NOTESON

SEISMICLOADSACCORDINGTOASCE0710

Ss ,S1mappedMCER,5percentdamped,spectralresponseaccelerationparameteratshortperiodsand1second(AccordingtoSiteorOwner)

Sms ,Sm1mappedMCER,5percentdamped,spectralresponseaccelerationparameteratshortperiodsand1second(adjustedtositebyfaandfv

Sds ,Sd1Designspectralresponseaccelerationparameter

SaDesignspectralresponseacceleration

SDs ,SD1 DesignSpectralAccelerationParameter

Ss,S1mappedspectralAccelerationParameter(AccordingtoSiteorOwner)

SiteClass(fromSoilReportorfromtable20.31)

Fa,Fv Sms,Sm1

+ +

TL(fromOwner)andT(STR.Period

SaDesignSpectralResponseAcceleration(forResponseSpectrumdiagram)

BuildingRiskCategory(Table1.51)andIp ImportanceFactor(Table1.52)

+ Ss,S1

SeismicDesignCategorySDC

EQ=V=Cs*W

Eh=*EQor *EQ

R,Cd,

+ Structuralsystemused

+TBuildingfundamentalPeriod

Ev =0.2SDSD

RedundancyfactorforclassDtoF(refertoslide

Briefstepsofseismicloadcalculations

1GetS1andSs(mappedMCER Spectralresponseacceleration) fromtheclient(DependsonsiteLocation)

2GetSoilclass(fromsoilreportortable(20.3.1)

3FromsoilclassandS1andSs(slide4)getFvandFa

4FvandFa CalcSm1Sms (slide5)andthenSd1andSds (slide6)

Ss,S1shouldbeprovidedbytheClient(theydependonthesitelocation)

ForFa,Fv:FromSiteClass(givenbysoilreportortakenfromtable20.31accordingtobearingcapacity)gototable11.41inthenextslide

1

2

11.4.1MappedAccelerationParameters

11.4.1MappedAccelerationParameters

3

11.4.4DesignSpectralAccelerationParameters

4

TLprovidedbytheClient

11.4.5DesignResponseSpectrum

5AssignyourbuildingaRiskCategoryaccordingtoTable1.51,thenthroughtheriskCategorygototable1.52togetIp

11.6SeismicDesignCategory

6

1for:RiskCategoryI,II,orIIIstructures with,S1,>=0.75shallbeassignedtoSeismicDesignCategoryE.

2forRiskCategoryIVstructureswith,S1>=0.75shallbeassignedtoSeismicDesignCategoryF.

3AllotherstructuresbasedontheirRiskCategoryand SDSandSD1,shallbeassignedtothemoresevererSeismicDesignCategoryinaccordancewithTable11.61or11.62

AwaytoescapeSDC:EandFifapplicable

11.6SeismicDesignCategory

SEISMICDESIGNREQUIREMENTSFORBUILDINGSTRUCTURESCHAPTER12

Connectionsshalldevelopthestrengthoftheconnectedelementsortheforcesin12.1.1(seismicForces)

Anysmallerportionofthestructureshallbetiedtotheremainderofthestructurewithelementshavingadesignstrengthcapableoftransmittingaseismicforceof0.133timestheshortperioddesignspectralresponseaccelerationparameter,SDS,timestheweightofthesmallerportionor5percentoftheportionsweight,whicheverisgreater

ThebasiclateralandverticalseismicforceresistingsystemshallconformtooneofthetypesindicatedinTable12.21oracombinationofsystemsaspermittedinSections12.2.2,12.2.3,and12.2.4

12.2StructuralSystemSelection

AwaytoescapeSDC:EandFifapplicable

12.2StructuralSystemSelection

Wheredifferentseismicforceresistingsystemsareusedincombinationtoresistseismicforcesinthesamedirection,otherthanthosecombinationsconsideredasdualsystems,themoststringentapplicablestructuralsystemlimitationscontainedinTable12.21shallapply

12.2.3LateralCombinationinthesameDirection

12.2.2LateralCombinationintheDifferentDirection

Thecommonlogicalprocedure,itsdirectionwithitsfactors

LateralCombination

12.2.4CombinationFramingDetailingRequirements accordingtocodes

VerticalCombination 12.2StructuralSystemSelection

12.2.5SystemSpecificRequirements

Foradualsystem,themomentframesshallbecapableofresistingatleast25percentofthedesignseismicforces.Thetotalseismicforceresistanceistobeprovidedbythecombinationofthemomentframesandtheshearwallsorbracedframesinproportiontotheirrigidities.

Alateralloadanalysisofatypicaldualsystemwillshowthatalmosttheentiresheariscarriedbyheshearwallsatthebase,whereastheframesworkthehardestintheupperstories.Ifcolumnsofframesaredesignedusingtheresultsofthewallframeanalysis,theywouldbequitefrailnearthebaseofthestructurewheretheyareneededthemost.The25%backupframerequirementsensuresthatthecolumnswillbesufficientlystrongandstiffnearthebase.Thesecondaryframeanalysisfor25%ofthedesignlateralforcestypicallygovernsthedesignoflowerlevelcolumns.

12.2.5.1DualSystem

12.2StructuralSystemSelection

12.2.5.2CantileveredColumnSystems

Therequiredaxialstrengthofindividualcantilevercolumnelements,consideringonlytheloadcombinationsthatincludeseismicloadeffects,shallnotexceed15percentoftheavailableaxialstrength,includingslendernesseffects.Foundationandotherelementsusedtoprovideoverturningresistanceatthebaseofcantilevercolumnelementsshallbedesignedtoresisttheseismicloadeffectsincludingoverstrength factorofSection12.4.3.

