the assumption that a significant crack will form at the mid height of the wall, where an effective hinge will form. The two parts are then assumed to remain effectively rigid. While this assumption is not always correct, the errors introduced by the resulting approximations are not significant.
One example is that significant deformation occurs in the upper part of top-storey walls. In particular, where the tensile strength of the mortar is small the third hinge will not necessarily form at the mid height.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-93
Updated 22 April 2015 ISBN 978-0-473-26634-9
Step 2
Calculate the weight of the wall parts: Wb (in N) of the bottom part and Wt (in N) of the top part, and the weight acting at the top of the storey, P (in N).
Note:
The weight of the wall should include any render and linings, but these should not be included in tnom or t (in mm) unless the renderings are integral with the wall. The weight acting on the top of the wall should include all roofs, floors (including partitions and ceilings and the seismic live load) and other features that are tributary to the wall.
Step 3
From the nominal thickness of the wall, tnom, calculate the effective thickness, t.
Note:
The effective thickness is the actual thickness minus the depth of the equivalent rectangular stress block. The reduction in thickness is intended to reflect that the walls will not rock about their edge but about the centre of the compressive stress block.
The depth of the equivalent rectangular stress block should be calculated with caution, as the depth determined for static loads may increase under earthquake excitation. Appendix 10B suggests a reasonable value based on experiments, t = tnom (0.975-0.025 P/W). The thickness calculated by this formula may be assumed to apply to any type of mortar, provided it is cohesive. For weaker (and softer) mortars, greater damping will compensate for any error in the calculated t.
Step 4
Assess the maximum distance, ep, from the centroid of the top part of the wall to the line of action of P. Refer to Figure 10B.1 for definition of eb, et and eo. Usually, the eccentricities eb and ep will each vary between 0 and t/2 (where t is the effective thickness of the wall). Exceptionally they may be negative, i.e. where P promotes instability due to its placement. When considering the restraint available from walls on foundations assume the foundation is the same width as the wall and use the following values for eb:
0 if the factor of safety for bearing under the foundation, for dead load only (FOS), is equal to 1
t/3 if FOS = 3 (commonly the case) t/4 if FOS = 2
Note:
Figure 10B.2 shows the positive directions for the eccentricities for the assumed direction of rotation (angle A at the bottom of the wall is positive for anti-clockwise rotation).
The walls do not need to be rigidly attached or continuous with a very stiff section of wall beyond to qualify for an assumption of full flexural restraint.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-94
Updated 22 April 2015 ISBN 978-0-473-26634-9
Care should be taken not to assign the full value of eccentricity at the bottom of the wall if the foundations are indifferent and may themselves rock at moments less than those causing rocking in the wall. In this case, the wall might be considered to extend down to the supporting soil where a cautious appraisal should then establish the eccentricity. The eccentricity is then related to the centroid of the lower block in the usual way.
Step 5
Calculate the mid-height deflection, i, that would cause instability under static conditions. The following formula may be used to calculate this deflection.
…10.11
where:
…10.12
and:
…10.13
Note:
The deflection that would cause instability in the walls is most directly determined from virtual work expressions, as noted in Appendix 10B.
Step 6
Assign the maximum usable deflection, m (in mm), as 0.6 i.
Note:
The lower value of the deflection for calculation of instability limits reflects that response predictions become difficult as the theoretical limit is approached. In particular, the response becomes overly dependent on the characteristics of the earthquake, and minor perturbances lead quickly to instability and collapse.
Step 7
Calculate the period of the wall, Tp, as four times the duration for the wall to return from a displaced position measured by t (in mm) to the vertical. The value of Δt is less than Δm. Research indicates that t = 0.6m =0.36i for the calculation of an effective period for use in an analysis using a linear response spectrum provides a close approximation to the results of more detailed methods. The period may be calculated from the following equation:
4.07 …10.14
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-95
Updated 22 April 2015 ISBN 978-0-473-26634-9
where J is the rotational inertia of the masses associated with Wb, Wt and P and any ancillary masses, and is given by the following equation:
…10.15
where Jbo and Jto are mass moment of inertia of the bottom and top parts about their centroids, and Janc is the inertia of any ancillary masses, such as veneers, that are not integral with the wall but that contribute to the inertia. When treating cavity walls, make the following provisions:
When the veneer is much thinner than the main wythe, the veneer can be treated as an appendage. For inelastic analysis, the veneers can be accounted through Janc.
If both wythes are a one - brick (110 mm) thick, then these could be treated as independent walls. Allocate appropriate proportion of overburden on them and solve the problem in the usual way.
Where an accurate solution is the objective, solve the general problem with the kinematic constraint that the two walls deflect the same.
Note:
The equations are derived in Appendix 10B. You can use the method in this appendix to assess less common configurations as necessary.
Step 8
Calculate the design response coefficient Cp(Tp) in accordance with Section 8 NZS 1170.5 taking p =1 and substituting C (Tp):
…10.16
where: Chc(Tp) = the spectral shape factor ordinate, Ch(Tp), from NZS 1170.5 for
Ground Class C and period Tp, provided that, solely for the purpose of calculating Chc(Tp), Tp need not be taken less than 0.5 sec.
When calculating CHi from NZS 1170.5 for walls spanning vertically and held at the top, hi should be taken as the average of the heights of the points of support (typically these will be at the heights of the diaphragms). In the case of vertical cantilevers, hi should be measured to the point from which the wall is assumed to cantilever. If the wall is sitting on the ground and is laterally supported above, hi may be taken as half of the height to the point of support. If the wall is sitting on the ground and is not otherwise attached to the building it should be treated as an independent structure, not as a part. This will involve use of the appropriate ground spectrum for the site.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-96
Updated 22 April 2015 ISBN 978-0-473-26634-9
Note:
The above substitution for Ci(Tp) has been necessary because the use of the tri-linear function given in NZS 1170.5 (Equations 8.4(1), 8.4(2) and 8.4(3) does not allow appropriate conversion from force to displacement demands. The revised Ci(Tp) converts to the following, with the numerical numbers available from NZS 1170.5 Table 3.1.
Ci(Tp) = 2.0 for Tp < 0.5sec
= 2.0(0.5/ Tp)0.75 for 0.5 < Tp < 1.5sec
= 1.32/ Tp for 1.5 < Tp < 3sec
= 3.96/ Tp2 for Tp > 3sec
Only 5% damping should be applied. Experiments show that expected levels of damping from impact are not realised: the mating surfaces at hinge lines tend to simply fold onto each other rather than impact.
Step 9
Calculate , the participation factor for the rocking system. This factor may be taken as:
…10.17
Note:
The participation factor relates the response deflection at the mid height of the wall to the response deflection for a simple oscillator of the same period and damping.
Step 10
From Cp(Tp), Tp, Rp and calculate the displacement response, Dph (in mm) as:
/2 . . ...10.18
where: Cp(Tp) = the design response coefficient for face-loaded walls (refer Step 8
above, and for more details refer to Section 10.10.3) Tp = Period of face-loaded wall, sec Rp = the part risk factor as given by Table 8.1, NZS 1170.5 Cp(Tp) Rp ≤ 3.6.
Note that with Tp expressed in seconds, the multiplied terms (Tp/2π)2 × Cp(Tp) × g may be closely approximated in metres by:
/2 MIN /3, 1 …10.19
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-97
Updated 22 April 2015 ISBN 978-0-473-26634-9
Step 11
Calculate
% 100 ∆ / 60 ∆ / …10.20
Note:
The 0.6 factor applied to i reflects that response becomes very dependent on the characteristics of the earthquake for deflections larger than 0.6i.
The previous version of these guidelines allowed a 20% increase in %NBS calculated by the above expression. However that is not justified now that different displacements are used for capacity and for the period and the subsequent calculation of demand. Note:
Steps 12 to 14 are only required for anchorage design.
Step 12
Calculate the horizontal accelerations that would just force the rocking mechanism to form. The acceleration may be assumed to be constant over the height of the panel, reflecting that it is associated more with acceleration imposed by the supports than with accelerations associated with the wall deflecting away from the line of the supports. Express the acceleration as a coefficient, Cm, by dividing by g.
Note:
Again, virtual work proves the most direct means for calculating the acceleration. Appendix 10B shows how and derives the following expression for Cm, in which the ancillary masses are assumed part of Wb and Wt.
…10.21
Note:
To account for the initial enhancement of the capacity of the rocking mechanism due to tensile strength of mortar and possible rendering, we recommend that Cm be cautiously assessed when mortar and rendering are present or in the case of retrofit likely to be added. The value of Cm may also be too large to use for the design of connections. Accordingly, it is recommended that Cm need not be taken greater than the maximum part coefficient determined from Section 8 NZS 1170.5 setting Rp and p =1.0.
Step 13
Calculate Cp(0.75), which is the value of Cp(Tp) for a part with a short period from NZS 1170.5 and define a seismic coefficient for the connections which is the lower of Cm, Cp(0.75) or 3.6
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-98
Updated 22 April 2015 ISBN 978-0-473-26634-9
Note:
Cp(0.75) is the short period ordinate of the design response coefficient for parts from NZS 1170.5, and 3.6g is the maximum value of Cp(Tp) required to be considered by NZS 1170.5 when Rp and p =1.0 .
Step 14
Calculate the required support reactions using the contributing weight of the walls above and below the connection (for typical configurations this will be the sum of Wb and Wt for the walls above and below the support accordingly) and the seismic coefficient determined in Step 13.
Step 15
Calculate
%NBS = Capacity of connection from Section 10.8.4 x 100 …10.22 Required support reaction from Step 14
Note:
If supports to face-loaded walls are being retrofitted, we recommend that the support connections are made stronger than the wall(s) and not less than required using a seismic coefficient of Cp(0.75), i.e. do not take advantage of a lower Cm value.
Simplifications for regular walls
You can use the following approximations if wall panels are uniform within a storey (approximately rectangular in vertical and horizontal section and without openings) and the inter-storey deflection does not exceed 1% of the storey height. The results are summarised in Table 10.12. The steps below relate to the steps for the general procedure set out above.
Step 1 Divide the wall as before.
Step 2 Calculate the weight of the wall, W (in N), and the weight applied at the top of the storey, P (in N).
Step 3 Calculate the effective thickness as before, noting that it will be constant.
Step 4 Calculate the eccentricities, eb, et and ep. Each of these may usually be taken as either t/2 or 0.
Step 5 Calculate the instability deflection, i from the formulae in Table 10.12 for the particular case.
Step 6 Assign the maximum usable deflection, m, for capacity as 60% of the instability deflection.
Step 7 Calculate the period, which may be taken as 4.07√(J/a), where J and a are given in Table 10.12. Alternatively, where the wall is fairly thin (h/t is large), the period may be approximated as:
SeUpd
St
St
St
St
N
Chvaw Ta
BoCoNu
No
1.
2.
3.
ection 10 - Seismdated 22 April 2015
in w
tep 8 Calc
tep 9 Calcthe evaluTabl
tep 10 Calcmeth
tep 11 Calc
Note:
harts are prarious boun
wall, gravity
able 10.12: S
oundary ondition umber
ep
eb
b
a
i = bh/(2a)
J
Cm
ote:
The boundary
The top eccenis the horizonboundary con
The eccentricshould be ent
mic Assessmen
.
which h is ex
culate Cp(Tp
culate the paexpression
ue of 1.5 or le 10.12.
culate Dph hod.
culate %NB
rovided in ndary condiload on the
Static instab
(W
(W
{(W/1
+
(2+4
y conditions of
ntricity, et, is nontal distance frondition.
cities shown in tered as a negat
t of Unreinforce
/
xpressed in
p) following
articipationexpanded tomay be ass
from Cp(Tp
S in the sam
Appendix 1itions for re wall and fa
bility deflect
0
0
0
W/2+P)t
W/2+P)h
t/2
2)[h2 +7t2]
+Pt2}/g
4P/W)t/h
the piers shown
ot related to a bom the central p
the sketches isive number.
ed Masonry Buil
metres.
g Equation 1
n factor as foo give =
sessed by us
p), Tp and
me manner a
10C that alregular wallactors defin
tion for unif
1
0
t/2
(W+3P/
(W/2+P
(2W+3P(2W+4
{(W/12)[h2
+9Pt2/4
(4+6P/W
n above are for
boundary condipivot point to t
s for the positiv
Seismic As
ldings
10.16.
or the generWh2/8J. Thsing the sim
in the s
as for the ge
llow the %Nls spanning
ning the dem
form walls –
/2)t
P)h
P)t P)
+16t2]
4}/g
{(
W)t/h
clockwise pote
ition, so is not ithe centre of ma
ve sense. Where
ssessment of U
IS
ral method, his may be tmplified exp
same mann
eneral meth
NBS to be g vertically,mand.
– various bo
2
t/2
0
(W/2+3P/2)t
(W/2+P)h
(W+3P)t (2W+4P)
(W/12)[h2+7t2]
+9Pt2/4}/g
(2+6P/W)t/h
ential rocking.
included in the ass of the top b
e the top eccen
Unreinforced Ma
SBN 978-0-4
with the nutaken at the
pression for
ner as for t
hod.
calculated , given h/tG
oundary con
(W
(W
] {(W/1
+
4(1+
table. The top block which is
ntricity is in the
asonry Buildings
10-99473-26634-9
…10.23
umerator ofe maximumJ shown in
the general
directly forGross for the
nditions
3
t/2
t/2
W+2P)t
W/2+P)h
t
2)[h2+16t2]
4Pt2}/g
+2P/W)t/h
eccentricity, et,not related to a
e other sense ep
s
9
9
f m n
l
r e
, a
p
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-100
Updated 22 April 2015 ISBN 978-0-473-26634-9
Vertical cantilevers
Parameters for assessing vertical cantilevers, such as partitions and parapets are derived in Appendix 10B. Please consult this appendix for general cases. For parapets of uniform rectangular cross-section, you may use the following approximations. These steps relate to the steps set out earlier for the general procedure for walls spanning between vertical diaphragms.
Step 1 You do not need to divide the parapet. Only one pivot is assumed to form: at the base.
Step 2 The weight of the parapet is W (in N). P (in N) is zero.
Step 3 The effective thickness is t (in mm) = 0.98tnom.
Step 4 Only eb is relevant. It is equal to t/2.
Step 5 The instability deflection measured at the top of the parapet i = t.
Step 6 The maximum usable deflection measured at the top of the parapet m = 0.3i = 0.3t.
Step 7 The period may be calculated from the assumption that t = 0.8m = 0.24i.
0.65 1 …10.24
in which h, the height of the parapet above the base pivot, and t, the thickness of the wall, are expressed in metres. The formulation is valid for P = 0, eb = t/2, yb = h/2 and approximating t = tnom.
Step 8 Calculate Cp(Tp) (refer to Step 8 of the general procedure for walls spanning vertically between diaphragms).
Step 9 Calculate = 1.5/[1+(t/h)2] ≤ 1.5. …10.25
Step 10 Calculate Dph from Cp(Tp), Tp and and as before.
Step 11 Calculate %NBS as for the general procedure for walls spanning between a floor and an upper floor or roof, from;
% 100∆ / 30∆ / 30 / . ...10.26
Note:
Steps 12 to 14 are only required for anchorage design.
Step 12 Calculate Cm = t/h. …10.27
Step 13 Calculate Cp(0.75) which is the value of Cp(Tp) for a part with a short period from NZS 1170.5. and define a seismic coefficient for the connections which is the lower of Cm, Cp(0.75) and 3.6.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-101
Updated 22 April 2015 ISBN 978-0-473-26634-9
Step 14 Calculate the base shear from W, Cm and Cp(0.75). This base shear adds to the reaction at the roof level restraint.
Note:
Charts are provided in Appendix 10C that allow the %NBS to be calculated directly for various boundary conditions for regular walls cantilevering vertically, given h/tGross for the wall, gravity load on the wall and factors defining the demand.
Gables
Figure 10.63(a) shows a gable that is:
free along the vertical edge
simply supported along the top edge (at roof level), and
continuous at the bottom edge (ceiling or attic floor level). This somewhat unusual case is useful in establishing parameters for more complex cases. The following parameters can be derived from this gable:
2 3 …10.28
32 …10.29
Note:
In the above equations, W and P are total weights, not weights per unit length. Also note that the participation factor now has a maximum value of 2.0 (t << h, P = 0). These results can be used for the gable in Figure 10.63(b) to provide a cautious assessment that does not recognise all of the factors that could potentially enhance the performance of such gables, such as the beneficial effects of membrane action Note:
There are several factors that enhance performance in gables like those shown in Figure 10.63(a), all of which relate to the occurrence of significant membrane action. Guidance on this aspect will be provided in future versions of this document when the necessary research (including testing) has been undertaken. (Please also refer to the following section on walls spanning horizontally and vertically.)
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-102
Updated 22 April 2015 ISBN 978-0-473-26634-9
(a) Basic gable wall for defining parameters
(b) Typical gable for which results from (a) can be applied
Figure 10.63: Gable configurations
SeUpd
10
Pashspstuacre
N
Cbegoprm
Thstrbythcobeex
ection 10 - Seismdated 22 April 2015
H0.8.5.3
ast earthquhowing yiepanning slabudy is recoccount diffeesulting from
Note:
omputationeen shown ood reliabilroperties, th
makes them u
he approacrength desigy Lawrencehat, at the pontributionsending mecxperimental
mic Assessmen
Horizonta
uakes have ld line patb if the wammended i
erent elastic m the expec
Figure 1
nally intensito predict lity. Howe
he high comunsuitable f
h prescribegn of two-w
e and Marshpoint of ults of momenchanisms (Fl data set ha
t of Unreinforce
al and ve
shown thatterns (Figualls are attacif two-wayproperties,
cted behavio
10.64: Idealis
ive analyticthe out-of-ver, their
mputational for everyday
ed by the Away spanninhall (1996).timate strennt capacitieFigure 10.6ave been sh
ed Masonry Buil
rtical-ho
at URM waure 10.64) ched to thespanning is displacemeour of the w
sed crackin
cal methodo-plane strenreliance oneffort and
y design use
Australian mng walls is t This is a fngth, the loes along ve64). Compahown to be
Seismic As
ldings
rizontal s
alls can acsimilar to
e supports os to be assuent compati
wall in the or
ng patterns f
ologies suchngth of twon knowing the high ane.
masonry cothe so-calledform of rigioad resistanertical and arisons of slargely fav
ssessment of U
IS
spanning
ct as a twothose that
on four sideumed. This bility, and arthogonal d
for masonry
h as finite -way spannthe precis
nalytical ski
ode AS 370d virtual woid plastic annce of the wdiagonal crstrength preourable in t
Unreinforced Ma
SBN 978-0-4
g panels
o-way spant occur in es. Howevestudy shoulany detrime
direction.
y walls
element anning URM se values oill required
00: 2011 fork methodnalysis whiwall is obtrack lines iedictions wthe sources
asonry Buildings
10-103473-26634-9
nning panela two-way
er, a specialld take intoental effects
nalysis havewalls with
of materialof the user
for ultimate, developedch assumestained fromin two-way
with a large mentioned
s
3
9
l y l o s
e h l r
e d s
m y e d
Section 10 - SeUpdated 22 April 20
before, in sthe method
More recenexpressionimprovememechanicadimensionaexpressioninto the vir
The currendesign offbehaviour proceduresupdate.
10.8.6
10.8.6.1
The capaccapacity of Wall compwalls witho The capaciSection 10 The recompenetration Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
eismic Assessm015
spite of numd which are
ntly, Willisns for calents over
al models, aally consis
ns perform frtual work a
ntly availablfice enviroof walls of
s suitable f
Walls u
General
city of wallf the compo
ponents undout penetrat
ity of wall .8.6.2.
mmended ans is as follo
Divide thebetween penetratio
Determineaccordancloads on th
DetermineSection 10secondary
Determinecapacity. Tsway inde
Based on governed b
ment of Unreinfo
merous shorstill curren
s et al. (200culating ththe AS 37account forstent. Furthfavourably iapproach.
le research onment. Hof this kind, for design
under in-
l
l componenonent.
der in-planetion and wa
component
approach tows:
e wall comthe penetrans.
e the capacce with Secthe element
e the capa0.8.6.3. Fy elements a
e if the capaThis will ne
ex as defined
the sway by the pier
orced Masonry B
rtcomings otly prescrib
04) and Grhe momen700 expresr the benefhermore, Win predicting
is not suffiowever, sige.g. Vaculioffice use
-plane lo
nts will typ
e load can alls with pen
ts without p
o assessing
mponent intoations and
city of the ption 10.8.6.due to grav
acity of tFor basic band ignored
acity of the eed to be evd in Section
index deteritself or the
Seismic
Buildings
of the momebed in AS 37
riffith et al.nt capacitiessions as tficial effectWillis et ag the ultima
icient for asgnificant pik, (2012),and routin
oad
pically be r
be broadly netrations.
penetrations
g the capa
o individua‘spandrel’
pier elemen2. This wil
vity loads.
the spandrbuildings tin the asses
penetrated valuated for n 10.8.6.4 ca
rmine if the abutting sp
c Assessment o
ent capacity700 (AS, 20
(2007) haves which they are bs of verticaal. (2004) ate load cap
ssessing twoprogress haand we exp
ne assessme
represented
categorised
s should be
acity of a
al ‘elements’ elements
nts in a simll require an
rel elementthe spandressment of la
wall is goveeach spand
an be used t
e capacity pandrel elem
of Unreinforced
ISBN 978-
y expression011).
ve developeincorporat
based on mal compresdemonstra
pacity when
o-way panelas been mapect to tranent in time
by the hor
d into two
e assessed a
wall com
s’ comparinabove an
milar mannen assessmen
ts in accoels may bateral capac
erned by spdrel to pier cto do this.
of each piment.
Masonry Buildi
10-1-0-473-26634
ns used with
ed alternatite significamore rationssion, and aated that tn implement
ls in a typicmade into tnslate this in
for the ne
rizontal she
main group
as outlined
mponent w
ng the ‘piend below t
er to walls nt of the ax
ordance wbe treated city.
pandrel or pconnection.
ier element
ngs
104
4-9
hin
ive ant nal are the ted
cal the nto ext
ear
ps:
in
ith
rs’ the
in xial
ith as
ier A
is
SeUpd
St
Thbresit ea
10
Thlostrthth Fodi(mis m
D
Th Thw(A
w
Ta
Cr
Sle
Sq
NoLin
ection 10 - Seismdated 22 April 2015
tep 6: CthS
he degree toroken downstablish the is expected
ach storey in
In0.8.6.2
he in-planeower of the rength capa
he basis for hese may als
or the purpisplacementmaking allow
subjected mechanism a
iagonal te
his is one o
he maximuwhere you ASCE 41-13
where:
βAfd
fa
able 10.13: S
riterion
ender piers, w
quat piers, wh
ote: near interpolati
mic Assessmen
Carry out anhe capacity
Section 10.8
o which a wn into indivbuilding’s gd that it win the buildin
n-plane c
e strength cassessed di
acities as dethe calcula
so limit the
poses of asst, y, may bwance for cto a later
as given belo
ensile cap
f the most i
um diagonahave decid3). Refer to
β = fAn = afdt = mfa = a
o
Shear stress
where heff/l > 1
ere heff/l < 0.5
ion is permitted
t of Unreinforce
n analysis ofy of the
8.6.4.
wall on a sividual compglobal capaill be necesng.
capacity
capacity ofiagonal tenetermined bation of theshear that c
sessing the be taken as tcracking etcral shear cow. Refer a
acity
mportant ch
l tensile strded to ignthe section
1
factor to corarea of net mmasonry diaaxial comprof the wall/p
s factor, β, f
.5
5
d for intermedia
ed Masonry Buil
f the wall cindividual
ingle line, bponents wilacity. This isssary to ass
of URM w
URM wallnsile, toe crubelow. Thie deformatiocan be resist
wall or pithe sum of tc as recomm
consistent walso Section
hecks to be
rength of anore them) below if yo
rrect nonlinmortared/gragonal tensiression strespier, MPa.
for Equation
ate values of hef
Seismic As
ldings
omponent tl pier elem
but extendinl depend ons discussed ess the cap
walls and
ls and pier ushing, in-pis then becoon capacityted.
er capacitiethe flexural mended in Swith achievn 10.9.4.5.
carried out
a wall, piercan be c
ou decide to
near stress drouted sectioion strengthss due to gr
n 10.30
ff/l
ssessment of U
IS
to determinements acti
ng over seven the methofurther in S
pacity for ea
d pier ele
elements shplane rockinomes the m. Where D
es for each and shear i
Section 10.7ving the sh
.
r or spandrealculated u
o account fo
istribution (on of the wa
h (Equation ravity loads
β
0.67
1.00
Unreinforced Ma
SBN 978-0-4
e its capaciting in ser
eral storeysod of analySection 10.9ach wall lin
ements
hould be tang or bed jo
mode of behDPC layers
h mechanismin-plane dis7.6) when thear streng
el without using Equaor the effect
(Table 10.1all web, mm10.3), MPa
s calculated
asonry Buildings
10-105473-26634-9
ty based onries. Refer
s, should beysis used to9. Typicallyne between
aken as theoint slidinghaviour andare present
m the yieldsplacementsthe elementth for that
flanges (oration 10.30t of flanges.
…10.30
3) m2 a
at the base
s
5
9
n r
e o y n
e g d t
d s t t
r 0
e
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-106
Updated 22 April 2015 ISBN 978-0-473-26634-9
Refer to Figure 10.65 for the definition of heff. This failure mode occurs when the diagonal tensile strength of a wall or pier is exceeded by the principal stresses. It is one of the undesirable failure modes as it causes a rapid degradation in strength and stiffness after the formation of cracking, ultimately leading to loss of load path. For this reason a deformation limit of y for this failure mode is recommended. This failure mode is more common where axial stresses are high, piers are squatter and the tensile strength of masonry is low. Diagonal tension failure leads to formation of an inclined diagonal crack that commonly follows the path of bed and head joints through the masonry, because of the lower strength of mortar compared to brick. However, cracking through brick is also possible if the mortar is stronger. In New Zealand masonry, the crack pattern typically follows the mortar joint. For conditions where axial stresses on walls or piers are relatively low and the mortar strengths are also low compared to the splitting strengths of the masonry units, diagonal tension actions may be judged not to occur prior to bed-joint sliding. However, there is no available research to help determine a specific threshold of axial stress and relative brick and mortar strengths that differentiates whether cracking occurs through the units or through the mortar joints (ASCE, 2013).
