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SEISMIC DESIGN CODE FOR DUBAI

Dubal MUnicipality

I 2013 I

SEISMIC LYSIS DDESIGREQUIREMETS FORBUILDIGS

1.GEER LREQUIREMETS 1 1.1.SCOPE,NOT TIONS,REFERENCEST ND RDS 1 1.1.1.Scope 1 1.1.2.Notations 1 1.1.3.Referencestandards 6 1.2.SEISMICGROUNDMOTION 7 1.2.1.Earthquakelevels 7 1.2.2.Representationofgroundmotion:ElasticResponseSpectrum 7 1.2.3.Representationofgroundmotionintimedomain 8 1.3.SEISMICPERFORM NCEOBJECTIVES 10 1.3.1.Classificationofbuildings 10 1.3.2.Performancelevelsandranges 10 1.3.3.Minimumperformanceobjectiveforlow=tomedium=risebuildings 11 1.3.4.Multipleminimumperformanceobjectivesfortallbuildings 11

1.4.GENER LGUIDELINESFOR RR NGEMENTOFBUILDING STRUCTUR LSYSTEMS 13 1.4.1.Structuralsimplicity 13 1.4.2.Uniformity,symmetryandredundancy 13 1.4.3. dequateresistanceandstiffness 13 1.4.4.Diaphragmaction 14 1.4.5. dequatefoundation 14

1.5.REGUL RITYREQUIREMENTS 15 1.5.1.DefinitionofIrregularBuildings 15 1.5.2.ConditionsforIrregularBuildings 15 1.6.PRIM RY NDSECOND RYSEISMICMEMBERS 17 1.6.1.Primarymembers 17 1.6.2.Secondarymembers 17 2.SEISMIC LYSISREQUIREMETSOFBUILDIGS 18 2.1.P R METERSOFDESIGNRESPONSESPECTRUM 18 2.1.1.ImportanceFactors 18 2.1.2.SeismicLoadReductionFactors 18 2.1.3.DesignResponseSpectrum 19 2.2.SEISMIC N LYSIS 20 2.2.1. pplicableanalysismethods 20

2.2.2.Selectionofanalysismethodforlow=tomedium=risebuildings 20 2.2.3.Definitionofseismicmass 20 2.2.4.Considerationofverticalcomponentofearthquake 21 2.3.EQUIV LENTSEISMICLO DMETHOD 22 2.3.1.Displacementcomponentsandapplicationpointsofseismicloads 22 2.3.2.Baseshear 22 2.3.3.Storeyseismicloads 22

2.3.4.Predominantperiod 23 2.3.5.Directionalcombination 24

2.4.MULTI=MODERESPONSESPECTRUM N LYSISMETHOD 25 2.4.1.Dynamicdegreesoffreedom 25 2.4.2.Modalseismicloads 25 2.4.3.Numberofvibrationmodes 26

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2.4.4.Modalcombination 26 2.4.5.Scalingofresponsequantities 26 2.4.6.Directionalcombination 27

2.5.RESPONSEHISTORY N LYSISMETHOD 28 2.5.1.LinearResponseHistory nalysis 28 2.5.2.NonlinearResponseHistory nalysis 28 2.6.S FETYVERIFIC TION 29 2.6.1.Strengthverification 29 2.6.2.Loadcombinationsforseismicdesign 29 2.6.3.Second=ordereffects 29 2.7.D M GELIMIT TION 31 2.7.1.Limitationofstorydrifts 31 2.7.2.Seismicjoints 31 2.8. N LYSISREQUIREMENTSFORNONSTRUCTUR LSYSTEMS 33 3.SEISMICDESIGREQUIREMETSFORREIFORCEDCOCRETE BUILDIGS 34 3.1.SCOPE NDDESIGNCONCEPTS 34 3.1.1.Scope 24 3.1.2.DesignConcepts 34 3.1.3.StructuraltypesandBehaviourFactors 34

3.1.4.Designactions 35 3.1.5.CapacityDesignRules 36 3.1.6.Materialrequirements 37 3.1.7.Localductilityrequirements 37

3.2.SEISMICDESIGNREQUIREMENTSFORREINFORCEDCONCRETE BE MS 38 3.2.1.Geometricalrequirements 38 3.2.2.Designshearforcesofbeams 38 3.2.3.Seismicdetailingofbeams 39 3.3.SEISMICDESIGNREQUIREMENTSFORREINFORCEDCONCRETE COLUMNS 40 3.3.1.Geometricalrequirements 40 3.3.2.Designshearforcesofcolumns 40 3.3.3.Seismicdetailingofcolumns 40 3.3.4.Seismicdetailingofbeam=columnjoints 41 3.4.SEISMICDESIGNREQUIREMENTSFORREINFORCEDCONCRETE STRUCTUR LW LLS 43 3.4.1.Geometricalrequirements 43 3.4.2.Designbendingmomentsandshearforcesofstructuralwalls 43 3.4.3.Seismicdetailingofstructuralwalls 44

3.5.REQUIREMENTSFOR NCHOR GE NDSPLICINGOFREB RS 45 3.5.1.General 45 3.5.2. nchorageofrebars 45 3.5.3.Splicingofrebars 46

3.6.DESIGN NDDET ILINGOFSECOND RYSEISMICELEMENTS 3.7.SEISMICDESIGNREQUIREMENTSFORFOUND TIONS 48 3.7.1.General 48 3.7.2.Tie=beamsandfoundationbeams 48 3.7.3.Connectionofverticalelementswithfoundationbeamsandwalls 48 3.7.4.Cast=in=placeconcretepilesandpilecaps 49

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50

55

60

65

70

75

4.SEISMICDESIGREQUIREMETSFORSTRUCTUR LSTEEL BUILDIGS 50 4.1.SCOPE NDDESIGNCONCEPTS 50

4.1.1.Scope 50 4.1.2.DesignConcepts 50

4.1.3.StructuraltypesandBehaviourFactors 4.1.4.Materialrequirements 51

4.2.GENER LDESIGNCRITERI NDDET ILINGRULES 53 4.2.1.Designrulesforductileelementsincompressionorbending 53 4.2.2.Designrulesforductileelementsintension 53 4.2.3.Designrulesforconnections 53 4.3.DESIGN NDDET ILINGRULESFORMOMENTRESISTINGFR MES 54 4.3.1.Designcriteria 54 4.3.2.Beams 54 4.3.3.Columns 4.3.4.Beam=columnconnections 56 4.4.DESIGN NDDET ILINGRULESFORFR MESWITHCONCENTRIC BR CINGS 57 4.4.1.Designcriteria 57 4.4.2. nalysis 57 4.4.3.Diagonalmembers 57 4.4.4.Beamsandcolumns 58 4.5.DESIGN NDDET ILINGRULESFORFR MESWITHECCENTRIC BR CINGS 4.5.1.Designcriteria 60 4.5.2.Seismiclinks 60 4.5.3.Membersnotcontainingseismiclinks 62 4.5.4.Connectionsofseismiclinks 63

4.6.DESIGNRULESFORSTEELBUILDINGSWITHCONCRETECORESOR CONCRETEW LLS 64

4.7.DESIGNRULESFORINVERTEDPENDULUMSTRUCTURES 5.SEISMICDESIGREQUIREMETSFORSTEEL–COCRETE

COMPOSITEBUILDIGS 66 5.1.SCOPE NDDESIGNCONCEPTS 66 5.1.1.Scope 66 5.1.2.Designconcepts 66 5.1.3.StructuraltypesandBehaviourFactors 67 5.1.4.Materialrequirements 68 5.2.STRUCTUR L N LYSIS 5.2.1.Scope 70 5.2.2.Stiffnessofsections 70 5.3.DESIGNCRITERI NDDET ILINGRULESFORDISSIP TIVE STRUCTUR LBEH VIOURCOMMONTO LLSTRUCTUR LTYPES 71 5.3.1.Designcriteriafordissipativestructures 71 5.3.2.Plasticresistanceofdissipativezones 71 5.3.3.Detailingrulesforcompositeconnectionsindissipativezones 71 5.4.RULESFORMEMBERS 73 5.4.1.General 73 5.4.2.Steelbeamscompositewithslab 74 5.4.3.Effectivewidthofslab

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5.4.4.Fullyencasedcompositecolumns 76 5.4.5.Partially=encasedmembers 77 5.4.6.Filledcompositecolumns 78 5.5.DESIGN NDDET ILINGRULESFORMOMENTFR MES 79 5.5.1.Specificcriteria 79 5.5.2. nalysis 79 5.5.3.Rulesforbeamsandcolumns 79 5.5.4.Beamtocolumnconnections 80 5.5.5.Conditionfordisregardingthecompositecharacterofbeamswithslab 80 5.6.DESIGN NDDET ILINGRULESFORCOMPOSITE CONCENTRIC LLYBR CEDFR MES 81 5.6.1.Specificcriteria 81 5.6.2. nalysis 81 5.6.3.Diagonalmembers 81 5.6.4.Beamsandcolumns 81 5.7.DESIGN NDDET ILINGRULESFORCOMPOSITE ECCENTRIC LLYBR CEDFR MES 82 5.7.1.Specificcriteria 82 5.7.2. nalysis 82 5.7.3.Seismiclinks 82 5.7.4.Membersnotcontainingseismiclinks 83

5.8.DESIGN NDDET ILINGRULESFORSTRUCTUR LSYSTEMS M DEOFREINFORCEDCONCRETESTRUCTUR LW LLS

COMPOSITEWITHSTRUCTUR LSTEELELEMENTS 84 5.8.1.Specificcriteria 84 5.8.2. nalysis 84 5.8.3.Detailingrulesforcompositewalls 84 5.8.4.Detailingrulesforcouplingbeams 85

5.9.DESIGN NDDET ILINGRULESFORCOMPOSITE STRUCTUR LW LLS 86 5.9.1.Specificcriteria 86 5.9.2. nalysis 86 5.9.3.Detailingrules 86 6.PERFORM CEB SEDSEISMICDESIGREQUIREMETSFOR T LLBUILDIGS 87 6.1.SEISMIC N LYSISPROCEDURESFORT LLBUILDINGS 87 6.2.REQUIREMENTSFOR N LYSISMODELING 88 6.3.PERFORM NCE=B SEDSEISMICDESIGNST GESOFT LL BUILDINGS 90

6.3.1.DesignStage(I– ):PreliminaryDesign(dimensioning)withLinear nalysisforControlledDamage/LifeSafetyPerformanceObjective

under(E2)LevelEarthquake 90 6.3.2.DesignStage(I–B):DesignwithNonlinear nalysisforLifeSafety/ ControlledDamagePerformanceObjectiveunder(E2)Level

Earthquake 90 6.3.3.DesignStage(II):DesignVerificationwithLinear nalysisforMinimum Damage/ImmediateOccupancyPerformanceObjectiveunder(E1)Level

Earthquake 91

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6.3.4.DesignStage(III):DesignVerificationwithNonlinear nalysisfor ExtensiveDamage/CollapsePreventionPerformanceObjectiveunder

(E3)LevelEarthquake 91 6.4.DESIGNREQUIREMENTSFORNONSTRUCTUR L RCHITECTUR L

NDMECH NIC L/ELECTRIC LELEMENTS/COMPONENTS 93 6.4.1.Generalrequirements 93 6.4.2.Equivalentseismicloads 93 6.4.3.Limitationofdisplacements 96 6.4.4.Nonstructuralfaçadeelementsandconnections 96 6.5.INDEPENDENTDESIGNREVIEW 96

7.STRUCTUR LHE LTHMOITORIGSYSTEMSFOR T LLBUILDIGS 97 EX .SOILCL SSIFIC TIOFORSPECIFIC TIOOFSEISMIC

GROUDMOTIO 98 .1.Soilclassificationprocedure 98 .2.StepsforclassifyingSoilClassesC,D,E,F 99 .3.ClassifyingSoilClasses ,B 100

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CH PTER1 GEER LREQUIREMETS

1.1. SCOPE,OT TIOS,REFERECEST D RDS 1.1.1.Scope 1.1.1.1 – This standard covers the seismic analysis and design requirements of reinforced concrete and steel building structures to be constructed within boundaries of Emirate of Dubai. 1.1.1.2 – This standard is applicable to low= to medium rise buildings as well as to tall buildings,asdefinedin1.3.1.

(a) llpartsof thisstandardexcludingChapters6and7areapplicabletolow=tomedium risebuildings.

(b)Specialseismicanalysisanddesignrequirementsapplicabletotallbuildingsaregivenin Chapters6and7.Partsofsections1.2and1.3ofChapter1aswellaspartsofChapter2 thatarereferredtoinChapter6arealsoapplicabletotallbuildings. 1.1.1.3–Civilengineeringstructuresotherthanbuildingsareoutsidethescopeofthiscode. 1.1.1.4–Base=isolatedbuildingsaswellasbuildingsequippedwithactiveorpassivecontrol systemsanddevicesareoutsidethescopeofthiscode. 1.1.2.otations A =Grossareaofseismiclink Ac =Totaleffectiveareaofstructuralwallsinthefirststoreyforempiricalcalculationof predominantperiodintheeartquakedirection[m

2]

Ae =Maximumaccelerationactingonnonstructuralelementorcomponent Aj =Effectiveareaofthej’thstructuralwallsinthefirststoreyforempiricalcalculation ofpredominantperiodintheeartquakedirection[m

2]

Apl =Horizontalareaoftheplate Ast = reaofonelegofthetransversereinforcement;areaofstiffener Be = mplificationfactorfornonstructuralelementorcomponent b =Widthoftheflange bb =Widthofcompositebeamorbearingwidthoftheconcreteoftheslabonthe column bc =Crosssectionaldimensionofcolumn be =Partialeffectivewidthofflangeoneachsideofthesteelweb beff =Effectiveflangewidthofbeamintensionatthefaceofasupportingcolumn;total effectivewidthofconcreteflange bi =Distancebetweenconsecutivebarsengagedbyacornerofatieoracross=tieina column bo =Widthofaconfinedcoreinacolumnorintheboundaryelementofawall(to centerlineofhoops) bw =Widthofthewebofabeam bwo =Webthicknessofwall Ct =Empiricalfactorforthecalculationofpredominantperiodintheearthquake

1

direction Di =Torsionamplificationfactorati’thstorey Do =Diameterofconfinedcoreinacircularcolumn d =Effectivedepthofsection dbL =Longitudinalbardiameter dbw =Diameterofhoop dfi =Fictitiousdisplacementsati’thstoreyusedinRayleighquotient dji =Reducedstoreydisplacementofthej’thverticalelementati’thstorey Ea =ModulusofElasticityofsteel Ecm =MeanvalueofModulusofElasticityofconcreteinaccordancewithEN1992=1= 1:2004 Ed =Designvalueofanactioneffect Edi =Designvalueoftheactioneffectonthezoneorelementiintheseismicdesign situation EE = ctioneffectduetoseismicload EFd =Designvalueofanactioneffectonthefoundation EG = ctioneffectduetodeadload EF,E = ctioneffectfromtheanalysisofthedesignseismicaction EF,G = ctioneffectduetothenon=seismicactionsincludedinthecombinationof actionsfortheseismicdesignsituation EQ = ctioneffectduetoliveload e =Lengthofseismiclink Ffi =Fictitiousforcesati’thstoreyusedinRayleighquotient Fi =Equivalentseismicloadactingati’thstorey Fxin =Modalseismicloadinthen’thmodeactingati’thstoreyinxdirection Fyin =Modalseismicloadinthen’thmodeactingati’thstoreyinydirection Fθin =Modalseismictorqueinthen’thmodeactingati’thstoreyaroundtheverticalaxis passingthroughmasscentre cd =Designvalueofconcretecompressivestrength ce =Exopectedvalueofconcretecompressivestrength ck =Characteristicvalueofconcretecompressivestrength ctm =Meanvalueofconcretetensilestrength y =Nominalvalueofsteelyieldstrength yd =Designvalueofsteelyieldstrength ye =Expectedvalueofsteelyieldstrength ydf =Designyieldstrengthofsteelintheflange yd,v =Designvalueofyieldstrengthoftheverticalwebreinforcement ydw =Designstrengthofwebreinforcement yk =Characteristicvalueofsteelyieldstrength yld =Designvalueofyieldstrengthoflongitudinalreinforcement ywd =Designvalueofyieldstrengthoftransversereinforcement e =Equivalentseismicloadactingatthemasscentreofnonstructuralelement Gi =Totaldeadloadati’thstoreyofbuilding g = ccelerationofgravity(9.81m/s

2)

