Seismic Code Requirements

Prof. J. W. Wallace

Fall 04 1

CE 243A Behavior & design of RC Elements

SeismiSeismicc CodCodee RequirementsRequirements

JohJohnn WW.. WallaceWallace,, Ph.D.Ph.D.,, P.P.EE..AssociatAssociate e ProfessorProfessor

UniversitUniversity y oof f CaliforniaCalifornia, , LoLoss Angeles Angeles

CE243A 1

1971San Fernando,

California Earthquake

CE243A 2

Olive View Hospital Complex

1971 San Fernando EarthquakeCE243A 3

Soft-story


Confinement

Ties @ 18 o.c. Spiral @ 3 o.c.

1971 San Fernando Earthquake

CE243A 7

Cal State Northridge

1994 Northridge EarthquakeCE243A 8

Cal State Northridge


Northridge Fashion Mall


Barrington Building


Holiday Inn Van Nuys


Barrington Building

19941994 NorthridgeNorthridge EarthquakeEarthquake

MajorMajor failures:failures: SteelSteel moment-resistingmoment-resisting framesframes PrecastPrecast concreteconcrete parkingparking strucstructtuurreess TiltupTiltup && masonmasonrryy buildingsbuildings withwith woodwood

roofsroofs MajorMajor successessuccesses

retrofittedretrofitted unreinforcedunreinforced masonmasonrryystructuresstructures

retrofittedretrofitted bridgebridge structuresstructures

CE243A 13

19941994 NorthridgeNorthridge EarthquakeEarthquake

191997 97 UBUBC & C & NNEEHRPHRPchanges:changes: removalremoval ofof prpree--

qualifiequalifiedd steelsteel connectioconnectionn detailsdetails

additioadditionn ooff neanearr-- faulfaultt factofactorr ttoo basebasesheashearr eqequuationation

prohibitioprohibitionn onon highlyhighly irregularirregular structurestructuress iinn nea near-r-faulfaultt regionsregions

stricter detailing fornonnon-parti-particcipaipattinging elementselements

deformationdeformation compatibilitycompatibilityrequirementsrequirements

chordchordss && collectorscollectorsdesignedesignedd foforr realrealforcesforces

redundancyredundancy factorfactor addeaddedd ttoo designdesign forcesforces

CE243A 14

SummarySummary

ObservatioObservationn ooff ththee behaviobehaviorr ooff reareall buildingbuildingss ininreareall earthquakeearthquakess havhavee beebeenn ththee singlsinglee largestlargest influencinfluencee oonn ththee developmendevelopmentt ooff ouourr buildingbuilding codescodes

ThThee lullulll iinn earthquakeearthquakess iinn populatepopulatedd areasareas betbetwweeeenn approximateapproximatellyy 19419400 an andd 19719700 gavgavee aa falsfalsee sincsincee o off securit securityy a att aa tim timee wwhehenn the the populatiopopulationn ooff CaliforniCaliforniaa wwaass expandinexpandingg rapidrapidllyy

PerformancePerformance ofof nneewweerr bbuuildingildingss anandd bridgebridgess hashasgeneralgeneralllyy beebeenn googoodd iinn recent earthquakes; hohowweverever,, oldeolderr buildingbuildingss posposee aa substantialsubstantial hazard.hazard.

CE243A 15

SeismicSeismic CodesCodes andand SourceSource DocumentsDocuments

NEHRP SEAOC

ASCE 7

StandardStandard BuilBuilddinging CodeCode

BOCABOCA NationalNationalBuilBuilddinging CodeCode UniformUniform BuilBuilddinging

CodeCode

InternatiInternatioonanall BuilBuilddiinngg CodeCode

CE243A 16

IBIBCC 2000 2000,, 2003 2003

InternationaInternationall CodeCode CounciCouncill (ICC),(ICC), establisheestablishedd iinn 19941994

SeismiSeismicc provisionsprovisions AASSCCE E 77--0202

ModelingModeling ForcesForces

MateriaMaterial l codescodes ACIACI, , ASCEASCE

IBC 2003 (ASCE 7-7-02,02,ACI 31ACI 3188--02)02)