Toe crushing capacity
The maximum toe crushing strength, Vtc, of a wall, pier or spandrel can be calculated using Equation 10.31 if no flanges are present or if you have decided to ignore them. If flanges are to be accounted for, refer to the section below.
0.5 1.
…10.31
where:
α = factor equal to 0.5 for fixed-free cantilever wall/pier, or equal to 1.0 for fixed-fixed wall/pier
P = superimposed and dead load at top of the wall/pier Pw = self-weight of wall/pier Lw = length of the wall/pier, mm heff = height to resultant of seismic force (refer to Figure 10.65), mm fa = axial compression stress due to gravity loads at mid height of
wall/pier, MPa f’m = masonry compression strength, MPa (refer to Section 10.7.3).
SeUpd
Asp Aorthth
R
RunetXexbu Ash Thca
w
WEqfoth
ection 10 - Seismdated 22 April 2015
A deformatiopandrels res
A toe crushinr piers durinhe walls havhat inhibits t
Rocking ca
ocking failndertaken bt al. (2001),
Xu and Abraxhibiting rout also exhib
A generalisedhown in Fig
he maximuman be calcul
where: Vα
P
PLh
When assessquation 10.
orce. This che point of f
mic Assessmen
on limit of pectively.
ng failure mng in-planeve been retthe diagona
apacity
lure is oneby Knox (20
Magenes aams (1992)
ocking behabit very low
d relationshgure 10.66.
m probablelated using E
0.9
Vr = sα = f
fP = s
cPw = sLw = lheff = h
ing the cap32 will nee
can be assumfixity.
t of Unreinforce
Figu
y or ϕy is
mode is not aloading. H
trofitted witl tension fai
e of the s012), Anthoand Calvi (1), and Bothaviour havew levels of h
hip between
e rocking strEquation 10
0.5
strength of wfactor equalfixed-fixed superimposeconsideratioself-weight length of waheight to res
acity of waed to be adjmed to be a
ed Masonry Buil
ure 10.65: A
recommend
an expectedHowever, it th un-bondeilure mode.
stable modoine et al. (1995), Moonhara et al. (e substantiahysteretic da
n strength an
rength of a 0.32.
wall or walll to 0.5 for wall pier. ed and deaon of the wall/all or wall/psultant of se
alls without usted to acapplied at tw
Seismic As
ldings
A rocking pie
ded for this
d failure mostill needs ed post-ten
des of failu1995), Costn et al. (200(2010) have
al deformatiamping.
nd deformat
wall (cons
l pier basedfixed-free c
ad load at
/pier pier, mm eismic force
openings fcount for thwo thirds o
ssessment of U
IS
er
s failure mo
de of low-rito be assessioning or
ure. Experitley and Ab06), Bruneaue confirmedion capacity
tion for the
idered over
on rockingcantilever w
the top o
e (refer to F
for the full hhe different of the heigh
Unreinforced Ma
SBN 978-0-4
ode for wall
ise New Zesed; particua seismic i
imental invbrams (1996u and Paqud that URMy past initi
rocking me
r one level)
g wall, or equa
of the wall/
Figure 10.65
height of tht location ofht of the bu
asonry Buildings
10-107473-26634-9
ls/piers and
ealand wallsularly whenntervention
vestigations6), Franklinette (2004),
M elementsal cracking
echanism is
or pier, Vr,
…10.32
al to 1.0 for
/pier under
5), mm.
he building,f the lateralilding from
s
7
9
d
s n n
s n , s g
s
,
r
r
, l
m
Section 10 - SeUpdated 22 April 20
Nonlinear yield slopearea at the(refer Figutypically o
Figure 1
Deformatioa moment-compressioshould be rocking pie Under raregovern theassume elawall piers.
Note:
It is recoma wall/pierof a rockinconsideredare not parmm (3 wyhigher deflbe used foincluded iredistributi
eismic Assessm015
response oe due to P-e toe of theure 10.66). ccurs at larg
0.66: Gener
on associate-curvature oon fibre of based on a
er that is in
e conditionse ultimate dastic unload
mmended thar lateral drifng wall is cod appropriatrt of the se
ythes), are elections appor all wall/in the analion of the la
ment of Unreinfo
of rocking U effects bue rocking pi
This latenger rotation
ralised strenmaso
ed with the or similar a0.0035. Than equivalebearing.
s, the geomdeformationding hyster
at the capacft equal to thonsidered tote when theeismic resistexpected be proaching tw/pier elemelysis methoateral loads
orced Masonry B
URM piers ut will be liier reduces nt toe crushns and lower
ngth-deformnry walls or
onset of toeanalytical ae axial com
ent compres
metric stabilin capacity. etic charact
city of a rockhe lower of o be less ree deflectionting systemable to pro
wice the liments when od used. Sbetween ele
Seismic
Buildings
is generallimited by to
to zero unhing differr shears.
mation relatior piers (ASC
e crushing, Δapproach anmpressive stssion zone
ity of the roIn the abs
teristics for
king wall/pf 0.003heff/Lliable and n
ns exceed thm and whichovide reliabmits given acyclic stiff
Such an anements whe
c Assessment o
y characteroe crushing,nder increass from tha
onship for rCE 41-13)
Δtc,r / heff, shnd a maximtress on the of the effe
ocking piersence of sur rocking U
ier be limitew or 0.011.not to provihese values.h have a thble vertical labove. Thesfness and snalysis wilen this is ne
of Unreinforced
ISBN 978-
rised by a n, as the effesing lateral at discussed
ocking of un
hould be calmum usable
toe due to ective net s
r due to P-ubstantiatingURM in-pla
ed to that co The lateralde the level. Wall/pier ickness greload carryinse greater listrength degll automaticcessary.
Masonry Buildi
10-1-0-473-26634
negative poective bearidisplaceme
d above as
nreinforced
lculated usie strain at t
gravity loasection of t
effects mg test resulane walls a
onsistent wl performanl of resilienelements th
eater than 3ng capacityimits can algradation acally inclu
ngs
108
4-9
st-ing ent
it
d
ing the ads the
may lts,
and
ith nce nce hat 50 at
lso are ude
SeUpd
Athtraadpico NEq Th(h
B
Bvabe ThpiFibe
F
Th
w
Th
ection 10 - Seismdated 22 April 2015
Assumption he spandrelsansmit vertdjacent pieriers acting aonditions.
Note that if quation 10.3
his behavioheight to len
ed-joint s
ed-joint slidarious reseehaviour ha
he recommiers governeigure 10.67een adopted
Figure 10.67
he maximum
where: PP
he 0.7 facto
mic Assessmen
of fixity ors above antical shears rs may not as cantileve
the self-we32 may ove
our mode isngth ratio >
liding she
ding failurearchers hav
ave substant
mended geneed by bed-j
7. A simplifd.
: Generalisepiers go
m probable
0.7
f = mP = sPw = s
or is to refle
t of Unreinforce
cantilever nd below th
and bendinprovide fix
ers. In gene
eight of the erestimate th
s common w2) and mor
ear capaci
is one of thve confirmtial deforma
eralized forjoint slidingfied form o
ed force-defoverned by b
sliding she
masonry coesuperimposeself-weight
ct the overa
ed Masonry Buil
action depehe rocking ng. Conversxity at the teral, deep sp
pier is larghe rocking c
where axialrtar strength
ty
he stable mmed that Uation capaci
rce-deformag or slidingof the ASC
formation rebed-joint sli
ear strength,
efficient of ed and deadof wall/pier
all reliability
Seismic As
ldings
ends on thepier and o
sely, wall sptops and bopandrels co
ge and boucapacity.
l stresses arh are relative
modes of failURM eleme
ty past initi
ation relatiog stair-steppCE 41-13 fo
elationship fiding or stai
, Vs, can be
f friction d load at topr above the
y of the slid
ssessment of U
IS
e stiffness an how effepandrels thaottoms of piuld provide
undary cond
re low, walely better.
lure. Investients exhibital cracking
onship for ped failure morce-deform
for unreinfoir-stepped s
found from
p of the wallsliding plan
ding mechan
Unreinforced Ma
SBN 978-0-4
and overall ectively spaat are weakiers and mae fixed-fixe
ditions are f
lls or piers
igations undting bed-jo.
URM wallmodes is il
mation relati
orced masonsliding
m Equation 1
l/pier ne being con
nism calcul
asonry Buildings
10-109473-26634-9
integrity ofandrels cank relative toay result ind boundary
fixed-fixed,
are slender
dertaken byoint sliding
ls and walllustrated inionship has
nry walls or
10.33.
…10.33
nsidered
ation.
s
9
9
f n o n y
,
r
y g
l n s
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-110
Updated 22 April 2015 ISBN 978-0-473-26634-9
The capacity for bed-joint sliding in masonry elements is a function of bond and frictional resistance. Therefore, Equation 10.33 includes both factors. However, with increasing cracking, the bond component is progressively degraded until only the frictional component remains. The probable residual wall sliding shear capacity, Vs,r, is therefore found from Equation 10.33 setting the cohesion, c, equal to 0.
Note:
It is recommended that the bed joint sliding capacity of a rocking wall/pier be limited to a lateral drift of 0.003. The lateral performance of a wall/pier is considered to be unreliable and not able to provide the level of resilience considered appropriate when the deflections exceed this value. Wall/pier elements that are not part of the seismic resisting system are expected be able to provide reliable vertical load carrying capacity at higher drifts, approaching 0.075. These greater limits can also be used for all wall/pier elements when cyclic stiffness and strength degradation are included in the analysis method used. Such an analysis will automatically include redistribution of the lateral loads between elements when this is necessary.
Slip plane sliding
A DPC layer, if present, will be a potential slip plane, which may limit the capacity of a wall. The capacity of a slip plane for no slip can be found from Equation 10.34:
…10.34
where: dpc = DPC coefficient of friction. Typical values are 0.2-0.5 for
bituminous DPC, 0.4 for lead, and higher (most likely governed by the mortar itself) for slate DPC
Other terms are as previously defined. Note:
Where sliding of a DPC layer is found to be critical, testing of the material in its current/in situ state may be warranted. Alternatively, parametric checks, where the effects of low/high friction values are assessed, may show that the DPC layer is not critical in the overall performance. Sliding on a DPC slip plane does not necessarily define the deformation capacity of this behaviour mode. Evaluating the extent of sliding may be calculated using the Newmark sliding block (Newmark, 1965) or other methods. However, exercise caution around the sensitivity to different types of shaking and degradation of the masonry above/below the sliding plane. Where sliding is used in the assessment to give a beneficial effect, this should be subject to peer review.
SeUpd
Ef
It thC(2thstwmreth N
Orein
If inleflarecoco
10
G
Thillis (2(2
ection 10 - Seismdated 22 April 2015
ffect of wa
is commonhe in-plane ostley and
2008) and Rhe response iffness than
where estimamodes of faecommendehe critical be
Note:
ne of the premain integrntegrity of th
f flanges aren compressioengths of thanges (to r
elating to uponsider diffeorrespondin
U0.8.6.3
General
he recommlustrated in based on e
2012) Grazi2014).
Figu
mic Assessmen
all and pie
n practice tocapacity ofAbrams (19
Russell & Inof in-plane
n those withated rockinailure), are d approach ehaviour mo
reconditionsral with the he connectio
e taken into on are the lhe flanges. resist globaplift in flanferent flangeng sequence
URM span
mended genFigure 10.
experimentaotti et al (20
ure 10.68: G
t of Unreinforce
er flanges
o ignore thef walls and996), Brune
ngham (2010e walls. Fla
hout flangesg, sliding sclose to tis to assess
ode and bas
s for taking in-plane pi
ons must be
account, it esser of sixIt is also c
al or componge walls (Ye lengths qus of actions
ndrel cap
neralized fo68. The rec
al work und012) and Gr
Generalized f
ed Masonry Buil
e effects of d piers. Howeau and Pa0) has showanged wallss. The assessshear, or stthe diagonas how muchsed on this d
into accouniers and wale ascertaine
t is commonx times the tcommon toonent overtYi, et al., 2ualitatively s.
pacity
orce-deformcommendeddertaken byraziotti et al
force-deformmasonry s
Seismic As
ldings
flanges on wever, expeaquette (200wn that flangs can have sment couldair-step craal tensile sh flange is rdetermine if
nt the effectlls during thd before ign
n to assumehicknesses
o assume thturning) are008). Othermay result
mation relatd generalize Beyer andl (2014) and
mation relatspandrels
ssessment of U
IS
the walls orerimental re04), Moon eges have theconsiderabl
d be particuacking strenstrength of equired for f further inv
t of the flanhe seismic snoring or in
that the lenof the in-pl
hat equivalee based onr approachein a variety
tionship foed force-deDazio (201
d as recomm
tionship for
Unreinforced Ma
SBN 978-0-4
r piers whilesearch undet al. (2006e potential tly higher st
ularly non-cngth (whichf pier and
diagonal tevestigation i
nges is that tshaking. Thncluding the
ngths of flalane walls oent lengths
n likely craes that eithey of crack p
or URM speformation r12a and 20mended by C
unreinforce
asonry Buildings
10-111473-26634-9
le assessingdertaken by6), Yi et al.to influencetrength andonservative
h are stablewalls. The
ension to beis required.
they shouldherefore, theem.
anges actingor the actual
of tensionck patternser model orpatterns and
pandrels isrelationship12b), KnoxCattari et al
ed
s
9
g y . e d e e e e
d e
g l n s r d
s p x l
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-112
Updated 22 April 2015 ISBN 978-0-473-26634-9
Expected in-plane strength of URM spandrels should be the lesser of the flexural and shear strengths. is the chord rotation of the spandrel, relative to the piers.
Note:
It is considered prudent to limit the deformation capacity of a spandrel panel to a panel drift of 3y if its capacity is to be relied on as part of the seismic resisting system. Panel chord rotation capacities beyond 0.02 or 0.01 for rectangular and arched spandrels respectively, for panels that are not assumed to be part of the lateral seismic resisting system, are not recommended as the performance of the spandrel (ie ability to remain in place) could become unreliable at rotations beyond these limits. These greater limits can also be used for all spandrel elements when cyclic stiffness and strength degradation are included in the analysis method used. Such an analysis will automatically include redistribution of the lateral loads between elements when this is necessary and therefore the need to distinguish, in advance, between elements of the lateral and non-lateral load resisting systems is not required. Two generic types of spandrel have been identified: rectangular and those with shallow arches. Recommendations for the various capacity parameters for these two cases are given in the following sections. Investigations are continuing on appropriate parameters for deep arched spandrels. In the interim, until more specific guidance is available, it is recommended that deep arched spandrels be considered as equivalent rectangular spandrels with a depth that extends to one third of the depth of the arch below the arch apex. The geometrical definitions used in the following sections are shown on Figure 10.69.
Figure 10.69: Geometry of spandrels with timber lintel (a) and shallow masonry arch (b)
(Beyer, 2012)
Rectangular spandrels
The expected in-plane strength of URM spandrels with and without timber lintels can be determined following the procedures detailed below.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-113
Updated 22 April 2015 ISBN 978-0-473-26634-9
Note:
There is limited experimental information on the performance of URM spandrels with lintels made from materials other than timber. However, URM spandrels with steel lintels are expected to perform in a similar manner to those with timber lintels.
When reinforced concrete lintels are present the capacity of the spandrel can be calculated neglecting the contribution of the URM.
Peak flexural strength
The peak flexural strength of rectangular spandrels can be estimated using Equation 10.35 (Beyer, 2012). Timber lintels do not make a significant contribution to the peak flexural capacity of the spandrels so can be ignored.
…10.35
where: ft = equivalent tensile strength of masonry spandrel psp = axial stress in the spandrel hsp = height of spandrel excluding depth of timber lintel if present bsp = width of spandrel lsp = clear length of spandrel between adjacent wall piers.
Unless the spandrel is prestressed the axial stress in the spandrel can be assumed to be negligible when determining the peak flexural capacity. Equivalent tensile strength of masonry spandrel, ft, can be estimated using Equation 10.36:
1.3 0.5 …10.36
where: pp = mean axial stress due to superimposed and dead load in the
adjacent wall piers f = masonry coefficient of friction c = masonry bed-joint cohesion.
Residual flexural strength
Residual flexural strength of rectangular URM spandrels can be estimated using Equation 10.37 (Beyer, 2012). Timber lintels do not often make a significant contribution to the residual flexural capacity of URM spandrels so they can be ignored.
, 1
. ...10.37
where: psp = axial stress in the spandrel fhm = compression strength of the masonry in the horizontal direction
(0.5f’m).
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-114
Updated 22 April 2015 ISBN 978-0-473-26634-9
Axial stresses are generated in spandrel elements due to the restraint of geometric elongation. Results from experimental research indicate that negligible geometric elongation can be expected when peak spandrel strengths are developed (Beyer, 2012; and Graziotti et al., 2012), as this is at relatively small spandrel rotations. As a result, there is little geometric elongation. Significant geometric elongation can occur once peak spandrel strengths have been exceeded, and significant spandrel cracking occurs within the spandrel, as higher rotations are sustained in the element. An upper bound estimate of the axial stress in a restrained spandrel, psp, can be determined using Equation 10.38 (Beyer, 2014):
1 ...10.38
where: fdt = masonry diagonal tension strength s = spandrel aspect ratio (lsp/hsp).
Equation 10.38 calculates the limiting axial stress generated in a spandrel associated with diagonal tension failure of the spandrel. The equation assumes the spandrel has sufficient axial restraint to resist the axial forces generated by geometric elongation. In most typical situations you can assume that spandrels comprising the interior bays of multi-bay pierced URM walls will have sufficient axial restraint such that diagonal tension failure of the spandrels could occur. Spandrels comprising the outer bays of multi-bay pierced URM walls typically have significantly lower levels of axial restraint. In this case the axial restraint may be insufficient to develop a diagonal tension failure in the spandrels. Sources of axial restraint that may be available include horizontal post-tensioning, diaphragm tie elements with sufficient anchorage into the outer pier, or substantial outer piers with sufficient strength and stiffness to resist the generated axial forces. For the latter to be effective the pier would need to have enough capacity to resist the applied loads as a cantilever. It is anticipated that there will be negligible axial restraint in the outer bays of many typical unstrengthened URM buildings. In this case you can assume the axial stress in the spandrel is nil when calculating the residual flexural strength.
Peak shear strength
Peak shear strength of rectangular URM spandrels can be estimated using Equations 10.39 and 10.40 (Beyer, 2012). Timber lintels do not make a significant contribution to the peak shear capacity of URM spandrels so can be ignored.
...10.39
.1 ...10.40
Unless the spandrel is prestressed you can assume the axial stress in the spandrel is negligible when determining the peak shear capacity. Equation 10.39 is the peak shear
SeUpd
strthbrEq
R
Odefixad
Resthof
Th
Yab
S
P
YEq
ection 10 - Seismdated 22 April 2015
rength assohe entire herick. If the quation 10.4
Residual sh
nce shear cemands. Whxed at the djacent pier
Figure 1
esidual shestimated as he applied lof URM span
he applied l
You can calcbove. Confi
pandrels w
Peak flexur
You can estiquation 10.4
mic Assessmen
ociated witheight of the
mortar is s40.
hear stren
cracking hashen presentother) can (Figure 10
0.70: Shear
ar strength the minimu
oad (Beyer,ndrels is neg
,
load, F, to b
culate spandrm the abili
with a sha
ral strengt
imate peak 43 (Beyer 2
t of Unreinforce
h the format spandrel: stronger tha
ngth
s occurred tt, timber lin
transfer th.70).
r mechanism
of crackedum of Equa2012). Wh
gligible and
be resisted b
drel axial stity of the tim
allow arch
th
flexural ca2012):
ed Masonry Buil
tion of cracuse this eqan the brick
the URM spntels acting he vertical
m of URM sp
d rectangulaation 10.41
hen no timbed can be assu
by the timbe
tresses, psp,mber lintel t
h
apacity of a
tan
Seismic As
ldings
cks throughquation whek and fract
pandrel canas beams (component
pandrels wit
ar URM spaor the capa
er lintel is pumed to be
er lintel can
, in accordato sustain th
a URM spa
ssessment of U
IS
h head and ben the morture of the
n no longer t(simply supt of the spa
th timber lin
andrels withacity of thepresent the rnil.
n be calculat
ance with thhe applied lo
andrel with
Unreinforced Ma
SBN 978-0-4
bed joints otar is weakbricks will
transfer in-pported at oandrel load
ntels (Beyer
h timber line timber linresidual she
ted as:
he proceduroad.
h a shallow
asonry Buildings
10-115473-26634-9
over almostker than the
occur, use
plane shearone end andd, F, to the
, 2012)
ntels can betel to resistear capacity
...10.41
...10.42
res outlined
arch using
...10.43
s
5
9
t e e
r d e
e t y
d
g
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-116
Updated 22 April 2015 ISBN 978-0-473-26634-9
where a is the arch half angle of embrace computed as:
tan ...10.44
where dimensions ri, ra and lsp are defined in Figure 10.69. The arch is considered shallow if the half angle of embrace, a, satisfies Equation 10.45 where ro is also defined in Figure 10.69.
cos ...10.45
Unless the spandrel is prestressed you can assume the axial stress in the spandrel is negligible when determining the peak flexural capacity.
Residual flexural strength
You can estimate the residual flexural capacity of a URM spandrel with a shallow arch using Equation 10.46 (Beyer 2012) and by referring to Figure 10.69.
, 1
. …10.46
where dimension htot is defined in Figure 10.69. You can calculate spandrel axial stresses, psp, with the procedures set out in the previous section.
Figure 10.71: Spandrel with shallow arch. Assumed load transfer mechanism after flexural
(a) and shear (b) cracking. (Beyer, 2012)
Peak shear strength
You can estimate peak shear strength of a URM spandrel with a shallow arch using Equations 10.47 and 10.48 (Beyer, 2012):
tan ...10.47
.
1 tan ...10.48
SeUpd
UnestrthEq
R
Oshth
Yin
10
Thcaman
Asimprwlefow
Li20K(K
ection 10 - Seismdated 22 April 2015
Unless the segligible whrength asso
he entire heiquation 10.4
Residual sh
nce shear chear demandhe shear cap
You can calcn the previou
A0.8.6.4
his section apacity of a
made regardinalyses of U
Analysis of implified “procedure as
wall piers wiead to non-cor structures
with shears c
Fi
inear and n006) can be
Knox has exKnox 2012)
mic Assessmen
spandrel is hen determ
ociated withight of the 48 if the mo
hear stren
cracking hasds (Figure 1
pacity of the
,
culate spandus section.
Analysis
provides aa penetrateding modelli
URM compo
in-plane loapier only” msumes that ill govern thconservatives assessed ocalculated pr
igure 10.72:
nonlinear eqe used to axtended the.
t of Unreinforce
prestressedmining the ph the formatspandrel: itortar is stron
ngth
s occurred t10.71). Thee arch which
tan
drel axial st
methods
an overviewd wall madeng assumptonents.
aded URM model showthe spandre
he seismic re assessmenon the assumro rata on th
Forces and
quivalent fraanalyse the e equivalen
ed Masonry Buil
d you can peak shear tion of cract applies whnger than th
the URM spe residual cah you can co
tresses, psp,
s for pene
w of analyse up of comtions for glo
walls and pwn in Figuels are infinresponse of nts for thosemption that phe rocking r
d stresses in
ame modelin-plane re
nt frame m
Seismic As
ldings
assume thecapacity. E
cks throughhen the morhe brick and
pandrel itseapacity of thompute as f
in accordan
etrated w
sis methodsmponents an
obal analys
perforated wure 10.72 (Tnitely stiff af the buildine structures piers of dissresistance.
n in-plane p
ls as shownesponse of pmodel to in
ssessment of U
IS
e axial streEquation 10h head and brtar is weakd fracture of
elf can no lohe lintel is tfollows (Bey
nce with th
walls
s that can bd of elemenes in Sectio
walls can beTomazevic,and strong,
ng. This simwhich contsimilar widt
piers (Tomaz
n in Figure perforated Unclude wea
Unreinforced Ma
SBN 978-0-4
ess in the 0.47 is the bed joints oker than thef the bricks
onger transftherefore eqyer, 2012):
he procedure
be used tonts. Recommon 10.9.4 al
e carried ou, 1999). Thand therefo
mplified proctain weak spth rock simu
zevic, 1999)
10.73 (MagURM walls
ak spandrel
asonry Buildings
10-117473-26634-9
spandrel ispeak shear
over almoste brick. Usewill occur.
fer in-planequivalent to
…10.49
es provided
assess themendationslso apply to
ut using thehis analysisfore that thecedure maypandrels, orultaneously
genes et al,s. Work byl behaviour
s
7
9
s r t e
e o
d
e s o
e s e y r y
, y r
Section 10 - SeUpdated 22 April 20
To investiga sway podemand: ca
where:
When Si > Si < 1.0 a s
You can astress elemstrains devcompatibilanalysis m
For URM stronger sprocking pie
eismic Assessm015
gate whethetential indeapacity ratio
∗
,∗
,
V*u,Pier
Vn,Pier
V*u,Spandre
Vn,Pier
1.0 a weak strong pier -
also carry oments or solveloped in lity is main
model to acco
walls with pandrels, Mer be repres
ment of Unreinfo
Fig
er perforateex, Si, can bos for the pi
,
,
= sumand
= sum
el = sumto th
= sumjoin
k pier - stron- weak span
out non-linelid 3D elemthe URM
ntained. Coount for pie
openings oMoon et al (2
sented as th
orced Masonry B
gure 10.73:
d wall behabe defined iers and spa
m of the 100d below the j
m of the pier
m of the 100he left and r
m of the spnt.
ng spandrel ndrel mecha
ear analysisments. This
componenompression
er rocking (K
of differing 2004) have he height ov
Seismic
Buildings
Equivalent f
aviour is gofor each sp
andrels at ea
0%NBS sheajoint calcul
rs’ capacitie
0%NBS sheright of the
pandrel cap
mechanismanism may b
s of URM pmethod ha
nts can be n-only gap Knox, 2012
sizes and rrecommend
ver which a
c Assessment o
frame
overned by pandrel-pierach joint:
ar force demated using K
es above and
ear force dejoint calcul
acities to t
m may be exbe expected
piers and spas the advanassessed delements c).
relatively wded that the
a diagonal c
of Unreinforced
ISBN 978-
spandrel or r joint by c
mands on thKR = 1.0
d below the
emands on lated using K
the left and
pected to foto form.
pandrels usntage that t
directly andcan be inc
weaker pierse effective hompression
Masonry Buildi
10-1-0-473-26634
r pier capaccomparing t
…10.5
he piers abo
e joint.
the spandreKR = 1.0
d right of t
orm and wh
sing 2D plathe stress a
d deformaticluded in t
s compared height of ean strut is mo
ngs
118
4-9
ity the
0
ove
els
the
hen
ane and ion the
to ach ost
SeUpd
likreunpimefba
Thfrthfoelwheth
1
Itefo
ection 10 - Seismdated 22 April 2015
kely to deveesistance (Fnequal size iers general
mortar jointsffective heigand, as appr
Figure 10com
he capacityom the capa
hat displaceorce deformlement. Thi
whole wall deight. This hese guidelin
O0.8.7
ems of a seor parts and
mic Assessmen
elop in the igure 10.74openings wlly depend s. If the diaght of the propriate.