Hi =Totalheightofbuildingmeasuredfromthetopfoundationlevel (Inbuildingswithrigidperipheralbasementwalls,totalheightofbuilding measuredfromthetopofthegroundfloorlevel)[m] HN =Totalheightofbuildingmeasuredfromthetopfoundationlevel (Inbuildingswithrigidperipheralbasementwalls,totalheightofbuilding measuredfromthetopofthegroundfloorlevel)[m]

2

Hw =Totalwallheightmeasuredfromtopfoundationlevelorgroundfloorlevel h =Crosssectionaldepth hb =Depthofcompositebeam hc =Crosssectionaldepthofacolumninagivendirection hf =Flangedepth hi =Heightofi’thstoreyofbuilding[m] ho =Depthofconfinedcoreinacolumn(tocenterlineofhoops) hw =Depthofbeam I =BuildingImportanceFactor Ia =Secondmomentofareaofthesteelsectionpartofacompositesection,with respecttothecentroidofthecompositesection Ic =Secondmomentofareaoftheconcretepartofacompositesection,withrespectto thecentroidofthecompositesectionIeqequivalentsecondmomentofareaofthe compositesection Ie =Element(nonstructural)ImportanceFactor Is =Secondmomentofareaoftherebarsinacompositesection,withrespecttothe centroidofthecompositesection ke =Effectivestiffnesscoefficientofthenonstructuralelementorcomponent. kr =Ribshapeefficiencyfactorofprofiledsteelsheeting kt =ReductionfactorofdesignshearresistanceofconnectorsinaccordancewithEN 1994=1=1:2004 L =Beamspan lc =Columnheight lcl =Clearlengthofabeamoracolumn lcr =Lengthofcriticalregion lw =Lengthofwallcross=section lwj =Planlengthofj’thstructuralwallorapieceofcoupledwallatthefirststory MEd =Designbendingmomentobtainedfromanalysisfortheseismicdesignsituation MEd,E =Bendingmomentduetodesignseismicaction MEd,G =Bendingmomentduetonon=seismicactionsinseismicdesignsituation MEd,W =Designbendingmomentobtainedfromanalysisatthebaseofthewallforthe seismicdesignsituation Mi =i’thstoreymassofbuilding(Mi=Wi/g) Mi,d =Endmomentofabeamorcolumnforcalculatingcapacitydesignshear MN =NominalplasticmomentofRCsection M * =Modalmassofthen’thnaturalvibrationmode n

Mpl,Rd =Designvalueofplasticmomentresistance Mpl,Rd, =Designvalueofplasticmomentresistanceatend ofamember Mpl,Rd,B =DesignvalueofplasticmomentresistanceatendBofamember Mpl,Rd,c=Designvalueofplasticmomentresistanceofcolumn,takenaslowerboundand computedtakingintoaccounttheconcretecomponentofthesectionandonlythe steelcomponentsofthesectionclassifiedasductile MRb,i =Designmomentresistanceofabeamatendi MRc,i =Designmomentresistanceofacolumnatendi MRd =Designbendingmomentresistance MRd,W =Designbendingmomentresistanceatthebaseofthewall Mxn =Effectiveparticipatingmassofthen’thnaturalvibrationmodeofbuildingin thexearthquakedirectionconsidered Myn =Effectiveparticipatingmassofthen’thnaturalvibrationmodeofbuildingin

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theyearthquakedirectionconsidered Mt =Totalmassofbuilding(Mt=Wt/g) MU,Rd,b=Upperboundplasticresistanceofbeam,computedtakingintoaccounttheconcrete componentofthesectionandallthesteelcomponentsinthesection,including thosenotclassifiedasductile MY =Bendingmomentcorrespondingtothestateoffirst=yieldinRCsection me =Nonstructuralelementmass =Totalnumberofstoriesofbuildingfromthefoundationlevel (Inbuildingswithrigidperipheralbasementwalls,totalnumberofstoriesfromthe groundfloorlevel) Ed =Designaxialforceobtainedfromanalysisfortheseismicdesignsituation Ed,E = xialforceduetodesignseismicaction Ed,G = xialforceduetonon=seismicactionsinseismicdesignsituation pl,Rd =Designvalueofyieldresistanceintensionofthegrosscross=sectionofamemberin accordancewithEN1993=1=1:2004 n =Steel=to=concretemodularratioforshorttermactions n1 =LiveLoadMassReductionFactor n2 =LiveLoadParticipationFactor QCx =ResponsequantityobtainedbymodalcombinationinResponseSpectrum Methodforanearthquakeinxdirection QCy =ResponsequantityobtainedbymodalcombinationinResponseSpectrum Methodforanearthquakeinydirection QD =Designresponsequantityduetoseismicaction Qi =Totalliveloadati’thstoreyofbuilding QSx =ScaledresponsequantityobtainedbymodalcombinationinResponseSpectrum Methodforanearthquakeinxdirection QSy =ScaledresponsequantityobtainedbymodalcombinationinResponseSpectrum Methodforanearthquakeinydirection Qx =ResponsequantityobtainedinEquivalentSeismicLoadMethodforanearthquake inxdirection Qy =ResponsequantityobtainedinEquivalentSeismicLoadMethodforanearthquake inydirection q =BehaviourFactor qe =BehaviourFactorfornonstructuralelementorcomponent qR(T) =SeismicLoadReductionFactor Rd =Designresistanceofanelement;resistanceofconnectioninaccordancewithEN 1993=1=1:2004 Rdi =Designresistanceofthezoneorelementi Rfy =Plasticresistanceofconnecteddissipativememberbasedondesignyieldstrength ofmaterialasdefinedinEN1993=1=1:2004 S E(T)=Elasticspectralacceleration[m/s

2]

S R(T) =Design(reduced)spectralacceleration[m/s2]

SSD =Shortperiod(0.2second)elasticspectralacceleration[m/s2]

S1D =1.0secondelasticspectralacceleration[m/s2]

s =Spacingoftransversereinforcement[mm] T =Naturalperiodofvibration[s] TL =Transitionperiodofresponsespectrumtolong=periodrange[s] To =Responsespectrumshortcornerperiod[s] TS =Responsespectrumlongcornerperiod[s] T1 =Naturalperiodofpredominantmode(firstmode)[s]

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Tn =Naturalperiodofn’thmode[s] tf =Flangethicknessofaseismiclink tw =Webthicknessofaseismiclink Vb =Baseshearintheearthquakedirectionconsidered Vbx =Baseshearinxearthquakedirection VbCx =Baseshearobtainedbymodalcombinationinxearthquakedirection Vby =Baseshearinxearthquakedirection VbCy =Baseshearobtainedbymodalcombinationinyearthquakedirection VEd =Shearforceobtainedfromanalysisfortheseismicdesignsituation V'Ed =Designshearforcedeterminedinaccordancewithcapacitydesignrule VEd,E =Shearforceduetodesignseismicaction VEd,G =Shearforceduetonon=seismicactionsinseismicdesignsituation VEd,M =Shearforceduetoapplicationofplasticmomentresistancesatthetwo ends Vi =i’thstoreyseismicshearintheearthquakedirectionconsidered Vic =Sumofseismicshearforcesofallcolumnsatthei’thstoreyintheearthquake directionconsidered Vis =Sumofseismicshearforcesintheearthquakedirectionconsideredatthei’thstorey columnswherestrongcolumn–weakbeamconditionissatisfiedatbothbottom andtopjoints Vpl,Rd =DesignvalueofshearresistanceofamemberinaccordancewithEN1993=1=1: 2004 Vwb,Rd =Shearbucklingresistanceofthewebpanel Vwp,Ed =Designshearforceinwebpanelduetodesignseismicactioneffects Vwp,Rd =ShearresistanceofthewebpanelinaccordancewithEN1993=1=8:2004,6.2.4.1 Wi =Seismicweightofi’thstoreyofbuilding Wt =Totalseismicweightofbuildingcorrespondingtototalmass,Mt α =Confinementeffectivenessfactor;ratioofthesmallerbendingmomentsMEd, at oneendofthelinkintheseismicdesignsituation,tothegreaterbendingmoments MEd,Battheendwheretheplastichingedevelops,bothmomentsbeingtakenas absolutevalues. αG =Coefficientusedfordeterminingthegapsizeofaseismicjoint αi =RatioofVis/Viccalculatedforanyi’thstorey Nji =Reducedstoreydriftofthej’thverticalelementati’thstorey (Ni)avg= veragereducedstoreydriftofthei’thstorey δji =Effectivestoreydriftofthej’thverticalelementati’thstorey (δi)max=Maximumeffectivestoreydriftofthei’thstorey NFN = dditionalequivalentseismicloadactingontheN’thstorey(top)ofbuilding ε =Shearamplificationfactorofwall εa =TotalstrainofsteelatUltimateLimitState εcg =Upperlimit(capacity)ofconcretecompressivestrainintheextremefiberinsidethe confinementreinforcement εcu2 =Ultimatecompressivestrainofunconfinedconcrete εs =Upperlimit(capacity)ofstraininsteelreinforcement εsy,d =Designvalueofsteelstrainatyield ηti =TorsionalIrregularityFactordefinedati’thstoreyofbuilding ηci =StrengthIrregularityFactordefinedati’thstoreyofbuilding ηki =StiffnessIrregularityFactordefinedati’thstoreyofbuilding Φxin =Inbuildingswithfloorsmodelledasrigiddiaphragms,horizontalcomponent ofn’thmodeshapeinthexdirectionati’thstoreyofbuilding

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Φyin =Inbuildingswithfloorsmodelledasrigiddiaphragms,horizontalcomponent ofn’thmodeshapeintheydirectionati’thstoreyofbuilding Φθin =Inbuildingswithfloorsmodelledasrigiddiaphragms,rotationalcomponent ofn’thmodeshapearoundtheverticalaxisati’thstoreyofbuilding ϕy =Yieldcurvaturecorrespondingtonominalplasticmoment ϕ'y =Curvaturecorrespondingtofirst=yield Γxn =ParticipationFactorofn’thmodeforxdirectionearthquake γov =Materialoverstrengthfactor γpb =Factorappliedtodesignvaluepl,Rdofyieldresistanceintensionofthe compressionbraceinaVbracing λ =Non=dimensionalslendernessofamemberasdefinedinEN1993=1=1:2004 ϕ =Curvatureductilityfactor ν = xialforceinseismicdesignsituation,normalisedto A d c cd

W =Valueof(Rdi/Edi)≤q/Ioftheelementiofthestructurewhichhasthehighest influenceontheeffectEFunderconsideration w =Mechanicalratioofverticalwebreinforcement( v=ρv yd,v/ cd) wd =Mechanicalvolumetricratioofconfiningreinforcement ρ =Tensionreinforcementratio ρ' =Compressionreinforcementratio ρmax =Maximumtensionreinforcementratioallowedinthecriticalregionofaprimary beam ρmin =Minimumtensionreinforcementratiotobeprovidedalongabeam θi =SecondOrderEffectIndicatordefinedati’thstoreyofbuilding θp =Rotationcapacityoftheplastichingeregion ∑ MRb =Sumofdesignvaluesofmomentresistancesofbeamsframinginajointinthe directionconsidered

=Sumofdesignvaluesofmomentresistancesofcolumnsframinginajointinthe ∑ MRc

directionconsidered 1.1.3.ReferenceStandards 1.1.3.1 – The following standards are acceptable reference standards to be utilized in combinationwiththisstandard:

EN1990:Eurocode–Basisofstructuraldesign

EN1992=1=1:Eurocode2–Designofconcretestructures–Part1=1:General=Common rulesforbuildingandcivilengineeringstructures

EN1993=1=1:Eurocode3–Designofsteelstructures–Part1=1:General=Generalrules

EN1993=1=1:Eurocode4–Designofcompositesteelandconcretestructures–Part1=1: Generalrulesandrulesforbuildings

EN1997=1:Eurocode7–Geotechnicaldesign–Part1:Generalrules

EN1998=5:Eurocode8–Designofstructuresforearthquakeresistance–Part5: Foundations,retainingstructuresandgeotechnicalaspects 1.1.3.2–Regarding theutilizationof theabove=referencedEurocodes,National pplication DocumentsoftheUnitedKingdommaybeapplied.

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1.2.SEISMICGROUDMOTIO 1.2.1.Earthquakelevels

TheearthquakelevelstobeconsideredinthisCodearedefinedinthefollowing: 1.2.1.1–(E1)EarthquakeLevel:Thisearthquakelevelrepresentsrelativelyfrequentbutlow= intensityearthquakegroundmotionswithahighprobabilitytooccurduringtheservicelifeof buildings within the scope of this Code. The probability of exceedance of (E1) level earthquakein50yearsis50%,whichcorrespondstoareturnperiodof72years. 1.2.1.2– (E2)EarthquakeLevel:Thisearthquake level represents the infrequentandhigher intensityearthquakegroundmotionswithalowprobabilitytooccurduringtheservicelifeof buildings within the scope of this Code. The probability of exceedance of (E2) level earthquakein50yearsis10%,whichcorrespondstoareturnperiodof475years. 1.2.1.3–(E3)EarthquakeLevel:Thisearthquakelevelrepresentsthehighestintensity,very infrequentearthquakegroundmotionsthatthebuildingswithinthescopeofthisCodemaybe subjectedto.Theprobabilityofexceedanceof(E3)levelearthquakein50yearsis2%,which correspondstoareturnperiodof2475years.

1.2.2.Representationofgroundmotion:ElasticResponseSpectrum 1.2.2.1–WithintheboundariesofEmirateofDubai,5%dampedhorizontalelasticspectral accelerations corresponding to short period (0.2 second), SSD , and 1.0 second natural vibrationperiod,S1D , aregiven for (E1), (E2)and (E3)earthquake levels inTable1.1 for localsoilclassesdefinedin nnex . 1.2.2.2 – Elastic response spectrum representing the horizontal component of earthquake groundmotionisdefinedasfollows(Fig.1.1):

SSD S (T ) = 0.4 S + 0.6 T (T ≤ T ) E SD oT o

S E (T ) = SSD (To ≤ T ≤ TS) (1.1)S1D S (T ) = (T ≤ T ≤ T ) E S L

T

S E (T ) = S1D

T 2TL (TL ≤ T )

SpectrumcornerperiodsToandTSaredefinedas:

S1D T = ;T = 0.2T (1.2)S o SSSD

Transitionperiodtolong=periodrangeshallbetakenforEmirateofDubaiasTL=8s.

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Table1.1.Shortperiodand1.0secondelasticspectralaccelerations

Soil Class

EarthquakeLevel

(E1) (E2) (E3)

SSD/g S1D/g SSD/g S1D/g SSD/g S1D/g

0.080 0.032 0.120 0.053 0.180 0.080

B 0.100 0.040 0.150 0.067 0.225 0.100

C 0.120 0.068 0.180 0.113 0.270 0.170

D 0.160 0.096 0.240 0.160 0.360 0.240

E 0.250 0.140 0.375 0.233 0.563 0.350

F Site=specificgeotechnicalinvestigationanddynamicsite responseanalysisrequired(see nnex )

S E SSD

S1D

0.4SSD

S E=____S1D

T

S E= S1D

To TS 1.0 TL T

TL

T2

____

Figure1.1.ElasticResponseSpectrum

1.2.2.3 – When required, elastic acceleration spectrum may be determined through special investigations by considering local seismic and site conditions. However 5% damped acceleration spectrum ordinates shall in no case be less than those determined by Eq.(1.1) basedonshort=periodand1.0secondspectralaccelerationsgiveninTable1.1.