CE243A 17

MaterialMaterial CodesCodesInternatiInternatioonanall BuilBuilddiinngg CodeCode

MANUALOF

STEELCONSTRUCTION

LOAD &RESISTANCE

FACTORDESIGN

Volume I

Structural

Members,Specifications,

& Codes

AISC

ACI 318-02ACI 318R-02

Building Code Requirementsfor Structural Concrete (ACI318-02) and Commentary (ACI318R-02)

An ACI

Standard Reported by ACI

Committee 318

american concrete instituteP.O. BOX 9094

FARMINGTON HILLS, MI 48333

Second Edition

CE243A 18

aci

ShakeShake TableTable TestTest FlatFlat PlatePlate

CE243A 19

EarthquakeEarthquake BuildingBuilding RespRespoonnseseF4 = m4a4(t)

F3 = m3a3(t)

F2 = m2a2(t)

F1 = m1a1(t)

Note: Forces generallyIncrease with height

V(t) = miai(t) i=1,4

TimeTimeCE243A 20

SShahakikingng

BuildinBuildingg ResponsResponsee AnalysisAnalysis

IInn gener generaall,, threthreee ttyypepess o off an anaallyysesess a arreedondonee t too d deessiiggnn building buildingss subje subjecctetedd totoeaearrthquakthquakeess ResResponponssee HiHistostorryy AAnnaallysisysis

LinLineaearr oror nnoonnllinineaearr aappropproacachh toto calccalcuulatlatee timtime e vvararyyiingng res responponsesses(P,(P, M,M, VV,, ))

ResResponponssee S Sppectrectrumum AAnnaallysiysiss

SSaa LinLineaearr aapppprrooacachh ttoo calc calcuulatlatee mmododaall

resresponponsesess ((pepeaakk vvalaluueses)) aanndd ccoommbbiinene mmoodadall resresponponsesses

F EquEquiivvaalleentnt LLaatteerraall ForForccee NNononlilinneaearr a appprprooacach uh usesedd foforr F3

rehabilitationrehabilitation (e.g.,(e.g., FEFEMMAA 356)356) F2 LinLineaearr aappropproacach h assassuummee F1resresponponssee iiss dodomiminnateatedd byby firstfirst

mmodeode resresponponssee ((vveeryry ccomommmon)on)

TimeTime

SSdd

V

baseCE243A 21

BuildinBuildingg ResponsResponsee AnalysisAnalysis

ResponsResponsee HistoHistorryy AnaAnallysisysis AnalAnalyyzeze strstruuctucturree bbyy apapppllyyiinngg

acceaccellereraationtion histhistoorryy atat basebaseofof strustruccttureure

TTyypicallypically rereqquiresuires uussee ooff sesevveraleral recorrecorddss

ElastElastiicc o orr i innelaelasstiticc resprespoonnsese TimTimee cons consuuminmingg an andd r reesultsultss cacann vvaaryry

substantsubstantiiallyally bebettwweeeenn rrececordsords ResponsResponsee Spectru Spectrum m AnaAnallysiysiss

SSaa ElastElastiicc r reesspponseonse

DetermineDetermine p peakeak rresponesponsseses forfor eeachachmodmodee o off reressponseponse

CombinCombinee m moodadall r reesponsponsseess (SRSS,(SRSS,

CQCQCC))

Shaking

Shaking

4

TimeTime

TT

CE243A 22

AccelerationAcceleration ResponseResponse SpectrumSpectrum

Maximum Acceleration

Aground

T = 2 M

K

Structural Period, T MK

CE243AShakingShaking

TimeTime 23

DisplacementDisplacement ResponseResponse SpectrumSpectrum

Maximum Displacement

T = 2 M

K

Structural Period, T MK

CE243AShakingShaking

TimeTime 24

ModalModal AnalysisAnalysis

Sd,1

Sd,2

Sd,3T3 T2 T1

Tn = 2 T M T K

max,n

= n Sd ,n

CE243A 25

DynamicDynamic BuildingBuilding ResponseResponseMDOF System SDOF Model

x=4

x=4

Story Forces

Sd,n

x=2

x=1

Sd,nx=2

x=1

Base Shear

nn

nn

CE243A 26

ADRSADRS SpectrumSpectrum

AlternativeAlternative formatformat forfor responsresponse e spectrumspectrum

CaCappaciacittyy Spectrum Spectrumapproacapproachh ATATCC 4040

SpectrSpectraall AccelerAcceleraatitioonn

T = constant

SpectruSpectrumm foforr aa givengivenearthquakearthquake e versusversus smootsmoothh spectrumspectrum