0.74: URM rmpression st
y of a peneacity (strengment comp
mation relatios can also bdetermined can be connes.
Other ite
econdary nacomponent
t of Unreinforce
pier at the 4). As a resuwill vary dep
on bed andaphragms ariers may be
ocking pier truts that va
trated wall gth and defo
patibility muonships defibe extendedif you have
nsidered a v
ms of a
ature such asts loads.
ed Masonry Buil
steepest poult, effectivpending upod head joinre rigid or e limited to
effective heary with dire
componenformation) oust be main
fined above d to multiple some kno
variant of th
seconda
s canopies
Seismic As
ldings
ssible angleve heights foon the direcnt dimensioreinforced the bottom
eights basedection of sei
t at particuof the indivintained alofor the gov
le levels, if owledge of he SLAMa
ary natu
and architec
ssessment of U
IS
e that wouldor some rocction of loadons and staiconcrete ba
m of the diap
d on develosmic force (
ular level caidual wall/png the comerning modrequired, athe lateral approach d
re
ctural featur
Unreinforced Ma
SBN 978-0-4
d offer the lcking piers ding. The an
air-step cracands are prphragm or th
opment of di(ASCE 41-1
an also be pier elementmponent andde of behaviand the capa
load distribdescribed el
ures should b
asonry Buildings
10-119473-26634-9
least lateraladjacent tongles to thecking alongrovided, thehe concrete
iagonal 3).
determinedts assumingd using theiour of eachacity of thebution withlsewhere in
be assessed
s
9
9
l o e g e e
d g e h e h n
d
Section 10 - SeUpdated 22 April 20
10.9
10.9.1
The globaltaken as a loaded masprimary suDiaphragmopposed tcomponentthrough coglobal capa The globalin-plane stmasonry wthis sense as outlinederroneous acceleratioelements (models usithe additioconcrete fl Consideratleads to a (elastic) leassessmentrecommenprovides. When morvarying strensure dispThis is oftretrofitted When assebuilding stand the glooverly sopcomponentassessmentare also us The objecload/displamost critic
eismic Assessm015
Asses
Genera
l capacity owhole, ignsonry wallsupport to th
ms distributto providints and ther
onnections facity.
l capacity otiffness of
walls. Timband this all
d below. Asassessmen
ons and ina(Oliver, 201ing linear oronal compleoor and roo
tion of the nhigher glo
evels. Const approach.ded for the
re than one rengths andplacement en the casewith flexibl
essing the gtructure to obal demanphisticated ts that will t. When soped to provid
ctive of gloacement thacal compone
ment of Unreinfo
sment
al
f the buildinoring the p
s are considehe buildingting lateral ng support refore the cfrom walls
of the buildthe diaphraer and croslows simplisuming hignt results,ccurate esti10). Flexiblr nonlinear
exity will raof slabs in sm
non-linear cobal capacitsideration o. In many e greater un
lateral loadd stiffness, compatibili
e for masonle and assum
global capaassess the rds. Simple methods wbe difficul
phisticated ade order of
obal capaciat is consisteent. The rec
orced Masonry B
of Glob
ng is the strerformanceered to be s
g or buildinshears beto face-lo
capacity of to diaphrag
ing is likelyagms compss-braced stfications toh diaphragm, e.g. noimates of lole diaphragm2D plane st
arely be wamall buildin
capacity of ty than if tof non-linesituations
nderstandin
d mechanisma displacemity is achievnry buildingmed ductile
acity it willrelationshiphand metho
which may lt to achievanalyses aremagnitude v
ity assessment with reacommended
Seismic
Buildings
bal Cap
rength and de of secondasecondary eng part, e.getween lateoaded wallf primary logms need to
y to be signpared with tteel diaphrao be made im stiffness won-conservaoad distribums can be tress or she
arranted for ngs may be
masonry cothe componear behaviothis is reas
ng of buildi
m is presenment based ved and the
gs, particulae (low streng
l be necessp between tods of analyimply unre
ve in practice used, it is verification
ment is to aching the sd approach
c Assessment o
acity
deformationary elementlements unl
g. by cantilral load res) are conoad paths to be consid
nificantly inthe in-planeagms will tyn the asseswhere this itive assesution betweexplicitly m
ell elementsbasic buildassumed to
omponents nent capaciour requiressonably easing seismic
nt, or when approach ise global ca
arly those thgth) system
ary to comhe individuysis are encealistic trance and mayrecommend
n.
find the hstrength/deffor URM b
of Unreinforced
ISBN 978-
n capacity ots. For this pless the walever actionesisting comnsidered tothrough diadered when
nfluenced be lateral stiypically besment of glis not assuressments ofeen lateral lmodelled in, but care isdings. Wello be rigid.
is encouragties are lims a displacsy to imple
c behaviour
there are cos considere
apacity is nohat have bes.
mplete an anual componecouraged in nsfers in shy go unrecoded that sim
highest globformation cbuildings is
Masonry Buildi
10-1-0-473-26634
of the buildipurpose facll is providin of the wamponents (
o be primaaphragms a
assessing t
by the relatiiffness of t
e “flexible” lobal capaced can leadf diaphragload resistin 3D analys required al-proportion
ged as it oftmited to yiecement basement and r that it oft
omponents ed essential not overstateeen previous
nalysis of tent capacitipreference
hear betweognised in tmpler metho
bally applicapacity in ts described
ngs
120
4-9
ing ce-ing all. (as ary and the
ive the in
ity to
gm ing sis
and ned
ten eld sed
is ten
of to
ed. sly
the ies to
een the ods
ied the in
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-121
Updated 22 April 2015 ISBN 978-0-473-26634-9
Figure 10.75. The global strength capacity can be referred to in terms of base shear capacity. The deformation capacity will be the lateral displacement at heff for the building consistent with the base shear capacity accounting for non-linear behaviour as appropriate. This section provides guidance on the assessment of the global capacity for both basic and complex buildings. It also provides guidance on methods of analysis and modelling parameters.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-122
Updated 22 April 2015 ISBN 978-0-473-26634-9
Figure 10.75: Global capacity assessment approach for URM buildings
Determine component capacity for each "line" of the seismic system
Compare the seismic shear distribution and the shear capacity of each component
to determine the criticality of each component
Scale the base shear from the analysis to to the shear capacity of the critical
component to determine (Vprob)global, base
Check that the implied shears can be transferred by the diaphragms and the
shear connections between the diaphragms and each component
Carry out a lateral load analysis for each "line" of the seismic system to determine
the shear distibution between components and over the height of each
component
Diaphragm stiffness?
RIGID
FLEXIBLE
Carry out a lateral load analysis to determine the seismic shear distribution
over the height of each component, taking into account accidental eccentricities and any strength/stiffness eccentricities from
the centre of mass
Diaphragm and
connections adequate?
NO
YES
Factor down (Vprob)global, base accordingly
(Vprob )global, base
Check the horizontal deformation of the diaphragms
Horizontal diaphragm
deformation limits met?
NO
YES
Factor down (Vprob)global, base accordingly
SeUpd
1
DCdicathcawpa
F
Fobethhocagr Solathcade Bsimovwsu
ection 10 - Seismdated 22 April 2015
G0.9.2
etermining onsider, foiaphragm isapacity on ahere are moapacity of t
where Vprob articular lin
igure 10.76:
or such buehaviour of he non-lineaowever, proalculated in reater than 1
ome small ateral load phis is the opeantilever acependent on
asic buildinmilar fashiover the heig
will be limiteum of the co
(Vprob)wall1
mic Assessmen
Global ca
the globalr example,
s flexible thany system ore than twothe line in tin this cone of the seis
: Relationsh
uildings thef the compoar capabilitovide confiaccordance
1.
buildings wpaths to proen front comction of then the restrain
ngs of two on, after firght of each ed to the caomponent c
Wall lin
t of Unreinforce
apacity o
l capacity the single
he global caline in that
o system lithat directio
ntext is the smic system
hip between
re would bonents wheny, without idence that e with Secti
with flexibovide laterammercial bue ends of tnt available
or three stst completinline of the pacity of th
capacities al
ne 1
ed Masonry Buil
of basic
of basic Ue storey buiapacity in et direction wines then thon which hsum of th
m.
demand andiaphr
be little to n determininjeopardisinthe buildin
ion 10.10.2
ble diaphragal resistanceuilding whethe side w
e from the w
tories with ng a simpleseismic sy
he line wherlong a line
(Vprob)wall2
Wall li
Seismic As
ldings
building
URM buildildings shoeach directiwhen there he global cahas the lowhe compone
nd capacity ragm
gain fromng the glob
ng the verting has resi
2.2, non-line
gms will ne to all partere the sole
walls, the cawall foundat
flexible diae analysis toystem. The gre (Vprob)line
of the seism
Line of inert
(prob)wall2
ne 2
Wall line 3
Wall line 4
Tributary ma
ssessment of U
IS
gs
dings can bwn in Figuon will be are only tw
apacity in awest value oent probable
for a basic b
consideratbal capacityical load cailience. If ear behavio
not have ides of the buimeans of laapacity of tion, and lik
aphragms co determineglobal capa,i/i is the lomic system
tial force associ
ass associated
Dire
Unreinforced Ma
SBN 978-0-4
be a simplure 10.76. the lowest
wo system la direction of Vprob/tribue capacities
building wit
tion of the y. An underarrying cap
f the demanour is assum
dentifiable ouilding. An ateral suppowhich will
kely to be ne
can be conse the variatiacity of sucowest. (Vpro
at level i a
iated with wall
with wall line 2
ction under co
asonry Buildings
10-123473-26634-9
le exercise.If the roofcomponentines. Whenwill be theutary mass,s along the
th a flexible
non-linearrstanding ofpacity, will,nd is to be
med if A is
or effectiveexample of
ort might bel be highlyegligible.
sidered in aion in shearh buildings
ob)line,i is theand i is the
l line 2
2
nsideration
s
3
9
. f t n e , e
r f , e s
e f e y
a r s e e
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-124
Updated 22 April 2015 ISBN 978-0-473-26634-9
ratio of the applied shear at level i to the shear at the base of the line under consideration. For most basic buildings i will be the same for all lines of the seismic system. The presence of rigid diaphragms in basic buildings introduces an additional level of complexity into the building analysis. However, this analysis can still be kept quite simple for many buildings. For buildings with rigid diaphragms it will be necessary to consider the effect of the demand and resistance eccentricities (accidental displacement of the seismic floor mass and the location of the centre of stiffness or strength as appropriate). Refer Figure 10.77. If the lines of the seismic system in the direction being considered have some non-linear capability it is considered acceptable to resist the torque resulting from the eccentricities solely by the couple available from the lines of the seismic system perpendicular to the direction of loading. This will lead to a higher global capacity in many buildings than would otherwise be the case. If this approach is to be followed it would be more appropriate to consider the centre of strength rather than the centre of stiffness when evaluating the eccentricities. NZS 1170.5 requires that buildings not incorporating capacity design be subjected to a lateral action set comprising 100% of the specified earthquake actions in one direction plus 30% of the specified earthquake actions in the orthogonal direction. The 30% actions perpendicular to the direction under consideration are not shown in Figure 10.77 for clarity and, suitably distributed, would need to be added to the shears to be checked for the perpendicular walls. These are unlikely to be critical for basic buildings. If the diaphragm is flexible, concurrency of the lateral actions should be ignored.
Figure 10.77: Relationship between demand and capacity for a basic building with rigid diaphragms
In the above discussion it has been assumed that the diaphragms are stiff enough to provide the required support to the face-loaded walls orientated perpendicular to the direction of loading. Diaphragms are considered as primary structural components for the transfer of these actions and their ability to do so may affect the global capacity of the building in that direction. Limits have been suggested in Section 10.8.3.2 for the maximum diaphragm
(Vprob) w
all1
(Vprob) w
all1
e
CoStiff (Vprob) w
all2
Wall line 2Wall line 1
Wall line 3
Wall line 4
Line of action of inertial force
Direction under consideration
CoM
+ +e
CoStrength
(Vprob) w
all2
Wall line 2Wall line 1
Wall line 3
Wall line 4
CoM
Additional shear demand due to eccentricity (typ)
Shear demand due to inertial force
a) Linear elastic b) With non-linear capability on wall lines 1 and 2
SeUpd
defleexac
1
Mouofof Thbuterean UbeH Abu
1
10
Fo
LiSLbu Nwprstr
ection 10 - Seismdated 22 April 2015
eflections toexible diaphxceeded, thccordingly.
G0.9.3
Many complutlined abovften requiref such build
he overall uilding theechniques secommendend to verify
Use of lineaehaviour m
However, no
Aspects that uildings inc
foundatiodiaphragmnon-lineamechanispotential non horiz
G0.9.4
S0.9.4.1
our analysis
equivalen
modal res
non-linea
non-linea
inear analyLaMA) are uildings.
Nonlinear anwhen higher
rocedures arength and
mic Assessmen
o ensure adhragms, eve
he global ca
Global ca
ex URM buve for basi a first prin
dings.
objective more likeimply to kd that simpthe order o
ar-elastic anmay signific
n-linear con
are likely lude:
on stiffness m stiffness ar behaviousms soft storeys
zontal diaph
Global an
Selection
s methods a
nt static ana
sponse anal
ar pushover
ar time histo
sis techniqulikely to be
nalysis technlevels of n
are used, incstiffness de
t of Unreinforce
dequate waen in small apacity of t
apacity o
uildings wilic buildingsnciples appr
discussed iely it will keep track le techniquef magnitude
nalysis techcantly undensiderations
to require
ur of multi
s hragms.
nalysis
of analy
are generally
lysis (linear
ysis (linear
(nonlinear
ory (nonline
ues suppleme appropriat
niques are aon-linear beclude appro
egradation.
ed Masonry Buil
all support.basic buildithe building
of comp
ll be able tos. Howeverroach and a
in 10.9.1 rbe necess
of elementes be used ie of the outp
hniques anerestimate ts can compl
specific c
i-storey, pe
ysis meth
y considered
r static)
dynamic)
static)
ear dynamic
mented withte for all bu
appropriate fehaviour ar
opriate allow
Seismic As
ldings
These limings, and shg in that d
plex build
o be assesser, the assessgood under
remains. Hsary to utit actions ain all cases puts.
nd limiting the global letely alter t
onsideration
enetrated w
hods
d:
c).
h simple nout the most
for buildingre anticipatewances in t
ssessment of U
IS
mits are likehould be chirection wil
dings
ed adaptingsment of corstanding of
However, thilise more and appliedto identify t
componentcapacity o
the mechani
n in the as
walls, and d
on-linear teccomplex of
gs which coned. If nonlinhe analysis
Unreinforced Ma
SBN 978-0-4
ely to be ehecked. If th
ll need to
g the recommomplex buif the past p
he more cocomplicate
d inertial fothe primary
t capacitiesof complexisms that ca
ssessment o
developmen
chniques (ef New Zeala
ntain irregunear pushovs for anticip
asonry Buildings
10-125473-26634-9
exceeded inhe limits arebe reduced
mendationsildings willerformance
omplex theed analysisorces. It isy load paths
s to elasticx buildings.an occur.
of complex
nt of sway
e.g. adaptedand’s URM
ularities andver analysispated cyclic
s
5
9
n e d
s l e
e s s s
c .
x
y
d M
d s c
Section 10 - SeUpdated 22 April 20
Non-linearable to acccomplex. experienceparametersreferences
Note:
Non-linearanalytical rvariability include sevearthquake
Special carmix of lowmode consassessing considered
10.9.4.2
Mathematicracked inshear and f If using nothe non-libackbone modelling URM failu
10.9.4.3
The mass ostiffness wground (focalculate wfall withinbuildings considerati In the caseloaded at include suelements afor compaThese sectthan 30 m.
eismic Assessm015
r time histocount explicThey shou
e in the pros and the likfor non-line
r modellingresults will in actual
veral analye motion.
re is requirw and high sidered shouURM build
d.
Mathem
ical modelsn-plane stiffflexural def
on-linear anainear load-curves). Incwhen appr
ure modes ar
Fundam
of URM buwill depend oundation rowith precision the platea
(tall or lion of these
e of large buthe same t
ub-structurinand all massatibility wittions should
ment of Unreinfo
ory analysescitly for cyculd not be ocesses invkely sensitiear acceptan
g of URM not alwaysmaterial st
yses to test
red with theperiod mo
uld be invesdings, Cau
matical mo
s used for lfness of theformations.
alysis techndeformationclude cyclic
ropriate. Rere given in
mental pe
uildings is non the rela
otation). Whon and therau section long), espee effects may
uildings, it time and hng: i.e. subs tributary tth neighboud typically b
orced Masonry B
s can be usclic strength
undertakenolved. A fuivity of the nce criteria.
walls is fes provide retrength and
sensitivity
e applicatioodes. The restigated by ghey damp
odelling
linear analye primary
niques, the mn characterc degradaticommendedSection 10.
eriod
normally domtive flexibilhile the perre are severof the spec
ecially thoy be require
may not behaving the bdividing tho it. Each suring sectiobe no more
Seismic
Buildings
sed to analyh and stiffnn lightly aull appreciaoutputs to
.
feasible, bueliable estimd condition.
to materia
on of dampesulting fora special st
ping rather
ysis techniqlateral load
mathematicristics of on of strend nonlinear8.6.2.
minated by lity of the w
riod of theseral modes octra, so prese with loed.
e sufficient same time
he structuresection is thons along te than one t
c Assessment o
yse most Uness degradaand then onation of thethese is req
ut experiencmates of per. Any analal variation,
ping, especirce reductiotudy for fin
than Rale
ques shouldd-resisting e
al model shindividual
ngth and stir analysis p
the mass owalls, the fe structuresf vibration ecision is nong flexib
to considerperiod. Co
e into secthen analysedthe marginthird of the
of Unreinforced
ISBN 978-
URM buildination. Thesenly by thoe reliabilityquired. Ref
ce to date rformance bytical mod, modelling
ally when on from damnite elementigh dampin
d include thelements. C
hould directlin-plane e
ffness in tharameters f
f the masonfloor diaphrs can be quito considernot requirele diaphra
r all parts oommonly uions, each d separatelys between
e building w
Masonry Buildi
10-1-0-473-26634
ngs. They ae analyses aose that hay of the inpfer to releva
suggests thbecause of tdelling shoug method a
consideringmping for tt analysis. Fng should
he elastic, uConsider bo
ly incorporaelements (ihe componefor non-brit
nry. Howevragms and tite difficult r, it will ofted. For largagms, spec
f the buildiused methoincluding
y and checkthe section
width or mo
ngs
126
4-9
are are ave put ant
hat the uld and
g a the For be
un-oth
ate i.e. ent ttle
ver, the to
ten ger ial
ing ods its
ked ns. ore
SeUpd
N
Thif
10
U10bumunmw Hsethcothsh
10
Thcobeco Fobeex Lafosuus
w
ection 10 - Seismdated 22 April 2015
Note:
he effectivef this is the c
S0.9.4.4
URM buildin0-20% of thuildings wit
mass systemndertaken t
masses lumpwould be tran
However, foreismic demahe seismic onsidered. The lower halhear.
S0.9.4.5a
he stiffnessonsidering fe a homogeompression,
or elastic ane linear anxcluding any
aboratory teorce levels uch cases, tsing Equatio
where: hAIg
EG
mic Assessmen
e period of case, this fin
Seismic m
ngs are essehe seismic mth timber flo
m is problemto capture tped at diapnsferred to t
r shear cheand should force due
This is in colf of the bot
Stiffness actions
s of in-planflexural, shneous mate, Em, as disc
nalysis, the nd proportioy wythe, tha
ests of soliusing conv
the lateral inon 10.51:
heff = wAn = n
g = mb
Em = mGm = m
t of Unreinforce
individual snal step will
mass
entially systmass contriboors and ligmatic. Howthe effect o
phragm levethe in-plane
ecks at the binclude accto the tota
ontrast to attom storey
of URM w
ne URM wear and axi
erial for stiffcussed in ea
stiffness of onal with tat does not
d shear waventional prn-plane stif
wall height,net plan aremoment of behaviour, mmasonry elamasonry she
ed Masonry Buil
sections of l not be req
tems with mbuted by flo
ghtweight rowever, unleof distributels is accepe walls throu
base of thecumulated fal mass ofssessments is ignored
walls and
walls subjecial deformaffness comparlier section
f an in-planethe geometmeet the cr
alls have shrinciples offfness of a
, mm a of wall, m
f inertia formm4 astic moduluear modulu
Seismic As
ldings
URM buildquired.
mass distriboors and rooofs. In thisess a more ted mass syptable as lough the diap
e in-plane wfloor level ff the in-plaof concretewhen estim
d wall pie
cted to seistions. The m
putations wins.
e URM waltrical properiteria given
hown that bf mechanicssolid cantil
mm2 r the gross
us, MPa s, MPa.
ssessment of U
IS
dings will o
buted over tof. This is
s context, thsophisticat
ystems, an oads from phragm.
walls and piforces from ane wall ae constructi
mating the ac
ers subje
mic loads masonry shth an expec
l and pier sherties of thn in Section
behaviour cs for homolevered wal
s section re
Unreinforced Ma
SBN 978-0-4
often still be
the height, especially t
he concept oted analysi
assessmenthe face-lo
iers of any m the upper above the lion, where tctive mass f
ect to in-p
should be hould be cocted elastic
hould be cohe un-crack
10.2.4.3.
an be depicogeneous mll, k, can be
epresenting
asonry Buildings
10-127473-26634-9
e short and,
with barelythe case forof a lumpeds has been
nt based onoaded walls
storey, thestoreys andlevel beingthe mass offor the base
plane
determinedonsidered to
modulus in
onsidered toked section,
cted at lowmaterials. Ine calculated
…10.51
uncracked
s
7
9
,
y r d n n s
e d g f e
d o n
o ,
w n d
d
Section 10 - SeUpdated 22 April 20
The lateralat its top an
Note that a
10.10
10.10.1
This sectioon URM b Section 5 d For the purload and prseismic resthe overalland/or stabneed to besystem. Therefore else, such and compo
10.10.2
10.10.2.1
Determine taking =any non-lin
10.10.2.2
For basic spandrels mby Equatiothe structur
eismic Assessm015
l in-plane stnd bottom c
a completely
AssesDispla
Genera
on sets out buildings an
describes ho
rposes of drovides latesisting systel resistance bility shoule assessed
all in-planeas face-load
onents.
Primary
General1
the horizon1, Sp = 1 annear deform
Basic b2
buildings, may be deteon 10.53 whral perform
ment of Unreinfo
tiffness of acan be calcu
y fixed cond
sment acemen
al
the procedud their parts
ow the earth
efining seiseral resistanem (primarof the struc
ld be assumfor any im
e walls and dded walls an
y structu
l
ntal demandnd e = 15%
mations from
uildings
a force-basermined usihere a load
mance factor
orced Masonry B
a pier betweulated using
dition is oft
of Eartht Dema
ures for ests.
hquake dem
smic demance to the gly structure)cture and w
med to be pmposed defo
diaphragmsnd parapets
ure
ds on the p%. Althougm the assess
sed assessming a horizoreduction fand structu
, ⁄
Seismic
Buildings
een openingg Equation 1
ten not prese
hquakeands
timating bot
mands are to
nds, the struobal buildin). The comp
which rely oparts and coformations f
s are classifs, and ornam
primary strugh is set asment of the
ment of in-pontal demanfactor, R, hural ductility
⁄
c Assessment o
gs with full 10.52:
ent in actua
e Force
th force an
be assessed
uctural systeng should bponents wh
on the primaomponents.from the p
fied as primmentation, a
ucture, in acat 1 it is intee capacity ar
plane demand seismic has been usy factor give
of Unreinforced
ISBN 978-
restraint ag
al buildings.
and
d displacem
d.
em which cae considere
hich do not ary structur Parts andrimary seis
ary structurare consider
ccordance wended that thre also taken
ands for wacoefficient,
sed in lieu oen in NZS 1
Masonry Buildi
10-1-0-473-26634
gainst rotati
…10.52
.
ment deman
arries seismed the prima
participate re for strengd componensmic resisti
re. Everythired to be pa
with Sectionthe benefits n.
walls/piers a, C(T1), givof the ratio 1170.5.
…10.5
ngs
128
4-9
ion
2
nds
mic ary
in gth nts ing
ing arts
n 5 of
and ven
of
3
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-129
Updated 22 April 2015 ISBN 978-0-473-26634-9
where: Ch(T1) = the spectral shape factor determined from Clause 3.1.2,
NZS 1170.5 for the first mode period of the building, T1, g Z = the hazard factor determined from Clause 3.1.4, NZS 1170.5 Ru = the return period factor, Ru determined from Clause 3.1.5,
NZS 1170.5 N(T1,D) = the near fault factor determined from Clause 3.1.6, NZS 1170.5 KR = the seismic force reduction factor determined from Table 10.14.
