Bachmann - What happens during an earthquake Presentation 0000.pdf
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Transcript of Bachmann - What happens during an earthquake Presentation 0000.pdf
![Page 1: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/1.jpg)
Rapid ground-motion:
Structural (Building) response:
How long?How much?
– Strong vibrations– Large stresses and strains– Local failure– Total failure = Collapse
What happens during an earthquake?
Prof. Hugo Bachmann ibk – ETH Zurich
E/1
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Time (s)
�
�
�
�
Time history of ground motion parameters
E/2
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 3: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/3.jpg)
��
1%7%
47%
Earthquakes Windstorms Floods Others
28%
7%
Great natural catastrophes 1950-1999
45%
Munich Re Group, 2000
E/3
Fatalities: 1.4 mio Economic losses: US$ 960 bn
30%35%
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��
Even the cleverest calculations and detailed design cannot compensate for errors and defects in the conceptual seismic design of the structural and non-structural elements!
Close collaboration between architect and civil engineer from the earliest planning stage!
Basic principles for the seismic design of buildings
1/1
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 5: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/5.jpg)
Wrong:
1. Architect: Conceptual design
of structure and non-structural
elements
2. Engineer: Calculations…
1. Structure for gravity loads
2. Non-structural elements
3. Structure for seismic action
Much better and more economical:
• The architect and engineer
collaborate• General purpose structure
and non-structural elements
«Serial-design»
«Parallell-design»
Basic principles for the seismic design of buildings
1/2
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 6: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/6.jpg)
The architect and engineer collaborate from the outset!
Architect
Building owner
Civil Engineer
Basic principles for the seismic design of buildings
1
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 7: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/7.jpg)
Internationally harmonized standards:
Basic principles for the seismic design of buildings
2
T. Wenk
ISO 3010 International Building Code (IBC)Uniform Building Code (UBC)Eurocode 8
National standards:SIA 261 (Switzerland)IS 1893 (India)DIN 4149 (Germany)PS 92 (France)….
Follow the seismic provisions of the codes!
![Page 8: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/8.jpg)
��
No significant additional costs thanks to modern methods!
The costs of earthquake resistance depends on:
• planning approach• applied method
Basic principles for the seismic design of buildings
3
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 9: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/9.jpg)
Avoid soft-storey ground floors!
Basic principles for the seismic design of buildings
4
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 10: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/10.jpg)
Avoid soft-storey upper floors!
Basic principles for the seismic design of buildings
5
Prof. Hugo Bachmann ibk – ETH Zurich
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MS W
Avoid asymmetrical horizontal bracing!
W, S
M
Basic principles for the seismic design of buildings
6
Prof. Hugo Bachmann ibk – ETH Zurich
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Avoid bracing offset!
Basic principles for the seismic design of buildings
7
Prof. Hugo Bachmann ibk – ETH Zurich
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Discontinuities in stiffness and resistance
cause problems!
Basic principles for the seismic design of buildings
8
Prof. Hugo Bachmann ibk – ETH Zurich
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Two slender reinforced concrete structural walls in each principal direction!
Basic principles for the seismic design of buildings
9
Prof. Hugo Bachmann ibk – ETH Zurich
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Avoid mixed systems of
columns and structural
masonry walls!
Reinforced concrete frame
Structural masonry wall
Basic principles for the seismic design of buildings
10
Prof. Hugo Bachmann ibk – ETH Zurich
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Avoid «bracing» of frames with masonry infills!
Basic principles for the seismic design of buildings
11
Prof. Hugo Bachmann ibk – ETH Zurich
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Stiffen masonry buildings with reinforced concrete structural walls!
MasonryStructural
concrete wall Masonry
Basic principles for the seismic design of buildings
12
Prof. Hugo Bachmann ibk – ETH Zurich
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Reinforce structural masonry walls to
resist horizontal actions!
Minimum reinforcement
Edge reinforcement
Basic principles for the seismic design of buildings
13
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 19: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/19.jpg)
Match structural and non-structural elements!
Governing size: Inter-storey
displacement
Basic principles for the seismic design of buildings
14
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 20: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/20.jpg)
Rubber10–40 mm
In skeleton structures, separate
non-structural masonry walls
by joints!
Basic principles for the seismic design of buildings
15
Prof. Hugo Bachmann ibk – ETH Zurich
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Avoid short columns!
Enormous moment gradient
shear failure!
Mpl
Mpl
l
Basic principles for the seismic design of buildings
16
Prof. Hugo Bachmann ibk – ETH Zurich
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Avoid partially infilled frames!
Basic principles for the seismic design of buildings
17
Prof. Hugo Bachmann ibk – ETH Zurich
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Design diagonal steel bracing carefully!
Basic principles for the seismic design of buildings
Prof. Hugo Bachmann ibk – ETH Zurich
18
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Design steel structures to
be ductile!Critical zones
Basic principles for the seismic design of buildings
19
Prof. Hugo Bachmann ibk – ETH Zürich
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Separate adjacent buildings by joints!