SpectrSpectraall DisplacementDisplacement

CE243A 27

CodeCode AnalysisAnalysis ProceduresProcedures

UBUBCC-97-97 andand IBIBCC-2000-2000 EquivalenEquivalentt statistaticc anaanallyysisiss approachapproach ResponsResponsee spectruspectrumm approachapproach ResponsResponsee (Time(Time)) histohistorryy apprapprooachach OtheOtherr (Pee(Peerr revierevieww))

FEMFEMAA 273/35273/3566 && AATTCC 4040 LineaLinearr StatiStaticc && DDyynaminamicc ProcedureProceduress (LSP(LSP,, LDP)LDP) NonlineaNonlinearr StatiStaticc AnaAnallyyssisis (NSP)(NSP) pushopushovverer NonlineaNonlinearr DyDynnamiamicc ProcedurProceduree (NDP)(NDP)

CE243A 28

1997 UBC 1997 UBC DesignDesign ResponseResponse SpectrumSpectrum

2.5CA

CA

CV/T

Control Per i odsTS = CV/2.5CAT0 = 0.2TS

Long-Period Limits

T0 TSPeriod (Seconds)

CE243A 29

UBC-UBC-9797: : ResponsResponse e SpectruSpectrum m AnalysisAnalysis

Vbase = Cv I

W RT

Eq. (30 - 4)

Vbase 2.5Ca I

W R

Eq. (30 - 5)

Vbase 0.11Ca IW

Eq. (30 - 6)

Ca = Seismic Coefficient (Acceleration) Cv = Seismic Coefficient (Velocity)

V/W(Accele rati

CE243A 30

ModalModal AnalysisAnalysis EigeEigenn AnaAnallyysissis

RequireRequiress mas masss (M (M)) an and d stiffnstiffneessss (K (K)) matrices matrices MM iiss ofteoftenn assuassummeedd ttoo bbee diagonaldiagonal

KK (e.g.(e.g.,, frofromm direcdirectt stiffnes stiffnesss assembassembllyy)) FrequencieFrequenciess ((,, TT==22//)) anandd modmodee shapeshapess (())

ModModee shapeshapess araree columncolumnss ooff matrixmatrix (orthogona(orthogonall propertpropertyy))

ModaModall AnaAnallyysisiss solvsolvee uncoupleuncoupledd equationsequations[M ]{v } + [C]{v } + [K ]{v} = {p}(t);

{v} = []{y}

T TM n = [] [M ][] = {m} [M ]{n} T

m = n

M n y n + Cn y n + Kn yn = n p(t)

solve for yn

Combine modal responses (e.g., SRSS, CQC)CE243A 31

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum

MDOF System Model Equivalent SDOFx=4

x=4

Story Forces

Sd,n

x=2

x=1

Sd,nx=2

x=1

Base ShearCE243A 32

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum Peak Peak mmoodal resdal respponsesonses 1 1sstt ModeMode

{ 1,4}1{ 11, 21, 31, 41

d ,1

F1 = M1Sa,1

x= = S

x=4T1 = 2 1

1Vbase,1

=M1S

2

a,1

F =M S T = C (h )3/ 4 Sd ,1 = 1 Sa,11 1 a,1

K1

x=3Sd,1x=2

x=1

1 t n

Vbase,1T0 T1 TSPe

Period (sec)

CE243A 33

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum PeaPeak k modamodal l responseresponsess 22nndd tto o nntthh ModeMode

{ x=1,4}2 = {12 ,22 ,32 ,42 } Sd ,2

T = {T ,T ,T ,T}

F2 = M 2Sa,2

F2=M2Sa,2

K2

x=4

x=3Sd,2

x=2

x=1

1 2 3 4

M iTi = 2 K i

Vbase,2 = M 2Sa,2

S = S (T 2 / 4 2 )

)notiarelcce(AW

riod (Se conds)

}

T

d ,2 a,2 2

Acceleration,

T

M

K

Vbase,2 T2 T0 TS Period (sec)

CE243A 34

od (Se conds)Peri

)notiarelcce(AW

Acceleration,

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum ModaModall Combinations Combinations

PeaPeakk modamodall responseresponsess ddoo no nott occuoccurr aatt th thee samesame time, thathatt isis,, ththee peapeakk roorooff displacement for modeoneone occursoccurs atat tt11 ,, wwhhereaereass ththee pea peakk displacedisplacemmentent foforr modmodee ttwwoo occuroccurss aatt tt22,, anandd ssoo onon.. Therefore,Therefore, peapeakk modamodall responseresponsess musmustt bbee combinecombinedd basedbased oonn ththee correlatiocorrelationn betbetwweeeenn modes.modes.