Table 10.14: Recommended force reduction factors for linear static method
Seismic performance/ controlling parameters
Force reduction factor, KR
Notes
Pier rocking, bed joint sliding, stair-step failure modes
3 Failure dominated by strong brick-weak mortar
Pier toe failure modes 1.5
Pier diagonal tension failure modes (dominated by brick splitting)
1.0 Failure dominated by weak brick-strong mortar
Spandrel failure modes 1.0
Note:
The concept of a ductility factor (deflection at ultimate load divided by the elastic deflection) can be meaningless for most URM buildings. The introduction of KR primarily reflects an increase in the damping available and therefore reduced elastic response rather than ductile capability assessed by traditional means. Therefore the displacements calculated from the application of C(T1) are the expected displacements and should not be further modified by KR. These force reduction factors apply in addition to relief from period shift (if any). Redistribution of seismic demands between individual elements of up to 50% is permitted when KR = 3.0 applies, provided that the effects of redistribution are accounted for in the analysis. When there are mixed behaviour modes among the walls/piers in a line of resistance, you can ignore the capacity of any piers for which KR is less than the value that has been adopted for the line of resistance. Otherwise, consider lower force reduction factors. If you have adopted higher force reduction factors, carefully evaluate the consequences of loss of gravity load support from any walls/piers that have been ignored. If there are mixed failure modes among the walls and piers in a line of resistance, the displacement compatibility between these piers and walls should be evaluated. For the case of perforated walls when a strong pier – weak spandrel mechanism governs the wall behaviour KR = 1.0 shall be adopted for the wall line as a whole, or the capacities of the spandrels can be ignored. When the contribution of the spandrels is ignored the higher KR factors detailed in Table 10.14 may be used provided the consequences of loss of the ignored spandrels are considered.
Section 10 - SeUpdated 22 April 20
10.10.3
Refer to Scomponent For face-lodemands aCi(Tp), definto a displ
10.10.4
Vertical gr However, performanc While vertforces in tinstalled totypically ahorizontal In advancevertical acembedded When verNZS 1170.
10.10.5
10.10.5.1
Masonry Consequendiaphragmfrom diaphplane. Seismic dewalls shoucoefficientto reflect ifrom NZSdiaphragm If the diapseismic demlimit of C
eismic Assessm015
Parts a
Section 8 ots.
oaded wallsare includedfined in NZlacement sp
Vertica
round motio
opinion isce of URM
tical groundthe walls, o restrain tha time delaacceleration
e of furtherccelerations
anchors.
rtical accel.5.
Flexible
General1
walls loadntly, the d
ms is likely tohragm self-
emands on uld, therefort assuming tits height in 1170.5 (i.e
m.
phragm is brmands can C(0) where
ment of Unreinfo
nd comp
of NZS 117
, assessed ud within theZS 1170.5 hpectrum for
al deman
ons in close
s divided buildings.
d acceleratioreducing th
hem back toay between ns, meaning
r investigatiwhen asse
lerations ar
e diaphr
l
ded in-plandominant mo be the res
-weight and
flexible dire, be basedthat the diapn the buildie. Sp and
raced by flebe determine Fi is th
orced Masonry B
ponents
70.5 for det
using the dise method. N
has been repthis purpos
nds
proximity t
on how s
ons could pheir stabilito the diaphr
the maximg that they a
ions on thisessing the s
re consider
ragms
ne are typmode of sponse of thd the conne
aphragms id on the perphragm is sing). The se =1) where
exible (i.e. ned using a he equivale
Seismic
Buildings
termination
splacement-Note that thplaced withse.
to earthquak
significant
potentially rty, and redragms, theremum verticaare unlikely
s subject, itstability of
red the de
pically relaresponse f
he diaphragmcted URM
in URM buriod of the supported aeismic coefe T is the f
non-URM)seismic coe
ent static h
c Assessment o
n of seismic
-based methhe Part Speh a formula
ke sources c
vertical ac
reduce the ducing the pe is evidencal accelerat
y act togethe
t is considemasonry w
emands ma
atively rigfor buildinms themselvboundary w
uildings whdiaphragm
at ground lefficient to bfirst horizo
) lateral loaefficient equhorizontal
of Unreinforced
ISBN 978-
c demands
hod in Sectiectral Shapeation that be
can be subst
ccelerations
gravity andpull-out str
ce to suggestions and ter at full inte
red reasonawalls and th
ay be dete
gid structurngs containves, due to iwalls respo
ich are braand a horizvel (i.e. no
be used is thntal mode
ad resisting ual to Fi/mi,force dete
Masonry Buildi
10-1-0-473-26634
on parts a
ion 10.8.5, te Coefficieetter conve
tantial.
s are on t
d compressirength of tist that therethe maximuensity.
able to ignohe capacity
ermined fro
ral elemenning flexibinertial forc
onding out-o
aced by URzontal seismamplificati
herefore C(period of t
elements, t, with a low
ermined fro
ngs
130
4-9
and
the nt,
erts
the
ion ies
e is um
ore of
om
nts. ble ces of-
RM mic ion (T) the
the wer om
SeUpd
Ninlast
F
10
ThEq
w
Thexet
ection 10 - Seismdated 22 April 2015
NZS 1170.5 ntention is ateral load-roreys.
Figure 10.78
T0.10.5.2
he diaphraquation 10.5
where:
C
WLBGT
he period, Txcited in ant al, 2013c).
mic Assessmen
at the leveindicated i
resisting ele
8: Distributiodiaphrag
Timber di
agm in-pla54.
mm
C(Td) = sa
Wtrib = uL = sB = dG’d,eff = eTd = l
a
Td, of a timn approxim
0
t of Unreinforce
l of the dian Figure 1ments may
on of accelems braced o
iaphragm
ane mid-sp
,
seismic coeaccordance uniformly dspan of diapdepth of diaeffective shelateral firstaccordance
mber diaphramately parab
0.7,
ed Masonry Buil
aphragm an10.78. This
cause the a
eration withoff flexible l
ms
an lateral
efficient at rwith Sectio
distributed trphragm, maphragm, mear stiffnesst mode pwith Equati
agm, based bolic distrib
Seismic As
ldings
nd mi is therequiremen
amplificatio
height for elateral load
displacem
required heion 10.10.5.1ributary we
s of diaphraperiod of ion 10.55, s
on the defbution, is g
ssessment of U
IS
e seismic mnt recognis
on of ground
evaluating thresisting ele
ment deman
ight for per ight, kN/m
agm, refer Ethe diaph
sec.
formation priven by Eq
Unreinforced Ma
SBN 978-0-4
mass at thatses that mod motions i
he demand ements
nd, d, is
riod, Td, det
Equation 10hragm dete
rofile of a quation 10.5
asonry Buildings
10-131473-26634-9
t level. Theore flexiblen the upper
on flexible
given by
...10.54
termined in
.55, MPa ermined in
shear beam55 (Wilson
…10.55
s
9
e e r
y
n
n
m n
Section 10 - SeUpdated 22 April 20
where:
10.10.6
Rigid diapwith NZS
10.10.7
The demancalculated Assume thspecific wareversing l
10.10.8
Wall-diaphin-plane) sevaluated uniformly Unless capµ =Sp = 1.
10.11
where capappropriate The %NBSfor each inprimary str The %NBSscores for noted.
eismic Assessm015
Wtrib =
Rigid d
phragms are1170.5 as o
Connec
nds on conin accordan
hat the demall-diaphragloading regi
Connec
hragm connshould be cin accordadistributed
pacity desig
Asses
%NBS = C
pacities ande.
S score (or rndividual seructure for e
S for the gcomponen
ment of Unreinfo
total tribuweight ofand abovtributary walls triband diapNZS 1170Other term
diaphrag
e primary soutlined in S
ctions pr
nnections pnce with Ste
mand is ungm interfaceimes for a g
ctions tr
nections reqconsidered ance with along the w
gn principle
sment
Capacity/De
d demands
rating) for tecondary coeach princip
global perfonts and elem
orced Masonry B
utary weightf the tribute the diaphheight, thic
butary to thephragm se0.5 Section ms are as de
ms
structure anSection 10.1
roviding
roviding sueps 12, 13 a
iformly dise. Repeat th
given anchor
ransferri
quired to trato be primSection 10
wall to diaph
es are appli
of %NB
emand x100
can be def
the buildingmponent anpal direction
ormance of ments, and
Seismic
Buildings
t acting on tary face-lohragm beingckness ande diaphragm
elf-weight 4.2).
efined for E
nd the dem10.2.
g suppor
upport to faand 14 in Se
stributed ache exercise frage.
ng diaph
ansfer shearmary structu0.10.2. Thehragm conn
ed, the dem
BS
0
fined in ter
g is the minnd the %NBn.
the buildinthe hierarc
c Assessment o
the diaphraoaded wallsg consideredd density ofm accountinplus live
Equation 10.
ands are de
rt to face
face-loaded ection 10.8.5
cross all anfor the ortho
hragm s
rs from diapure and the demand m
nection.
mands shou
rms of stre
nimum of thBS for the g
ng will be chy of thes
of Unreinforced
ISBN 978-
gm, being ts both half-d (i.e. the pf the out-ofng for wall
load (ψE
.54.
etermined i
e-loaded
masonry w5.2.
nchorages loogonal load
hear loa
phragms to erefore the may be as
ld be asses
ength or de
he %NBS valobal perfor
a function e scores sh
Masonry Buildi
10-1-0-473-26634
the sum of t-storey beloproduct of tf-plane URpenetrationx Qi as p
in accordan
d walls
walls shall
ocated at tding directio
ads
walls (loaddemands a
ssumed to
ssed assumi
…10.5
eformation
alues assessrmance of t
of individuhould also
ngs
132
4-9
the ow the
RM ns) per
nce
be
the on,
ded are be
ing
6
as
sed the
ual be
SeUpd
ThCSW It thasre Athwlifof
1
Thdeco Th
Whaa setrish
R
AlclaEn
Anthe
AS
ection 10 - Seismdated 22 April 2015
he item witSW. All othWs.
is an impohat have beessociated wetrofit progr
Although theheir effect o
weaknesses ife safety issf the buildin
I0.12B
he overarchesigned for omponents t
he basic app
secure allparapets a
improve tdiaphragmother wal
strengthe
consider
When you aazard will mlow seismi
eismic capacigger a sequhould be car
Referen
mesfer, N., Day brick masngineering, 47
nthoine, A. 19eory, Int. J. So
S, 2011, AS37
mic Assessmen
th the loweher items w
ortant aspecten evaluated
with the builram if this is
e impact on on the capais reviewed sue, do not ang.
mproviBuilding
hing probleearthquake
to allow all
proach to im
l unrestrainand orname
the wall-diam; and imprlls) by impr
n specific s
adding new
are developmean that a ic area. Alscity, if that uence of farefully asses
ces
Dizhur, D., Lumsonry building7, 2, June, 75-
995. Derivatioolids Structure
700: Masonry
t of Unreinforce
est %NBS sith a score b
t of the assd are reportlding’s seisms to be cons
life safety acity of theagain to en
appear in th
ng Seisgs
em is that e loads and parts of the
mproving th
ed parts thaents)
aphragm conrove the peroving the co
tructural ele
w structural c
ping strengtsolution advo note that is limited b
ailure of othssed and mi
mantarna, R.,gs in New Z96.
on of the in-pes, Vol. 32, pp
structures, Sta
ed Masonry Buil
score is refbelow 67%N
essment proted as this wmic perform
sidered.
of elementse componennsure that ahe list of stru
smic Pe
New Zeald lacks a bae building to
he seismic p
at represent
nnections orformance oonfiguration
ements, and
components
thening optvised in a heven thoug
by a brittle mher elementitigated.
Ingham, J. MZealand’, Bul
plane elastic p 137-163.
andard Austra
Seismic As
ldings
ferred to asNBS are ref
ocess that awill providemance and
s will have nt, it is impny weaknesuctural wea
erforma
land’s URMasic degree o act togeth
performance
falling haz
or provide aof the face-n of the bui
d
s to provide
tions, note high seismicgh a buildinmode of failts, the risk
M., 2014. ‘Maletin of the
characteristic
alia.
ssessment of U
IS
the criticaferred to as
all of the ine a completwill aid in
been considportant thatsses, that doknesses and
ance of
M buildingof connectier (Goodwi
e of URM b
ards to the
lternative loloaded walllding and in
e extra supp
that differ area could
ng may havlure and/or tof failure o
terial propertieNew Zealand
cs of masonr
Unreinforced Ma
SBN 978-0-4
al structuralstructural w
ndividual %Nte picture othe develo
dered whenat the list oo not directd do not lim
URM
g stock is ion betweenin et al., 201
buildings is t
public (e.g
oad paths; ils (gables, fn-plane wal
port for the b
ring levels d be too conve more thathe failure m
of the limiti
es of existingd Society fo
ry through ho
asonry Buildings
10-133473-26634-9
l weakness,weaknesses,
NBS scoresf the issues
opment of a
n evaluatingof structuraltly lead to a
mit the score
simply notn structural11).
to:
. chimneys,
improve thefacades andlls
building.
of seismicservative in
an 34%NBSmode coulding element
g unreinforcedr Earthquake
omogenization
s
3
9
, ,
s s a
g l a e
t l
,
e d
c n S d t
d e
n
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-134
Updated 22 April 2015 ISBN 978-0-473-26634-9
ASCE, 2013, ASCE 41: Seismic Evaluation and Retrofit of Existing Buildings (41-13), American Society for Civil Engineers. Benedetti D, Petrini V. 1996. Shaking Table Tests on Masonry Buildings. Results and Comments. ISMES, Bergamo.Bruneau
Beyer, K. (2012) Peak and Residual Strengths of Brick Masonry Spandrels, Engineering Structures, Vol 41, August 2012, Pages 533-547
Beyer, K. (2014) Personal communication, July 2014
Beyer, K., Dazio, A., 2012a, Quasi-static monotonic and cyclic tests on composite spandrels, in Earthquake Spectra, vol. 28, num. 3, p. 885-906.
Beyer K., Dazio, A., 2012b, Quasi-static cyclic tests on masonry spandrels, in Earthquake Spectra, vol. 28, num. 3, p. 907-929.
Beyer K., Mangalathu, 2014, Numerical study on the force-deformation behaviour of masonry spandrels with arches, in Journal of Earthquake Engineering, vol. 18, num. 2, p. 169-186,, 2014.
Blaikie, E.L. & Spurr, DD. 1993. Earthquake Vulnerability of Existing Unreinforced Masonry Buildings. EQC.
Blaikie, E.L. (1999). Methodology for the Assessment of Face-loaded Unreinforced Masonry Walls under Seismic Loading. Opus International Consultants, Wellington, New Zealand.
Blaikie, E. L. (2001). Methodology for the Assessment of Face-Loaded Unreinforced Masonry Walls under Seismic Loading, EQC funded research by Opus International Consultants, under Project 99/422.
Blaikie, E.L. 2002. Methodology for Assessing the Seismic Performance of Unreinforced Masonry Single Storey Walls, Parapets and Free Standing Walls. Opus International Consultants, Wellington, New Zealand.
Bothara J. K., Dhakal, R. P., Mander J. B., 2010. ‘Seismic performance of an unreinforced masonry building: An experimental investigation’, Earthquake Engineering and Structural Dynamics, Volume 39, Issue 1, pages 45–68, January 2010.
Bothara, J. K., Hiçyılmaz, K, 2008, General Observations of the Building Behaviour during the 8th October 2005 Pakistan Earthquake, Bulletin of the New Zealand Society for Earthquake Engineering, Vol 41, No 4.
Bruneau, M. and Paquette, J. (2004). Testing of full-scale single story unreinforced masonry building subjected to simulated earthquake excitations. SÍSMICA 2004 - 6º Congresso Nacional de Sismologia e Engenharia Sísmica.
Campbell, J., Dizhur, D., Hodgson, M., Fergusson, G., and Ingham, J. M., 2012, Test results for extracted wall-diaphragm anchors from Christchurch unreinforced masonry buildings, Journal of the Structural Engineering Society New Zealand (SESOC), Volume 25, Issue 1, pp: 57-67.
Cattari, S., Beyer K. & Lagomarsino, S., Personal communication November 2014.
Charlotte, K., 2012, Assessment of perforated unreinforced masonry walls responding in-plane, Doctoral dissertation, The University of Auckland, Auckland, New Zealand, January, 547p. https://researchspace.auckland.ac.nz/handle/2292/19422
Cole, G.L., Dhakal, R.P., Carr, A.J., Bull, D.K., 2011, Case studies of observed pounding damage during the 2010 Darfield earthquake, Proceedings of the Ninth Pacific Conference on Earthquake Engineering Building an Earthquake-Resilient Society, 14-16 April, 2011, Auckland, New Zealand, Paper Number 173.
Costley, A.C. and Abrams, S.P. (1996). “Dynamic Response of Unreinforced Masonry Buildings with Flexible Diaphragm”, Technical Report NCEER-96-0001, State University of New York at Buffalo, Buffalo, U.S.A.
CRGN, 2012, Section 5: Unreinforced masonry buildings and their performance in earthquakes, http://canterbury.royalcommission.govt.New Zealand/vwluResources/Final-Report-docx-Vol-4-S5/$file/Vol-4-S-5.docx.
Derakhshan, H. Dizhur, D. Y., Griffith, M. C., Ingham, J. M., 2014a, ‘Seismic assessment of out-of-plane loaded unreinforced masonry walls in multi-storey buildings’, Bulletin of the New Zealand Society for Earthquake Engineering, 47, 2, June, 119-138.
Derakhshan, H., Dizhur, D., Griffith, M.C., Ingham, J. M., 2014b, ‘In-situ out-of-plane testing of as-built and retrofitted unreinforced masonry walls’, ASCE Journal of Structural Engineering, 140, 6, 04014022. http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0000960.
Derakhshan, H., Griffith, M. C., Ingham, J. M., 2013a, ‘Out-of-plane behaviour of one-way spanning URM walls’, ASCE Journal of Engineering Mechanics, 139, 4, 409-417. http://dx.doi.org/10.1061/(ASCE)EM.1943-7889.0000347
Derakhshan, H., Griffith, M. C., Ingham, J. M., 2013b, ‘Airbag testing of unreinforced masonry walls subjected to one-way bending’, Engineering Structures, 57, 12, 512-522. http://dx.doi.org/10.1016/j.engstruct.2013.10.006
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-135
Updated 22 April 2015 ISBN 978-0-473-26634-9
Dizhur, D., Campbell, J., Schultz, A., Ingham, J. M., 2013, Observations from the 2010/2011 Canterbury earthquakes and subsequent experimental pull-out test program of wall-to-diaphragm adhesive anchor connections, Journal of the Structural Engineering Society of New Zealand, 26(1), April, 11-20.
Dizhur, D., Ingham, J.M., Moon, L., Griffith, M., Schultz, A., Senaldi, I., Magenes, G., Dickie, J., Lissel, S., Centeno, J., Ventura, C., Leiti, J. Lourenco, P., 2011, ‘Performance of Masonry Buildings and Churches in the 22 February 2011 Christchurch Earthquake’, Bulletin of the New Zealand Society for Earthquake Engineering, 44, 4, Dec., 279-297.
FEMA, 1998, FEMA 306-Evaluation of Earthquake Damaged Concrete and Masonry Wall Buildings, Federal Emergency Management Agency.
FEMA, 2000, FEMA 356: Prestandard and Commentary for the Seismic rehabilitation of Buildings, Federal Emergency Management Agency, Washington, DC.
FEMA, 2006, FEMA 454: Risk Management Series: Designing for Earthquakes - a Manual for Architects, Federal Emergency Management Authority,
FEMA, 2009, FEMA P-750: NEHRP Recommended Seismic Provisions for New Buildings and Other Structures, Federal Emergency Management Agency, 2000, FEMA 356: Prestandard and commentary for the seismic rehabilitation of buildings, Federal Emergency Management Agency.
Foss M, 2001. Diagonal Tension in Unreinforced Masonry Assemblages. MAEC ST-11: Large Scale Test of
Franklin, S., Lynch, J., and Abrams, D. P., 2001, Performance of Rehabilitated URM Shear Walls: Flexural Behaviour of piers, Department of Civil Engineering, University of Illinois at Urbana-Champaign Urbana, Illinois.
Giongo, I., Dizhur, D., Tomasi, R., Ingham, J. M. (2013). ‘In-plane assessment of existing timber diaphragms in URM buildings via quasi-static and dynamic in-situ tests’, Advanced Materials Research, 778, 495-502. http://dx.doi.org/10.4028/www.scientific.net/AMR.778.495
Giongo, I., Wilson, A., Dizhur, D., Derakhshan, H., Tomasi, R., Griffith, M. Quenneville, P., Ingham, J., 2014, ‘Detailed seismic assessment and improvement procedure for vintage flexible timber diaphragms’, Bulletin of the New Zealand Society for Earthquake Engineering, 47, 2, June, 97-118.
Goodwin, C., Tonks, G., Ingham, J, 2011, Retrofit techniques for seismic improvement of URM buildings, Journal of the Structural Engineering Society New Zealand Inc., Volume 24 No. 1, pp 30-45.
Graziotti, F., Magenes, G. and Penna, A., 2012, Experimental Behaviour of Stone Masonry Spandrels, Proceedings of 15th World Conference for Earthquake Engineering, Lisbon, Portugal, Paper No. 3261.
Graziotti, F., Penna, A., Magenes, G. (2014) Influence of timber lintels on the cyclic behaviour of stone masonry spandrels, International Masonry Conference 2014, Guimarães, PT.
Griffith, M.C., Lawrence, S.J. and Willis, C.R., (2005). “Diagonal bending of unreinforced clay brick masonry,” Masonry International, 18(3): 125-138.
Griffith, M.C., Vaculik, J., Lam, N.T.K., Wilson, J., and Lumantarna, E. (2007). Cyclic testing of unreinforced masonry walls in two-way bending. Earthquake Engineering and Structural Dynamics, 36(6), 801-821.
ICBO, “Guidelines for Seismic Evaluation and Rehabilitation of Tilt-Up Buildings and Other Rigid Wall/Flexible Diaphragm Structures” International Conference of Building Officials, 2000.
Ingham, J. M., Griffith, M. C., 2011, ‘The Performance of Unreinforced Masonry Buildings in the 2010/2011 Canterbury Earthquake Swarm’, Report to the Royal Commission of Inquiry into Building Failure Caused by the Canterbury Earthquake. http://canterbury.royalcommission.govt.nz/documents-by-key/20110920.46.
Ismail, N., 2012, Selected strengthening techniques for the seismic retrofit of unreinforced masonry buildings, A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy, University of Auckland.
Kitching, N., 1999, The Small Scaling Modelling of masonry, Masonry Research, Civil Engineering Division, Cardiff School of Engineering.
Knox, C. L. (2012) ‘Assessment of Perforated Unreinforced Masonry Walls Responding In-Plane’, University of Auckland, PhD Thesis, Auckland, New Zealand.
Lawrence, S.J. and Marshall, R.J. (1996). “Virtual work approach to design of masonry walls under lateral loading,” Technical Report DRM429, CSIRO Division of Building, Construction and Engineering, Sydney.
Lowndes, William S., (1994). “Stone masonry” (3rd. ed, p.69). International Textbook Company.
Lumantarna, R., Biggs, D. T., Ingham, J. M. (2014a). ‘Compressive, flexural bond and shear bond strengths of in-situ New Zealand unreinforced clay brick masonry constructed using lime mortar between the 1880s and
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-136
Updated 22 April 2015 ISBN 978-0-473-26634-9
1940s, ASCE Journal of Materials in Civil Engineering, 26, 4, 559-566. http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000685.
Lumantarna, R., Biggs, D. T., Ingham, J. M. (2014b). ‘Uniaxial compressive strength and stiffness of field extracted and laboratory constructed masonry prisms’, ASCE Journal of Materials in Civil Engineering, 26, 4, 567-575. http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000731.
Magenes G., (2006). “Masonry Building Design in Seismic Areas: Recent Experiences and Prospects from a European Standpoint”, Keynote 9, 1st European Conference on Earthquake Engineering and Engineering Seismology, 3-8 september 2006, Geneva, Switzerland, CDROM.
Magenes, G. and Calvi, G.M. (1995). “Shaking Table Tests on Brick Masonry Walls”, Proceedings of the 10th European Conference on Earthquake Engineering, Vienna, Austria, Vol. 3, pp. 2419–2424.
Magenes G., and Calvi G. M., 1997, In-Plane Seismic Response of Brick Masonry Walls, Earthquake Engineering and Structural Dynamics, 26, pp. 1,091-1,112.
Mann, W. & Müller, H., 1982, “Failure of Shear-Stressed Masonry - An enlarged theory, Tests and Applications to Shear Walls”. Proc. of the British Ceramic Society, No. 30.
Ministry of Business, Innovation and Employment: Determination 2012/043: Whether the special provisions for dangerous, earthquake-prone, and insanitary buildings in Subpart 6 of the Building Act that refer to a building can also be applied to part of a building. www.dbh.govt.nz/UserFiles/File/Building/Determinations/2012/2012-043.pdf
Moon, F. L., 2004, Seismic strengthening of low-rise unreinforced masonry structures with flexible diaphragms, PhD Dissertation, Georgia Institute of Technology, Atlanta, GA.
Moon, F. L., Yi, T., Leon, R. T., and Kahn, L. F. (2006). "Recommendations for Seismic Evaluation and Retrofit of Low-Rise URM Structures." Journal of Structural Engineering, 132(5), 663-672.
Moon, L., D. Dizhur, Griffith, M. & Ingham, J. (2011), Performance of Unreinforced Clay Brick Masonry Buildings during The 22nd February 2011 Christchurch Earthquake, SESOC, Vol 24 No 2.
Neill, S.J., Beer, A.S., Amende, D., 2014, The Church of Jesus Christ of Latter-Day Saints, New Zealand, Proceedings of NZSEE Conference 2014, Auckland.
Newmark, N.M., 1965. Effects of earthquakes on dams and embankments. Geotechnique 15, 139-159.