12.2.5.3InvertedPendulumTypeStructures

SupportingcolumnsorpiersofinvertedpendulumtypestructuresshallbedesignedforbendingmomentcalculatedatthebasedeterminedusingtheELFprocedureandvaryinguniformlytoamomentatthetopequaltoonehalfthecalculatedbendingmomentatthebase.

12.2.5.3IncreasedStructuralHeightLimitforSteel EccentricallyBracedFrames,SteelSpecialConcentricallyBracedFrames,SteelBucklingrestrainedBracedFrames,SteelSpecialPlateShearWallsandSpecialReinforcedConcreteShearWalls

Thelimitsonstructuralheight,hn,inTable12.21arepermittedtobeincreasedfrom160ft(50m)to240ft(75m)forstructuresassignedtoSeismicDesignCategoriesDorEandfrom100ft(30m)to160ft(50m)forstructuresassignedtoSeismicDesignCategoryFprovidedtheseismicforceresistingsystemsarelimitedtosteeleccentricallybracedframes,steelspecialconcentricallybracedframes,steelbucklingrestrainedbracedframes,steelspecialplateshearwalls,orspecialreinforcedconcretecastinplaceshearwallsandbothofthefollowingrequirementsaremet:

1.Thestructureshallnothaveanextremetorsional irregularityasdefi ned inTable12.21(horizontalstructural irregularityType1b).2.Thesteeleccentricallybracedframes,steelspecialconcentricallybracedframes,steelbucklingrestrainedbracedframes,steelspecialplateshearwallsorspecialreinforcedcastinplaceconcreteshearwallsinanyoneplaneshallresistnomorethan60percentofthetotalseismicforcesineachdirection,neglectingaccidentaltorsional effects.

12.2.5SystemSpecificRequirements12.2StructuralSystemSelection

12.2.5.5SpecialMomentFramesinStructuresAssignedtoSeismicDesignCategoriesDthroughF

12.3.3.2twostageanalysis

12.2.5SystemSpecificRequirements12.2StructuralSystemSelection

2.3.2BasicCombinationsLRFD1.1.4D2.1.2D+1.6L+0.5(Lr orSorR)3.1.2D+1.6(Lr orSorR)+(Lor0.5W)4.1.2D+1.0W+L+0.5(Lr orSorR)5.1.2D+1.0E+L+0.2S6.0.9D+1.0W7.0.9D+1.0E

2.4.1BasicCombinationsASD1.D2.D+L3.D+(Lr orSorR)4.D+0.75L+0.75(Lr orSorR)5.D+(0.6Wor0.7E)6a.D+0.75L+0.75(0.6W)+0.75(Lr orSorR)6b.D+0.75L+0.75(0.7E)+0.75S7.0.6D+0.6W8.0.6D+0.7E

12.4.2SeismicLoadEffectTheseismicloadeffect,E,For:5inSection2.3.2or5and6inSection2.4.1,E=Eh+EvFor7inSection2.3.2or8inSection2.4.1,E=Eh Ev

12.4SeismicLoadEffectsandCombinations

RefertothefollowingslideforEhandEv

Eh=QE Ev =0.2SDSD

Deadload

Refertothefollowingslides(lateralSeismicforcefromStatic,Response,orTimehistoryAnalysis)

Eh=QE

ONLYUSEDFORDESIGNINGSPECIFICELEMENTS

12.6AnalysisProcedureSelection

12.7ModelingCriteria

Structureisallowedtobemodeledfixedtothefoundation

Conclusion:ModeltheslabasisandassignSemiRigidinetabs

CALCULATIONOFSEISMICEFFECT

12.8EQUIVALENTLATERALFORCEPROCEDURE

12.9MODALRESPONSESPECTRUMANALYSIS

RESPONSEHISTORYchapter16

Theseismicbaseshear,V

12.8EquivalentLateralForceProcedure

Thefundamentalperiod,T,shallnotexceedtheproductofthecoeffi cient forupperlimitoncalculatedperiod(Cu)fromTable12.81andtheapproximatefundamentalperiod,Ta,determinedinaccordancewithSection12.8.2.1.

12.8EquivalentLateralForceProcedure

Timeperiod

InherenttorsionduetotheeccentricityofcenterofmassawayFromcenterorigidity(CalculatedsimultaneouslybyFEA)

Extratensionalcriterionofthe5%eccentricity

SystemTorsionissue 12.8EquivalentLateralForceProcedure

12.8EquivalentLateralForceProcedure

StoryDrift

Thedesignstorydrift()shallbecomputedasthedifferenceofthedeflectionsatthecentersofmassatthetopandbottomofthestoryunderconsideration.SeeFig.12.82.Wherecentersofmassdonotalignvertically,itispermittedtocomputethedeflectionatthebottomofthestorybasedontheverticalprojectionofthecenterofmassatthetopofthestory.

shallbecomputedusingthestrengthlevelseismicforcesspecifiedinSection12.8

ForstructuresassignedtoSeismicDesignCategoryC,D,E,orFhavinghorizontalirregularityType1aor1bofTable12.31,thedesignstorydrift,,shallbecomputedasthelargestdifferenceofthedeflectionsofverticallyalignedpointsatthetopandbottomofthestoryunderconsiderationalonganyoftheedgesofthestructure.

12.8.6.2PeriodforComputingDriftitispermittedtodeterminetheelasticdrifts,(xe),basedonthecomputedfundamentalperiodofthestructurewithouttheupperlimit(CuTa)

12.8EquivalentLateralForceProcedure

StoryDrift

12.9MODALRESPONSESPECTRUMANALYSIS