ModaModall CombinatioCombinationn ApproachesApproaches SRSSSRSS:: SquarSquaree--rooroot-t-susum-m-squasquarreses,, wworkorkss wweellll

foforr ssyystestemmss wwitithh wwellell--separaseparatteedd modemodess (2D(2D models)models)

CQC:CQC: CompletCompletee--QuadraticQuadratic--CombinatioCombinationn (3D)(3D)

CE243A 35

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum MasMass s ParticipationParticipation

ThThee (force(force)) participatioparticipationn ooff eaceachh modmodee cacann bebegaugegaugedd bbyy ththee masmasss participatioparticipationn factor.factor.

PF = {n

}T [M ]{r = 1}

m,n {n

}T [M ]{ }

TTyypicapicall masmasss participatioparticipationn factorsfactors:: PFPFmm FramFramee buildingsbuildings:: 11stst ModModee 8800 ttoo 8855%% SheaShearr wwaallll buildingsbuildings:: 11stst ModModee 6600 ttoo 70%70% TToo achievachievee 101000%% mmasasss participationparticipation,, alalll modesmodes

musmustt bbee includeincludedd iinn ththee modamodall anaanallyysissis

CE243A 36

n

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum SpecifiSpecificc Requirements Requirements

1631.5.21631.5.2 -- FoForr regulregulaarr buildingsbuildings,, includincludee ssufficientufficientmodemodess ttoo capturcapturee 9090%% ooff participatinparticipatingg massmass.. InIn general,general, tthhisis isis relarelatitivelyvely ffeeww mmodesodes

1631.5.31631.5.3 -- ModaModall combinationcombinationss UsUsee aapppropriatepropriatemethodmethodss (SRSS(SRSS,, CQC)CQC).. FoForr 33DD modelmodelss wwithith closeclosellyy ssppaceacedd modemodess neeneedd CQC.CQC.

1630.5.41630.5.4 RR factorfactorss anandd limitlimitss oonn reducinreducingg basebase sheashearr wwhheerere responsresponsee specspecttrumrum anaanallyyssisis isis usedused

1630.5.51630.5.5 DirectionalDirectional effects:effects: considerconsider seismicseismic forceforcess iinn aannyy horizontahorizontall directiodirectionn (1630.1)(1630.1)

1630.5.61630.5.6 AccounAccountt foforr torsiontorsion

CE243A 37

UBCUBC--997 7 ApproachApproach:: Respons Responsee Spectrum Spectrum

Dead & Live Loads

CombineCombine rresesponseponse spespecctrumtrum aannalalyysissis resuresullttss wwiitthh an anaallyyssiiss resresuultltss forfor gragravviittyy forcforceess

LoaLoadd comb combiinnationationss (16(16112)2) SamSamee a ass n neeww ACACII load load

combinationscombinations DrDriiftft lim limiitsts ((11630.630.110)0)

hhss == StStooryry hheeightight ss == DDiispspll.. ffoorr

codecode levellevel ffoorcesrcesm = 0.7RsT < 0.7 sec : m < 0.025hs T 0.7 sec : m < 0.025hs

CE243A 38

19971997 UBCUBC EquivalentEquivalent StStaatictic

2.5CA

CA

CV/T

Control Per i odsTS = CV/2.5CAT0 = 0.2TS

Long-Period Limits

T0 T1 TSPeriod (Seconds)

CE243A 39

UBC-UBC-997 7 BasBase e SheaShear r EquationsEquationsEquivalenEquivalentt StatiStaticc AnalysisAnalysis

Vbase = Cv I

W RT

Eq. (30 - 4)

Vbase 2.5Ca I

W R

Eq. (30 - 5)

Vbase 0.11Ca IW

Eq. (30 - 6)