NZIS, 1965, NZSS 1900, Chapter 8: Basic Design Loads, New Zealand Standards Institute, Wellington
NZS, 2004. NZS 1170.5:2004: Structural Design Actions: Part 5: Earthquake actions New Zealand. Standards New Zealand.
NZSEE, 1995, Draft guidelines for assessing and strengthening earthquake risk buildings, New Zealand Society for Earthquake Engineering.
NZSEE, 2006. New Zealand Society for Earthquake Engineering (NZSEE): Assessment and Improvement of the Structural Performance of Buildings in Earthquakes. Recommendations of a NZSEE Study Group on Earthquake Risk Buildings.
Oliver, S. J., 2010, ‘A design methodology for the assessment and retrofit of flexible diaphragms in unreinforced masonry buildings’, Journal of the Structural Engineering Society of New Zealand (SESOC), 23(1), 19-49.
Russell, A., 2010, Characterisation and Seismic Assessment of Unreinforced Masonry Buildings, Doctoral dissertation, The University of Auckland, Auckland, New Zealand, 344p. https://researchspace.auckland.ac.nz/handle/2292/6038
Russell, A. P., Ingham, J. M., (2010), The influence of flanges on the in-plane performance of URM walls in New Zealand buildings. In Proceedings of the 2010 NZSEE Annual Conference (pp. 1-10). Wellington.
Russell, A. P,, Ingham, J. M., 2010, Prevalence of New Zealand’s unreinforced masonry buildings, Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 43, No. 3, pp 183-202.
Tena-Colunga, A. and Abrams, D. (1996). ”Seismic Behavior of Structures with Flexible Diaphragms.” J. Struct. Eng., 122(4), 439–445.
Tomazevic, M., 1999, Earthquake resistant Design of Masonry Buildings, ISBN 1-86094-066-8, Imperial College Press.
Vaculik, J, 2004, Unreinforced Masonry Walls Subjected to Out-of-Plane Seismic Action, A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, The University of Adelaide, School of Civil, Environment & Mining Engineering.
Vaculik, JJ., 2012, “ Unreinforced Masonry Walls subject to Out-of-plane Seismic Actions”, University of Adelaide, School of Civil, Environmental and Mining Engineering, April 2012.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-137
Updated 22 April 2015 ISBN 978-0-473-26634-9
W. Mann, H. Muller – Proc. Br. Ceram. Soc., 1982. Failure of Shear-Stressed Masonry An Enlarged Theory, Tests and Application to Shear Walls
Willis, CR, Griffith, MC and Lawrence, SJ, (2004). “Horizontal bending of unreinforced clay brick masonry walls,” Masonry International, 17(3): 109-121.
Wilson, A., Kelly, P. A., Quenneville, P. J. H., Ingham, J. M. (2013b). ‘Non-linear in-plane deformation mechanics of timber floor diaphragms in unreinforced masonry buildings’, ASCE Journal of Engineering Mechanics, http://dx.doi.org/10.1061/(ASCE)EM.1943-7889.0000694
Wilson, A., Quenneville, P. J. H., Ingham, J. M. (2013). ‘In-plane orthotropic behaviour of timber floor diaphragms in unreinforced masonry buildings’, ASCE Journal of Structural Engineering, http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0000819
Wilson, A., Quenneville, P. J. H., Moon, F. L., Ingham, J. M. (2013a). ‘Lateral performance of nail connections from century old timber floor diaphragms’, ASCE Journal of Materials in Civil Engineering, http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000792
Wilson, A., Quenneville, P., Ingham, J. (2013c). ‘Natural Period and Seismic Idealization of Flexible Timber Diaphragms’, Earthquake Spectra, 29(3), in press.
Xu, W., and Abrams, D.P. (1992). Evaluation of Lateral Strength and Deflection for Cracked Unreinforced Masonry Walls, U.S. Army Research Office, Report ADA 264-160, Triangle Park, North Carolina.
Yi, T., Moon, F.L., Leon, R.T. and Kahn, L.F. (2008). Flange Effects on the Nonlinear Behavior of URM Piers. TMS Journal. November 2008
Yokel, F.Y. and Dikkers, R.D. (1971). Strength of load bearing masonry walls. Journal of the Structural Division, American Society of Civil Engineers, 120(ST 5), 1593-1609.
Suggested Reading
Clifton, N. C., 2012, (1990). ‘New Zealand Timbers; Exotic and Indigenous’, GB Books, Wellington, 170p.
Curtin, W. G. , Shaw, G., Beck, J. K., Bray, W. A., Easterbrook, D., 1999, Structural Masonry Designers' Manual, Blackwell Publishing.
De Felice, G. and Giannini, R. (2001). Out-of-plane seismic resistance of masonry walls. Journal of Earthquake Engineering, 5(2), 253-271.
Doherty, K., Griffith, M.C., Lam, N., and Wilson, J. (2002). Displacement-based seismic analysis for out-of-plane bending of unreinforced masonry walls. Earthquake Engineering and Structural Dynamics, 31(4), 833-850.
Ghobarah, A. and El Mandooh Galal, K. , 2004, Out-of-plane strengthening of unreinforced masonry walls with openings. Journal of Composites for Construction, 8(4), 298-305.
Griffith, M.C., Magenes, G., Melis, G., and Picchi, L. (2003). Evaluation of out-of-plane stability of unreinforced masonry walls subjected to seismic excitation. Journal of Earthquake Engineering, 7(SPEC. 1), 141-169.
Lam, N.T.K., Griffith, M., Wilson, J., and Doherty, K. (2003). Time-history analysis of URM walls in out-of-plane flexure. Engineering Structures, 25(6), 743-754.
Najafgholipour, M. A., Maheri, M. R., Lourenço, P. B., 2012, Capacity Interaction in Brick Masonry under Simultaneous In-plane and Out-of-plane Loads, Construction and Building Materials. 38:619–626.
Magenes G. and Calvi G. M., 1992, Cyclic behavior of brick masonry walls. In: Tenth world conference on earthquake engineering. 1992. p. 3517–22.
Magenes G., della Fontana, A., 1998, Simplified non-linear seismic analysis of masonry buildings. Proceedings of the Fifth International Masonry Conference. British Masonry Society, London.
Naeim, F, (ed), 2001, The Seismic Design Hand Book, 2nd edition, Springer,
Priestley, M.J.N., Calvi, G.M., Kowalsky, M.J., 2007, Displacement Based Design of Structures
Paulay, T., Priestley, M.J.N., 1992, Seismic design of reinforced concrete and masonry buildings, J. Wiley.
Chena, S.-Y. Moona, F.L. Yib, T. 2008, A macroelement for the nonlinear analysis of in-plane unreinforced masonry piers, Engineering Structures, 30 (2008) 2242–2252.
Simsir, C.C. (2004). Influence of diaphragm flexibility on the out-of-plane dynamic response of unreinforced masonry walls. PhD Thesis, University of Illinois at Urbana-Champaign, United States-- Illinois.
Seismic Assessment of Unreinforced Masonry Buildings
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings 10-138
Updated 22 April 2015 ISBN 978-0-473-26634-9
STM. (2002). Standard Test Method for Conducting Strength Tests of Panels for Building Construction (No. E72-02). ASTM International.
Wilson, A., 2012, (2012).’ Seismic assessment of timber floor diaphragms in unreinforced masonry buildings’, Doctoral dissertation, The University of Auckland, Auckland, New Zealand, March, 568p. https://researchspace.auckland.ac.New Zealand/handle/2292/14696
Yi, T., Moon, F. L., Leon, R. T., and Kahn, L. F _2006a. Lateral load tests on a two-storey unreinforced masonry building.” J. Struct. Eng., 132_5_ 643–652.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-1 Updated 22 April 2015 ISBN 978-0-473-26634-9
Appendix 10A: On-site Testing
10A.1 General
While the seismic response of URM buildings is significantly influenced by characteristics such as boundary conditions and the behaviour of inter-element connections, on-site testing of material properties improves the reliability of the seismic assessments, the numerical models that describe the seismic behaviour of URM buildings and may lead to less conservative retrofit designs. However, the non-homogenous nature of masonry combined with the age of URM buildings make it difficult to reliably predict the material properties of masonry walls. It is recommended that field sampling or field testing of URM elements is conducted. Field sampling refers to the extraction of samples from an existing building for subsequent testing offsite, while field testing refers to testing for material properties in-situ. A set of techniques are described in subsequent sections that can be used to determine masonry material properties. Before proceeding to on-site testing, it is important to sensibly understand what information will be collected from the investigation, how that would be used and what value the information will add to reliability of the assessment. Before deciding an investigation programme, sensitivity analyses should be undertaken to determine what assessment parameters are more important and likely to influence the assessment result and whether the default parameter values given are likely to be appropriate/sufficient. Only rarely should on-site testing be considered necessary for basic buildings.
10A.2 Masonry Assemblage (Prism) Material Properties
If masonry assemblage (prism) samples are to be extracted for laboratory testing they should be single leaf and at least three bricks high. If they are two leafs thick or more, cut them into single leaf samples. If present, remove rendering plaster from both sides of the samples. Cap the prepared samples using gypsum plaster to ensure uniform stress distribution. Test individual brick units and mortar samples as per Section 10A.3 when sampling of larger assemblages is not permitted or practical. Masonry properties can then be predicted using the obtained brick and mortar properties as set out in Section 10.7.
10A.2.1 Masonry compressive strength
Determine masonry compressive strength in accordance with ASTM C 1314-03b (ASTM 2003a). Figure 10A.1 shows a typical prism sample before testing. Aluminium frames are attached to the sample ends and a displacement gauge spans between the frames to measure the sample displacement.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-2 Updated 22 April 2015 ISBN 978-0-473-26634-9
ASTM C 1314-03b (ASTM 2003a) also enables you to determine the masonry modulus of elasticity (further detailed in Section 10A.2.2.1).
Figure 10A.1: Example of extracted sample with test rig attached for the prism
compression test
10A.2.2 Masonry modulus of elasticity
10A.2.2.1 Laboratory calibrated displacement measurement
Laboratory calibrated displacement measurement devices may be attached to the masonry prisms during the compression tests detailed in Section 10A.2.1. Incorporate a minimum of two measurement devices to record displacements at opposing sample faces. Their gauge lengths should cover the distance from the middle of the top brick to the middle of the bottom brick. Use the recorded measurement to derive the masonry stress-strain relationship and subsequently the masonry modulus of elasticity, Em. The stress and strain values considered in the calculation of Em are those between 0.05 and 0.70 times the masonry compressive strength (f’m).
10A.2.2.2 In situ deformability test incorporating flat jacks
Flat jack testing is a versatile and effective technique that provides useful information on the mechanical properties of historical constructions. In-situ measurements of masonry modulus of elasticity should be performed in accordance with the ASTM C 1197 - 04 (ASTM 2004) in situ deformability test. Note:
Extensive studies have been conducted to confirm the reliability of this test, including the work by Noland J.L., Atkinson R.H., Schuller M.P. (1991), Gregorczyk and Lourenço (2000); Parivallal et al. (2011); and Simões (2012).
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-3 Updated 22 April 2015 ISBN 978-0-473-26634-9
The in-situ deformability test is moderately destructive as it requires the removal of horizontal mortar joints (bed-joint) for the insertion of the two flat jacks (Figure 10A.2a). The horizontal slots are separated by at least five courses of brickwork, but the separation distance should not exceed 1.5 times the flat jack length. A pressure controlled hydraulic pump is used to inflate the flat jacks, applying vertical confinement pressure to the masonry between the two jacks. To monitor displacement, typically three measurement devices are attached between the two flat jacks (Figure 10A.2b). These flat jacks need to be calibrated, following ASTM C 1197 - 04 (ASTM 2004).
(a) Cutting mortar bed-joints and insertion of
flat jacks into clay brick masonry
(b) In-situ deformability test set-up under
preparation in clay brick masonry
Figure 10A.2: In situ deformability test preparation (EQ STRUC Ltd)
10A.2.3 Masonry flexural bond strength
Extract masonry prisms two bricks high and a single brick wide, and subject these to the flexural bond test of AS 3700-2001 (Australian Standards, 2001). Remove any rendering plaster from the sides of the sample before performing this test. Cut any samples that are two leafs thick or more into single leaf masonry prism samples. Alternatively, you may conduct the flexural bond test in situ if this is more practical.
(a) Plan view
Measurement device
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-4 Updated 22 April 2015 ISBN 978-0-473-26634-9
(b) Elevation view
Figure 10A.3: Flexural bond test-set-up (AS 3700-2001)
10A.2.4 Masonry bed-joint shear strength
Conduct the ASTM C 1531-03 (ASTM 2003b) in-situ bed-joint shear test to determine masonry bed-joint properties. This type of test is moderately destructive as it requires the removal of at least one brick on one side of the test specimen to allow for insertion of a hydraulic jack, as well as the removal of a vertical mortar joint on the opposite side to allow horizontal bed joint movement to occur. The hydraulic jack is then loaded, using a pressure controlled hydraulic pump, until visible bed-joint sliding failure occurred. You can then derive the bed-joint shear strength from the peak pressure records. Alternatively, extract three brick high masonry prisms for laboratory testing following the triplet shear test BS EN 1052-3 (BSI 2002). This test should be conducted while applying axial compression loads of approximately 0.2 MPa, 0.4 MPa and 0.6 MPa. At least three masonry prism samples should be tested at each level of axial compression. Remove any rendering plaster from both sides of the sample before testing. Cut any masonry samples that are two leafs thick or more into single leaf samples. Bed-joint shear tests performed in the laboratory and in situ are shown in Figure 10A.4.
(a) Laboratory shear triplet test (b) In situ shear test without flat jacks (EQ
STRUC Ltd)
Figure 10A.4: In situ and laboratory bed- joint shear test
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-5 Updated 22 April 2015 ISBN 978-0-473-26634-9
The in situ bed-joint shear test is limited to tests of the masonry face leaf. When the masonry unit is pushed in a direction parallel to the bed joint, shear resistance is provided across not only the bed-joint shear planes but also the collar joint shear plane. Because seismic shear is not transferred across the collar joint in a multi-leaf masonry wall, the estimated shear resistance of the collar joint must be deducted from the test values. This reduction is achieved by including a 0.75 reduction factor in Equation 10.33, which is the ratio of the areas of the top and bottom bed joints to the sum of the areas of the bed and collar joints for a typical clay masonry unit. The term P in Equation 10.33 represents the axial overburden acting on the bed joints. This value multiplied by the bed-joint coefficient of friction, (µf), allows estimation of the frictional component contributing to the recorded bed-joint stress. Due to the typical large variation of results obtained from individual bed-joint shear strength tests, the equation conservatively assumes µf = 1.0 for the purposes of determining cohesion, c. Therefore, for simplicity, the µf term has been omitted from the equation.
10A.3 Constituent Material Properties
10A.3.1 Brick compressive strength
Extract individual brick units for the ASTM C 67-03a (ASTM 2003a) half brick compression test. Cut these brick units into halves and cap them using gypsum plaster before compression testing (Figure 10A.5). Note that it is possible to obtain half brick units from the residual samples of the Modulus of Rupture test described in Section 10A.3.2.
Figure 10A.5: Brick and mortar sample and compression test set-up (EQ STRUC Ltd)
10A.3.2 Brick modulus of rupture
Extract individual brick units from the building and subject these to the modulus of rupture (MoR) test ASTM C 67-03a (ASTM 2003a). The tested brick specimens from the MoR test may be subjected to the half brick compression test ASTM C 67-03a (ASTM 2003a) in order to obtain a direct relationship between the brick MoR and compressive strength, f’b. Previous experimental investigation has confirmed that the brick unit MoR can be approximated to equal 0.12f’b.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-6 Updated 22 April 2015 ISBN 978-0-473-26634-9
10A.3.3 Mortar compressive strength
Extract irregular mortar samples for laboratory testing. As it is common for URM walls to have eroded mortar joints that were later repaired using stronger mortar, take care when selecting the location for mortar sample extraction to ensure that your samples are representative. The method to determine mortar compressive strength is detailed in ASTM C 109-08 (ASTM 2008). This method involves testing of 50 mm cube mortar samples, which generally are not attainable in existing buildings as most mortar joints are only 10 to 18 mm thick. Therefore, cut the irregular mortar samples into approximately cubical sizes with two parallel sides (top and bottom). The height of the mortar samples should exceed 15 mm in order to satisfactorily maintain the proportion between sample size and the maximum aggregate size. Cap the prepared samples using gypsum plaster to ensure a uniform stress distribution and testing in compression (Valek and Veiga, 2005): see Figure 10A.6 for examples. Measure the height to minimum lateral dimension (h/t) ratio of the mortar samples and use this to determine the mortar compressive strength correction factors. Divide the compression test result by the corresponding correction factors in Equation 10A.1. The average corrected strength is equal to the average mortar compressive strength, f’j.
…10A.1
where:
= normalised mortar compressive strength = t/l ratio correction factor = t/l ratio correction factor
= measured irregular mortar compressive strength. Equation 10A.1 normalises the measured compressive strength of irregular mortar samples to the compressive strength of a 50 mm cube mortar. Factors and are calculated as per Equations 10A.2 and 10A.3 (where . should be calculated as per Equation 10A.4) respectively. Factor is required in order to normalise the sample t/l ratio to 1.0, while factor is required in order to normalise the sample h/t ratio to 1.0, corresponding to a cubic mortar sample that is comparable to a 50 mm cube. These factors were derived based on the study detailed in Lumantarna (2012).
0.42 0.58 …10A.2
. …10A.3
. 2.4 5.7 4.3 …10A.4
When conducting tests on laboratory manufactured samples make 50 mm mortar cubes, leave these to cure under room temperature (±20 °C) for 28 days, and test them in compression following the mortar cube compression test ASTM C 109-08 (ASTM 2008).
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-7 Updated 22 April 2015 ISBN 978-0-473-26634-9
(a) Example of typical extracted mortar samples
(b) Example of typical mortar sample preparations
(c) Example of typical test set-up
Figure 10A.6: Determination of mortar compression strength (EQ STRUC Limited)
10A.4 Proof Testing of Anchor Connections
An epoxied or grouted anchorage system is a typical method of connecting the floor and roof diaphragms of the building to masonry walls. Reliable anchor pull-out and shear strength is important for assessment or design of anchors and the specification of anchor spacing. Standard installation procedures of embedded anchors involve drilling the masonry wall, cleaning the drilled hole and epoxying or grouting threaded steel bars to the specified embedment depth, typically 50 mm less than the wall thickness. Two-part epoxy or high strength grouts are typically used with surface preparation conducted in accordance with the manufacturer’s specifications. On-site quality control and proof testing should be undertaken on at least 15% of all installed adhesive anchors, of which 5% should be tested prior to the installation of more than 20% of all anchors. Testing is required to confirm workmanship (particularly the mixing of epoxy and cleaning of holes) and anchor capacity against load requirements. If more than 10% of the tested anchors fail below a test load of 75% of the nominated probable capacity, discount the failed anchors from the total number of anchors tested as part of the quality assurance test. Test additional anchors to meet the 15% threshold requirements. Failures that cannot be attributed to workmanship issues are likely to be indicative of an overestimation of the available capacity and a reassessment of the available probable capacity is likely to be required.
10A.4.1 Anchors loaded in tension
Once the adhesive is cured (typically over 24 hours), the steel anchors can be loaded in tension using a hydraulic jack until ultimate carrying capacity is reached (ASTM, 2003) or when the load exceeds two times the specified load. The typical test set-up is shown in Figure 10A.7. A 600 mm clear span of reaction frame allows testing of up to 300 mm embedment depth without exerting any confining pressures onto the test area, as the reaction frame supports are outside the general zone of influence. On completing the test, the anchor stud is typically cut flush with the wall surface.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Testing
Section 10 - Seismic Assessment of Unreinforced Masonry Buildings App-8 Updated 22 April 2015 ISBN 978-0-473-26634-9
(a) Typical anchor pull test
set up
(b) Close up of the typical test set-up with an
alternative test frame
Figure 10A.7: Typical anchor pull-out test set-up (EQ STRUC Ltd)
10A.4.2 Anchors loaded in shear
The test set-up that could be adopted for in situ testing of anchors loaded in shear is shown in Figure 10A.8. Monotonic shear loading can be applied by using a single acting hydraulic actuator, with the external diameter of the actuator selected to be as small as possible. The bracket arrangements should minimise the tension loads in the anchors. The aim is to determine the shear capacity in the absence of tension.
(a) Typical anchor shear tests set-up (push cycle)
(b) Typical anchor shear tests set-up (pull cycle)
Figure 10A.8: Shear tests set-up used (EQ STRUC Ltd)
10A.5 Investigation of Collar Joints and Wall Cavities
Investigation of collar joints quality and wall cavities can be undertaken using a Ground Penetrating Radar (GPR) structural scanner (Figure 10A.9a). The scanner is capable of accurately determining the member thickness, metallic objects, voids and other
SeUpd
inFi
1
Ththinbr
ection 10 - Seismdated 22 April 2015
nformation. igure 10A.9
(a) Ground
Figure 10A
0A.6
he main foche cavity tinspection carick or an ai
(a) Bores
mic Assessmen
An examp9b.
Penetrating
A.9: Example
Cavity
cus of the cies embeddamera can bir vent (Figu
cope inspec
Figure 10
t of Unreinforce
le of the in
g Radar (GPR
e of non-invascanner
Tie Exa
cavity tie exded betweenbe used to inure 10A.10)
ction camer
0A.10: Bores
Seismic Ass
ed Masonry Buil
nformation
R) scanner
asive scannr technology
aminati
xamination n the leavenspect the a).
ra (
scope inspe
sessment of Un
ldings
provided b
ning using Gy (EQ STRU
on
is to identifes of the cair cavity th
(b) Typical e
ection came
reinforced Maso
IS
by GPR sca
(b) Typical
Ground PeneC Ltd)
fy the condcavity URMhrough a voi
example of c
ra (EQ STRU
Poor co
Header coursesover the ca
onry Buildings –
SBN 978-0-4
anning is p
results outp
etrating Rad
dition and frM walls. Aid left from
cavity obse
UC Ltd)
ollar joint
s bridging avity
– Appendix 10AOn-site Testing
App-9473-26634-9
presented in
put
dar (GPR)
requency ofA borescopem a removed
rvations
A g
9 9
n
f e d
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10A On-site Investigation
Appendix 10A–Detailed Assessment of Unreinforced Masonry Buildings App-10 Updated 22 April 2015 ISBN 978-0-473-26634-9
References ASTM (2003). “Standard Test Methods for Strength of Anchors in Concrete and Masonry Elements.” E488-96. ASTM International. Pennsylvania, United States.Se
ASTM. (2000). "Standard Test Method for Measurement of Masonry Flexural Bond Strength." C 1072 - 00a. ASTM International, Pennsylvania, United States.
ASTM. (2003a). “Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile.”, C 67-03a. ASTM International, Pennsylvania, United States.
ASTM. (2003b). "Standard Test Methods for In Situ Measurement of Masonry Mortar Joint Shear Strength Index." C 1531 - 03. ASTM International, Pennsylvania, United States.
ASTM (2004). "Standard Test Method for In Situ Measurement of Masonry Deformability Properties Using the Flatjack Method." C 1197 - 04, ASTM International, Pennsylvania, United States.
ASTM. (2008). "Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens).”, C 109/C 109M - 08, ASTM International, Pennsylvania, United States.BSI (2002). "Methods of test for masonry. Determination of initial shear strength." BS EN 1052-3:2002, British Standards Institution, United Kingdom.
Noland J.L., Atkinson R.H., Schuller M.P. (1991) "A Review of the Flat Jack Method for Non-destructive Evaluation of Civil Structures and Materials.” The National Science Foundation. Grant No. MSM 9005818.
Gregorczyk P. and Lourenço P. (2000). “A Review on Flat-Jack Testing.” Universidad do Minho, Departamento de Engenharia Civil Azurém, P – 4800-058 Guimarães, Portugal.
Parivallal S., K. Kesavan, K. Ravisankar, B Arun Sundram and A K Farvaze Ahmed (2011). “Evaluation of In-situ Stress in Masonry Structures by Flat Jack Technique.” Proceedings of the National Seminar & Exhibition on Non-Destructive Evaluation. NDE 2011, December 8-10, 2011 CSIR-Structural Engineering Research Centre, Chennai 600 113.
Lumantarna, R. (2012). “Material Characterisation of New Zealand’s Clay Brick Unreinforced Masonry Buildings.” Doctoral Dissertation, University of Auckland, Department of Civil and Environmental Engineering Identifier: http://hdl.handle.net/2292/18879.
Simões A., A. Gago, M. Lopes & R. Bento (2012). “Characterization of Old Masonry Walls: Flat-Jack
Method.” 15th World Conference on Earthquake Engineering (15WCEE) Lisbon, Portugal 24-28 September 2012.
Standards Australia (2001). "Appendix D: Method of Test for Flexural Strength." AS 3700 - 2001, Standards Australia, Homebush, New South Wales, Australia.
Valek, J., and Veiga, R. (2005). ”Characterisation of Mechanical Properties of Historic Mortars - Testing of Irregular Samples”, Structural studies, repairs and maintenance of heritage architecture XI: Ninth international conference on structural studies, repairs and maintenance of heritage architecture, Malta, 22-24 June.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-11 Updated 22 April 2015 ISBN 978-0-473-26634-9
Appendix 10B: Derivation of Instability Deflection and Fundamental Period for Face-Loaded Masonry Walls
10B.1 General considerations and approximations
There are many variations that need to be taken into account when considering a general formulation for URM walls that might fail out-of-plane. These include:
Walls will not usually be of a constant thickness in a building, or even within a storey.
Walls will have embellishments, appendages and ornamentation that may lead to eccentricity of masses with respect to supports.
Walls may have openings for windows or doors.
Support conditions will vary.
Existing buildings may be rather flexible, leading to possibly large inter-storey displacements that may adversely affect the performance of face-loaded walls.
You can use the following approximations to simplify your analysis while still accounting for some the key important factors. 1 Deformations due to distortions (straining) in the wall can be ignored. Assume
deflections to be entirely due to rigid body motion.
Note:
This is equivalent to saying that the change in potential energy from a disturbance of the wall from its initial position is mostly due to the movement of the masses of the elements comprising the wall and the movements of the masses tributary to the wall. Strain energy contributes less to the change in potential energy.