1.2.2.4–Elasticresponsespectrumrepresentingtheverticalcomponentofearthquakeground motionmaybetakenashalfthevalueofthecorrespondingtohorizontalcomponent. 1.2.3.Representationofgroundmotionintimedomain 1.2.3.1– minimumthreeorsevensetsofearthquakegroundmotions(accelerationrecords intwoperpendicularhorizontaldirections)withthefollowingpropertiesshallbeselectedfor theanalysis tobeperformedinthetimedomain.Realaccelerationrecordsmaybeobtained fromthefollowingdatabanks:

CosmosVirtualDataCenterhttp://db.cosmos=eq.org/

PeerStrongMotionDatabasehttp://peer.berkeley.edu/smcat/

8

EuropeanStrong=MotionDatabasehttp://www.isesd.cv.ic.ac.uk/ESD/frameset.htm

JapanK=NETNIEDhttp://www.k=net.bosai.go.jp/ 1.2.3.2 – In the cases where sufficient number of acceleration records cannot be found, artificialearthquakegroundmotionsgeneratedascompatiblewiththeearthquakesimulations or theelastic responsespectrummaybeused.Thesameaccelerationrecord(accelerogram) shall not be used for both directions. The ground motion simulations shall be based on a physical model considering the fault mechanism, rupture characteristics and the geological structureofthemediumbetweentheearthquakesourceandrecordingstation. 1.2.3.3–Theaverageof5%dampedspectralamplitudescalculatedatzeroperiodfromeach setofearthquakegroundmotionshallnotbeless thanzero=periodspectralamplitudeofthe elasticresponsespectrum(0.4SSD). 1.2.3.4 – The duration between the two points where acceleration amplitude first and last exceed±0.05gshallnotbeshorterthan5timesthedominantnaturalvibrationperiodofthe buildingnor15secondsforeachearthquakegroundmotionrecord. 1.2.3.5–Theresultantspectrumofanearthquakegroundmotionsetshallbeobtainedthrough square=root=of=sum=of=squaresof5%dampedspectraofthetwodirections.Theamplitudesof earthquake ground motions shall be scaled according to a rule such that the average of amplitudes of the resultant spectra of all records between the periods 0.2T and 1.2T (T=Dominantnaturalvibrationperiodof thebuilding) shallnotbe less than1.3 times the amplitudesoftheelasticresponsespectrumalongthesameperiodrange.Thescalingofboth componentsshallbemadewiththesamefactors. 1.2.3.6–Regarding the seismicdesignof tallbuildingsaccording toChapter5, ifneeded, parametersrelatedtoverticalcomponentoftheearthquakegroundmotionmaybespecified, subjecttotheapprovaloftheIndependentReviewBoardwhereapplicable.

9

1.3.SEISMICPERFORM CEOBJECTIVES 1.3.1.Classificationofbuildings Forthepurposeofidentifyingseismicperformanceobjectivesaswellasanalysisanddesign requirements, buildings shall be classified into two groups, namely low= to medium=rise buildingsandtallbuildings. 1.3.1.1 – Tall buildings are those of minimum 60 meter height measured from the lowest groundlevel,excludingbasementstoriescompletelyundergroundandsurroundedwithhigh= stiffnessperipheralwallsallaround. 1.3.1.2–Buildingsother thanthosedescribedin1.3.1.1aredefinedas low=tomedium=rise buildings. 1.3.2.Performancelevelsandranges Performance levels of low= to medium=rise and/or tall buildings, whereever applicable, are definedbelowwithrespecttoestimateddamagelevelsinearthquakes. 1.3.2.1–ImmediateOccupancy–MinimumDamage(IO–MD)Per ormanceLeveldescribes a performance condition such that no structural or nonstructural damage would occur in buildingsandintheirelementsundertheeffectofanearthquakeor,ifany,thedamagewould be very limited. In this condition, the building can be occupied uninterruptedly and the problems,ifany,canbefixedinafewdays. 1.3.2.2 – Li e Sa ety – Controlled Damage (LS – CD) Per ormance Level describes a performance condition where limited and repairable structural and nonstructural damage is permitted in buildings and in their elements under the effect of an earthquake. In this condition,shortterm(afewweeksormonths)problemsrelatedtooccupancyofthebuilding maybeexpected. 1.3.2.3–CollapsePrevention–ExtensiveDamage(CP–ED)Per ormanceLeveldescribesa performanceconditionwhereextensivedamagemayoccurinbuildingsandintheirelements undertheeffectofanearthquakepriortothecollapseofthebuilding.Inthiscondition,long term problems related to occupancy of the buildings may occur or the occupancy of the buildingsmaybeterminated. 1.3.2.4 – The regions in between the above=defined performance levels are identified as per ormance ranges as indicated in a strength – typical deformation curve (Fig. 1.2). The regionbelow(IO–MD)PerformanceLevelisdefinedasImmediateOccupancy/Minimum DamagePer ormanceRange,theregioninbetween(IO–MD)PerformanceLeveland(LS– CD)PerformanceLevel isdefinedasLi eSa ety /ControlledDamagePer ormanceRange, the region inbetween (LS –CD)Performance Level and (CP –ED)Performance Level is definedasCollapsePrevention/ExtensiveDamagePer ormanceRangeandtheregionabove the(CP–ED)PerformanceLevelisdefinedasCollapseRange.

10

Strength

Immediate Occupancy/

MinimumDamage Performance Range

LSCD CPED

Life Safety/

ControlledDamage Performance Range

Collapse Prevention/ Ext.Damage Performance Range

Collapse Range

IOMD

Figure1.2.Performancelevelsandranges

Typical Deformation

1.3.3.Minimumperformanceobjectiveforlowtomediumrisebuildings 1.3.3.1 – Minimum performance objective for low= to medium=rise buildings with an ImportanceFactorofI=1.0accordingtoTable2.1isidentifiedasLi eSa ety/Controlled Damage Per ormance Objective under (E2) level earthquake specified in 1.2. Without any analytical verification, it is implicitly assumed that abuildingdesigned to thisperformance objectivewouldautomaticallysatisfyImmediateOccupancy/MinimumDamagePer ormance Objective under (E1) level earthquake as well as Collapse Prevention / Extensive Damage Per ormanceObjectiveunder(E3)levelearthquake. 1.3.3.2 – Minimum performance objective for low= to medium=rise buildings with an ImportanceFactorofI=1.5accordingtoTable2.1isidentifiedasImmediateOccupancy/ Minimum Damage Per ormance Objective under (E2) level earthquake specified in 1.2. Withoutanyanalyticalverification, it is implicitly assumed that abuildingdesigned to this performance objective would automatically satisfy Li e Sa ety / Controlled Damage Per ormanceObjectiveunder(E3)earthquakelevelearthquake. 1.3.3.3 – Minimum performance objective for low= to medium=rise buildings with an Importance Factor between I = 1.0 and I = 1.5 according to Table 2.1 is identified as in betweenImmediateOccupancy/MinimumDamagePer ormanceObjectiveandLi eSa ety/ ControlledDamagePer ormanceObjectiveunder(E2)levelearthquakespecifiedin1.2. 1.3.3.4–UpontherequirementoftheOwnerortherelevantState uthority,theabove=given minimumperformanceobjectivesforspeciallow=tomedium=risebuildingsmaybeenhanced byassigninghigherimportancefactorswithinthelimitsofTable2.1. 1.3.4.Multipleminimumperformanceobjectivesfortallbuildings Minimum performance objectives identified for tall buildings are given below (Table 1.2) dependingupontheearthquakelevelsdefinedin1.2: 1.3.4.1–Themultipleperformanceobjectivesof tallbuildings inormalOccupancyClass (residence, hotel, office building, etc.) are identified as Immediate Occupancy / Minimum Damage Per ormance Objective under (E1) level earthquake, Li e Sa ety / Controlled

11

Damage Per ormance Objective under (E2) level earthquake, and Collapse Prevention / ExtensiveDamagePer ormanceObjectiveunder(E3)levelearthquake. 1.3.4.2 – The performance objectives of tall buildings in Special Occupancy Class (health, education, public administration buildings, etc.) are identified as Immediate Occupancy / Minimum Damage Per ormance Objective under (E2) level earthquake, and Li e Sa ety / ControlledDamagePer ormanceObjectiveunder(E3)levelearthquake. 1.3.4.3 – Upon the requirement of the Owner or the relevant State uthority, higher performanceobjectives,suchasthosegivenin13.4.2,maybeidentifiedfortallbuildingsin ormalOccupancyClass (residence,hotel,officebuilding,etc.) insteadof thosedefined in 1.3.4.1.

Tablo1.2.Minimumperformanceobjectivesidentifiedfortallbuildings undervariousearthquakelevels

BuildingOccupancy Class

(E1) Earthquake Level

(E2) Earthquake Level

(E3) Earthquake Level

Normaloccupancyclass: Residence,hotel,office

building,etc. IO/MD LS/CD CP/ED

Specialoccupancyclass: Health,education,public admin.buildings,etc.

–– IO/MD LS/CD

12

1.4.GEER LGUIDELIESFOR RR GEMETOFBUILDIG STRUCTUR LSYSTEMS 1.4.1.Structuralsimplicity 1.4.1.1–Structuralsimplicity ischaracterisedby theexistenceofclearanddirectpaths for thetransmissionoftheseismicforces. 1.4.1.2 – Modeling, analysis, dimensioning, detailing and construction of simple structures aresubjecttomuchlessuncertaintyandthusthepredictionoftheirseismicbehaviourismuch morereliable. 1.4.2.Uniformity,symmetryandredundancy 1.4.2.1–Uniformityinplanischaracterisedbyanevendistributionofthestructuralelements whichallowsdirecttransmissionoftheinertiaforcescreatedinthedistributedmassesofthe building. If necessary, uniformity may be realised by subdividing the entire building by seismic joints into dynamically independent units, provided that these joints are designed againstpoundingoftheindividualunitsinaccordancewith2.7.2. 1.4.2.2–Uniformity in thedevelopmentof the structurealong theheightof thebuilding is alsoessential,asittendstoeliminatetheoccurrenceofsensitivezoneswherehighstressor ductilitydemandsmightconcentrate. 1.4.2.3– similaritybetweenthedistributionofmassesandthedistributionofresistanceand stiffnesseliminateslargeeccentricitiesbetweenmassandstiffness. 1.4.2.4 – If the building configuration is symmetrical or quasi=symmetrical, a symmetrical layoutofstructuralelements,whichshouldbewell=distributedin=plan,isappropriateforthe achievementofuniformity. 1.4.2.5–Theuseofevenlydistributedstructuralelementsincreasesredundancyandallowsa morefavourableredistributionofactioneffectsandwidespreadenergydissipationacrossthe entirestructure. 1.4.3. dequateresistanceandstiffness 1.4.3.1 – Horizontal seismic motion is a bi=directional phenomenon and thus the building structureshallbeable to resisthorizontalactions inanydirection. In this respect, structural elements should be arranged in an orthogonal in=plan structural pattern, ensuring similar resistanceandstiffnesscharacteristicsinbothmaindirections. 1.4.3.2 – In addition to lateral resistance and stiffness, building structures should possess adequate torsional resistance and stiffness in order to limit the development of torsional motionswhich tend tostress thedifferentstructuralelements inanon=uniformway. In this respect,arrangementsinwhichthemainelementsresistingtheseismicactionaredistributed closetotheperipheryofthebuildingpresentclearadvantages.

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1.4.4.Diaphragmaction 1.4.4.1 – In buildings, floors (including the roof) play a very important role in the overall seismicbehaviourofthestructure.Theyactashorizontaldiaphragmsthatcollectandtransmit theinertiaforcestotheverticalstructuralsystemsandensurethatthosesystemsacttogether in resisting the horizontal seismic action. The action of floors as diaphragms is especially relevant in cases of complex and non=uniform layouts of the vertical structural systems, or wheresystemswithdifferenthorizontaldeformabilitycharacteristicsareusedtogether(e.g.in dualormixedsystems). 1.4.4.2–Floorsystemsandtheroofshouldbeprovidedwithin=planestiffnessandresistance and with effective connection to the vertical structural systems. Particular care should be taken in casesofnon=compactorvery elongated in=plan shapes and in casesof large floor openings, especially if the latter are located in the vicinity of the main vertical structural elements, thus hindering such effective connection between the vertical and horizontal structure. 1.4.4.3 – Diaphragms should have sufficient in=plane stiffness for the distribution of horizontalinertiaforcestotheverticalstructuralsystemsinaccordancewiththeassumptions of the analysis, particularly when there are significant changes in stiffness or offsets of verticalelementsaboveandbelowthediaphragm. 1.4.4.4–Thediaphragmmaybetakenasbeingrigid,if,whenitismodeledwithitsactualin= planeflexibility, itshorizontaldisplacementsnowhereexceed thoseresultingfromtherigid diaphragm assumption by more than 10% of the corresponding absolute horizontal displacementsunderseismicloads. 1.4.5. dequatefoundation 1.4.5.1–Withregardtotheseismicaction,thedesignandconstructionofthefoundationsand oftheconnectiontothesuperstructureshallensurethat thewholebuildingissubjectedtoa uniformseismicexcitation. 1.4.5.2–Forbuildingswith individual foundationelements (footingsorpiles), theuseofa foundationslabortie=beamsbetweentheseelementsinbothmaindirectionsisrecommended.

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1.5.REGUL RITYREQUIREMETS Regularity requirements of building structural systems are indirectly specified through the definitionofirregularbuildings. 1.5.1.DefinitionofIrregularBuildings Regardingthedefinitionofirregularbuildings,typesofirregularitiesinplanandinelevation aregiveninTable1.3andrelevantconditionsaregivenin1.5.2. 1.5.2.ConditionsforIrregularBuildings ConditionsrelatedtoirregularitiesdefinedinTable1.3aregivenbelow: 1.5.2.1–Irregularitytypes 1andB2governtheselectionofthemethodofseismicanalysis asspecifiedin2.2.2.1. 1.5.2.2–Inbuildingswithirregularitytypes 2and 3,itshallbeverifiedbycalculationthat the floor systems are capable of safe transfer of seismic loads between vertical structural elements. 1.5.2.3–InbuildingswithirregularitytypeB1,intherange0.60≤(ηci)min<0.80,Behaviour Factor,giveninChapter3orChapter4,asappropriate,shallbemultipliedby1.25(ηci)min which shall be applicable to the entire building in both earthquake directions. In no case, however,ηci<0.60shallbepermitted.Otherwise strengthandstiffnessof theweakstorey shallbeincreasedandtheseismicanalysisshallberepeated. 1.5.2.4–ConditionsrelatedtobuildingswithirregularitiesoftypeB3aregivenbelow:

(a) With the exception of paragraph (b) below, all internal force components induced by seismic loads shall be increased by 50% for beams and columns supporting discontinuous verticalelements.

(b)Structuralwallsshallinnocasebepermittedintheirownplanetorestonthebeamspan oronslabsatanystoreyofthebuilding.

15

Table1.3–IrregularBuildings

–IRREGUL RITIESIPL RelatedItems

1–TorsionalIrregularity: ThecasewhereTorsionalIrregularityFactorηbi,whichisdefined foranyofthetwoorthogonalearthquakedirectionsastheratioof themaximumstoreydriftatanystoreytotheaveragestoreydriftat thesamestoreyinthesamedirection,isgreaterthan1.2. [ηti=(i)max/(i)avg>1.2] Storeydri tsshallbecalculatedinaccordancewith2.3,by consideringthee ectso ±%5accidentaleccentricities.

1.5.2.1

2–FloorDiscontinuities: Inanyfloor; I=Thecasewherethetotalareaoftheopeningsincludingthoseof stairsandelevatorshaftsexceeds1/3ofthegrossfloorarea, II–Thecaseswherelocalflooropeningsmakeitdifficultthesafe transferofseismicloadstoverticalstructuralelements, III–Thecasesofabruptreductionsinthein=planestiffnessand strengthoffloors.

1.5.2.2

3–ProjectionsinPlan: Thecaseswhereprojectionsbeyondthere=entrantcornersinbothof thetwoprincipaldirectionsinplanexceedthetotalplandimensions ofthebuildingintherespectivedirectionsbymorethan20%.

1.5.2.2

B–IRREGUL RITIESIELEV TIO RelatedItems

B1–InterstoreyStrengthIrregularity(WeakStorey): Inreinforcedconcretebuildings,thecasewhereineachofthe orthogonalearthquakedirections,StrengthIrregularityFactorηci, whichisdefinedastheratiooftheshearstrengthofanystoreyto theshearstrengthofthestoreyimmediatelyabove,islessthan0.80. [ηci=Vi/Vi+1<0.80] Shearstrengtho astoreyisthesumo designshearstrengthso verticalelementsaccordingtoChapter3orChapter4,as appropriate.

1.5.2.3

B2–InterstoreyStiffnessIrregularity(So tStorey): Thecasewhereineachofthetwoorthogonalearthquakedirections, Sti nessIrregularityFactorηki,whichisdefinedastheratioofthe averagestoreydriftatanystoreytotheaveragestoreydriftatthe storeyimmediatelyaboveisgreaterthan1.5. [ηki=(i/hi)ort/(i+1/hi+1)ort>1.5 Storeydri tsshallbecalculatedinaccordancewith2.3,by consideringthee ectso ±%5accidentaleccentricities.

1.5.2.1

B3=DiscontinuityofVerticalStructuralElements: Thecaseswherecolumnsareremovedatsomestoriesandsupported bybeamsorcolumnsunderneath,orstructuralwallsofupperstories 1.5.2.4 aresupportedbycolumnsorbeamsunderneath.