Basic principles for the seismic design of buildings
20
Prof. Hugo Bachmann ibk – ETH Zurich
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Favour compact plan configurations!
unfavourable better
Basic principles for the seismic design of buildings
21
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 27: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/27.jpg)
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��
Use the slabs to «tie in» the elements and distribute the forces!
unfavourable better
Basic principles for the seismic design of buildings
22
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 28: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/28.jpg)
Ductile structures through capacity design!
Fragile structure
Ductile structure
Failure
Basic principles for the seismic design of buildings
23
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 29: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/29.jpg)
�� Use ductile
reinforcing steel with:
Rm/Re ≥ 1.15 and Agt ≥ 6 %!
strain hardening ratio
total elongation at maximum tensile stress
Elongation [%]
Stre
ss [
MPa
]Basic principles for the seismic design of buildings
24
Prof. Hugo Bachmann ibk – ETH Zurich
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Hys
tere
tic
Beh
avio
ur
of
Stat
ic-C
yclic
Tes
t W
alls
Bending moment (kNm)Bending moment (kNm)
Ho
rizo
nta
l to
p d
efle
ctio
n (
mm
)
Ho
rizo
nta
l to
p d
efle
ctio
n (
mm
)
Actuator force (kN) Actuator force (kN)
24/1
Pro
f. H
ug
o B
ach
man
nib
k –
ETH
Zü
rich
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Use transverse reinforcement
with 135° hooks and spaced at s ≤ 5d in
structural walls and columns!
Basic principles for the seismic design of buildings
25
Prof. Hugo Bachmann ibk – ETH Zurich
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No openings or recesses in plastic zones!
prohibited!
Basic principles for the seismic design of buildings
26
Prof. Hugo Bachmann ibk – ETH Zurich
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Secure connections in prefabricated buildings!
Mobile bearing
Dowel
In addition: secure against lateral buckling
Fixed bearing
Basic principles for the seismic design of buildings
27
Prof. Hugo Bachmann ibk – ETH Zurich
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Protect foundations through
capacity design!Overstrengthsectional forces
Basic principles for the seismic design of buildings
28
Prof. Hugo Bachmann ibk – ETH Zurich
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Develop a site specific
response spectrum!
Basic principles for the seismic design of buildings
29
Prof. Hugo Bachmann ibk – ETH Zurich
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Site specific response spectrum
Lutzelhof site
EC 8, soil class B
EC 8, soil class A
EC 8, reduced for rock
Period (s)
Spec
tral
acc
eler
atio
n (
m/s
2 )
29/1
Prof. Hugo Bachmann ibk – ETH Zurich
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Assess the potential for soil liquefaction!
Basic principles for the seismic design of buildings
30
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 38: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/38.jpg)
Softening may be more beneficial than
strengthening!
Softening StrengtheningA
ccel
erat
ion
Rel
ativ
e d
isp
lace
men
t
Frequency
Frequency
Basic principles for the seismic design of buildings
31
Prof. Hugo Bachmann ibk – ETH Zurich
![Page 39: Bachmann - What happens during an earthquake Presentation 0000.pdf](https://reader034.fdocuments.us/reader034/viewer/2022052603/55cf9d93550346d033ae3acd/html5/thumbnails/39.jpg)
�
Pro
f. H
ug
o B
ach
man
nib
k –
ETH
Zü
rich
Freq
uen
cy (
Hz)
Site
sp
ecif
ic r
esp
on
se s
pec
tru
m
= 5
%
Site
sp
ecif
ic r
esp
on
se s
pec
tru
m
= 8
%
Spec
tru
m f
or
med
ium
-sti
ff s
oil
acco
rdin
g t
o S
IA 1
60
= 5
%
Freq
uen
cy (
Hz)
Incr
ease
in d
amp
ing
Freq
uen
cy s
hif
ted
du
e to
bas
e is
ola
tio
n
Incr
ease
in d
amp
ing
Freq
uen
cy s
hif
ted
du
e to
bas
e is
ola
tio
n
Displacement (mm)Acceleration (m/S2)
Bem
essu
ng
ssp
ektr
en G
ross
tan
k
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Anchor facade elements against horizontal forces!
insufficient better
Basic principles for the seismic design of buildings
32
Prof. Hugo Bachmann ibk – ETH Zurich
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Basic principles for the seismic design of buildings
33
Prof. Hugo Bachmann ibk – ETH Zurich
Anchor free standing parapets
and walls!Horizontal
seismic force
Overturning moment
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Fasten suspended ceilings and light fittings!
Basic principles for the seismic design of buildings
34
Prof. Hugo Bachmann ibk – ETH Zurich
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Fasten installations and equipment!
Basic principles for the seismic design of buildings
35
Prof. Hugo Bachmann ibk – ETH Zurich