2 Assume that potential rocking occurs at the support lines (e.g. at roof or floor levels)
and, for walls that are supported at the top and bottom of a storey, at the mid-height. The mid-height rocking position divides the wall into two parts of equal height: a bottom part (subscript b) and a top part (subscript t). The masses of each part are not necessarily equal.
Note:
It is implicit within this assumption and (1) above that the two parts of the wall remain undistorted when the wall deflects. For walls constructed of softer mortars or walls with little vertical pre-stress from storeys above, this is not actually what occurs: the wall takes up a curved shape, particularly in the upper part. Nevertheless, errors occurring from the use of the stated assumptions have been found to be small and you will still obtain acceptably accurate results.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-12 Updated 22 April 2015 ISBN 978-0-473-26634-9
3 Assume the thickness to be small relative to the height of the wall. Assume the slope, A, of both halves of the wall to be small; in the sense that cos(A) ≈ 1 and sin(A) ≈ A.
Note:
The approximations for slope are likely to be sufficiently accurate for reasonably thin walls. For thick walls where the height to thickness ratio is smaller, the formulations in this appendix are likely to provide less accurate results and force-based approaches provide an alternative.
4 Inter-storey slopes due to deflection of the building are assumed to be small.
Note:
Approximate corrections for this effect are noted in the method. 5 In dynamic analyses, the moment of inertia is assumed constant and equal to that
applying when the wall is in its undisturbed position, whatever the axes of rotation.
Note:
The moment of inertia is dependent on the axes of rotation. During excitation, these axes continually change position. Assuming that the inertia is constant is reasonable within the context of the other approximations employed.
6 Damping is assumed at the default value in NZS 1170.5:2004, which is 5% of
critical.
Note:
For the aspect ratio of walls of interest, additional effective damping due to loss of energy on impact is small. Furthermore, it has been found that the surfaces at rocking (or hinge) lines tend to fold onto each other rather than experience the full impact that is theoretically possible, reducing the amount of equivalent damping that might be expected. However, for in-plane analysis of buildings constructed largely of URM, adopting a damping ratio that is significantly greater than 5% is appropriate.
7 Assume that all walls in storeys above and below the wall under study move “in
phase” with the subject wall.
Note:
Analytical studies have found this to be the case. One reason for this is that the effective stiffness of a wall as it moves close to its limit deflection (e.g. as measured by its period) becomes very low, affecting its resistance to further deflection caused by accelerations transmitted to the walls through the supports. This assumption means that upper walls, for example, will tend to restrain the subject wall by exerting restraining moments.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-13 Updated 22 April 2015 ISBN 978-0-473-26634-9
10B.2 Vertically spanning walls
10B.2.1 General formulation
Figures 10B.1 and 10B.2 show the configuration of a wall panel within a storey at two stages of deflection. The wall is intended to be quite general. Simplifications to the general solutions for walls that are simpler (e.g. of uniform thickness) are made in a later section. Figure 10B.1 shows the configuration at incipient rocking. Figure 10B.2 shows the configuration after significant rocking has occurred, with the wall having rotated through an angle A and with mid-height deflection, , where = Ah/2. In Figure 10B.1 the dimensions eb and et relate to the mass centroids of the upper and lower parts of the panel. The dimension ep relates to the position of the line of action of weights from upper storeys (walls, floors and roofs) relative to the centroid of the upper part of the panel. The arrows on the associated dimensioning lines indicate the positive direction of these dimensions for the assumed direction of motion (angle A at the bottom of the wall is positive in the anti-clockwise sense). Under some circumstances the signs of the eccentricities may be negative; for example for ep when an upper storey wall is much thinner than the upper storey wall represented here, particularly where the thickness steps on one face. When the lines of axial force from diaphragm and walls from above are different, the resultant force should be calculated.
Figure 10B.1: Configuration at incipient rocking
ICR
Wt
Wb
P
eb eo
eo+ebeP
et
yt
yb
h2
h
ICR
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-14 Updated 22 April 2015 ISBN 978-0-473-26634-9
The instantaneous centres of rotation (ICR) are also marked on these figures. These are useful in deriving virtual work expressions.
10B.2.2 Limiting deflection for static instability
You can write the equation of equilibrium directly by referring to Figure 10B.2 and using virtual work expressions. For static conditions this is given by:
0 …10B.1
The final term represents the effect of any inter-storey drift. In the derivation presented, the total deformation has been assumed to be that resulting from the summation of the drift and the rocking wall. Writing:
…10B.2
and:
…10B.3
and collecting terms in A, the equation of equilibrium is rewritten as:
0 …10B.4
from which:
…10B.5
when the wall becomes unstable.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-15 Updated 22 April 2015 ISBN 978-0-473-26634-9
Figure 10B.2: Configuration when rotations have become significant and there is inter-
storey drift
Therefore, the critical value of the deflection at mid-height of the panel, at which the panel will be unstable, is:
∆ …10B.6
It is assumed that m, a fraction of this deflection, is the maximum useful deflection. Experimental and analytic studies indicate that this fraction might be assumed to be about 0.6. At larger displacements than 0.6i, analysis reveals an undue sensitivity to earthquake spectral content and a wide scatter in results.
10B.2.3 Equation of motion for free vibration
When conditions are not static, the virtual work expression on the left-hand side in the equation above is unchanged, but the zero on the right-hand side of the equation is replaced by mass x acceleration, in accordance with Newton’s law. This gives:
…10B.7
This uses the usual notation for acceleration (a double dot to denote the second derivative with respect to time; in this case indicating angular acceleration), and J as the rotational inertia. The rotational inertia can be written directly from Figures 10B.1 and 10B.2, noting that the centroids undergo accelerations vertically and horizontally as well as rotationally, and these accelerations relate to the angular acceleration in the same way as the displacements relate to the angular displacement. While the rotational inertia is dependent on the
support reaction
ICR
Wt
Wb
P
eb eo
eo+ebeP
et
yt
yb
h2
h
Wt Wt
Wb
support reaction
ICR
Wt
Wb
P
eb
eP
et
yt
yb
h2
h
Wt
eb - Ayb
eo +eb - Ah2
eo +eb +et +ep - Ah
ICRP
h +
A(e
0+
eb
+ e
t+
eP)
ICR
Wt
Wb
A, A
A, A
eo +eb +et - A(h -yt)
Drift (max = 0.025)
+
Rocking Wall
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-16 Updated 22 April 2015 ISBN 978-0-473-26634-9
displacements, the effects of this variation are ignored. Therefore, the rotational inertia is taken as that when no displacement has occurred. This gives the following expression for rotational inertia.
…10B.8
where Jbo and Jto are the mass moments of inertia of the bottom and top parts respectively about their centroids, and Janc is the inertia of any ancillary masses, such as veneers, that are not integral with the wall but contribute to its inertia. For a wall with unit length, held at the top and bottom, and rocking crack at mid-height, with a density of ρ per unit volume, the mass moment of inertia about the horizontal axis through the centroid is given by:
kgm …10B.9
The corresponding mass moment of inertia about the vertical axis through the centroid is:
kgm …10B.10
The polar moment of inertia through the centroid is the sum of these, or:
kgm
…10B.11
where m is the mass (kg) and W (N) is the weight of the whole wall panel and g is the acceleration of gravity. Note that in this equation the expressions in square brackets are the squares of the radii from the instantaneous centres of rotation to the mass centroids, where the locations of the instantaneous centres of rotation are those when there is no displacement. Some CAD programs have functions that will assist in determining the inertia about an arbitrary point (or locus), such as about the ICR shown in Figure 10B.2. Collecting terms and normalising the equation so that the coefficient of the acceleration term is unity gives the following differential equation of free vibration:
…10B.12
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-17 Updated 22 April 2015 ISBN 978-0-473-26634-9
10B.2.4 Period of free vibration
The solution of the equation for free vibration derived in the previous section is:
…10B.13
The time, , is taken as zero when the wall has its maximum rotation, A (=/2h). Using this condition and the condition that the rotational velocity is zero when the time = 0, the solution becomes:
∆ ….10B.14
Take the period of the “part”, Tp, as four times the duration for the wall to move from its position at maximum deflection to the vertical. Then the period is given by:
4 ∆ …10B.15
This can be simplified further by substituting the term for i found from the static analysis and putting the value of used for the calculation of period as Δt to give:
4 ∆∆
…10B.16
If we accept that the deflection ratio of interest is 0.6 (i.e. ∆ ∆ = 0.6), then this becomes:
6.27 …10B.17
as in the 2006 guidelines. However, research (Derakhshan et al, (2014a)) indicates that the resulting period and responding displacement demand is too large if a spectrum derived from linear elastic assumptions is used. Rather, this research suggests that an effective period calculated from an assumed displacement of 60% of the assumed displacement capacity should be used. Therefore, the period is based on Δt = 0.36Δi so that:
4.07 …10B.18
10B.2.5 Maximum acceleration
The acceleration required to start rocking of the wall occurs when the wall is in its initial (undisturbed) state. This can be determined from the virtual work equations by assuming that A=0. Accordingly:
…10B.19
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-18 Updated 22 April 2015 ISBN 978-0-473-26634-9
However, a more cautious appraisal assumes that the acceleration is influenced primarily by the instantaneous acceleration of the supports, transmitted to the wall masses, without relief by wall rocking. Accordingly:
…10B.20
where Cm is the acceleration coefficient to just initiate rocking.
10B.2.6 Participation factor
The participation factor can be determined in the usual way by normalising the original form of the differential equation for free vibration, modified by adding the ground acceleration term. For the original form of the equation, the ground acceleration term is added to the RHS. Written in terms of a unit rotation, this term is (Wbyb + Wtyt) times the ground acceleration. The equation is normalised by dividing through by J, and then multiplied by h/2 to convert it to one involving displacement instead of rotation. The participation factor is then the coefficient of the ground acceleration. That is:
…10B.21
10B.2.7 Simplifications for regular walls
You can make simplifications where the thickness of a wall within a storey is constant, there are no openings, and there are no ancillary masses. Further approximations can then be applied:
The weight of each part (top and bottom) is half the total weight, W.
yb = yt = h/4
The moment of inertia of the whole wall is further approximated by assuming that all e are very small relative to the height (or, for the same result, by ignoring the shift of the ICR from the mid-line of the wall), giving J = Wh2/12g. Alternatively, use the simplified expressions for J given in Table 10B.1.
10B.2.7.1 Approximate displacements for static instability
Table 10B.1 gives values for a and b and the resulting mid-height deflection to cause static instability when eb and/or ep are either zero or half of the effective thickness of the wall, t. In this table eo and et are both assumed equal half the effective wall thickness. While these values of the eccentricities are reasonably common, they are not the only values that will occur in practice. The effective thickness may be assumed as follows:
0.975 0.025 …10B.22
where tnom is the nominal thickness of the wall.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-19 Updated 22 April 2015 ISBN 978-0-473-26634-9
Experiments show that this is a reasonable approximation, even for walls with soft mortar. In that case, there is greater damping and that reduces response, which compensates for errors in the expression for effective thickness. 10B.2.7.2 Approximate expression for period of vibration Noting that:
…10B.23
and using the approximation for J relevant to a wall with large aspect ratio, the expression for the period is given by:
4.07 …10B.24
where it should be noted that the period is independent of the restraint conditions at the top and bottom of the wall (i.e. independent of both eb and ep). If the height is expressed in metres, this expression simplifies to:
.
/ …10B.25
It should be appreciated that periods may be rather long. This approximation errs on the low side, which leads to an underestimate of displacement demand and therefore to slightly incautious results. The fuller formulation is therefore preferred. 10B.2.7.3 Participation factor Suitable approximations can be made for the participation factor. This could be taken at the maximum value of 1.5. Alternatively, the numerator can be simplified as provided in the following expression, and the simplified value of J shown in Table 10B.1 can be used. 10B.2.7.4 Maximum acceleration By making the same simplifications as above, the maximum acceleration is given by:
…10B.26
Or, more cautiously, the acceleration coefficient, Cm, is given in Table 10B.1 for the common cases regularly encountered.
Appendix 10B–Updated 22 April 20
10B.2.8
Using the h/4, b is percentage31% for Caffects shosteel mome Table 10B.1
Boundary condition nu
ep
eb
b
a
i = bh/(2
J
Cm
Note: 1. The boun2. The top e
et, is the ha boundar
3. The eccenshould be
10B.3
10B.3.1
Figure 10Boverburdenload does horizontallextent thanthe wall ina continuouapplication
–Detailed Asses015
Adjustis larg
common limfound to b
e reduction Cases 0 and ould be asseent-resisting
1: Static ins
umber
2a)
{(W
(
ndary conditioneccentricity, et ihorizontal dista
ary condition. ntricities showne entered as a n
Vertic
Gener
B.3 shows n load at thexist it is imly. As a resn if the walln such a wayus beam or
n of P.
De
ssment of Unre
tments rge
mit on ofbe Wh/160.in the insta2, and 16%essed especg frames.
stability defe
0
0
0
(W/2+P)t
(W/2+P)h
t/2
W/12)[h2 +7t2]
+Pt2}/g
(2+4P/W)t/h
s of the piers shis not related toance from the ce
n in the sketcheegative number
cal cant
ral formu
a general ae top, but thmportant tosult the inerl was suppoy that its poslab that cr
Seismic Aerivation of Inst
inforced Mason
required
f 0.025, and Taking h/ability defle
% for Cases cially in bui
ection for un
0
t/
(W+3
(W/2
(2W+(2W
{(W/12)
+9Pt
(4+6P
hown above are a boundary conentral pivot poi
es are for the por.
tilevers
ulation
arrangemenhis load wi
o realise thartia of the worted horizonint of appli
rosses the w
Assessment of tability Deflectio
nry Buildings
d when in
d substitutin/t = 25, in ection for e1 and 3. Th
ildings with
niform walls
1
0
t/2
3P/2)t
2+P)h
W+3P)t W+4P)
[h2+16t2]
t2/4}/g
P/W)t/h
e for clockwise ndition, hence iint to the centre
ositive sense. W
s
nt of a cantill commonlat the mass wall is affecntally at thecation can c
wall, there w
Unreinforced Mn and Fundame
nter-stor
ng for Wb =the absenc
each case shese are noh flexible p
s, various bo
2
t/2
0
(W/2+3P/2
(W/2+P)h
(W+3P)t(2W+4P)
{(W/12)[h2+7
+9Pt2/4}/g
(2+6P/W)t/
potential rockinis not included e of mass of the
Where the top ec
tilever. Thely be zero, associated cted by thee top. If thechange, as i
will be an ec
Masonry Buildingental Period for
ISBN 978-
rey displ
Wt = W/2 ce of any sshown in Tat insignificarincipal fra
oundary con
2)t
h (
7t2]
g
{(W/
/h 4(1
ng. in the table. Th
e top block whic
ccentricity is in
e wall illusas in a parawith that lo overburdentop load is
is the case iccentricity o
gs – Appendix 1Masonry Buildi
App-0-473-26634
lacemen
and yb = yt
surcharge, table 10B.1 ant, and the
aming such
nditions
3
t/2
t/2
(W+2P)t
(W/2+P)h
T
W/12)[h2+16t2]
+4Pt2}/g
1+2P/W)t/h
he top eccentricch is not related
n the other sense
strated has apet. Whereoad can mon to a grea
s supported if it is throuof the point
10B ngs
p-20 4-9
nt
t = the
is ese as
city, d to
e ep
an e a ove ter on
ugh of
ApUpd
Soprmpr Fowth
N
ppendix 10B–Dedated 22 April 2015
ometimes srovide the
methods derirovided here
or the singlwall at the tohe following
Note that in t
etailed Assessm
everal walllateral resiived from e.
e wall illusop and that pg parameter
these equati
Deriv
ment of Unreinfo
ls will be liistance to athe general
trated, it is point of apps:
ions ep is tak
Figure
Seismic Assvation of Instabi
orced Masonry B
inked; for ea single-stol formulatio
assumed thplication rem
ken as posit
10B.3: S
sessment of Unlity Deflection a
Buildings
example, whorey buildinon, but exp
hat P is appmains const
tive in the s
Single canti
reinforced Masond Fundamenta
IS
hen a seriesng. This capress formu
plied eccentrant. It is str
ense shown
ilever
onry Buildings –al Period for Ma
SBN 978-0-4
s of face-loase can be ulations for
tric to the ceraightforwar
n in Figure 1
– Appendix 10Basonry Buildings
App-21473-26634-9
oaded wallssolved by
r it are not
entre of therd to obtain
…10B.27
…10B.28
…10B.29
10B.3.
B s
9
s y t
e n
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10B Derivation of Instability Deflection and Fundamental Period for Masonry Buildings
Appendix 10B–Detailed Assessment of Unreinforced Masonry Buildings App-22 Updated 22 April 2015 ISBN 978-0-473-26634-9
10B.3.2 Limiting deflection for static instability
When the wall just becomes unstable, the relationship for A remains the same as before but the deflection is Ah. Thus, the limiting deflection is given by:
∆ ...10B.30
For the case where P=0 and yb=h/2 this reduces to i = 2eb = t.
10B.3.3 Period of vibration
If Δt = 0.36Δi as for the simple case, the general expression for period would remain valid. However, cantilevers are much more susceptible to instability under real earthquake stimulation than wall panels that are supported both top and bottom. Therefore, the maximum useable displacement for calculation of capacity, Δm, is reduced from 0.6Δi to 0.3Δi and the displacement for calculation of period changes from 0.6Δm to 0.8Δm = 0.24Δi
so that:
3.1 …10B.31
Where P=0, eb=t/2, yb=h/2, approximating t=tnom and expressing h in metres, the period of vibration is given by:
0.65 1 …10B.32
Note that P, whether eccentric or not, will not affect the static instability displacement, and therefore neither the displacement demand (by affecting the period), nor the displacement capacity.
10B.3.4 Participation factor
The expression for the participation factor remains unaffected; that is, = Wh2/2J. This may be simplified for uniform walls with P=0 (no added load at the top) by inserting the specific expression for J. This gives:
…10B.33
10B.3.5 Maximum acceleration
Using the same simplifications as above:
…10B.34
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10C Charts for Assessment of Out-of-Plane Walls
Appendix 10C– Charts for Assessment of Out-of-Plane Walls App-23 Updated 22 April 2015 ISBN 978-0-473-26634-9
Appendix 10C: Charts for Assessment of Out-of-Plane Walls
10C.1 General
This appendix presents simplified ready-to-use charts for estimation of %NBS for face-loaded unreinforced masonry walls with uniform thickness. The charts have been developed for walls with various slenderness ratios (wall height/thickness) vs Basic Performance Ratio (BPR). The BPR can be converted to %NBS after dividing it by the product of the appropriate spectral shape factor (Ch(0), required to evaluate C(0) for parts), return period factor (R), hazard factor (Z), near-fault factor (N(T, D)), and part risk factor (Rp) which have been assigned unit values for developing the charts. The charts are presented for various boundary conditions and ratio of load on the wall to self-weight of the wall. Refer to Section 10 and Appendix 10B for symbols and sign conventions. This appendix includes charts for the following cases:
one-way vertically spanning walls laterally supported both at the bottom and the top with no inter-storey drift
one-way vertically spanning walls laterally supported at the top and the bottom with inter-storey drift of 0.025
vertical cantilever walls. The following section presents how these charts should be used.
10C.2 One-way Vertically Spanning Face-Loaded Walls
Charts for one-way vertically spanning walls are presented in Figures 10C.1a-f, 10C.2a-f and 10C.3a-f for 110 mm, 230 mm and 350 mm thick walls respectively for inter-storey drift of 0.00. Similarly, charts for an inter-storey drift of 0.025 are presented in Figures 10C.4a-f, 10C.5a-f and 10C.6a-f for 110 mm, 230 mm and 350 mm thick walls respectively. The charts have been developed for et = eo = t/2 and various values for ep. Follow the following steps for estimation of %NBS for a vertically spanning face-loaded wall:
Identify thickness, tGross and height, h of the wall.
Calculate slenderness ratio of the wall (h/tGross).
Calculate the total self-weight, W of the wall.
Calculate vertical load, P on the wall. This should include all the dead load and appropriate live loads on the wall from above.
Calculate P/W.
Calculate eccentricities (eb and ep). eb could be t/2 or 0, whereas ep could be ±t/2 or 0. To assign appropriate values, check the base boundary condition and location of P on the wall. Calculation of effective thickness, t is not required.
Seismic Assessment of Unreinforced Masonry Buildings – Appendix 10C Charts for Assessment of Out-of-Plane Walls
Appendix 10C– Charts for Assessment of Out-of-Plane Walls App-24 Updated 22 April 2015 ISBN 978-0-473-26634-9
Refer to the appropriate charts (for appropriate eb and ep, P/W and inter-storey drift).
Estimate Basic Performance Ratio (BPR) from the charts. Linear interpolation between plots may be used as necessary for inter-storey drifts between 0 and 0.025.
Refer NZS 1170.5 for Ch(0) required to evaluate C(0) for parts, R, Z, N(T, D), CHi and Rp. For estimation of CHi, hi is height of the mid-height of the wall from the ground.
% /
,
10C.3 Vertical Cantilevers
Charts for one-way vertically spanning walls are presented in Figures 10C.7a-c, 10C.8a-c and 10C.9a-c for 110 mm, 230 mm and 350 mm thick walls respectively. Follow the following steps for estimation of %NBS of a face-loaded cantilever wall:
Identify thickness, tGross and height, h of the wall.
Calculate slenderness ratio of the wall (h/tGross).
Calculate total self-weight, W of the wall above the level of cantilevering plane.
Calculate vertical load, P on the wall, if any. This should include all the dead load and appropriate live loads on the wall from above.
Calculate P/W.
Calculate eccentricity, ep, for loading P(ep). ep could be ±t/2 or 0, which depends upon location of P on the wall. Calculation of effective thickness, t is not required.
Refer to the appropriate charts (for appropriate ep, and P/W).
Estimate Basic Performance Ratio (BPR) from the charts. Interpolation between plots may be used as necessary.
Refer NZS 1170.5 for Ch(0) required to evaluate C(0) for parts, R, Z, N(T, D), CHi and Rp. For estimation of CHi, hi shall be taken as height of the base of the cantilever wall.