16

1.6.PRIM RY DSECOD RYSEISMICMEMBERS 1.6.1.Primarymembers llstructuralmembersnotdesignatedasbeingsecondaryseismicmembersaccordingto1.6.2 aretakenasbeingprimaryseismicmembers.Theyshallbetakenasbeingpartofthelateral forceresistingsystem,anddesignedanddetailedforearthquakeresistanceinaccordancewith therulesofChapters3,4and5. 1.6.2.Secondarymembers 1.6.2.1 – Certain structural members (e.g. beams and/or columns) may be designated as secondary seismic members (or elements), not forming part of the seismic action resisting systemof thebuilding.Thestrength andstiffnessof theseelements against seismicactions shallbeneglected.TheydonotneedtoconformtotherequirementsofChapters3,4and5. Nonethelessthesemembersandtheirconnectionsshallbedesignedanddetailedtomaintain support of gravity loading when subjected to the displacements caused by the most unfavourable seismicdesign condition. llowanceof second=order effects shall bemade in thedesignofthesemembers. 1.6.2.2 – Total contribution to lateral stiffness of all secondary seismic members shall not exceed15%ofthatofallprimaryseismicmembers. 1.6.2.3–Thedesignationofsomestructuralelementsassecondaryseismicmembers isnot allowedtochangetheclassificationofthestructurefromnon=regulartoregularasdescribed in1.5.

17

CH PTER2 SEISMIC LYSISREQUIREMETSOFBUILDIGS

2.1.P R METERSOFDESIGRESPOSESPECTRUM 2.1.1.ImportanceFactors Dependingonpurposeofoccupancyofbuilding,BuildingImportanceFactors(I)aredefined asgiveninTable2.1.

Table2.1–BuildingImportanceFactors(I)

PurposeofOccupancyofBuilding (I)

a)Buildingsrequiredtobeutilisedimmediatelyaftertheearthquake (Hospitals,dispensaries,healthwards,firefightingbuildingsand facilities,PTTandothertelecommunicationfacilities,transportation stationsandterminals,powergenerationanddistributionfacilities, governorate,countyandmunicipalityadministrationbuildings,first aidandemergencyplanningstations) b)Buildingscontainingorstoringtoxic,explosiveand/orflammable materials,etc.

1.5

a)Schools,othereducationalbuildingsandfacilities,dormitories andhostels,militarybarracks,prisons,etc. b)Museums

1.4

Sportfacilities,cinema,theatreandconcerthalls,etc. 1.2

Buildingsotherthanabove=definedbuildings.(Residentialand officebuildings,hotels,building=likeindustrialstructures,etc.)

1.0

2.1.2.SeismicLoadReductionFactors 2.1.2.1–Elastic seismic loadsdetermined in termsofspectralaccelerationsdefined in1.2 shallbedivided tobelow=definedSeismicLoadReductionFactor toaccount for theductile behaviour of the structural system during earthquake. Period=dependent Seismic Load ReductionFactor, qR (T ) ,shallbedeterminedbyEqs.(2.1)intermsofBehaviourFactor,q, representing the ductility capacity of the structure and the Building Importance Factor, I, indicatingtheperformanceobjectiveofthebuilding.

q T q (T )=1+ −1 (0 ≤ T ≤ T )R S

I T S (2.1) qR (T )=

q (TS < T )

I

where(q/I)ratioshallnotbetakenlessthanunity.

18

2.1.2.2–BehaviourFactorsaregiveninChapter3forvarioustypesofreinforcedconcrete buildings, in Chapter 4 for structural steel buildings and in Chapter 5 for composite concrete=steelbuildings. . 2.1.3.DesignResponseSpectrum Reducedspectral accelerations representing the DesignResponseSpectrum shallbedefined by dividing the Elastic Response Spectrum ordinates given in 1.2.2 to the Seismic Load ReductionFactorgivenin2.1.2.

S (T ) E S (T )= R q (T )R

(2.2)

19

2.2.SEISMIC LYSIS 2.2.1. pplicableanalysismethods The analysis methods applicable for the seismic analysis of building structural systems are giveninthefollowing: 2.2.1.1 – Equivalent Seismic Load Method described in 2.3 is the simplified single=mode response=spectrum analysis method, which can be used for low= to medium=rise buildings withconditionsgivenin2.2.2. 2.2.1.2 – Multi8Mode Response Spectrum Analysis Method described in 2.4 is an advanced lineardynamicanalysismethod,whichcanbeusedforbothlow=tomedium=riseaswellas tallbuildings. 2.2.1.3–LinearResponseHistoryAnalysisMethoddescribedin2.5.1 is themostadvanced lineardynamicanalysismethod,whichcanbeusedforbothlow=tomedium=riseaswellas tallbuildings. 2.2.1.4 – onlinear Response History Analysis Method described in 2.5.2 is the most advancednonlineardynamicanalysismethod,whichcanbeusedforboth low= tomedium= riseandtallbuildings. 2.2.2.Selectionofanalysismethodforlowtomediumrisebuildings 2.2.2.1–EquivalentSeismicLoadMethodcanbeusedforstructureswithHN≤40mprovided thattype 2 torsionalirregularityfactorinanystorydoesnotexceed2(ηti≤2–seeTable 1.3)typeB2irregularitydoesnotexistswithreferenceto1.5. 2.2.2.2–Multi8ModeResponseSpectrumAnalysisMethodistheacceptableanalysismethod foralllow=tomedium=risebuildings. 2.2.3.Definitionofseismicmass Totalseismicmassofthebuilding,Mt,shallbedeterminedbyEq.(2.3):

W N t 1

M = = ∑W ;W =G + n n Q (2.3) t i i i 1 2 i g g i=1

whereliveloadmassreduction actor n1 andliveloadparticipation actor n2 shallbetaken fromTable2.3andTable2.4,respectively.

Table2.3–Liveloadmassreductionfactor( n1 )

Typeofoccupancy n 1

Storeyswithcorrelatedoccupancies 0.80

Storeyswithindependentoccupancies 0.30

20

2.2.4.Considerationofverticalcomponentofearthquake 2.2.4.1–Verticalcomponentoftheseismicaction,asdefinedin1.2.2.4,shallbetakeninto accountforthecaseslistedbelow:

(a)Horizontalornearlyhorizontalstructuralmembersspanning20mormore;

(b)Horizontalornearlyhorizontalcantilevercomponentslongerthan5m;

(c)Horizontalornearlyhorizontalpre=stressedcomponents;

(d)Beamssupportingcolumns. 2.2.4.2 – The analysis for determining the effects of the vertical component of the seismic actionmaybebasedonapartialmodelofthestructure,whichincludestheelementsonwhich theverticalcomponentisconsideredtoact(e.g.thoselistedin2.2.4.1)andtakesintoaccount thestiffnessoftheadjacentelements. 2.2.4.3 – The effects of the vertical component need be taken into account only for the elements under consideration (e.g. those listed in 2.2.4.1) and their directly associated supportingelementsorsubstructures.

21

2.3.EQUIV LETSEISMICLO DMETHOD 2.3.1.DisplacementComponentsand pplicationPointsofSeismicLoads 2.3.1.1 – Where floors act as rigid horizontal diaphragms, two lateral displacement componentsandtherotationaroundtheverticalaxisshallbetakenintoaccountateachfloor as independent static displacement components. t each floor, equivalent seismic loads determinedinaccordancewith2.3.3shallbeappliedtothefloormasscentreaswellastothe pointsdefinedbyshiftingit+5%and−5%ofthefloorlengthintheperpendiculardirectionto theearthquakedirectionconsideredinordertoaccountfortheaccidentaleccentricitye ects. 2.3.1.2 – Where floors do not act as rigid horizontal diaphragms, sufficient number of independent staticdisplacementcomponents shallbeconsidered toaccount for the in=plane deformationoffloors. 2.3.2.BaseShear Totalequivalentseismicload,i.e.,thebaseshear,Vb,intheearthquakedirectionconsidered shallbecalculatedbyEq.(2.4):

V =M S (T ) ≥ . M S I (2.4) 0 11 b t R 1 t SD

wheredesignspectral accelerationS R(T1) andelastic shortperiodspectral accelerationSSD correspond to (E2) level earthquake. Predominant natural period in the direction of earthquake,T1,shallbecalculatedinaccordancewith2.3.4. 2.3.3.StoreySeismicLoads 2.3.3.1–Totalequivalentseismic loaddeterminedbyEq.(2.4) isexpressedbyEq.(2.5)as thesumofseismicloadsactingatstoreylevels.

N Vb =FN + ∑ Fi (2.5)

i=1

2.3.3.2–Theadditionalequivalentseismicload,FN,actingatthe’thstorey(roof)ofthe buildingshallbedeterminedbyEq.(2.6).

FN =0.0075 Vb (2.6)

Excluding FN , remaining part of the total equivalent seismic load shall be distributed to storiesofthebuilding(including’thstorey)inaccordancewithEq.(2.7).

Wi Hi F =(V −F ) (2.7) i b N N ∑ Wk Hk k=1

2.3.3.3–InthecasewheretorsionalirregularitydefinedinTable1.3existsatanyi’thstorey suchthatthecondition1.2<ηti≤2.0issatisfied,±5%accidentaleccentricityappliedtothis floor according to 2.3.1.1 shall be amplified by multiplying with coefficient Di given by Eq.(2.8)foreachearthquakedirection.

22

ηti 2

Di = (2.8) 1.2

2.3.3.4–Inbuildingswithverystiffreinforcedconcreteperipheralwallsattheirbasements, equivalentseismicloadsactingonstiffbasementstoriesandthoseactingonrelativelyflexible upperstoriesshallbecalculatedseparatelyasgivenin(a)and(b)below.Suchloadsshallbe combinedfortheanalysisofthecompletestructuralsystem.

(a) In determining the base shear and equivalent storey seismic loads acting on relatively flexibleupperstories,Clauses2.3.2and2.3.3shallbeappliedwithseismicmassesofupper storiesonlytakenintoaccount.Foundationtoplevelconsideredintherelevantdefinitionsand expressions shall be replaced by the ground floor level. Fictitious loads used for the calculationofthefirstnaturalvibrationperiodinaccordancewith2.3.4.2shallalsobebased onseismicmassesofupperstoriesonly. ppropriatebehaviourfactorqshallbeselectedfrom Chapter 3 or Chapter 4, as appropriate, based on the structural type of the upper stories only.

(b)Incalculatingequivalentseismicloadsactingonthestiffbasementstories,seismicmasses of basements only shall be taken into account. Equivalent seismic loads acting on each basement storey shall be calculated with elastic spectral acceleration of 0.4SDS to be multiplieddirectlywiththerespectivestoreymass,andtheresultingelasticloadsshallnotbe reduced(i.e.,qR=1).

(c) In the analysis of the complete structural system under the combined action of the equivalentseismicloadsasdefinedin(a)and(b)above,interactionwiththesoilsurrounding basementstoriesmaybeconsideredwithanappropriatesoilmodeling.

(d) In=plane strength of ground floor system, which is surrounded by very stiff basement wallsand located in the transitionzonewith theupperstories,shallbecheckedfor internal forcesobtainedfromtheanalysisaccordingto(c)above.

2.3.4.Predominantperiod 2.3.4.1–Predominantnaturalvibrationperiodofthebuildingintheearthquakedirection,T1,

maybeapproximatelyestimatedbythefollowingexpression:

T1 =Ct HN3/4 (2.9)

Ct may be taken as 0.085 for moment resistant steel frames, 0.075 for moment resistant concrete frames / eccentrically braced steel frames and 0.050 for all other structures. For structureswithconcretestructuralwallsCtmaybecalculatedbyEq.(2.10).

0.075 Ct = (2.10)

A c

whereAciscalculatedfromEq.(2.11).

Ac =∑ [Aj (0.2+lwj /HN )2 ] (2.11)

j

withtheconditionthat lwj /H ≤ 0 9. . N

2.3.4.2–Predominantnaturalvibrationperiodofthebuildingintheearthquakedirection,T1, shallnotbetakenlongerthanthevaluecalculatedbyEq.(2.12).

23

1/ 2 N 2 ∑ M idfi

T1 =2π i=1 N (2.12)

∑ Ffidfi i=1

FictitiousloadFfiactingonthei’thstoreymaybeobtainedfromEq.(2.7)bysubstitutingany value( orexampleaunitvalue)inplaceof(Vb−FN). 2.3.5.DirectionalCombination 2.3.5.1–Themaximumvalueofeachresponsequantityduetotwohorizontalcomponentsof theearthquakemaybeestimatedbythesquarerootof thesumof thesquaredvaluesof the responsequantitiescalculatedduetoeachhorizontalcomponent.

2.3.5.2– sanalternativeto2.3.5.1,thecombinationproceduregivenbyEq.(2.13)maybe employed:

Q =±Q ±0.30QD x y (2.13)

Q =±0.30Q ±QD x y

24

2.4.MULTIMODERESPOSESPECTRUM LYSISMETHOD Inthismethod,maximuminternalforcesanddisplacementsaredeterminedbythestatistical combination of maximum contributions obtained in sufficient number of natural vibration modestobeconsidered. 2.4.1.Dynamicdegreesoffreedom 2.4.1.1 – In buildings where floors behave as rigid horizontal diaphragms, two horizontal degrees of freedom in perpendicular directions and a rotational degree of freedom with respecttotheverticalaxispassingthroughmasscentreshallbeconsideredateachstorey. t eachfloor,modalseismicloadsdefinedforthosedegreesoffreedomshallbeappliedtothe floormass centre aswell as to thepointsdefinedby shifting it +5% and −5%of the floor length in theperpendiculardirection to theearthquakedirectionconsidered.The latter is to accountfortheaccidentaleccentricitye ects. 2.4.1.2 – In buildings where torsional irregularity exists and floors do not behave as rigid horizontaldiaphragms,sufficientnumberofdynamicdegreesoffreedomshallbeconsidered tomodelin=planedeformationoffloors. 2.4.2.Modalseismicloads 2.4.2.1 – In a typical n’th vibration mode considered in the analysis, modal seismic loads acting on the i’th story level at the mass centre of the floor diaphgram is expressed by Eqs.(2.14).

F = Φ S R ( )xin M i xin Γ xn Tn

F =M Φ Γ S (T ) (2.14) yin i yin xn R n

=M Φ (T )Fθin θi θin Γ xn S R n

where Γ xn represents the participation factor of the n’th mode under an eartquake ground motioninxdirection.Forbuildingswithrigidfloordiaphragms Γ xn isdefinedas

xn Γ xn = L * (2.15)

M n

inwhichLxnand M n* areasexpressedin2.4.3.

2.4.2.2–Inbuildingswithverystiffreinforcedconcreteperipheralwallsattheirbasements, unless a full modal analysis of the structural system is performed, modal seismic loads (as defined in 2.4.2.1) acting on stiff basement stories and those acting on relatively flexible upperstoriesmaybecalculatedseparatelyasgivenin(a)and(b)below.

(a) Incalculatingmodalseismic loadsactingonrelatively flexibleupperstories, the lowest vibration modes that are effective in the upper stories may be considered, which can be achieved by taking into account the seismic masses of the upper stories only. In this case, appropriatebehaviourfactorqmustbeselectedfromChapter3orChapter4,asappropriate, basedonthestructuraltypeoftheupperstoriesonly.

(b)Indeterminingmodalseismicloadsactingonstiffbasementstories,thehighestvibration modesthatareeffectiveinthebasementsmaybeconsidered,whichcanbeachievedbytaking

25

into account the seismic masses of the basement stories only. In this case, resulting elastic modalloadsshouldnotbereduced(i.e.,qR=1).

(c)Sincevibrationmodes affecting the stiff basement stories and flexibleupper stories are expectedtobefarapart,twoseparateresponsespectrumanalysesmaybeperformedbasedon modalseismicloadsdefinedin(a)and(b)above.Ineachofthoseanalyses,interactionwith thesoilsurroundingbasementstoriesmaybeconsideredwithanappropriatesoilmodeling. Theresultsofsuchanalysesmaybedirectlysuperimposed.

(d) In=plane strength of ground floor system, which is surrounded by very stiff basement wallsand located in the transitionzonewith theupperstories,shallbecheckedfor internal forcesobtainedfromtheanalysisexplainedin(c)above.

2.4.3.umberofVibrationModes Su icient numbero vibrationmodes,NS, tobe taken into account in the analysis shall be determinedtothecriterionthatthesumofeffectiveparticipatingmassescalculatedforeach modeineachofthegivenxandyperpendicularlateralearthquakedirectionsshallinnocase belessthan90%ofthetotalbuildingmass.