Ca = Seismic Coefficient (Acceleration) Cv = Seismic Coefficient (Velocity)

V/W(Accele rati

CE243A 40

UBC-UBC-9977 ApproachApproach:: EquivalenEquivalentt StaticStaticCv = 0.40NvCa = 0.40Na

For Z = 0.4, SB For Z = 0.4, SB

(Table16 - R) (Table16 -Q)

Z = Seismic Zone Factor (0.075 to 0.4)S = Soil Profile TypeNv = Near Source Coefficient (velocity)

Seismic Source A (M > 7.0, SR > 5 mm/yr) Distance = 5 km -+ Nv = 1.6 (Table 16-T)

Na = Near Source Coefficient (acceleration) Seismic Source A (M > 7.0, SR > 5 mm/yr) Distance = 5 km -+ Na = 1.2 (Table 16-S)

CE243A 41

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysis

Vbase = Cv I

W RT

Eq. (30 - 4)

I = Importance Factor (1.0 to 1.25; Table 16-K)W = Building Seismic Dead LoadR = Force Reduction Coefficient (Table 16-N)T = Fundamental Structural Period

T = Ct (hn

)3 / 4

= 0.02(48 ft)3 / 4

= 0.37 sec

Ct = Coefficient (e.g., 0.02 for rc walls)hn = Building height (feet)

CE243A 42

EquivalentEquivalent StaticStatic LateralLateral ForcesForces

Ft F4

F3

F2

Dead & Live Loads

(Vbase Ft )wx hx x n

wi hii=1

Ft = 0.07TVFt = 0.01

T > 0.7 secT < 0.7 sec

VbaseCE243A 43

LateralLateral ForceForce ResistingResisting SystemSystemLFRS Gravity System

CE243A 44

=F

F

DetailsDetails ofof aabuildingbuilding ininEmeryvilleEmeryville

NoNonn--ParticipatingParticipating SystemSystem AlsAlsoo referrereferredd t too asas:: Gravi Gravittyy SystemSystem FlaFlatt platplatee floofloorr systemsystemss (Gravit(Gravityy loads)loads)

EfficienEfficientt anandd economicaleconomical EaEassyy toto form,form, llooww ssttoorryy heightsheights StronStrongg columcolumnn wweaeakk beabeamm conceptconcept

CE243A 46

CE243A 45

PerimetePerimeter r LFRLFRSS anand d IInnterioterior r GGFFRRSS

CE243A 47

UBCUBC--9797:: LFRLFRSS Design DesignEquivalenEquivalentt Stati Staticc o orr Respons Responsee Spectrum Spectrum

LFRSModel

100 ft

12 ft

12 ft

12 ft

12 ft

50 ftFloor Plan Elevation View LFRS

Note: Neglecting torsionCE243A 48

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisVbase =

Cv I

W

0 . 4 ( 1. 6) ( 1.0 ) 3 / 4

RT

R(T

= Ct hn )

W4 = (100' x 50')(100 psf) = 500 kips

W3 = (100' x 50')(100 psf) = 500 kips

W2 = (100' x 50')(100 psf) = 500 kips

W1 = (100' x 50')(100 psf) = 500 kips

W = 500 kips (4 floors) = 2000 kips

CE243A 49

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisV =

Cv I W =

0.4(1.6)(1.0)

(W = 2000 kips)

base

RT

R(T

= C h3 / 4 )

t n

R = Force Reduction Coefficient (Table 16-N) Accounts for nonlinear response of building (Building strength, ductility, damping)R = 1 is associated with elastic response

=

Typical Values:R = 8.5 for a rc special moment frameR = 5.5 for a rc wall building

CE243A 50

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisVbase =

Cv I

W RT=

0 . 4 ( 1 . 6 )( 1 .0 )

W R(0.63)

Vbase = 0 . 64

W R(0.37)= 1 .7 3

W R

= 1 . 7 3 g

M R

Vbase 2.5Ca I

W R =

2. 5 ( 0.4)( 1 . 2 )

W R=

1.2 g

M R

Vbase = 1.2(2000) / R = 1 = 2400 kips

(elastic)

Vbase = 2400 /(R = 5.5) = 435 kips

(design)

R > 1.0 requires inelastic response Structure must be specially detailed to control inelastic behavior

CE243A 51

19971997 UBCUBC SeismiSeismicc CriteriaCriteria(Seismi(Seismicc ZonZonee 4 4,, Soi Soill Typ Typee SSBB,, NNaa ==NNvv ==1)1)

1.5

1.25

1

0.75

Response Spectrum Design Spectrum (CN)Design Force - R/I = 4.5 Design Force - R/I = 8.5

0.5

0.25

00 0.25 0.5 0.75 1 1.25 1.5 1.75 2

V/W(Acceleratio

Period (Seconds)

CE243A 52

Confinement

Ties @ 18 o.c. Spiral @ 3 o.c.


UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisF4 (Vbase Ft )wx hx

x n

wi hii=1

2

FtF1 Ft

= 0.07TV= 0.0

T > 0.7 secT < 0.7 sec

Base Shear Vbase = 435 kips

CE243A 54

F3=F

F

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisn

F4 wi hi = (500 kips)(12'+24'+36'+48')i=1

F3Fx=4

F2 Fx=3F1 Fx=2

Fx=

1 4

= 60,000 kip - ft( 435 0 ) ( 500 k ) ( 4 8 ' ) k= = 0.4V = 174

60,000 ft k

( 435 0 ) ( 500 k ) ( 36' ) k= = 0.3V =13160,000 ft k

= ( 435 0 ) ( 500 ) ( 24' )

= 0.2V =87k60,000 ft k

( 435 0) ( 500 k ) ( 12' ) k= = 0.1V = 4360,000 ft k

Base Shear Vbase = 435 kips

Fx = 174 +131+ 87 + 43 = 435 kipsx=1

CE243A 55

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisDead & Live Loads

F4

F3

F2

F1

Base Shear =EEhh

LoaLoadd CombinationsCombinationsUBUBCC-97 --97 - S16.12.2.1 S16.12.2.1 UU == 1.21.2DD ++ 0.5 0.5LL ++ 1.0E 1.0E UU == 0.9 0.9D D +/+/-- 1.0E 1.0E Where:Where: EE == EEhh++

EEvv EEvv=0.5=0.5CCaaIIDD == 0.24D0.24D

UU == 0.90.9DD +/+/-- 1.0(1.0(EEhh++ EEvv))UU == ((00.9+.9+/-/-0.24)D0.24)D +/- EEhh == redundancredundancyy facfacttoorr 11.0.0

Conduct static analysis e.g., use SAP2000

CE243A 56

k

UBUBC-97C-97 EquivalentEquivalent StaticStatic AnalysisAnalysisDead & Live Loads

F4

F3

F2

F1

Vbase

LoaLoadd CombinationsCombinationsUBUBCC-97 --97 - S16.12.2.1 S16.12.2.1 UU == 1.21.2DD ++ 0.5 0.5LL ++ 1.0E 1.0E UU == 0.9 0.9D D +/+/-- 1.0E 1.0E Where:Where: EE == EEhh++

EEvv EEvv=0.5=0.5CCaaIIDD == 0.24D0.24D

UU == 0.90.9DD +/+/-- 1.0(1.0(EEhh++ EEvv))UU == ((00.9+.9+/-/-0.24)D0.24)D +/- EEhh == redundancredundancyy facfacttoorr 11.0.0

Conduct static analysis e.g., use SAP2000

CE243A 57

UBUBC-97:C-97: DriftDrift && DriftDrift LimitsLimits

1630.9 Drift for all analysis is defined Defines drift for

Maximum Inelastic

Code level Design forces:(e.g., R=8.5)

Story Displ.: s s,x=4

Response Displacement (M ) and for Design Seismic Forces (S ): M= 0.7RS

1630.10 Drift limits defined Drift < 0.025 times

story height if T < 0.7 sec

Drift < 0.02 times story height if T 0.7

Elevation View

s,x=3 s,x=2 s,x=1

CE243A 58

UBUBC-97C-97 RequirementsRequirements

16316333 DeDettaileailedd ssyystemstemss desigdesignn requirementsrequirements 1633.1633.1 1 General:General:

OnOnllyy ththee elementelementss ooff ththee designatedesignatedd LFRSLFRSshalshalll bbee useusedd ttoo resisresistt desigdesignn forcesforces