% /
,
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
a
sment of Out-of
a) For eb = +
b) For eb =
Seismic Ass
f-Plane Walls
+ t/2 and ep =
+ t/2 and ep
sessment of Unr
= + t/2 (tGross
p = 0 (tGross =
reinforced MasoCharts for Asse
IS
=110 mm)
110 mm)
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-25473-26634-9
C s
5 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
c) For eb =
d) For e
Seismic A
ut-of-Plane Wall
= + t/2 and e
eb = 0 and ep
Assessment of
s
ep = -t/2 (tGro
p = t/2 (tGross
Unreinforced MCharts for A
oss = 110 mm
= 110 mm)
Masonry BuildingAssessment of O
ISBN 978-
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-26 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Figure 10
Charts for Asses
C.1: 110
sment of Out-of
e) For eb =
f) For eb =
0 mm thick o
Seismic Ass
f-Plane Walls
= 0 and ep =
0 and ep = -
one-way ve
sessment of Unr
= 0 (tGross = 1
-t/2 (tGross =
rtically span
reinforced MasoCharts for Asse
IS
10 mm)
110 mm)
nning face-l
onry Buildings –sessment of Out
SBN 978-0-4
oaded walls
– Appendix 10Ct-of-Plane Walls
App-27473-26634-9
s ( = 0)
C s
7 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
a) For eb =
b) For eb
Seismic A
ut-of-Plane Wall
= + t/2 and e
b = + t/2 and
Assessment of
s
ep = + t/2 (tGr
d ep = 0 (tGros
Unreinforced MCharts for A
ross =230 mm
ss =230 mm)
Masonry BuildingAssessment of O
ISBN 978-
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-28 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
c
sment of Out-of
c) For eb = +
d) For eb =
Seismic Ass
f-Plane Walls
+ t/2 and ep =
= 0 and ep =
sessment of Unr
= -t/2 (tGross =
t/2 (tGross = 2
reinforced MasoCharts for Asse
IS
= 230 mm)
230 mm)
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-29473-26634-9
C s
9 9
Appendix 10C–Updated 22 April 20
Figure 1
– Charts for Ass015
10C.2: 2
sessment of Ou
e) For e
f) For eb
230 mm thic
Seismic A
ut-of-Plane Wall
eb = 0 and e
b = 0 and ep
ck one-way v
Assessment of
s
ep = 0 (tGross =
= -t/2 (tGross
vertically sp
Unreinforced MCharts for A
= 230 mm)
= 230 mm)
panning face
Masonry BuildingAssessment of O
ISBN 978-
e-loaded wa
gs – Appendix 1Out-of-Plane W
App-0-473-26634
alls ( = 0 )
10C Walls
p-30 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
a
sment of Out-of
a) For eb = +
b) For eb =
Seismic Ass
f-Plane Walls
t/2 and ep =
+ t/2 and ep
sessment of Unr
= + t/2 (tGross
p = 0 (tGross =
reinforced MasoCharts for Asse
IS
= 350 mm)
350 mm)
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-31473-26634-9
C s
9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
c) For eb =
d) For e
Seismic A
ut-of-Plane Wall
= + t/2 and e
eb = 0 and ep
Assessment of
s
ep = -t/2 (tGro
p = t/2 (tGross
Unreinforced MCharts for A
oss = 350 mm
= 350 mm)
Masonry BuildingAssessment of O
ISBN 978-
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-32 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Figure 10C
Charts for Asses
C.3: 350
sment of Out-of
e) For eb =
f) For eb =
0 mm thick o
Seismic Ass
f-Plane Walls
= 0 and ep =
0 and ep = -
one-way ver
sessment of Unr
= 0 (tGross = 3
-t/2 (tGross = 3
rtically span
reinforced MasoCharts for Asse
IS
350 mm)
350 mm)
nning face-lo
onry Buildings –sessment of Out
SBN 978-0-4
oaded walls
– Appendix 10Ct-of-Plane Walls
App-33473-26634-9
s ( = 0 )
C s
3 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
a) For e
b) For
Seismic A
ut-of-Plane Wall
eb = + t/2 and
r eb = + t/2 an
Assessment of
s
d ep = + t/2 (
nd ep = 0 (tG
Unreinforced MCharts for A
tGross = 110
Gross = 110 m
Masonry BuildingAssessment of O
ISBN 978-
mm)
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-34 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Assessment of Out-of
c) For eb =
d) For e
Seismic Ass
f-Plane Walls
= + t/2 and e
eb = 0 and ep
sessment of Unr
ep = -t/2 (tGro
p = t/2 (tGross
reinforced MasoCharts for Asse
IS
oss = 110 mm
= 110 mm)
onry Buildings –sessment of Out
SBN 978-0-4
m)
– Appendix 10Ct-of-Plane Walls
App-35473-26634-9
C s
5 9
Appendix 10C–Updated 22 April 20
Figure 10
– Charts for Ass015
C.4: 110
sessment of Ou
e) Fo
f) For
0 mm thick o
Seismic A
ut-of-Plane Wall
or eb = 0 and
r eb = 0 and
one-way ver
Assessment of
s
d ep = 0 (tGro
ep = -t/2 (tGr
rtically span
Unreinforced MCharts for A
oss = 110 mm
ross = 110 mm
nning face-l
Masonry BuildingAssessment of O
ISBN 978-
m)
m)
oaded walls
gs – Appendix 1Out-of-Plane W
App-0-473-26634
s ( = 0.025
10C Walls
p-36 4-9
)
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Assessment of Out-of
a) For eb =
b) For eb
Seismic Ass
f-Plane Walls
= + t/2 and e
b = + t/2 and
sessment of Unr
ep = + t/2 (tGr
d ep = 0 (tGros
reinforced MasoCharts for Asse
IS
ross =230 mm
ss =230 mm)
onry Buildings –sessment of Out
SBN 978-0-4
m)
)
– Appendix 10Ct-of-Plane Walls
App-37473-26634-9
C s
7 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
c) For e
d) Fo
Seismic A
ut-of-Plane Wall
eb = + t/2 an
or eb = 0 and
Assessment of
s
d ep = -t/2 (t
d ep = t/2 (tGro
Unreinforced MCharts for A
tGross = 230 m
oss = 230 mm
Masonry BuildingAssessment of O
ISBN 978-
mm)
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-38 4-9
ApUpd
F
ppendix 10C– Cdated 22 April 2015
Figure 10C.5
Charts for Asses
5: 230 m
sment of Out-of
e) For e
f) For e
mm thick on
Seismic Ass
f-Plane Walls
eb = 0 and e
eb = 0 and ep
e-way vertic
sessment of Unr
ep = 0 (tGross =
p = -t/2 (tGross
cally spanni
reinforced MasoCharts for Asse
IS
= 230 mm)
s = 230 mm)
ing face-loa
onry Buildings –sessment of Out
SBN 978-0-4
aded walls (
– Appendix 10Ct-of-Plane Walls
App-39473-26634-9
= 0.025 )
C s
9 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
a) For e
b) For
Seismic A
ut-of-Plane Wall
eb = + t/2 and
r eb = + t/2 an
Assessment of
s
d ep = + t/2 (
nd ep = 0 (tG
Unreinforced MCharts for A
tGross = 350
Gross = 350 m
Masonry BuildingAssessment of O
ISBN 978-
mm)
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-40 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Assessment of Out-of
c) For eb =
d) For e
Seismic Ass
f-Plane Walls
= + t/2 and e
eb = 0 and ep
sessment of Unr
ep = -t/2 (tGro
p = t/2 (tGross
reinforced MasoCharts for Asse
IS
oss = 350 mm
= 350 mm)
onry Buildings –sessment of Out
SBN 978-0-4
m)
– Appendix 10Ct-of-Plane Walls
App-41473-26634-9
C s
9
Appendix 10C–Updated 22 April 20
Figure 10
– Charts for Ass015
C.6: 350
sessment of Ou
e) Fo
f) For
0 mm thick o
Seismic A
ut-of-Plane Wall
or eb = 0 and
r eb = 0 and
one-way ver
Assessment of
s
d ep = 0 (tGro
ep = -t/2 (tGr
rtically span
Unreinforced MCharts for A
oss = 350 mm
ross = 350 mm
nning face-l
Masonry BuildingAssessment of O
ISBN 978-
m)
m)
oaded walls
gs – Appendix 1Out-of-Plane W
App-0-473-26634
s ( = 0.025
10C Walls
p-42 4-9
)
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
a
sment of Out-of
a) For eb = +
b) For eb =
Seismic Ass
f-Plane Walls
t/2 and ep =
+ t/2 and ep
sessment of Unr
= + t/2 (tGross
p = 0 (tGross =
reinforced MasoCharts for Asse
IS
= 110 mm)
110 mm)
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-43473-26634-9
C s
3 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
c) For eb =
Figure 10C
a) For eb =
Seismic A
ut-of-Plane Wall
= + t/2 and e
C.7: 110
= + t/2 and e
Assessment of
s
ep = -t/2 (tGro
mm thick c
ep = + t/2 (tGro
Unreinforced MCharts for A
oss = 110 mm
cantilever wa
oss = 230 mm
Masonry BuildingAssessment of O
ISBN 978-
m)
all
m)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-44 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
c
F
sment of Out-of
b) For eb =
c) For eb = +
igure 10C.8
Seismic Ass
f-Plane Walls
+ t/2 and ep
+ t/2 and ep =
8: 230 m
sessment of Unr
p = 0 (tGross =
= -t/2 (tGross =
m thick can
reinforced MasoCharts for Asse
IS
230 mm)
= 230 mm)
ntilever wall
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-45473-26634-9
C s
5 9
Appendix 10C–Updated 22 April 20
– Charts for Ass015
sessment of Ou
a) For eb =
b) For eb
Seismic A
ut-of-Plane Wall
= + t/2 and e
b = + t/2 and
Assessment of
s
ep = + t/2 (tGro
ep = 0 (tGross
Unreinforced MCharts for A
oss = 350 mm
s = 350 mm)
Masonry BuildingAssessment of O
ISBN 978-
m)
)
gs – Appendix 1Out-of-Plane W
App-0-473-26634
10C Walls
p-46 4-9
ApUpd
ppendix 10C– Cdated 22 April 2015
Charts for Asses
c
F
sment of Out-of
c) For eb = +
igure 10C.9
Seismic Ass
f-Plane Walls
+ t/2 and ep =
9: 350 m
sessment of Unr
= -t/2 (tGross =
m thick can
reinforced MasoCharts for Asse
IS
= 350 mm)
ntilever wall
onry Buildings –sessment of Out
SBN 978-0-4
– Appendix 10Ct-of-Plane Walls
App-47473-26634-9
C s
7 9
New Zealand SocietyFor Earthquake
Engineering
Assessment and Improvementof the Structural Performance
of Buildings in Earthquakes
Section 14 New SectionGeotechnical Considerations
Recommendations of a NZSEE Project Technical GroupIn collaboration with SESOC and NZGS
Supported by MBIE and EQCJune 2006
Issued as part of Corrigendum No. 4ISBN 978-0-473-32280-9 (pdf version)
This document is a new section which now forms part of an amendment to the NZSEE Guidelines which were published in 2006. Any comments will be gratefully received. Please forward any comments to NZSEE Executive Officer at [email protected] April 2015
SeUpd
S
ection 14 - Geotdated 22 April 2015
Section
14.1 Int
14.2 Sc
14.3 Th
14.4 Ro
14.
14.
14.
14.
14.5 As
14.6 Ma
14.7 Ge
14.8 As
14.9 Ide
14.10 So
14.11 Re
14.12 Su
technical Consid
14 - Ge
roduction ..
ope .............
e Holistic E
oles and Res
.4.1 Gene
.4.2 The S
.4.3 The G
.4.4 Level
sessment P
anaging Unc
eotechnical
sessment o
entification a
oil-Foundatio
eferences ....
ggested Re
derations
otechni
....................
....................
ngineering
sponsibilitie
eral ...............
Structural En
Geotechnical
of experienc
Principles ....
certainty ......
Performanc
of Site Subso
and Assess
on-Structure
....................
ading ..........
ical Con
....................
....................
System ......
es for Geote
....................
gineer .........
l Engineer ...
ce for Geote
....................
....................
ce Objective
oil Class ....
sment of Geo
e Interaction
....................
....................
Geotech
nsidera
....................
....................
....................
echnical Inp
...................
...................
...................
chnical Engi
....................
....................
es .................
....................
ohazards ....
n ..................
....................
....................
nical Considera
IS
tions ...
....................
....................
....................
uts ..............
....................
....................
....................
neers ..........
....................
....................
....................
....................
....................
....................
....................
....................
ations (24 March
SBN 978-0-4
............
....................
....................
....................
....................
...................
...................
...................
...................
....................
....................
....................
....................
....................
....................
....................
....................
h 2015 revision)
14-i473-26634-9
. 14-1
....... 14-1
....... 14-2
....... 14-3
....... 14-4
....... 14-4
....... 14-5
....... 14-6
....... 14-6
....... 14-7
....... 14-8
....... 14-9
..... 14-10
..... 14-11
..... 14-12
..... 14-14
..... 14-14
)
i 9
SeUpd
S
1
ThthAth Dgem Inlespge InSoas Thwbe
Gstr
Soa hastr
1 R
ection 14 - Geotdated 22 April 2015
Section
I4.1
his section hat should b
A brief overvhat expands
epending oeotechnical
material to th
n many instaevels of shakpecialist geeotechnical
n some caseome projecssessment.
he early dwarranted wi
e a structura
the possicondition
their pote
when it appropria
Geotechnicalructure that
Loss of (clayey so
Land insstructure)
Other getectonic m
ome of theswider viewazards will ructure’s ra
Refer to Section
technical Consid
n 14 - G
ntroduc
of the Guie borne in mview of theon the main
on the site input to an
he assessme
ances, howeking intensieotechnical engineer du
es the struccts may w
ecisions reill be underal engineer.
ible geotechns);
ential influe
is appropately experie
l hazards tht might not b
ground streoils)
tability – l), instability
eohazards –movement l
se geohazarw of potentia
not affect ating. Howe
n 3 Table IEP-2
derations
Geotec
ction
dance provmind in the e main topin topics is in
ground conn assessmennt. This cou
ever, the groity, can be c
advice anuring the en
ctural perforarrant spec
egarding thethe influenWith this c
hnical issue
nce on the s
priate, if nenced geote
hat have thebe readily a
ength and s
lateral sprey of retainin
– e.g. faulteading to fl
ds may proal hazard so
the %NBSever, if a haz
2
chnical
vides a comassessment
ics of interen preparatio
nditions andnt may be liuld be the c
ound and itscomplex annd close
ntire assessm
rmance macial studies
e complexince of the acomes the re
es (and the
seismic perf
not essentiaechnical eng
e potential apparent to
stiffness –
ading, rockng works
t rupture, clood inunda
opagate fromources, whicS score baszard is prese
Geotech
l Cons
mmentary ont of a structuest is providon (due 201
d the level imited withase for ISA
s interactiond non-lineacollaboratio
ment proces
ay be drivens, including
ity of the ssessing enesponsibility
e uncertaint
formance o
al, to seekgineer.
to significaa non-geote
liquefactio
kfall, slope
complexitieation.
m outside thch is essentised on the ent it should
nical Considera
IS
iderati
n the geoteure’s vulnerded. A fulle5).
of detail oh only the ss1.
ns with the sar, requiringon betweenss.
n by geotecg a site-spe
geotechnicgineer, whoy to identify
ties in the
f the buildin
k specialist
antly affect echnical eng
n (sandy so
instability
s of near-f
he building ial for a holcurrent ne
d be reporte
ations (24 March
SBN 978-0-4
ions
echnical conrability to eer guidance
of the assessite subsoil
structure, atg careful conn the stru
chnical conecific seism
cal assessmo will morey:
assumed g
ng
t assistance
the performgineer inclu
oils), cycli
(above or
fault effect
footprint nelistic assesseeds for ased.
h 2015 revision)
14-1473-26634-9
nsiderationsarthquakes.e document
ssment, theclass being
t increasingnsideration,
uctural and
siderations.mic hazard
ment that isthan likely
geotechnical
e from an
mance of aude:
c softening
below the
s, tsunami,
ecessitatingsment. Suchsessing the
)
9
s . t
e g
g ,
d
. d
s y
l
n
a
g
e
,
g h e
Section 14 - GUpdated 22 April 20
Note:
All structbehaviourfunction performan
The assesfor some p
Effective client/own
A collaboappropria
14.2
The geotecidentify theduring eartwill assist assessment It is anticip
Interac
The rol
Timing
Identifi
How toassessm
Selecti
Assessm
Geotec
How to
Case st Previous vsignificant
Near fa
Site ch The guidancomplete sassessment
eotechnical Co015
tural assessr can haveof the det
nce of the b
ssor should projects.
assessmenner/tenant, t
orative apprate for the pu
Scope
chnical guide level of in
rthquake shin the undet warrants.
pated the ma
ction betwee
les of the ge
g of input fr
fication of co
o screen gement
on of geote
ment and m
chnical repo
o prepare a b
tudies.
versions ofgeotechnic
ault factor, h
haracteristics
nce given section covet of a buildi
nsiderations
sments shoe on structutail of the
building to t
recognise t
nt of structthe structur
roach betweurpose to w
e
dance (in pnfluence thaaking, and,
erstanding o
ain topics c
en the geote
eotechnical
rom the geo
ommon geo
eohazards to
chnical des
mitigation of
orting
brief for a g
f the NZSEcal consider
hazard scali
s (Section 3
in this sectering the asing.
ould includeural perform
assessmenhe geotechn
that geotech
tures startsal engineer
een all partwhich it is to
preparation) at ground be where posf the compl
overed will
echnical eng
engineer
technical en
ohazards
o target the
ign paramet
f geohazard
geotechnica
EE Guidancations:
ing factor an
3.5.6(n) & T
tion can bessessment o
Geote
e consideramance. Thent and the nical condit
hnical supp
s with effeand the geo
ties is esseno be put.
will providehaviour massible, to qulexity, resou
l include:
gineer and th
ngineer
e influences
ters and stre
ds
al engineer
ce consider
nd site subs
Table 3A.4)
e consideredof geohazard
echnical Consid
ation of thee level of
likely sentions.
ort may be
ctive commotechnical e
ntial if the f
de the meanay play in auantify thesurces, time
he structura
s that are m
ength reduc
red only a
soil class (T
.
d interim pds and inclu
erations (24 Ma
ISBN 978-
e influenceconsiderati
nsitivity of
required du
munication engineer.
final assess
ns for the pa structure’sse effects. Tand cost tha
al engineer
material to
ction factors
few of th
Table IEP-2)
pending comuding this i
arch 2015 revisi
1-0-473-26634
es the grouion will bef the seism
uring the IS
between t
sment is to
practitioner s performanThe guidanat a particu
the structu
s
he potentia
)
mpletion ofin the seism
ion)
4-2
4-9
und e a mic
SA
the
be
to nce nce lar
ral
lly
f a mic
SeUpd
1
Thsydeso N
Tp
Hrc
Thelal
Th
ection 14 - Geotdated 22 April 2015
T4.3
he soil, fouystem with eeformation ometimes be
Note:
The assessmpotentially r
However, suresearch andconservative
his holistic lements is elso referred
his simple d
that a struengineeri
that the Smechanis
Geohazard
Mechanism&
Consequen
technical Consid
The Hol
undations aeach compoof the othee beneficial
ment may idreduce the s
uch effects d are not roe prediction
approach, encompassed
to as soil-st
Figur
diagram illu
uctural asseing system
SFSI systemsms and con
ds
ms
nce
derations
istic En
and superstronent havingr, often adv but any suc
dentify effeshaking inpu
should be utinely acce
ns of structu
where we ed in the asstructure inte
re 14.1: Soi
ustrates:
ssment shou
m is withinnsequences)
S
ngineer
ructure shoug the potenversely and ch effects sh
ects (e.g. kinut to the stru
consideredepted in Ne
ural behavio
examine anessment of eraction (S
il-Foundati
uld examine
n the spher)
St
Soil
Teledisin
Geotech
ring Sys
uld be contial to influsometimes
hould be ca
nematic intucture relat
d with cautiew Zealand our. Refer al
nd charactersoil-foundaSI), refer to
ion-Structu
e all three p
re of influe
ructure
F
The three ements are stinct but terlinked
nical Considera
IS
stem
sidered as ence the ea
s significantautiously app
eraction andive to the fr
on. They arpractice as
lso Section
rise the threation-structuo Figure 14.
ure Interact
primary elem
nce of geo
Foundation
ations (24 March
SBN 978-0-4
a holistic earthquake retly so. The praised.
nd damping)ree-field mo
re subject tthey may l14.10.
ee distinct, ure interact1.
tion
ments that m
ohazards (th
h 2015 revision)
14-3473-26634-9
engineeringesponse and
effects can
) that couldotion.
to on-goingead to non-
interlinkedtion (SFSI),
make up the
heir various
)
3
9
g d n
d
g -
d ,
e
s
Section 14 - GUpdated 22 April 20
that theimplemrefinem
the inte It is imporand the fousystem to l In this conof the geogroundwat
14.4
14.4.1
Effective client/ownapproach bpurpose to It is imporequiremenappropriateimportant s Note:
The scopebetween requireme
There shostages of design phgeohazardrequire co
The prospcomplexityassessment The expecstructure, fpotential cneeded to c
eotechnical Co015
e potential mentation oments to the
eraction nee
rtant to conundation wland instabi
ntext the terlogical mod
ter regime a
Roles Inputs
Genera
assessmenter/tenant, th
between all which it is
ortant that nts of eache geotechnstep in the a
e of the geothe geotechents.
ould be recoa project –
hase, as apprd identificaonsideration
ect of SFSy and timet with a clea
cted output foundation compoundincomplete th
nsiderations
influence oof the asses commonly
eded betwee
nsider SFSI with the stru
lity issues (
rm “soil” mdel, the reg
and the terra
and Res
al
t of structuhe structuraparties is eto be put.
there is a h team me
nical brief assessment p
otechnical ehnical and
ognition of the main staropriate for
ation and atn.
SI assessmee-consuminar, simple e
from the dand ground
ng interactihe assessmen
of geohazarssment procy used fixed-
en engineeri
as not just ucture, but a(e.g. lateral
eans the grgional seismain at and ar
esponsi
ures starts al engineer essential if t
common uember at thin collaborprocess.
engineer’s bstructural e
assessing tages being (r the particut what stage
ent tends tog, sophistixpression o
definition std vulnerabilions, and ant.
Geote
rds should cess (comm-base struct
ing disciplin
relating toalso wider spread, slop
round modemic hazard round the st
ibilities
with effecand the geothe final ass
understandihe outset ration with
brief shouldengineer an
the issues to(1) ISA, (2)
ular project. e in the ass
o immediateicated analyof the issues
tage would lities, the lian outline o
echnical Consid
be considemencing in tural model
nes.
the dynamaspects sucpe deformat
el. The groumodel, the tructure.
s for Ge
ctive commotechnical esessment is
ing of the of an asse
h the geote
d be preparnd be tailor
o the approp) DSA and (Table 14.1
sessment pr
ely lead toysis. It is
s.
be a collabkelihood anof the scop
erations (24 Ma
ISBN 978-
ered in the the ISA) -
mic interactioch as the retion, etc.).
und model isgeotechnic
otechn
munication engineer. A to be appro
expectationessment. Dechnical en
ed in activered to suit
priate degre(3) the mitigoutlines th
rocess they
expectatioimportant
borative sumnd consequepe of work
arch 2015 revisi
1-0-473-26634
planning a- not as la
on of the sesponse of t
s a composcal model, t
ical
between tcollaborati
opriate for t
ns, roles aDeveloping ngineer is
e consultatithe projec
ee at differegation/retro
he key steps y are likely
ons of projeto start t
mmary of tences of th
k likely to
ion)
4-4
4-9
and ter
oil the
ite the
the ive the
and an an
ion t’s
ent ofit
in to
ect the
the eir be
SeUpd
Apova Athcoenstr Ta
Pr
IS
No1.
14
ThseenlikreththD Thth
ection 14 - Geotdated 22 April 2015
At the outsetotential geoalue of geot
An experienche client thompletion ongineering ructure and
able 14.1: O
roject phase
A1 DS
ote:
It is expectcharacterise
T4.4.2
he structuraeismic assesngineer is rkely to inflecognise whhe building. he advice ofSA.
he structurahe load path
technical Consid
t of the projohazard infltechnical en
ced structure staged ap
of the ISA, input, dep
d the ground
utline of key
SA Mi
Ass
ess
acro
ss a
spe
ctru
m o
f ear
thq
uake
de
man
d
ted that the suthe geotechnic
The Stru
al engineerssment and required. T
fluence the hen these ar
If the strucf a geotechn
al engineer hs and mag
derations
ject it is verluences andngineer inpu
ral engineer pproach invor advanceending on
d conditions
y steps in g
Ttigation
S
Id
Athfo
Dm
Gin
M
Sst
A
uitably competal elements of a
ctural E
r will typictherefore fohis requireseismic pee likely to b
ctural enginnical engine
must identgnitudes of
ry importand makes theut at various
r will know volved ande into more
the clients.
geohazard id
Topic
Site subsoil cla
dentify the geo
Assess the sevhe vulnerabilityoundation sup
Determine the may become e
Ground shakinnclude both th
Magnitude of g
Soil and/or foutructural mode
Appropriate ge
tent structural an ISA without
ngineer
cally be theor recognisis a reasona
erformance be importan
neer is not ceer should b
tify the weaf foundatio
Geotech
nt that the se client awas stages of th
the processd that a par
detailed wo’s requirem
dentification
ass & near-fau
ohazards that
verity of the eay of the site to
pport.
earthquake deexcessive.
g level at whice level and du
ground deform
ndation capacelling, as appr
eohazard mitig
assessor leadia geotechnical
e professioning when spable knowlof the buil
nt consideraomfortable
be sought du
aknesses ann loads. Th
nical Considera
IS
structural enare of the phe project.
s and how brticular projork, with or
ments, the
n and assess
ult factor (if rele
the site is vuln
arthquake-induo any step cha
emand thresh
ch step changuration of shak
ation (vertical
city (strength aropriate.
ation measure
ing the projectengineer’s inpu
nal responspecialist inpedge of thelding and stions in the that he/she
uring an ISA
nd vulnerabihe structura
ations (24 March
SBN 978-0-4
ngineer is cpotential ne
best to commject may ter without gcharacteris
sment
evant).
nerable to.
uced degradaange in its abil
hold at which d
ge may occur. king.
l and lateral).
and stiffness)
es.
t should be aut in many case
sible for coput from a ge geotechnsite and the seismic ass
e is able to dA, and espe
ilities of thal engineer
h 2015 revision)
14-5473-26634-9
cognisant ofeed for and
municate toerminate at
geotechnicaltics of the
tion and/or ity to provide
degradation
This may
to enable
ble to suitablyes.
onducting ageotechnicalical factorse ability tosessment ofdo this thenecially for a
he structure,r must also
)
5
9
f d
o t l e
y
a l s o f n a
, o
Section 14 - GUpdated 22 April 20
identify whthe seismic The structuengagemen
14.4.3
The geoteccould impachange” beof this step Note:
Step changground conmaterial chthe range which therground pro
Routine inwhere the displacemeparticularly
A step chastructure sya brittle restructure in
It is often oand not obrelevant toearthquake The scopedepending behaviour.assessmentand refinem
14.4.4
To provideknowledgeare likely t It is very iexperienceCPEng ge
eotechnical Co015
hen geotechc performan
ural enginent of a speci
The Ge
chnical engiact directly ehaviour of p-change be
ge is an abrnditions cahange in itsof intensityre is an abruone to liquef
nvestigationthreshold
ent is typicay for high e
ange in soil ystem or stresponse in tnteraction is
only possiblbtain absolo provide e demand, ra
of the geoon the de
The scopt of a suit oment as a pr
Level o
e the level e of the eartto interact w
important, te in this fieleotechnical
nsiderations
hnical issuence of the bu
eer will moialist geotec
eotechnic
ineer must ion the stru
f the groundehaviour be
rupt changean withstands ability to sy of interestupt (and oftfaction and
n methods amay be. P
ally only poearthquake d
behaviour dructural colthe structurs adequately
le to gain imlute values a summaryather than a
otechnical iegree to whpe of geoof topics, soroject progr
of experi
of advice thquake behwith and infl
therefore thld or has theengineer. T
s are likely uilding.
re than likechnical advi
cal Engi
identify anducture’s beh
and foundaassessed (C
e in the soild an intenssupport a fot. Howeverten severe/islopes pron
and analytiPrediction oossible to +demand scen
does not autlapse. If theral performay assessed a
mpressions of deform
y of risks attempt to pr
input requirhich groun
otechnical-reome of whicresses.
ence for
and judgmhaviour of soluence the p
at the adviseir work revThe geotec
Geote
to be prese
ely be the isor is appro
neer
d advise on haviour. In ation suppo
Clayton et. a
’s ability tosity of seismoundation, r, some grointolerable) ne to failure
cal tools cof the mag
+/- 100mm, narios, i.e. g
tomatically ere is a stepance, howeas part of th
of how the mation sever
and conserovide quan
red will vand performaelated taskch potential
r Geotec
ments that woils and geoperformance
sing CPEngviewed by achnical pro
echnical Consid
ent that coul
person whoopriate.
the degree particular, rt be identif
al. 2014).
o provide fomic shakinor the degr
ound conditloss of fou
e.
an only givgnitude of and often w
greater than
lead to britp change in ever, then ithe seismic as
ground andrity. Accor
equences thntitative pre
ary from prance is likeks include lly have ove
chnical E
will often bohazards ane of structur
g geotechnica suitably efessional m
erations (24 Ma
ISBN 978-
ld significan
o recommen
to which anit is importfied and the
oundation sg for whichadation is tions have a
undation sup
ve crude imground an
with even ln 500 year re
ttle behaviosoil behaviot is crucial ssessment.
d foundationrdingly, it whrough the dictions of
oject to proely to gove
the identierlap to rep
Engineer
e necessarynd the way inres.
cal engineerxperienced
must be com
arch 2015 revisi
1-0-473-26634
ntly influen
nds when t
ny geohazartant that “ste consequen
support. Somch there is tolerable ova threshold pport, notab
mpressions nd foundatiless precisioreturn period
our of the soour leadingthat the so
n may behavwill be mospectrum
deformatio
oject, notabern structutification apresent revie
rs
y will requin which the
r has relevaand qualifimpetent w
ion)
4-6
4-9
nce
the
rds tep nce
me no
ver at
bly
of ion on, d.
oil-to
oil-
ve, ore of n.
bly ral
and ew
ire ese
ant ied ith
SeUpd
suea
1
Imex
N
Sptp
Tot%
NTiN
ection 14 - Geotdated 22 April 2015
uitable relevarthquake en
A4.5
mportant coxisting struc
In accordrelates on
Note:
Significant present outsthe buildingperformance
The holisticon damage pthe structure%NBS ratin
If the ISgeotechniscoping p
The assedamage pcollapse that will the buildi
The geotearthquakshaking f
Note: The spectruincrements NZS 1170.5
The SFSunderstoo
Potentiallfoundatio
Recognitiincreasingbehaviourequired t
technical Consid
vant traininngineering.