NS NS N xn ∑ M xn = ∑

L2

* ≥ 0.90 ∑ M i

n=1 n=1 M i=1

n (2.16)

NS NS L2 N

∑ M yn = ∑ yn ≥ 0.90 ∑ M i*

n=1 n=1 M i=1 n

Expressions for Lxn , Lyn and modal mass Mn shown in Eqs.(2.16) are given below for buildingswithrigidfloordiaphragms:

N N Lxn = ∑ M iΦxin ;Lyn = ∑ M iΦyin

i=1 i=1 (2.17)

N * 2 2 2M n = ∑ (M iΦxin +M iΦyin +MθiΦθin )

i=1

2.4.4.ModalCombination 2.4.4.1–CompleteQuadraticCombination(CQC)Ruleshallbeappliedforthecombination ofmaximummodalcontributionsofresponsequantitiescalculatedforeachvibrationmode, such as the base shear, storey shear, internal force components, displacements and storey drifts. It is imperative that modal combination is applied independently for each response quantity. 2.4.4.2–Inthecalculationofcrosscorrelationcoe icientstobeusedintheapplicationofthe rule,modaldampingfactorsshallbetakenas5%forallmodes. 2.4.5.ScalingofResponseQuantities In the case where the base shear in the given earthquake direction, VbCx or VbCy , which is obtainedthroughmodalcombinationaccordingto2.4.4,islessthan85%ofthecorresponding base shear, Vbx or Vby , obtained by Equivalent Seismic Load Method according to 2.3.2 (VbC < 0.85Vb), all internal force and displacement quantities determined by Response Spectrum nalysisMethodshallbeamplifiedinaccordancewithEq.(2.18).

26

0.85Vbx Q = QSx Cx VbCx

(2.18) 0.85Vby

Q = QSy Cy VbCy

InthecasewhereVbCxorVbCyisnotlessthan85%ofthecorrespondingbaseshearVbxorVby, thenQSx=QCxorQSy=QCyshallbeusedin2.4.6. 2.4.6.DirectionalCombination Directionalcombinationproceduresgiven in2.3.5 forEquivalentSeismicLoadMethodare applicablewithQxandQyreplacedbyQSxandQSy,respectively.

27

2.5.RESPOSEHISTORY LYSISMETHOD 2.5.1.LinearResponseHistory nalysis Linear responsehistory analysisbasedonmode8superpositionproceduremaybeperformed inlieuofmulti=moderesponsespectrumanalysisdescribedin2.4. 2.5.1.1 – The analysis shall be based on a set of earthquakes comprising three or seven earthquakerecordswithsimultaneouslyactingtwohorizontalcomponentstobeselectedand scaledaccordingto1.2.3. 2.5.1.2–Sufficientnumberofvibrationmodesshallbeusedasdescribedin2.4.3. 2.5.1.3 – In each analysis, linear response histories of design quantities obtained for each typical mode (n) shall be reduced by the corresponding Seismic Load Reduction Factor qR (Tn ) givenbyEqs.(2.1)basedonelasticspectrumcornerperiodTS. 2.5.1.4–Ifthreegroundmotionsareusedintheanalysis,themaximaoftheresultsshallbe considered for design. If at least seven ground motions are used, the mean values of the resultsmaybeconsideredfordesign. 2.5.2.onlinearResponseHistory nalysis Nonlinear response history analysis may be performed by direct integration of nonlinear equationsofmotion in lieuofmulti=mode response spectrum analysisdescribed in 2.4 and linear responsehistoryanalysisdescribed in2.5.1.Nonlinearanalysis requirementsshallbe thesameasthosegiveninChapter5.

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2.6.S FETYVERIFIC TIO 2.6.1.Strengthverification Thefollowingrelationshallbesatisfiedforallstructuralelementsincludingconnectionsand therelevantnon=structuralelements:

Ed ≤ Rd (2.19)

whereEd is thedesignvalueof theactioneffect,due to loadcombinationsdefined in2.6.2 including,ifnecessary,secondordereffectsdefinedin2.6.3,aswellasduetocapacitydesign rules, as described in Chapters 3 and 4. Rd is the corresponding design resistance of the element,calculatedinaccordancewiththerulesspecifictothematerialusedconsideringthe requirementsofChapters3and4. 2.6.2.Loadcombinationsforseismicdesign TheloadcombinationsgiveninEq.(2.20)shallbeusedtodefinethedesignvaluesofaction effects.Liveloadparticipationfactor n2 isgiveninTable2.4.

E + n E ∓ EG 2 Q E (2.20)

0.9EG ∓ EE

Table2.4–Liveloadparticipationfactor( n2 )

Loadingareas n 2

Domestic,residentialandofficeareas 0.3

Shoppingandcongregationareas 0.6

Storageareas 0.8

Trafficareas(vehicleweight≤30kN) 0.6

Trafficareas(30kN<vehicleweight≤160kN) 0.3

Roofareas 0

2.6.3.SecondOrderEffects Unless a more refined analysis considering the nonlinear behaviour of structural system is performed,second=ordereffectsmaybetakenintoaccountinaccordancewith2.6.3.1.

2.6.3.1–InthecasewhereSecond8OrderE ectIndicator,θi,satisfiestheconditiongivenby Eq.(2.21)fortheearthquakedirectionconsideredateachstorey,second=ordereffectsshallbe evaluated inaccordancewith thecurrentlyenforcedspecificationsof reinforcedconcreteor structuralsteeldesign.

N ( ) ∑ Wi avg k

k=i θi = ≤ 0.10 (2.21)

Vih i

29

where(i)avgshallbedeterminedinaccordancewith2.7.1.1astheaveragevalueofreduced storeydrifts,ji,calculatedfori’thstoreycolumnsandstructuralwalls. 2.6.3.2–Inthecasewhere0.10<θ≤0.20,second=ordereffectsmayapproximatelybetaken intoaccountbymultiplyingtherelevantseismicresponsequantitybyafactorof1/(1–θ). 2.6.3.3 – In the case where θ > 0.20, seismic analysis shall be repeated with sufficiently increasedstiffnessandstrengthofthestructuralsystem.

30

2.7.D M GELIMIT TIO 2.7.1.Limitationofstorydrifts 2.7.1.1–Thereducedstoreydri t,ji ,ofanycolumnorstructuralwallshallbedetermined byEq.(2.21)asthedifferenceofdisplacementsbetweenthetwoconsecutivestories.

=d ji − d − (2.22) ji j(i 1)

where dji and dj(i−1) represent lateral displacements obtained from the analysis at the j’th columnorstructuralwallatstoriesiand(i–1)underreducedseismicloads.Theminimum equivalentseismicloadconditiondefinedbyEq.(2.4)andthescalingproceduredescribedin 2.4.5maynotbeconsideredinthecalculationofdjiandji.

2.7.1.2 – When multi=mode response spectrum analysis described in 2.4 or linear response historyanalysisdescribedin2.5.1isused,thee ectivestoreydri t,δji,ofthej’thcolumnor structuralwallatthei’thstoreyofabuildingshallbeobtainedineachdirectionbyEq.(2.23).

δ = q (2.23) ji ji

I

2.7.1.3–Themaximumvalueofeffectivestoreydrifts,(δi)max,obtainedineachdirectionfor columnsorstructuralwallsofagiveni’thstoreyofabuildingshallsatisfytheconditiongiven byEq.(2.24):

(δ )i max ≤ . 0 02 (2.24) hi

This limit may be exceeded by 50% in single storey frames where seismic loads are fully resistedbysteelframeswithjointscapableoftransferringcyclicmoments. 2.7.1.4 – The limit given by Eq.(2.24) may be exceeded by 20% if nonlinear analysis procedure is performed in accordance with 2.5.2. For nonlinear analysis, the displacements determinedarethoseobtaineddirectlyfromtheanalysiswithoutfurthermodification. 2.7.1.5–Inthecasewheretheconditiongivenin2.7.1.3or2.7.1.4,whicheverapplicable,is not satisfied at any storey of the building, the seismic analysis shall be repeated with increasedstiffnessofthestructuralsystem. 2.7.2.SeismicJoints Excludingtheeffectsofdifferentialsettlementsandrotationsoffoundationsandtheeffectsof temperaturechange,sizesofgapstoberetainedintheseismicjointsbetweenbuildingblocks orbetween theoldandnewlyconstructedbuildingsshallbedetermined inaccordancewith thefollowingconditions: 2.7.2.1–Sizesofgapstobeprovidedshallnotbelessthanthesquarerootofsumofsquares of average storeydisplacementsof the adjacent buildings (orbuildingblocks)multipliedby the coefficient αG specified below. Storey displacements to be considered are the average valuesof reduceddisplacementsdji calculatedat thecolumnorstructuralwall jointsof i’th storey.Inthecaseswheretheseismicanalysisisnotperformedfortheexistingoldbuilding,

31

the storey displacements shall not be assumed to be less than those obtained for the new buildingatthesamestories.

(a)αG=0.67(q/I)shallbetakenifallfloorlevelsofadjacentbuildingsorbuildingblocksare thesame.

(b)αG=(q/I)shallbetakenifanyofthefloorlevelsofadjacentbuildingsorbuildingblocks arenotthesame. 2.7.2.2 – Seismic joints shall be arranged to allow the independent movement of building blocksinallearthquakedirections.

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2.8. LYSISREQUIREMETSFOROSTRUCTUR LSYSTEMS 2.8.1– nalysisrequirementsfornonstructuralelementsinlow=tomediumrisebuildingsare given in the followingparagraphs.The relevant requirements for tallbuildingsaregiven in 5.4. 2.8.2 – Equivalent seismic loads to be applied to structural appendages such as balconies, parapets,chimneys,etc.andtoallarchitecturalelementssuchasfaçadeandpartitionpanels, etc.aswellas theseismicloadstobeusedfor theconnectionsofmechanicalandelectrical equipmenttothestructuralsystemelementsaregivenbyEq.(2.25).

H e =0.2SSD Ie me 1+2 i

(2.25) H N

Seismic loadshallbeappliedhorizontally to themasscentreof theelementconcerned ina direction to result in most unfavourable internal forces. The seismic loads to be applied to non=verticalelementsshallbehalftheequivalentseismicloadcalculatedbyEq.(2.25). 2.8.3–Forthefollowingnon=structuralelementsthe,theElementImportanceFactorIeshall notbelessthan1.5:

(a) nchorageelementsofmachineryandequipmentrequiredforlifesafetysystems,

(b)Tanksandvesselscontainingtoxicorexplosivesubstancesconsideredtobehazardousto thesafetyofthegeneralpublic. Inallothercases,theElementImportanceFactorIemaybeassumedtobeequaltounity. 2.8.4–Inthecasewherethesumofmechanicalorelectricalequipmentmasses,asdenotedby meinEq.(2.25),exceeds0.2miatanyi’thstorey,equipmentmassesandstiffnesspropertiesof theirconnectionstothebuildingshallbetakenintoaccountintheearthquakeanalysisofthe buildingstructuralsystem. 2.8.5–Inthecasewhere looraccelerationspectrumisdeterminedbyappropriatemethodsto definethepeakaccelerationatthefloorwheremechanicalorelectricalequipmentislocated, Eq.(2.25)maynotbeapplied. 2.8.6–TwicetheseismicloadcalculatedbyEq.(2.25)ordeterminedaccordingto2.8.5shall be considered for fire extinguishing systems, emergency electrical systems as well as for equipmentsconnectingtoinfillwallsandfortheirconnections

33

CH PTER3 SEISMICDESIGREQUIREMETS

FORREIFORCEDCOCRETEBUILDIGS

3.1.SCOPE DDESIGCOCEPTS 3.1.1.Scope 3.1.1.1 – This chapter applies to the seismic design of elements of reinforced concrete buildings. 3.1.1.2–TherulesgiveninthischapterareadditionaltothosegiveninEN1992=1=1:2004.

3.1.2.DesignConcepts 3.1.2.1 – Design of earthquake resistant reinforced concrete buildings shall provide the structure with an adequate energy dissipation capacity without substantial reduction of its overallresistanceagainsthorizontalandverticalloading. dequateresistanceofallstructural elementsshallbeprovided,andnon=lineardeformationdemandsincriticalregionsshouldbe compatiblewiththeoverallductilityassumedincalculations. 3.1.2.2 – Reinforced concrete buildings may alternatively be designed for low dissipation capacityand lowductility,by applyingonly the rulesofEN1992=1=1:2004 for the seismic designsituation,andneglectingthespecificprovisionsgiveninthischapter.Theclassofsuch buildingsareidentifiedasLowDuctilityClass(DCL). 3.1.2.3 – Reinforced concrete buildings other than those to which 3.1.2.2 applies, shall be designed to provide energy dissipation capacity and an overall ductile behaviour. Overall ductilebehaviour isensuredif theductilitydemandinvolvesgloballya largevolumeof the structure spread to different elements and locations of all its storeys. To this end ductile modesoffailure(e.g.flexure)shouldprecedebrittlefailuremodes(e.g.shear)withsufficient reliability. The class of such buildings are identified as ormal Ductility Class (DCN), for whichreinforcedconcreteseismicdesignrequirementsaregivenintheremainderofChapter 3. 3.1.2.4 –Unless amore accurate analysisof the cracked elements is performed, the elastic flexural and shear stiffness properties of reinforced concrete elements may be taken to be equaltoone=halfofthecorrespondingstiffnessoftheuncrackedelements. 3.1.3.StructuraltypesandBehaviourFactors 3.1.3.1–Reinforcedconcretebuildingsareclassifiedwithrespecttostructuraltypesandtheir combinationsasfollows:

(a) Moment8resisting rame system is defined as a structural system composed of moment= resistingframesonly.

(b) Coupled structural wall system is defined as a structural system composed of coupled structural walls only. Coupled structural walls are made from isolated structural walls connectedwithrelativelystiffcouplingbeamssuchthatbaseoverturningmomentsofisolated wallsarereducedbyatleast25%underthesamelateralloads.

34

(c)Uncoupledstructuralwallsystemisdefinedasastructuralsystemcomposedofuncoupled (isolated)structuralwallsonly.

(d) Frame8dominant dual system is defined as a structural system composed of moment= resisting frames, which resist more than 50% of the total calculated base shear, in combinationwithcoupledoruncoupledwalls.

(e)Wall8dominantdualsystem(coupledwalls)isdefinedasastructuralsystemcomposedof coupled structural walls, which resist more than 50% of the total calculated base shear, in combinationwithmoment=resistingframesand/oruncoupledwalls.

(f)Wall8dominantdualsystem(uncoupledwalls)isdefinedasastructuralsystemcomposed ofuncoupled (isolated) structuralwalls,which resistmore than50%of the total calculated baseshear,incombinationwithmoment=resistingframesand/orcoupledwalls.

(g)Invertedpendulumsysteminwhich50%ormoreofthemassisintheupperthirdofthe heightofthestructure,orinwhichthedissipationofenergytakesplacemainlyatthebaseof a single building element. One=storey frames with column tops connected along both main directionsofthebuildingandwiththevalueofthecolumnnormalizedaxialloadlessthan0.3 areexcluded. 3.1.3.2–Reinforcedconcretebuildingsmaybeclassifiedtoonetypeofstructuralsystemin onehorizontaldirectionandtoanotherintheotherdirection. 3.1.3.3 – Behaviour factors for all structural types of Low Ductility Class (DCL) shall be takenasq=1. 3.1.3.4 – Behaviour factors for structural types of ormal Ductility Class (DCN) shall be takenfromTable3.1.

Table3.1–BehaviourFactors(q)forreinforcedconcretestructuraltypes

Structuraltype q

Momentresistingframesystem

Coupledstructuralwallsystem

Uncoupledstructuralwallsystem

Frame=dominantdualsystem

Wall=dominantdualsystem(coupledwalls)

Wall=dominantdualsystem(uncoupledwalls)

Invertedpendulumsystem

3.5

3.5

2.0

3.0

3.0

2.0

1.5

3.1.4.Designactions 3.1.4.1–Withtheexceptionofstructuralwalls,forwhichthespecialprovisionsof3.4apply, thedesignvaluesofbendingmomentsandaxialforcesshallbeobtainedfromtheanalysisof thestructurefortheseismicdesignsituationinaccordancewith2.6. 3.1.4.2 – The design values of shear forces of beams, columns and structural walls are determinedinaccordancewith3.2,3.3and3.4,respectively.