ConsideConsiderr botbothh seismiseismicc anandd gravigravittyy (D(D,, LL,, S)S) ForFor somesome structuresstructures (irr(irregular)egular),, musmustt considerconsider

orthogonorthogonaall effectseffects:: 101000%% ooff seismiseismicc forceforcess inin ononee directiondirection,, 3300%% iinn ththee perpendicularperpendicular directiondirection

CE243A 59


16333.216333.2 StructuralStructural FramingFraming SSyystemsstems 1633.2.11633.2.1 General:General:

DefineDefinedd bbyy ththee ttyypepess ooff verticaverticall elementelementss usedused 1633.2.21633.2.2 FoForr structurestructuress wwitithh mmuullttiipplele ssyystems,stems,

musmust t ususe e requirementrequirements s fofor r mormore e restrictiverestrictive ssyystemstem

1633.2.31633.2.3 ConnectionConnectionss iiff resistinresistingg seismicseismicforcesforces,, thethenn musmustt bbee oonn dradrawwingsings

1633.2.41633.2.4 DeformatioDeformationn compaticompatibbiliilittyy

CE243A 60

LFRSLFRS andand DeformationDeformation CompatibilityCompatibilityLFRS Gravity System

CE243A 61

LFRSLFRS andand DeformationDeformation CompatibilityCompatibility



s,x=3

s,x=4

s,x=2

s,x=1 diaphragm

Elevation View Plan View: Roof Rigid diaphragm Flexible diaphragm

CE243A 62


1633.2.41633.2.4 DeformatioDeformationn compaticompatibbiliilittyy RequireRequiress thathatt nononn--participatinparticipatingg structuralstructural

elementelementss bbee designedesignedd ttoo ensurensuree compatibilicompatibilittyyooff deformationdeformationss wwitithh lateralaterall forcforcee resistingresisting ssyystemstem

NonNon--participatinparticipatingg elements must be capable ofmaintaininmaintainingg supporsupportt foforr gravitygravity loadsloads atat deformationdeformationss expecteexpectedd duduee ttoo seismiseismicc forcesforces

DesigDesignn ooff LFRS:LFRS: ModelModel LLFFRSRS andand aappppllyy desidesiggnn sseeismicismic forcforceess NegleNeglecctt laterallateral stiffnstiffneessss andand sstrtreengthngth ooff nnoonn--

particparticiipatpatiningg elementselements

CE243A 63


16331633..2.42.4 Defo Deforrmmaattionioncompatibilcompatibiliityty ForFor LFRSLFRS



MM == 00..77RRS S forfor laterallateral frameframe atat eeaachchstorystory

ThatThat is,is, cocommpputeute stostorryy displacementsdisplacementsforfor designdesign sseeismicismic foforrcceses appliedapplied toto thetheLFRS,LFRS, thenthen multiplemultiple bbyy tthhemem bbyy 00..7R7R

s,x=3

s,x=2

s,x=1

Elevation View

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1633.2.4 Deformation compatibility Non-participating frame

Model the system (linear - element stiffness) Shear and flexural stiffness limited to gross

section values Must consider flexibility of diaphragm and

foundation Impose story displacements on the model of non-

participating frame The imposed displacements produce element

forces, consider these to be ultimate check stability (support for gravity loads) Detailing requirements: 21.11 in ACI 318-02

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Other items of interest Collectors (1633.2.6)

Must provide collectors to transfer seismicforces originating in other portions of the structure to the element providing the resistance to these forces

Diaphragms (1633.2.9) Deflection of diaphragm limited by the

permissible deflection of the attached elements Design forces specified in (33-1)

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ReinforcedReinforced Concrete:Concrete: ACIACI 313188-02-02 ChapteChapterr 2211 SeismiSeismicc ProvisionsProvisions

ProvidProvidee transverstransversee steelsteel- ConfinementConfinement,, bucklingbuckling- MaintainMaintain ggravityravity loadsloads

StrongStrong--columncolumn,, wweakeak--beambeam- BeamBeam flexuralflexural yyieldingielding

CaCappaciacittyy designdesign- BeaBeamm && columcolumnn shearshear- JoinJointt regionsregions

PrescriptivPrescriptive e requirementsrequirements- LLiittttlele ffllexibilexibiliittyy- QuickQuick,, easyeasy,, anandd usuallyusually

conseconserrvativevative

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Seismic Code Requirements

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