Assessm
onsiderationcture that m
dance with tnly to the ge
geohazard side the siteg, this doese or geohaz
c advice propotential ofe but propag for the bu
A identifieical engineprocess.
ssment is ppotential (iof the struclead to casuing owner a
technical aske demand,
for importan
um of earthof demand
5 Return per
SI and dynod compare
ly, there mon details an
ion that theg levels ofr of the siteto be the sam
derations
ng and exp
ment P
ns for the amay differ to
the NZ Buileohazards th
sources thae boundary.
not mean ards outside
ovided as thf geohazardsagate outsiduilding.
es any poteeer should
primarily co.e. to undercture, as it ualties). Daand, therefor
ssessment c, not just ance level 2 b
hquake demd, for examriod factor.
namic respod to newly d
may be connd subsurfac
e reliabilityf shaking me for a typime as for 50
perience in
rinciple
assessment that compl
lding Act, that are prese
at could imEven thougthat identife the site bo
he result of s that have de the site
ential geotebe conside
oncerned wrstand the mis generally
amage mitigre, does not
considers that the designbuildings de
mand couldmple as per
onse of exdesigned bu
nstraints regce informat
y of the permust reducical building00 year retu
Geotech
foundation
es
of the impleted for a n
the assessment within th
mpact on a bgh they mayfied damageoundary sho
an assessmbeen identiboundaries
echnical hazered to be
with the promechanismy the failuregation is cont affect the %
he ground’sn shaking lefined by N
d be modellr the range
xisting strucuildings.
garding theion at and a
rformance pce. The deg for 2500 urn period s
nical Considera
IS
n investigati
act of geotnew structur
ment of a buhe site boun
building’s sy not affecte potential ould be igno
ment should fied to haveand, theref
zards then part of the
otection of s that may e of the strunsidered to %NBS ratin
s behaviour level (i.e. 5
NZS 1170.5)
led by assee of events
ctures is li
e availabilitaround the s
predictions gree of relyear returnhaking, for
ations (24 March
SBN 978-0-4
ions and g
technical isre include:
uilding’s seindary.
seismic ratit the seismiresulting fr
ored.
also include the potentfore, do no
the involvee detailed
life-safety lead to par
ructure and/be at the d
ng for the bu
r across a s500 year re).
essing perfos given in
ikely to be
ty and/or astructure.
of the grouliability in
n period shaexample.
h 2015 revision)
14-7473-26634-9
geotechnical
ssues on an
ismic rating
ing may beic rating forrom ground
de commenttial to affectt affect the
ement of aassessment
rather thanrtial or full/or its partsiscretion of
uilding.
spectrum ofturn period
formance atTable 3.5;
e less well
accuracy of
und in everpredicting
aking is not
)
7
9
l
n
g
e r d
t t e
a t
n l s f
f d
t ;
l
f
r g t
Section 14 - GUpdated 22 April 20
14.6
We can galevels of spractical pincreases (reliably mcharacteris At the higgreatest intof the soibuildings, consequenconservativavoid beingto an appro It is importhe holisticinform on essential pa Note:
The geotperforman
Variat
Variat
Accurgroun
SFSI assesgreat meritstructural sthe solution Note:
It is impoand the fosystem to
For imporhazard anamight alsomagnitudeCare must Significantafter carefu
eotechnical Co015
Manag
ain relativelseismic shakpurpose in (coupled w
model the tstics become
gh end of tterest, the cl, foundatioso conservces associavely the ung overly-coopriate leve
rtant that “cc engineerinthe sensitivart of the as
technical asnce estimate
tion in the p
tion in the c
racy limitatnd and found
ssment oftent in startingsystem (incn is often a
ortant to conoundation w land instab
rtant buildinalysis to be allow conss to the habe taken to
t departuresul considera
nsiderations
ging Un
ly reliable imking for wha more-or
with increastrue behavie more prom
the seismic complex noons and str
vative assesated with ncertainties onservative l.
consistent cng system (svity of perfossessment.
ssessment es due to:
properties o
characteristi
tions inheredations.
n does not g with a simcluding the
lot clearer.
nsider SFSIwith the strubility issues
ngs, considetter informsideration oazard whereo recognises from Codation.
ncertain
mpressions hich the gror-less linearsed durationiour of theminent.
demand spn-linear behructure pre
ssment coupthe particushould be and at the s
crudeness” bsoil, foundaormance est
should mak
f materials
ics of the sit
ent in the
warrant in-mple sketchload paths)
I as not justucture, but (e.g. lateral
deration shm on the haof the impace duration oe the inherene defined s
Geote
nty
of the behound and st
ar elastic mn of shakine system,
pectrum whhaviour of tecludes relipled with sular geohazaddressed.
same time k
be applied ations & strutimates to a
ake due all
(linear and
te, and
methods u
-depth analyh of the grou. When the
t relating toalso wider l spread, slo
hould be giazard at thect of the conof shaking nt uncertain
shaking esti
echnical Consid
aviour of a tructure are
manner. Hong) we starmore so a
here the risthe soil andiable predicsound judgezard will tThere mus
keep geotech
to the modeucture). Parssumptions
lowance fo
non-linear)
used to pre
ysis or allowund model,
e problem is
o the dynamaspects suc
ope deforma
iven to usie site. The ntribution ois also connties associmates shou
erations (24 Ma
ISBN 978-
structural se expected towever, as rt to lose tas the soil
sk to life isd the complection of theement are rtypically inst be a balahnical inves
elling and arametric invmade are li
r the sensi
);
dict the sta
w for precis the foundas understood
mic interactich as the reation, etc.).
ing site-spesite-specifi
of earthquaknsidered to b
ated with suld only be
arch 2015 revisi
1-0-473-26634
system at loto behave fthe intens
the ability l’s non-line
s arguably ex interactie stability required. Tnfluence hoance struck stigation co
assessment vestigationslikely to be
itivity in t
ability of t
sion. Thereations and td the route
ion of the sesponse of t
ecific seismfic assessmekes of variobe importa
such analyscontemplat
ion)
4-8
4-9
ow for ity to
ear
of ion of
The ow to
sts
of to an
the
the
e is the to
oil the
mic ent ous ant. es. ted
SeUpd
Cancolamfr
1
Thof Ingeprprm Wwfomcore Thmofbea w Thbedi Athstrande
ection 14 - Geotdated 22 April 2015
onsiderationnd geotechnompound thate in the ea
may not be om liquefac
G4.7
he assessmef acceptable
n new buileotechnical rediction ofremium for
more appropr
While non-linwhere it is oundation su
may be an aconcept of econsidered,
herefore, thmay need to
ften acceptseyond that ospecific fo
would result
he geotechnearing streisplacement
Acceptable phe consequeructural pernd the desieformation,
technical Consid
n should benical influenhe threat to tarthquake shappropriate
ction and th
Geotech
ent of an exe performan
lding desigparameters
f SFSI behr new buildriate in seism
nearity in falso appro
ub-structurecceptable mgeotechnica, and the co
he commonlbe reconsi
s some degof the new oundation bin structura
nical assessength, etc.)t, foundation
performanceence of therformance, red structurbut the beh
derations
e given to wnces may bethe structurhaking seque to considehe full shaki
hnical P
xisting buildnce criteria a
gn, it is aps due to theaviour. Suc
dings. Howmic assessm
foundation bopriate to le may be acechanism toal “failure”
oncept of wh
ly applied gdered. The gree of nondesign. Forbehaviour mal instability
sment shoul) and alson rotation, s
e for geotece geotechniwhich in tural perform
haviour of th
when in theecome signire. For examuence or ever simultaning intensity
Perform
ding for proand objectiv
ppropriate e inevitable ch an appro
wever, a “prment of exis
behaviour mlimit the rcceptable froo achieve en” being what constitut
geotechnicaassessmen
nlinearity, r example, tmechanism y or loss of g
ld consider o the dispsoil deforma
chnical behaical inducedurn depends
mance levelhe ground m
Geotech
e earthquakificant, and
mple, the effven after shneous applicy on the bui
mance O
otection of lves compare
to adopt uncertainti
oach does robable behsting buildin
may not be isk of damom a life-sanergy dissip
when demantes capacity
l performannt of an exis
ground defthe assessor
(e.g. diffegravity-load
both the stplacement-bation, etc.).
aviour shoud deformats on the pa. As such,
may not nec
nical Considera
IS
e shaking swhether or
fects of liquaking has ccation of relding.
Objectiv
life-safety wed to a newl
a conservaes in grounnot general
haviour” mings.
desirable inmage, someafety preservpation in an nd exceedsy needs care
nce objectivsting structuformation ar would neerential sett
d path in the
rength aspebased aspe
uld be consiion/loads orticular struthe soil m
cessarily be
ations (24 March
SBN 978-0-4
sequence thr not these iuefaction maceased and educed soil
ves
warrants a dly designed
ative interpnd characterlly attract aind-set is l
n new struce non-linearvation perspn existing bus capacity eful conside
ves used in ure and its and structured to ascertatlement or e structure.
ects (earthqects (induc
idered as a on the founucture’s vul
may undergogoverning.
h 2015 revision)
14-9473-26634-9
he structuralinteract anday manifesttherefore itl resistance
different setd building.
pretation ofrisation anda high costikely to be
cture designarity in thepective and
uilding. Theshould be
eration.
new designfoundation
ral damageain whetherpad uplift)
uake loads,ced lateral
function ofndation andlnerabilitieso excessive
)
9
9
l d t t e
t
f d t e
n e d e e
n n e r )
, l
f d s e
Section 14 - GUpdated 22 April 20
14.8
A crude asbedrock anas maps arfound in W NZS 1170.implicationlikely to giimpact on for an exist Changes tosuccessive different frcase if theclasses. Care mustconsideratiground coresponse wespecially plan. In othin an ampl Site subsoiproblemati Provided trelative to to base thethe majoritconsideredarea. This suggdifferencesin the strucbuildings c Assessors together pr Note:
The rationarticulatedpresent.
eotechnical Co015
Asses
ssessment ond the like re typically
Wellington, f
.5 requiresn for sites wive the highthe cost of ting buildin
o the way codes ove
from that ase subsoil is
t therefore ion also givnditions. In
would be advif the founher cases thification of
il classificatic and may
that potentthe changes
e subsoil claty of the sit
d that the m
ested depas in soil stifctural assescompared w
are also rerovide an up
nale for anyd in the ass
nsiderations
sment
of site subsif these areprepared onfor example
that one where the shest low amf a new builng.
in which ther the last ssumed at thnow charac
be taken ven to the wn many casversely affe
ndation is qhe lateral dif torsional ef
tion solely also miss po
ial effects s in soil stifassification te under the
majority of t
arture from ffness can bsment to re
with the desi
eferred to Lpdated comm
y departuressessment, re
of Site
soil class cae available. n a regionale.
subsoil clsubsoil varie
mplitude sitelding it can
he influence20 years mhe time thecterised as b
when asseway in whichses it mighected if a smquite stiff anfference in ffects in the
by shear waotential top
from suchffness have for an exist
e building fhe building
the applicbe considereflect the difign of new b
Larkin & Vmentary on
s from the siecognising
Geote
Subsoi
an be madeHowever, sl-scale basis
ass be detes this wou
e period. Whn have a sign
e of groundmeans that e building wbeing close
essing the h the buildi
ht be difficumall part of nd has the soil stiffne
e building w
ave velocityographic an
h phenomenbeen accouting buildinfootprint. Fog footprint b
cation of Ned as synonfference in buildings.
Van Houtte n the assessm
implistic Nalways the
echnical Consid
il Class
e via referensite-specifics and can b
termined fould be basedhereas this nificant eff
d flexibilitythis influen
was designee to the bou
site soil cing might reult to concit extendedability to tss might ha
which should
y for complnd basin edg
na, and alsunted for, it ng on the soor the lack be defined a
NZS 1170.5nymous witapproach fo
(2014) andment of site
ZS 1170.5 aaccuracy im
erations (24 Ma
ISBN 978-
s
nce to mapc assessmene misleadin
or a new d on the proapproach m
fect on the s
y has been nce can beed. This is eundary betw
lass for suespond giveceive that td over a softtransfer seisave the poted not be ign
licated subsge amplifica
so the buildis consider
oil profile thof any betteas ≥80% of
5 to accounh the deparor assessme
d Bradley (response.
approach mmplied and
arch 2015 revisi
14-0-473-26634
ps of depth nt is preferrng as has be
building. Bofile that w
may have litseismic rati
dealt with e significanespecially t
ween previo
uch sites aen the varyithe buildingter soil profsmic loads ential to resnored.
soil profilesation effects
ding locatired reasonabhat applies fer advice itf the footpr
nt for laterrtures allowent of existi
(2015), whi
must be cleard uncertainti
ion)
4-10
4-9
to red een
By was ttle ing
in tly the ous
and ing g’s file
in ult
s is s.
ion ble for t is int
ral wed ing
ich
rly ies
SeUpd
1
Thtoscan
If coeadeor NosaalimM Ta
Ge
Fa
Liq
or
Cypla
Segro
Lo
ection 14 - Geotdated 22 April 2015
I4.9
he geotechno complex acreening prond desk stud
What are
What is tresponse
What are
Taking instructure)
Is a step c
Is there questions
f the influenompetent inarthquake dense sand/gr tsunami.
Non-competeatisfactory flso be vulnempact can b
Mixed found
able 14.2: Su
eohazard
ault rupture2
quefaction
yclic softeningastic silt)
ettlement of noound
ow seismic bea
technical Consid
dentific
nical influenand severe. ocess, conddy.
the potenti
the likely sand on the
the effects
nto account) what are it
change in p
enough exs?
nces are limn that it proemand bein
gravel, and s
ent ground foundation erable to lobe due to a dations can e
ummary of p
g (soft clay and
on-liquefiable
aring capacity
derations
cation a
nces in a strThe assesso
ducted using
al geohazar
severity of building as
of combina
t the initialts vulnerabi
erformance
xisting info
mited or noovides satisfng consideresites not vu
may be gsupport ovads (impactnumber of
exacerbate t
potentially d
Mech
Differsettle
d
y
and Ass
ructural assor should ag existing i
rds the site c
the impact a whole?
ations of geo
l knowledgilities?
e expected?
ormation av
ot significanfactory foued. Examplulnerable to
ground thaver the spect) from extef geohazardthe foundati
damaging m
hanism
rential ement1
Laex
Geotech
sessme
sessment caddress the finformation
could be im
if the geoh
ohazards?
e of the wh
vailable to
nt then the undation supes of compe slope insta
at is pronectrum of eaernal source
d mechanismion deforma
mechanisms
ateral xtension
Dimm
-
-
nical Considera
IS
ent of G
n be wide rfollowing qharvested
mpacted by?
hazard occu
hole system
satisfactori
ground maypport througetent groundability (mas
e to lose irthquake dees. Loss of ms as summation respon
s associated
Direct mpact of
mass
-
-
-
-
ations (24 March
SBN 978-0-4
Geohaza
ranging – frquestions in
from a site
urred, on th
m (ground,
ily answer
ay be considghout the s
nd include: sss impact or
its ability emand. Stru
f foundationmarised in Tnse.
d with geoha
Considered%NBS ratin
Yes, if strucinfluence zomain rupturassociated s
Yes
Check for inunlikely to b
Yes
Table 1
h 2015 revision)
14-11473-26634-9
ards
rom limiteditially via a
e inspection
he building
foundation,
the above
dered to bespectrum ofstrong rock,r underslip)
to provideuctures can
n support orTable 14.2.
azards
d in ISA ng?
cture is within one of the e and shear zone.
nfluence, but be an issue.
14.2 (cont…)
)
9
d a n
g
,
e
e f , )
e n r .
)
Section 14 - GUpdated 22 April 20
Table 14.2 (
Geohazard
Retaining wa
Seismic slope
(underslip)
Seismic slope
(site inundati
Discrete rock
(single or mu
Tsunami/Damdebris) includ
Note: 1. Includin2. Vulnerab
consider3. Consider
Note:
If a hazarfor an ISproviding
Refer to A
14.10
Structural the structua lower firspectra thatrue in man For exampshallow paand underebase underresulting ef Perhaps mbe underessufficientlybuildings l
eotechnical Co015
(cont…)
all instability3
e instability
e instability
on by soil/roc
k fall impact
ultiple boulders
m break (wateding foundatio
ng differential sebility to earthqured in coastal arr effects of reta
rd is known SA a broadg advice to b
SCE 41 (20
Soil-Fo
engineers hure and the grst mode o
an would beny cases it c
ple, over esads may proestimate ther a wall mffects of thi
more significstimated duy allowed flocated on d
nsiderations
Me
Difset
k)
s)
er & on scour
ettlement and/ouake-induced tereas aining walls ups
– report it. der view obuilding ow
014) for a co
oundat
have typicaground. Thiof vibration e obtained ifcan lead to a
stimating thovide an erre deformatio
may miss this.
cant, thoughue to ignorinfor by the cdeep soil site
echanism
fferential ttlement1
-
-
or foundation roectonic land su
slope and down
Although aof all relev
wners.
ommentary
ion-Stru
lly adoptedis is based o
for the strf flexibilityan invalid re
he restraint oneous ideaons in a latehe potential
h, is the potng a possibchoice of thes would be
Geote
Lateral extension
-
-
-
otation. ubsidence and s
nslope of the sit
a geohazardvant geoha
on Founda
ucture
d a fixed baon an assumructure and
y was introdesult in othe
available aa of the beneral load me
for “found
tential for thle resonanc
he specifiede such a cas
echnical Consid
Direct impact of mass
-
subsequent perm
e.
d may not inzards shou
ations and G
Interac
ase model fmption that d a higher lduced at the ers.
at the base onding momeechanism. Edation uplif
he building ce effect wid subsoil clase.
erations (24 Ma
ISBN 978-
Conside%NBS ra
Possible.wall and
Yes
No
No
No
manent inundati
nfluence theuld be cons
Geologic Site
tion
for the intera fixed baselateral loadbase. Whil
of a columnent profile inEqually, assft/wall rock
response, ath the grouassification.
arch 2015 revisi
14-0-473-26634
ered in ISA ating?
. Depends on site geometry
ion should also
e %NBS ratisidered wh
te Hazards.
rface betwee translates
d from desile this may
n founded n the colum
suming a rigking” and t
as a whole, und that is n. Multi-stor
ion)
4-12
4-9
y.
o be
ing hen
een to
ign be
on mn, gid the
to not rey
Geotechnical Considerations (24 March 2015 revision)
Section 14 - Geotechnical Considerations 14-13
Updated 22 April 2015 ISBN 978-0-473-26634-9
Allowing for soil-foundation-structure interaction can be very complicated and difficult to model. Precision should not be assumed in any assessment of the interaction, but the sensitivity to the expected response of the various assumptions should be understood. The process will require close collaboration between the structural engineer and the geotechnical engineer with each having an understanding of the issues faced by the other. For assessments of earthquake performance of buildings both the structural and geotechnical engineer must recognise and accommodate the potential for non-linear behaviour of the structure, foundations and the ground. Principles to work by include:
The ground’s behaviour cannot be represented by unique parameter values with uniform distributions (e.g. linear springs).
With close collaboration, the old fear of possible misinterpretations and abuse of numbers (e.g. spring stiffness, modulus of subgrade reaction) can be significantly reduced and possibly averted.
An iterative process between structural and geotechnical designers has to be established as soil behaviour is non-linear, spring stiffness depends on load, and load depends on structure (including foundation) stiffness.
Sensitivity to variations in assumptions should always be checked. There can be some beneficial influence of soil-foundation structure interaction on a building’s life-safety performance (e.g. elongation of building period, concentration of displacement demands in ‘ductile’ foundation rotation, damping resulting from plastic soil behaviour etc.). However, these beneficial influences are the subject of on-going research. The assessing engineer should be cautioned in adopting the various ‘benefits’ of SFSI if considering possible mechanisms that may significantly reduce the assumed seismic demands on the structure. The following are considerations for SFSI modelling:
Soil structure interaction is modelled directly by soil springs, because the structural model needs to be supported on something:
- The behaviour of springs is predictable and easy to understand.
- Springs are easy to incorporate into the software most structural engineers use.
- In a lot of cases structure response is not that sensitive to the spring values used (sensitivity test – 50% to 200% x spring value). If insensitivity is confirmed, this in itself is a useful finding.
Pinned or fixed supports are not necessarily realistic.
Load transfer and shearing depends on relative stiffness of both structural elements and supporting ground.
Multiple load cases to be considered (permanent, temporary, dynamic, different combinations, load factors etc.).
Serviceability deflections are often critical for the design of new structures but not for the assessment of existing structures. Therefore, bearing capacities capped to limit settlements to meet serviceability conditions are not appropriate for assessments of structures for earthquake life-safety protection.
Cost and time associated with more rigorous analysis methods.
Section 14 - GUpdated 22 April 20
14.11
ASCE 41 (20site characteand foundatiNew Zealand
Bradley (201Wellington, M
Clayton, Kamof existing bu
Larkin & Van
NZS 1170.5
14.12
Boulanger & 14/01, CenteCalifornia, Da
Bray & Das12:1129-1156
Day (1996) G
Kramer (2002
NZS 1170.5 S
NZGS Guide
Why Bui
Geotechmitigatio
Geotech[In prepa
Geotechpreparat
Idriss and Engineering
Pender (201challenges. 2
Refer to GNSand tsunami
Refer to Chcovering madocuments reare relevant a
http://www.cc
Note:
Web links be made to
eotechnical Co015
Refere
014) Seismic risation, geohon retrofit. Ca
d practice).
5) Site-specifMarch 2015.
m & Beer (201uildings. 2014
n Houtte (2014
(2004) Earthq
Sugge
Idriss (2014)er for Geotechavis, CA.
shti (2014) L6.
Geotechnical E
2) Geotechnic
Supp 1 (2004
elines http://ww
ildings Respon
hnical Engineeon of liquefacti
hnical Engineearation – due 2
hnical Engineetion – due 201
Boulanger (2Research Inst
4) Integrated2014 NZSEE C
S Science (wwhazard.
hristchurch Citass movemenelate to the Chacross the wid
cc.govt.nz/hom
and refereno the most re
nsiderations
ences
evaluation anhazard mitigatiare should be
fic hazard ana
4) InteractionNZSEE Confe
4) Determinatio
quake actions
ested Re
). CPT and Shnical Modelin
Liquefaction-in
Earthquake En
cal Earthquake
) Earthquake
ww.nzgs.org/p
nd Differently
ering Practiceon hazards. [U
ering Practice 2015].
ering Practice 5].
2008). Soil liqtitute, Oakland
d design of sConference. h
ww.gns.cri.nz)
ty Council wnt, rockfall anhristchurch Poder New Zeala
meliving/civilde
nce documeecent docum
nd retrofit of eon, foundation
e exercised to
alysis for geot
of geotechnicerence. http://
on of site perio
– New Zealan
eading
SPT based liqung, Departme
nduced buildin
ngineering
e Engineering
actions – New
publications/gu
to Earthquake
e – Module Under review.
– Module 2 –
– Module 3 –
quefaction dud, CA.
structure - fouhttp://db.nzsee
) and MfE (ww
ebsite (www.nd cliff collaport Hills but proand context.
efence/chchea
nts can chanments.
Geote
existing buildinn strength & s
o ensure advic
technical desig
cal and struct/db.nzsee.org.
od for NZS 11
nd.
uefaction triggnt of Civil and
ng movemen
Handbook
w Zealand - Co
uidelines.htm;
es
1 – Guidelin Revision due
– Guidelines f
– Guidelines fo
uring earthqu
undation syste.org.nz/2014/
ww.mfe.govt.n
ccc.govt.nz apse hazard ovide comme
arthquake/por
nge/evolve
echnical Consid
ngs (Note: ASstiffness, SSI ece taken from
gn in New Ze
ural engineeri.nz/2014/oral/3
170.5:2004. NZ
gering procedd Environmen
nts. Bull. Ear
ommentary
including:
ne for the ide 2015].
for earthquake
or seismic des
uakes. Monog
tems: the cur/keynote/3_Pe
nz) websites fo
and link belowidentification ntaries on geo
rthillsgeotech/
over time. R
erations (24 Ma
ISBN 978-
SCE 41 provideffects, seismi
m ASCE 41 is
aland. ANZ 2
ng in the seis39_Kam.pdf
ZSEE Bull. Vo
dures. Report ntal Engineerin
rthquake Eng
entification, a
e resistant fou
sign of retaini
graph MNO-
rrent situationender.pdf
or information
w) for GNS and risk ma
ohazard risk m
index.aspx
Reference s
arch 2015 revisi
14-0-473-26634
des guidance ic earth presscompatible w
2015 conferen
smic assessm
ol. 47, No. 1.
No. UCD/CGng, University
gineering (20
assessment a
undation desi
ing structures
12, Earthqua
n and emerg
n on active fau
Science repoanagement. Tmanagement t
should alwa
ion)
4-14
4-9
on ure
with
ce,
ent
GM-y of
14)
and
gn.
[In
ake
ging
ults
orts The hat
ays