35

3.1.5.CapacityDesignRules 3.1.5.1–Brittlefailureorotherundesirablefailuremechanisms(e.g.concentrationofplastic hinges in columns of a single storey of a multistorey building, shear failure of structural elements,failureofbeam=columnjoints,yieldingoffoundationsorofanyelementintendedto remain elastic) shall be prevented, by deriving thedesign action effects of selected regions from equilibrium conditions, assuming that plastic hinges with their possible overstrengths havebeenformedintheiradjacentareas.

3.1.5.2 – In moment resisting frame systems, including frame=dominant dual systems as definedin3.1.3.1,thefollowingconditionshouldbesatisfiedatallbeam=columnjoints:

∑ M ≥ 1.3∑ M (3.1) Rc Rb

3.1.5.3 – In order that Eq.(3.1) is applied, beams framing into the joint shall satisfy the dimensionalrequirementsgivenin3.2.1and3.3.1. 3.1.5.4–Slabreinforcementparalleltothebeamandwithintheeffectiveflangewidthshall be considered to contribute to the beam flexural capacities taken into account for the calculationof ∑ MRb inEq.(3.1),ifitisanchoredbeyondthebeamsectionatthefaceofthe joint. 3.1.5.5–Eq.(3.1)shallbesatisfiedseparatelyforbothearthquakedirectionsandsenseswith the column moments always opposing the beam moments to yield the most unfavourable result. Incalculatingthecolumnmomentresistances,axialforcesshallbetakentoyieldthe minimummomentsconsistentwiththesenseofearthquakedirection. 3.1.5.6–If thestructuralsystemisa frameorequivalent toa frame inonlyoneof the two main horizontal directions of the structural system, then Eq.(3.1) should be satisfied just withintheverticalplanethroughthatdirection. 3.1.5.7–SpecialsituationsregardingtheapplicationofEq.(3.1)aregiveninthefollowing:

(a)Eq.(3.1)neednottobesatisfiedinthecasewherenormalizedaxialforceisνd<0.10in bothcolumnsframingintothejoint.

(b)Eq.(3.1)neednottobesatisfiedatthebaseofanyframe.

(c)Eq.(3.1)neednottobecheckedinsinglestoreybuildingsandinjointsoftopmoststorey ofmulti=storeybuildings. 3.1.5.8–Eq.(3.1)may bepermittednot tobe satisfied inagiven earthquakedirectionat a certainnumberofjointsatthebottomand/ortopofastorey,providedthatEq.(3.2)holds.

Vis αi = ≥ 0.75 (3.2) Vic

Columnswithnormalizedaxialforceνd<0.10maybetakenintoaccountinthecalculationof ViseveniftheydonotsatisfyEq.(3.1). 3.1.5.9–InthecasewhereEq.(3.2)holds,bendingmomentsandshearsofcolumnssatisfying Eq.(3.1)atbothbottomandtopjointsshallbeamplifiedbymultiplyingwiththeratio(1/αi) withintherangeof0.75≤αi<1.00.

36

3.1.6.Materialrequirements 3.1.6.1–InbuildingsofbothLowDuctilityClass(DCL)andormalDuctilityClass(DCN) reinforcingsteelofclassBorCinEN1992=1=1:2004,TableC.1shallbeused. 3.1.6.2–ThefollowingmaterialrequirementsshallapplyforbuildingsofominalDuctility Class(DCN):

(a)ConcreteofaclasslowerthanC16/20shallnotbeused.

(b)Onlyribbedbarsshallbeusedasreinforcingsteel.

(c) Welded wire meshes may be used, if they meet the requirements in (b) above and in 3.1.6.1. 3.1.7.Localductilityrequirements 3.1.7.1–Fortherequiredoverallductilityofthestructuretobeachieved,thepotentialregions forplastichingeformation,tobedefinedlaterforeachtypeofbuildingelement,shallpossess highplasticrotationalcapacities. 3.1.7.2–Inordertosatisfytherequirementgivenin3.1.7.1,thefollowingconditionsshallbe met:

(a)Thecurvatureductilityfactoraφofallcriticalregionsofelements,includingcolumnends (dependingonthepotentialforplastichingeformationincolumns)shallbeatleastequalto thefollowingvalues:

q TS =1+2 − 1 (0 ≤ T ≤ T )ϕ 1 S I T 1 (3.3)

qϕ =2 −1(TS < T1)

I

(b) Local buckling of compressed steel within potential plastic hinge regions of primary seismicelementsshallbeprevented.Relevantapplicationrulesaregiven in3.2.3,3.3.3and 3.4.3. 3.1.7.3 – ppropriate concrete and steel qualities are adopted to ensure local ductility as follows:

(a) Steel used in critical regions of seismic elements should have high uniform plastic elongation(see3.1.6.1);

(b) Tensile strength to yield strength ratio of the steel used in critical regions of primary seismicelements shouldbe significantlyhigher thanunity.Reinforcingsteelconforming to therequirementsof3.1.6.1maybedeemedtosatisfythisrequirement;

(c)Concreteusedinprimaryseismicelementsshouldpossessadequatecompressivestrength and a fracture strain which exceeds the strain at the maximum compressive strength by an adequate margin. Concrete conforming to the requirements of 3.1.6.2 may be deemed to satisfytheserequirements. 3.1.7.4–IncriticalregionsofelementswithlongitudinalreinforcementofsteelclassBinEN 1992=1=1:2004, Table C.1, the curvature ductility factor aφ should be at least equal to 1.5 timesthevaluegivenbyEq.(3.3).

37

3.2.SEISMICDESIGREQUIREMETSFORREIFORCEDCOCRETEBE MS 3.2.1.Geometricalrequirements 3.2.1.1–Thedistancebetween thecentroidalaxesofabeamand thecolumn intowhich it framesshallbelimitedtolessthanbc/4. 3.2.1.2–Widthbwofabeamshallsatisfythefollowingexpression:

b ≤ min(bc+h ),2bc (3.4) w w

3.2.1.3–Theeffectiveflangewidthbeffmaybetakenasfollows:

(a) In beams framing into exterior columns, the effective flange width beff is taken, in the absenceofa transversebeam,asbeingequal to thewidthbc of thecolumn,or if there isa transverse beam of similar depth, equal to this width increased by 2hf on each side of the beam.

(b)Inbeamsframingintointeriorcolumnstheabovewidthsmaybeincreasedby2hfoneach sideofthebeam. 3.2.1.4–Forabeamsupportingcolumnsdiscontinuedbelow thebeam, the following rules apply:

(a)Thereshallbenoeccentricityofthecolumnaxisrelativetothatofthebeam.

(b)Thebeamshallbesupportedbyatleasttwodirectsupports,suchaswallsorcolumns.

3.2.2.Designshearforcesofbeams 3.2.2.1–Inbeamsthedesignshearforcesshallbedeterminedinaccordancewiththecapacity designrule,onthebasisoftheequilibriumofthebeamunder:a)thetransverseloadactingon it in the seismic design situation and b) end moments Mi,d (with i = 1,2 denoting the end sections of the beam), corresponding to plastic hinge formation for positive and negative directionsofseismicloading:

M + M1,d 2,d V =V ± (3.5) Ed Ed,G

lcl

Theplastichingesshouldbetakentoformattheendsofthebeamsor(iftheyformtherefirst) intheverticalelementsconnectedtothejointsintowhichthebeamendsframe. 3.2.2.2–EndmomentsMi,dmaybedeterminedasfollows:

∑ MRc M i,d =MRb,i min 1, (3.6) ∑ M Rb

The value of ∑ MRc shall be compatible with the the column axial force(s) in the seismic designsituationfortheconsideredsenseoftheseismicaction.

38

3.2.2.3– tabeamendwherethebeamissupportedindirectlybyanotherbeam,insteadof framingintoaverticalmember,thebeamendmomentMi,dtheremaybetakenasbeingequal totheactingmomentatthebeamendsectionintheseismicdesignsituation. 3.2.2.4 – End moments Mi,d need not exceed those obtained from seismic analysis with (q/I)=1.

3.2.3.Seismicdetailingofbeams 3.2.3.1–Theregionsofabeamuptoadistancelcr=hw(wherehwdenotesthedepthofthe beam)fromanendcross=sectionwherethebeamframesintoabeam=columnjoint,aswellas frombothsidesofanyothercross=sectionliabletoyieldintheseismicdesignsituation,shall beconsideredasbeingcriticalregions. 3.2.3.2 – In beams supporting discontinued (cut=off) vertical elements, the regions up to a distanceof2hwoneachsideofthesupportedverticalelementshouldbeconsideredasbeing criticalregions. 3.2.3.3–Thefollowingconditionsshallbemetatbothflangesofthebeamalongthecritical regions:

(a) tthecompressionzone,reinforcementofnotlessthanhalfofthereinforcementprovided atthetensionzoneshallbeplaced,inadditiontoanycompressionreinforcementneededfor theverificationofthebeamintheseismicdesignsituation.

(b)Thereinforcementratioofthetensionzone,ρ,shallnotexceedavalueρmaxequalto:

0.0018 cd ρ =ρ'+ (3.7) max ϕ ε sy,d yd

with the reinforcement ratios of the tension zone and compression zone, ρ and ρ', both normalisedtobd,wherebisthewidthofthecompressionflangeofthebeam.Ifthetension zone includes a slab, the amount of slab reinforcement parallel to the beam within the effectiveflangewidthdefinedin3.2.1.3isincludedinρ. 3.2.3.4 – long the entire lengthof abeam, the reinforcement ratioof the tension zone, ρ, shallbenotlessthanthefollowingminimumvalueρmin:

ctm ρmin =0.5 (3.8) yk

3.2.3.5–Withinthecriticalregionsofbeams,hoopssatisfyingthefollowingconditionsshall beprovided:

(a)Thediameterdbwofhoopsshallbenotlessthan6mm.

(b)Thespacing,s,ofhoops(inmillimetres)shallnotexceed:

s ≤ minh ,24d ,225,8d (3.9) w bw bL

(c)Thefirsthoopshallbeplacednotmorethan50mmfromthebeamendsection.

39

3.3.SEISMICDESIGREQUIREMETSFORREIFORCEDCOCRETE COLUMS 3.3.1.Geometricalrequirements 3.3.1.1 – Shorter dimension of columns with rectangular section shall not be less than 300 mmandsectionareashallnotbelessthan90000mm

2.Diameterofcircularcolumnsshallbe

at least 300 mm. Minimum column dimensions may be reduced to 250 mm and minimum area of rectangular section may be reduced to 62500 mm2

in buildings with no more than threestoriesaboveground. 3.3.1.2–Normalisedaxialforceofcolumn,νd,shallsatisfytheconditionofνd<0.65. 3.3.2.Designshearforcesofcolumns 3.3.2.1–Incolumnsthedesignvaluesofshearforcesshallbedeterminedinaccordancewith thecapacitydesign rule,on thebasisof the equilibriumof thecolumnunderendmoments Mi,d (with i = 1,2 denoting the end sections of the column), corresponding to plastic hinge formationforpositiveandnegativedirectionsofseismicloading.

M + M1,d 2,d VEd = (3.10)

lcl

Theplastichingesshouldbetakentoformat theendsof thebeamsconnectedtothejoints intowhichthecolumnendframes,or(iftheyformtherefirst)attheendsofthecolumns. 3.3.2.2–EndmomentsMi,dmaybedeterminedasfollows:

∑ MRb M i,d =1.1MRc,i min 1, (3.11) ∑ MRc

Thevaluesof ∑ M and ∑ M shallbecompatiblewiththecolumnaxialforce(s)inthe Rc,i Rc seismicdesignsituationfortheconsideredsenseoftheseismicaction.

3.3.2.3 – End moments Mi,d need not exceed those obtained from seismic analysis with (q/I)=1. 3.3.3.Seismicdetailingofcolumns 3.3.3.1–Thetotallongitudinalreinforcementratioρlshallbenotlessthan1%andnotmore than 4%. In symmetrical cross=sections symmetrical reinforcement should be provided (ρ=ρ′). 3.3.3.2 – t least one intermediate bar shall be provided between corner bars along each columnside,toensuretheintegrityofthebeam=columnjoints. 3.3.3.3 – The regions up to a distance lcr from both end sections of a column shall be consideredasbeingcriticalregions.

40

3.3.3.4– In theabsenceofmoreprecise information, the lengthof thecritical region lcr (in metres)maybecomputedfromthefollowingexpression:

l =maxhc ,l / 6 ,0.45 (3.12) cr cl

3.3.3.5–Iflc/hc<3,theentireheightofthecolumnshallbeconsideredasbeingacritical regionandshallbereinforcedaccordingly. 3.3.3.6–Confinement reinforcement for thecritical regions shallnotbe less thangivenby Eq.(3.13).

b c α =30 ν ε − 0.035 (3.13) wd ϕ d sy,d b o

whereαistheconfinementeffectivenessfactor,equaltoα=αnαswithcomponentsαnand αsdefinedasfollows:

(a)Forrectangularcross=sections:

b2 s s α n =1−∑

i ;α s = 1− 1− (3.14) n 6b h 2b 2h o o o o

wherenisthetotalnumberoflongitudinalbarslaterallyengagedbyhoopsorcrossties;and biisthedistancebetweenconsecutiveengagedbars.

(b)Forcircularcross=sectionswithcircularhoops:

s 2

α =1;α = 1− (3.15) n s 2D o

(c)Forcircularcross=sectionswithspiralhoops:

s α n =1;α s = 1− (3.16)

2D o

3.3.3.7– minimumvalueof wd=0.08shallbeprovidedwithinthecriticalregionatthe baseofcolumns. 3.3.3.8–Withinthecriticalregionsoftheprimaryseismiccolumns,hoopsandcross=ties,of atleast6mmindiameter,shallbeprovidedwiththefollowingconditions:

(a) The spacing, s, of the hoops (in millimetres) shall not exceed the value given by Eq.(3.17).

s ≤ minbo/2 ,175 ,8dbL (3.17)

(b)Thedistancebetweenconsecutivelongitudinalbarsengagedbyhoopsorcross=tiesshall notexceed200mm,takingintoaccountEN1992=1=1:2004,9.5.3(6). 3.3.4.Seismicdetailingofbeamcolumnjoints 3.3.4.1–Thehorizontalconfinementreinforcement injointsofbeamswithcolumnsshould benotlessthanthatspecifiedin3.3.3.6–3.3.3.8forthecriticalregionsofcolumns,withthe exceptionofthecaselistedinthefollowingparagraph.

41

3.3.4.2–Ifbeamsframeintoallfoursidesofthejointandtheirwidthisatleastthreequarters of the parallel cross=sectional dimension of the column, the spacing of the horizontal confinementreinforcementinthejointmaybeincreasedtotwicethatspecifiedin3.3.4.1,but maynotexceed150mm. 3.3.4.3 – t least one intermediate (between column corner bars) vertical bar shall be providedateachsideofajointofprimaryseismicbeamsandcolumns.

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3.4.SEISMICDESIGREQUIREMETSFORREIFORCEDCOCRETE STRUCTUR LW LLS 3.4.1.Geometricalrequirements 3.4.1.1–Structuralwallsaretheverticalelementsofthestructuralsystemwheretheratioof lengthtothicknessinplanisequaltoatleast4. 3.4.1.2 – Web thickness of structural walls, bwo , (in metres) should satisfy the following expression: bwo ≥ max . , hs /200 15 (3.18)

dditional requirements apply with respect to the thickness of the confined boundary elementsofwalls,asspecifiedin3.4.3.3. 3.4.1.3–Normalisedaxialforceofcolumn,νd,shallsatisfytheconditionofνd<0.40. 3.4.1.4 – Composite wall sections consisting of connected or intersecting rectangular segments(L=,T=,U=,I=orsimilarsections)shouldbetakenasintegralunits,consistingofa web or webs parallel or approximately parallel to the direction of the acting seismic shear force and a flange or flanges normal or approximately normal to it. For the calculation of flexuralresistance,theeffectiveflangewidthoneachsideofawebshouldbetakentoextend fromthefaceofthewebbytheminimumof(a) theactualflangewidth;(b)one=halfofthe distancetoanadjacentwebofthewall;and(c)25%ofthetotalheightofthewallabovethe levelconsidered.

3.4.1.5–Discontinuedstructuralwallsshallnotrelyfortheirsupportonbeamsorslabs. 3.4.2.Designbendingmomentsandshearforcesofstructuralwalls 3.4.2.1–InwallswithHw/ℓw≤2.0,designbendingmomentsandshearsdeterminedusing appropriateqfactorgivenin3.1.3shallbeamplifiedbyafactorof[3/(Hw/ℓw)].However thisfactorshallexceed2. 3.4.2.2–InwallssatisfyingtheconditionHw/ℓw>2.0,designbendingmomentsalongthe criticalwallheightdeterminedaccording to3.4.3.1shallbe takenasaconstantvaluebeing equal to the bending moment calculated at the wall base. bove the critical wall height, a linearbendingmomentdiagramshallbeapplicablewhichisparalleltothelineconnectingthe momentscalculatedatthebaseandatthetopofthewall. 3.4.2.3 – In walls satisfying the condition Hw / ℓw > 2.0, design shear forces at any cross sectionshallbecalculatedwithEq.(3.19).

V ' = ε V (3.19) Ed Ed

whereshearamplificationfactorεisdefinedas

M 2

Rd,W q ε = 2 + ≤ (3.20) M I Ed,W

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3.4.3.Seismicdetailingofstructuralwalls 3.4.3.1–HeightofthecriticalregionhcrabovethebaseofthewallisgivenbyEq.(3.21):

h =maxl ,h / 6 (3.21) cr w w

However,thecriticalwallheighthcrshallsatisfythefollowinglimitations:

h ≤ 2l cr w

hcr ≤ hs (n ≤ 6storeys) (3.22)

hcr ≤ 2hs (n ≥ 7storeys)

3.4.3.2–Boundaryelementsshallbeappropriatelydefinedattheextremitiesofthewallcross section.Thelengthofeachboundaryelementalongthecriticalwallheightshallnotbeless than 20% of the total plan length of the wall, nor shall it be less than two times the wall thickness.Theplanlengthofeachboundaryelementalongthewallsectionabovethecritical wallheightshallnotbelessthan10%ofthetotalplanlengthofthewall,norshallitbeless thanthewallthickness. 3.4.3.3–Thethicknessbwoftheconfinedpartsofthewallsection(boundaryelements)shall notbe less than200mm.Moreover, if the lengthof the confinedpart doesnot exceed the maximumof2bwand0.2lw,bwshallnotbelessthanhs/15.Ifthelengthoftheconfinedpart exceedsthemaximumof2bwand0.2lw,bwshallnotbelessthanhs/10.

3.4.3.4 – Mechanical volumetric ratio of the required confining reinforcement wd in boundaryelementsisgivenbyEq.(3.23):

b α =30 (ν + ) ε c − 0.035 (3.23) wd ϕ d v sy,d

b o

where visthemechanicalratioofverticalwebreinforcement( v=ρv yd,v/ cd). 3.4.3.5–Thelongitudinalreinforcementratiointheboundaryelementsshallbenotlessthan 0.5%.

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3.5.REQUIREMETSFOR CHOR GE DSPLICIGOFREB RS 3.5.1.General 3.5.1.1 – EN 1992=1=1:2004, Section 8 for the detailing of reinforcement applies, with the additionalrulesofthefollowingsub=clauses. 3.5.1.2 – For hoops used as transverse reinforcement in beams, columns or walls, closed stirrupswith135°hooksandextensionsoflength10dbwshallbeused. 3.5.1.3–Theanchoragelengthofbeamorcolumnbarsanchoredwithinbeam=columnjoints shallbemeasuredfromapointonthebaratadistance5dbLinsidethefaceofthejoint,totake intoaccounttheyieldpenetrationduetocyclicpost=elasticdeformations. 3.5.2. nchorageofrebars 3.5.2.1–Whencalculatingtheanchorageorlaplengthofcolumnbarswhichcontributetothe flexuralstrengthofelementsincriticalregions,theratiooftherequiredareaofreinforcement overtheactualareaofreinforcementshallbeassumedtobeunity. 3.5.2.2 – If, under the seismic design situation, the axial force in a column is tensile, the anchoragelengthsshallbeincreasedto50%longerthanthosespecifiedinEN1992=1=1:2004. 3.5.2.3 – The part of beam longitudinal reinforcement bent in joints for anchorage shall alwaysbeplacedinsidethecorrespondingcolumnhoops. 3.5.2.4 – To prevent bond failure the diameter of beam longitudinal bars passing through beam=columnjoints,dbL,shallbelimitedinaccordancewiththefollowingexpressions:

(a)Forinteriorbeam=columnjoints:

7.5 (1+0.8ν ) dbL = ctm d (3.24)

1+0.5 ρ'/ρyd max

(b)Forexteriorbeam=columnjoints:

7.5 ctm dbL =

(1 + 0.8νd ) (3.25) yd

Eq.(3.24)andEq.(3.25)arenotapplicabletodiagonalbarscrossingjoints. 3.5.2.5–If therequirementspecifiedin3.5.2.4cannotbesatisfiedinexteriorbeam=column jointsbecause thedepth,hc, of thecolumnparallel to thebars is too shallow, the following additionalmeasuresmaybe taken to ensure anchorageof the longitudinal reinforcementof beams.

(a)Thebeamorslabmaybeextendedhorizontallyintheformofexteriorstubs.

(b)Headedbarsoranchorageplatesweldedtotheendofthebarsmaybeused.

(c)Bendswithaminimumlengthof10dbLandtransversereinforcementplacedtightlyinside thebendofthebarsmaybeadded.

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3.5.2.6–Toporbottombarspassingthroughinterior joints,shall terminate in themembers framingintothejointatadistancenotlessthanlcr(lengthofthemembercriticalregionfrom thefaceofthejoint(see3.2.3.1). 3.5.3.Splicingofrebars 3.5.3.1 – There shall be no lap=splicing by welding within the critical regions of structural elements. 3.5.3.2–Theremaybesplicingbymechanicalcouplersincolumnsandwalls,ifthesedevices are covered by appropriate testing under conditions compatible with the selected ductility class. 3.5.3.3–Thetransversereinforcementtobeprovidedwithinthelaplengthshallbecalculated inaccordancewithEN1992=1=1:2004. Inaddition, thefollowingrequirementsshallalsobe met:

(a) If theanchoredand thecontinuingbararearranged inaplaneparallel to the transverse reinforcement,thesumoftheareasofallsplicedbarsshallbeusedinthecalculationofthe transversereinforcement.

(b)Iftheanchoredandthecontinuingbararearrangedwithinaplanenormaltothetransverse reinforcement,theareaoftransversereinforcementshallbecalculatedonthebasisofthearea ofthelargerlappedlongitudinalbar.

(c)Thespacing,s,of the transverse reinforcement in thelapzone(inmillimetres)shallnot exceed

s =minh / 4 ,100 (3.26)

3.5.3.4 – The required area of transverse reinforcement Ast within the lap zone of the longitudinalreinforcementofcolumnssplicedatthesamelocation(asdefinedinEN1992=1= 1:2004), or of the longitudinal reinforcement of boundary elements in walls, may be calculatedfromthefollowingexpression:

d yld Ast = s bl (3.27)

50 ywd

46

3.6.DESIG DDET ILIGOFSECOD RYSEISMICELEMETS 3.6.1–Secondaryseismicelements,whicharedefinedin1.6.2shallbedesignedanddetailed tomaintaintheircapacitytosupportthegravityloadspresentintheseismicdesignsituation, whensubjectedtothemaximumdeformationsundertheseismicdesignsituation. 3.6.2 – Maximum deformations due to the seismic design situation, as mentioned in 3.6.1, shallbecalculated inaccordancewith2.7.Theyshallbecalculatedfromananalysisof the structure in the seismic design situation, in which the contribution of secondary seismic elementstolateralstiffnessisneglectedandprimaryseismicelementsaremodeledwiththeir crackedflexuralandshearstiffness. 3.6.3–Bendingmomentsandshearforcesofsecondaryseismicelementsshallbecalculated withmaximumdeformationsdefinedin3.6.2,usingtheircrackedflexuralstiffnessesand,if necessary,shearstiffnesses.Theyshallnotexceedtheirdesignflexuralandshearresistances determinedonthebasisofEN1992=1=1:2004.

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3.7.SEISMICDESIGREQUIREMETSFORFOUD TIOS 3.7.1.General 3.7.1.1–Thefollowingparagraphsapplyforthedesignofconcretefoundationelements,such as footings, tie=beams, foundation beams, foundation slabs, foundation walls, pile caps and piles, as well as for connections between such elements, or between them and vertical concrete elements.The designof these elements shall follow the rulesofEN1998=5:2004, 5.4. 3.7.1.2 – Design values of the action effects EFd on the foundations shall be derived as follows: E =EF,G + E (3.28) Fd F,E

3.7.1.3–Inbox=typebasementsofdissipativestructures,comprising:a)aconcreteslabacting asarigiddiaphragmatbasementrooflevel;b)afoundationslaboragrillageoftie=beamsor foundation beams at foundation level, and c) peripheral and/or interior foundation walls, columns and beams (including those at the basement roof) are expected to remain elastic under the seismic design situation. Shear walls should be designed for plastic hinge developmentatthelevelofthebasementroofslab.Tothisend,inwallswhichcontinuewith thesamecross=sectionabovethebasementroof,thecriticalregionshouldbetakentoextend belowthebasementroofleveluptoadepthofhcr(see3.4.3.1).Moreover,thefullfreeheight of such walls within the basement should be dimensioned in shear assuming that the wall developsitsflexuraloverstrength1.1MRdatthebasementrooflevelandzeromomentatthe foundationlevel. 3.7.2.Tiebeamsandfoundationbeams 3.7.2.1–Stubcolumnsbetweenthetopofafootingorpilecapandthesoffitoftie=beamsor foundationslabsshallbeavoided.Tothisend,thesoffitoftie=beamsorfoundationslabsshall bebelowthetopofthefootingorthepilecap. 3.7.2.2 – xial forces in tie=beams or tie=zones of foundation slabs in accordance with 5.4.1.2(6)and(7)ofEN1998=5,shouldbetakenintheverificationtoact togetherwiththe actioneffectsderivedfortheseismicdesignsituation. 3.7.2.3 – Tie=beams and foundation beams should have a cross=sectional width of at least bw,min=250mmandacross=sectionaldepthofatleasthw,min=400mm. 3.7.2.4 – Foundation slabs arranged in accordancewithEN1998=5:2004,5.4.1.2(2) for the horizontalconnectionof individualfootingsorpilecaps,shouldhavea thicknessofat least tmin=200mmandareinforcementratioofatleastρs,min=0.2%atthetopandbottom. 3.7.2.5–Tie=beamsandfoundationbeamsshouldhavealongtheirfulllengthalongitudinal reinforcementratioofatleastρb,min=0.4%atboththetopandthebottom. 3.7.3.Connectionsofverticalelementswithfoundationbeamsorwalls 3.7.3.1–Thecommon(joint)regionofafoundationbeamorfoundationwallandavertical elementshallfollowtherulesof3.3.4.1asabeam=columnjointregion.

48

3.7.3.2–Theconnectionoffoundationbeamsorfoundationwallswithverticalelementsshall followtherulesof3.3.4. 3.7.3.3 – Bends or hooks at the bottom of longitudinal bars of vertical elements should be orientedsothattheyinducecompressionintotheconnectionarea. 3.7.4.Castinplaceconcretepilesandpilecaps 3.7.4.1–Thetopofthepileuptoadistancetotheundersideofthepilecapoftwicethepile cross=sectionaldimension,d,aswellastheregionsuptoadistanceof2doneachsideofan interfacebetweentwosoillayerswithmarkedlydifferentshearstiffness(ratioofshearmoduli greaterthan6),shallbedetailedaspotentialplastichingeregions.Tothisend,theyshallbe provided with transverse and confinement reinforcement following the rules for column criticalregionsgivenin3.3.3. 3.7.4.2 – Piles required to resist tensile forces or assumed as rotationally fixed at the top should be provided with anchorage in the pile cap to enable the development of the pile designupliftresistanceinthesoil,orofthedesigntensilestrengthofthepilereinforcement, whicheverislower.Ifthepartofsuchpilesembeddedinthepilecapiscastbeforethepile cap,dowelsshouldbeprovidedattheinterfacewheretheconnectionoccurs.

49

CH PTER4 SEISMICDESIGREQUIREMETS FORSTRUCTUR LSTEELBUILDIGS

4.1.SCOPE DDESIGCOCEPTS 4.1.1.Scope 4.1.1.1–ThisChapterappliestotheseismicdesignofelementsofstructuralsteelbuildings. 4.1.1.2–TherulesgiveninthisChapterareadditionaltothosegiveninEN1993=1=1:2004.

4.1.2.DesignConcepts 4.1.2.1 – Design of earthquake resistant steel buildings shall provide the structure with an adequate energy dissipation capacity without substantial reduction of its overall resistance againsthorizontalandverticalloading. dequateresistanceofallstructuralelementsshallbe provided,andnon=lineardeformationdemandsincriticalregionsshouldbecompatiblewith theoverallductilityassumedincalculations. 4.1.2.2–Steelbuildingsmayalternativelybedesignedforlowdissipationcapacityandlow ductility,byapplyingonlytherulesofEN1993=1=1:2005fortheseismicdesignsituation,and neglecting the specific provisions given in this chapter. The class of such buildings is identifiedasLowDuctilityClass(DCL). 4.1.2.3 – Steel buildings other than those to which 4.1.2.2 applies, shall be designed to provide energy dissipation capacity and an overall ductile behaviour. Overall ductile behaviourisensurediftheductilitydemandinvolvesgloballyalargevolumeofthestructure spread to different elements and locations of all its storeys. To this end ductile modes of failure should precede brittle failure modes with sufficient reliability. The class of such buildings is identified as ormal Ductility Class (DCN), for which steel seismic design requirementsaregivenintheremainderofChapter4. 4.1.3.StructuraltypesandBehaviourFactors 4.1.3.1–Steelbuildingsareclassifiedwithrespecttostructuraltypesandtheircombinations asfollows:

(a) Moment8resisting rame system is defined as a structural system composed of moment= resistingframesonly.

(b)Concentricbraced ramesystemisdefinedasastructuralsystemcomposedofconcentric bracedframesonly.

(c) Eccentric braced rame system is defined as a structural system composed of eccentric bracedframesonly.

(d) Frame8dominant dual system is defined as a structural system composed of moment= resisting frames, which resist more than 50% of the total calculated base shear, in combinationwitheccentricorconcentricbracedframes.

50

(e)Braced rame8dominantdualsystem(concentricbracing)isdefinedasastructuralsystem composedofconcentricallybracedframes,whichresistmorethan50%ofthetotalcalculated baseshear,incombinationwithmoment=resistingframesand/oreccentricbracedframes.

(f)Braced rame8dominantdualsystem(eccentricbracing) isdefinedasastructuralsystem composedofeccentricallybracedframes,whichresistmorethan50%ofthetotalcalculated baseshear,incombinationwithmoment=resistingframesand/orconcentricbracedframes.

(g)Wall8dominantdualsystem(coupledwalls)isdefinedasastructuralsystemcomposedof coupled structural walls, which resist more than 50% of the total calculated base shear, in combination with moment=resisting frames and/or uncoupled walls and/or eccentric or concentricbracedframes.

(h)Wall8dominantdualsystem(uncoupledwalls)isdefinedasastructuralsystemcomposed ofuncoupled (isolated) structuralwalls,which resistmore than50%of the total calculated base shear, in combination with moment=resisting frames and/or coupled walls and/or eccentricorconcentricbracedframes.

(i)Invertedpendulumstructures,whicharedefinedin3.1.3.1arestructureswheredissipative zonesarelocatedatthebasesofcolumns.

4.1.3.2–Steelbuildingsmaybeclassifiedtoonetypeofstructuralsysteminonehorizontal directionandtoanotherintheother. 4.1.3.3 – Behaviour factors for all structural types of Low Ductility Class (DCL) shall be takenasq=1. 4.1.3.4 – Behaviour factors for structural types of ormal Ductility Class (DCN) shall be takenfromTable4.1.

Table4.1–BehaviourFactors(q)forsteelstructuraltypes

Structuraltype q

Momentresistingframesystem

Eccentricbracedframesystem

Concentricbracedframesystem

Frame=dominantdualsystem

Bracedframe=dominantdualsystem (eccentricbracing)

Bracedframe=dominantdualsystem (concentricbracing)

Wall=dominantdualsystem(coupledwalls)

Wall=dominantdualsystem(uncoupledwalls)

Invertedpendulumsystem

5.0

5.0

3.5

4.0

4.0

3.5 3.0

2.0

1.5

4.1.4.MaterialRequirements 4.1.4.1–StructuralsteelshallconformtostandardsreferredtoinEN1993.

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4.1.4.2 – The toughnessof the steels and thewelds should satisfy the requirements for the seismic action at the quasi=permanent value of the service temperature (see EN 1993=1= 10:2004). 4.1.4.3–Inboltedconnectionsofprimaryseismicmembersofabuilding,highstrengthbolts ofboltgrade8.8or10.9shouldbeused. 4.1.4.4– Inthecapacitydesignchecksspecifiedin4.2 to4.5, thepossibility that theactual yieldstrengthofsteelishigherthanthenominalyieldstrengthshouldbetakenintoaccount byamaterialoverstrengthfactorγov=1.25.

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4.2.GEER LDESIGCRITERI DDET ILIGRULES 4.2.1.Designrulesforductileelementsincompressionorbending 4.2.1.1 – Sufficient local ductility of members which dissipate energy in compression or bending shall be ensuredby restricting thewidth=thickness ratio b/t according to the cross= sectionalclassesspecifiedinEN1993=1=1:2004,5.5. 4.2.1.2–Dependingontheductilityclassandthebehaviourfactorqusedinthedesign,the requirements regarding the cross=sectional classes of the steel elements which dissipate energyareindicatedinTable4.2.

Table4.2.Requiredcrosssectionalclass

BehaviourFactor Cross=sectional q class

1.5<q≤2 Class1,2or3

2<q≤4 Class1or2

4.2.2.Designrulesforductileelementsintension Fortensionmembersorpartsofmembersintension,theductilityrequirementofEN1993=1= 1:2004,6.2.3(3)shouldbemet. 4.2.3.Designrulesforconnections 4.2.3.1–Forfilletweldorboltedconnections,Eq.(4.1)shouldbesatisfied:

R ≥ 1.1 γ R (4.1) d ov fy

4.2.3.2–CategoriesBandCofboltedjointsinshearinaccordancewithEN1993=1=8:2004, 3.4.1andcategoryEofboltedjointsintensioninaccordancewithEN1993=1=8:2004,should be used. Shear joints with fitted bolts are also allowed. Friction surfaces should belong to class orBasdefinedinENV1090=1. 4.2.3.3 – For bolted shear connections, the design shear resistance of the bolts should be higherthan1.2timesthedesignbearingresistance.

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4.3.DESIG DDET ILIGRULESFORMOMETRESISTIGFR MES 4.3.1.Designcriteria 4.3.1.1–Momentresistingframesshallbedesignedsothatplastichingesforminthebeams orintheconnectionsofthebeamstothecolumns,butnotinthecolumns,inaccordancewith 4.3.1.2. 4.3.1.2 – In moment resisting frame systems, including frame=dominant dual systems as definedin4.1.3.1,thefollowingconditionshouldbesatisfiedatallbeam=columnjoints:

M ≥ 1.3∑ MRb (4.2) ∑ Rc

4.3.1.3–Slabreinforcementparalleltothebeamandwithintheeffectiveflangewidthshall be considered to contribute to the beam flexural capacities taken into account for the calculationof inEq.(4.2),ifitisanchoredbeyondthebeamsectionatthefaceofthe ∑ MRb joint. 4.3.1.4–Eq.(4.2)shallbesatisfiedseparatelyforbothearthquakedirectionsandsenseswith the column moments always opposing the beam moments to yield the most unfavourable result. Incalculatingthecolumnmomentresistances,axialforcesshallbetakentoyieldthe minimummomentsconsistentwiththesenseofearthquakedirection. 4.3.1.5–If thestructuralsystemisa frameorequivalent toa frame inonlyoneof the two main horizontal directions of the structural system, then Eq.(4.2) should be satisfied just withintheverticalplanethroughthatdirection. 4.3.1.6–SpecialsituationsregardingtheapplicationofEq.(4.2)aregiveninthefollowing:

(a)Eq.(4.2)neednottobesatisfiedatthebaseofanyframe.

(b)Eq.(4.2)neednottobecheckedinsinglestoreybuildingsandinjointsoftopmoststorey ofmulti=storeybuildings. 4.3.1.7–Eq.(4.2)may bepermittednot tobe satisfied inagiven earthquakedirectionat a certainnumberofjointsatthebottomand/ortopofastorey,providedthatEq.(4.3)holds.

αi = Vis ≥ 0.75 (4.3) Vic

4.3.1.8 – In the case where Eq.(4.3) is satisfied, bending moments and shears of columns satisfyingEq.(4.2)atbothbottomand top jointsshallbeamplifiedbymultiplyingwith the ratio(1/αi)withintherangeof0.75≤αi<1.00. 4.3.2.Beams 4.3.2.1–Beamsshouldbeverifiedashavingsufficient resistanceagainst lateraland lateral torsionalbucklinginaccordancewithEN1993,assumingtheformationofaplastichingeat oneendofthebeam.Thebeamendthatshouldbeconsideredisthemoststressedendinthe seismicdesignsituation.

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4.3.2.2–Forplastichingesinthebeamsitshouldbeverifiedthatthefullplasticmomentof resistance and rotationcapacityarenotdecreasedbycompressionandshear forces.To this end, for sections belonging to cross=sectional classes 1 and 2, the following inequalities shouldbeverifiedatthelocationwheretheformationofhingesisexpected:

MEd ≤ 1.0 M pl,Rd

Ed ≤ 0.15 (4.4) pl,Rd

VEd ≤ 0.5 Vpl,Rd

where

M + Mpl,Rd, pl,Rd,B V =V + V ;V = (4.5) Ed Ed,G Ed,M Ed,M

L

Forsectionsbelongingtocross=sectionalclass3,pl,Rd,Mpl,Rd,Vpl,Rdmustbereplacedwith el,Rd,Mel,Rd,Vel,RdinEq.(4.4)andEq.(4.5). 4.3.2.3–Thecondition in the secondexpressionofEq.(4.4)maynotbeverified,provided thattheprovisionsofEN1993=1=1:2004,6.2.9.1aresatisfied.

4.3.3.Columns 4.3.3.1 – The columns shall be verified in compression considering the most unfavourable combinationoftheaxialforceandbendingmoments.ed,Med,Vedshallbecalculatedas:

= +1.1 γ Ed Ed,G ov Ed,E

M =M +1.1 γ M (4.6) Ed Ed,G ov Ed,E

V =V +1.1 γ VEd Ed,G ov Ed,E

whereWistheminimumvalueofWi=Mpl,Rd,i/MEd,iofallbeams,MEd,iisthedesignvalueof thebendingmomentinbeamiintheseismicdesignsituationandMpl,Rd,iisthecorresponding plasticmoment. 4.3.3.2–Theresistanceverificationof thecolumnsshouldbemade inaccordancewithEN 1993=1=1:2004,Section6. 4.3.3.3–ThecolumnshearforceVEdresultingfromthestructuralanalysisshouldsatisfythe followingexpression:

VEd ≤ 0.5 (4.7)

Vpl,Rd

4.3.3.4 – The transfer of the forces from the beams to the columns should conform to the designrulesgiveninEN1993=1=1:2004,Section6. 4.3.3.5 – The shear resistance of framed web panels of beam/column connections should satisfythefollowingexpression:

55

Vwp,Ed ≤ 1.0 (4.8)

Vwp,Rd

whereVwp,Edisthedesignshearforceinthewebpanelduetotheactioneffects,takinginto account the plastic resistance of the adjacent beams or connections; Vwp,Rd is the shear resistanceofthewebpanelinaccordancewithEN1993=1=8:2004,6.2.4.1.Itisnotrequired to takeintoaccount theeffectof thestressesoftheaxialforceandbendingmomentonthe plasticresistanceinshear. 4.3.3.6–Theshearbucklingresistanceof thewebpanelsshouldalsobechecked toensure thatitconformstoEN1993=1=5:2004,Section5:

Vwp,Ed ≤ 1.0 (4.9)

Vwb,Rd

whereVwb,Rdistheshearbucklingresistanceofthewebpanel.

4.3.4.Beamcolumnconnections 4.3.4.1–Ifthestructureisdesignedtodissipateenergyinthebeams,theconnectionsofthe beamstothecolumnsshouldbedesignedfortherequireddegreeofoverstrengthtakinginto account the moment of resistance Mpl,Rd and the shear force (Ved,G + Ved,M) evaluated in 4.3.2.2. 4.3.4.2 – Energy dissipating semi=rigid and/or partial strength connections are permitted, providedthatallofthefollowingrequirementsareverified:

(a)Connectionshavearotationcapacityconsistentwiththeglobaldeformations

(b)Membersframingintotheconnectionsaredemonstratedtobestableattheultimatelimit state(ULS);

(c) Effect of connection deformation on global drift is taken into account using nonlinear static(pushover)globalanalysisornon=linearresponsehistoryanalysis. 4.3.4.3–Theconnectiondesignshouldbesuchthatthechordrotationcapacityoftheplastic hingeregionθpisnotlessthan25mradforstructureswithq>2. 4.3.4.4 – In experiments made to assess θp the column web panel shear resistance should conformtoEq.(4.7) and thecolumnwebpanelsheardeformationshouldnotcontribute for morethan30%oftheplasticrotationcapabilityθp. 4.3.4.5–Thecolumnelasticdeformationshouldnotbeincludedintheevaluationofθp. 4.3.4.6–Whenpartialstrengthconnectionsareused, thecolumncapacitydesignshouldbe derivedfromtheplasticcapacityoftheconnections.

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4.4.DESIG DDET ILIGRULESFORFR MESWITHCOCETRIC BR CIGS 4.4.1.Designcriteria 4.4.1.1 – Concentric braced frames shall be designed so that yielding of the diagonals in tensionwilltakeplacebeforefailureoftheconnectionsandbeforeyieldingorbucklingofthe beamsorcolumns. 4.4.1.2 – Diagonal elements of bracings shall be placed in such a way that the structure exhibitssimilar loaddeflectioncharacteristicsat eachstorey inopposite sensesof thesame braceddirectionunderloadreversals.Inthisregard,thefollowingruleshouldbemetatevery storey:

A+ − A−

+ −

≤ 0.05 (4.10) A + A

whereA+andA

–aretheareasofthehorizontalprojectionsofthecross=sectionsofthetension

diagonals, when the horizontal seismic actions have a positive or negative direction respectively. 4.4.2 nalysis 4.4.2.1–Undergravityloadconditions,onlybeamsandcolumnsshallbeconsideredtoresist suchloads,withouttakingintoaccountthebracingmembers. 4.4.2.2 – Diagonals shall be taken into account as follows in an elastic analysis of the structurefortheseismicaction:

(a)Inframeswithdiagonalbracings,onlythetensiondiagonalsshallbetakenintoaccount.

(b)InframeswithVbracings,boththetensionandcompressiondiagonalsshallbetakeninto account. 4.4.2.3 – Taking into accountofboth tension andcompressiondiagonals in the analysisof any type of concentric bracing is allowed provided that all of the following conditions are satisfied:

(a)Non=linearstatic(pushover)globalanalysisornon=lineartimehistoryanalysisisused,

(b)bothpre=bucklingandpost=bucklingsituationsaretakenintoaccountinthemodellingof thebehaviourofdiagonalsand,

(c)backgroundinformationjustifyingthemodelusedtorepresentthebehaviourofdiagonals isprovided. 4.4.3Diagonalmembers 4.4.3.1–InframeswithXdiagonalbracings,thenon=dimensionalslenderness λ asdefined inEN1993=1=1:2004shouldbelimitedto:1.3< λ ≤2.0. 4.4.3.2 – In frames with diagonal bracings in which the diagonals are not positioned as X diagonalbracings,thenon=dimensionalslenderness λ shouldbelessthanorequalto2.0.

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4.4.3.3–InframeswithVbracings,thenon=dimensionalslenderness λ shouldbelessthanor equalto2.0. 4.4.3.4–Instructuresofuptotwostoreys,nolimitationappliesto λ . 4.4.3.5–Yieldresistancepl,Rdofthegrosscross=sectionofthediagonalsshouldbesuchthat pl,Rd≥Ed. 4.4.3.6 – In frameswithVbracings, the compressiondiagonals shouldbedesigned for the compressionresistanceinaccordancewithEN1993. 4.4.3.7–Theconnectionsofthediagonalstoanymembershouldsatisfythedesignrulesof 4.2.3. 4.4.3.8–Inordertosatisfyahomogeneousdissipativebehaviourofthediagonals,itshould be checked that the maximum overstrength Wi defined in 4.4.4.1 does not differ from the minimumvalueWbymorethan25%. 4.4.3.9 – Energy dissipating semi=rigid and/or partial strength connections are permitted, providedthatallofthefollowingconditionsaresatisfied:

(a)Connectionshaveanelongationcapacityconsistentwithglobaldeformations;

(b) Effect of connections deformation on global drift is taken into account using nonlinear static(pushover)globalanalysisornon=lineartimehistoryanalysis. 4.4.4Beamsandcolumns 4.4.4.1–Beamsandcolumnswithaxialforcesshouldmeetthefollowingminimumresistance requirement:

(MEd ) ≥ Ed,G +1.1 γ Ed,E (4.11) pl,Rd ov

wherepl,Rd(MEd)isthedesignbucklingresistanceofthebeamorthecolumninaccordance withEN1993,takingintoaccounttheinteractionofthebucklingresistancewiththebending moment MEd , defined as its design value in the seismic design situation; Ed,G is the axial forceinthebeamorinthecolumnduetothenon=seismicactionsincludedinthecombination of actions for the seismic design situation; Ed,E is the axial force in the beam or in the column due to the design seismic action; γov is the overstrength factor, W is the minimum valueofWi=pl,Rd,i/Ed,ioverallthediagonalsofthebracedframesystem;wherepl,Rd,iis the design resistance of diagonal i; Ed,i is the design value of the axial force in the same diagonaliintheseismicdesignsituation. 4.4.4.2–InframeswithVbracings,thebeamsshouldbedesignedtoresist:

(a) all non=seismic actions without considering the intermediate support given by the diagonals;

(b)unbalancedverticalseismicactioneffectappliedtothebeambythebracesafterbuckling of the compression diagonal. This action effect is calculated using pl,Rd for the brace in tensionandγpbpl,Rdforthebraceincompression(Thefactorγpbisusedfortheestimationof thepostbucklingresistanceofdiagonalsincompression,whichmaybetakenas0.3).

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4.4.4.3–Inframeswithdiagonalbracingswheretensionandcompressiondiagonalsarenot intersecting, the design should take into account the tensile and compression forces which develop in the columns adjacent to the diagonals in compression and correspond to compressionforcesinthesediagonalsequaltotheirdesignbucklingresistance.

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4.5.DESIG DDET ILIGRULESFORFR MESWITHECCETRIC BR CIGS

4.5.1.Designcriteria 4.5.1.1–Frameswitheccentricbracingsshallbedesignedsothatspecificelementsorpartsof elementscalledseismiclinksareabletodissipateenergybytheformationofplasticbending and/orplasticshearmechanisms. 4.5.1.2–Seismiclinksmaybehorizontalorverticalcomponents. 4.5.2.Seismiclinks 4.5.2.1–Thewebofalinkshouldbeofsinglethicknesswithoutdoublerplatereinforcement andwithoutaholeorpenetration. 4.5.2.2 – Seismic links are classified into 3 categories according to the type of plastic mechanismdeveloped:

(a)Shortlinks,whichdissipateenergybyyieldingessentiallyinshear;

(b)Longlinks,whichdissipateenergybyyieldingessentiallyinbending;

(c)Intermediatelinks,inwhichtheplasticmechanisminvolvesbendingandshear. 4.5.2.3–ForIsections,thefollowingparametersareusedtodefinethedesignresistancesand limitsofcategories:

M = b t (d − t ) (4.12) p,link y f f

V =( / 3) t (d − t ) p,link y w f (4.13)

4.5.2.4 – If Ed / pl,Rd ≤ 0.15, the design resistance of the link should satisfy both of the followingrelationshipsatbothendsofthelink:

V ≤ VEd p,link (4.14)

M ≤ MEd p,link

whereEd ,MEd ,VEdare thedesignaxial force,designbendingmomentanddesignshear, respectively,atbothendsofthelink. 4.5.2.5 – If Ed / pl,Rd > 0.15, Eqs.(4.14) should be satisfied with the following reduced valuesVp,link,randMp,link,rusedinsteadofVp,linkandMp,link:

V = V − )2 p,link,r p,link 1 ( Ed / pl,Rd (4.15)

Mp,link,r = M p,link (1− Ed / )pl,Rd

4.5.2.6–IfEd/pl,Rd≤0.15,linklengtheshouldnotexceed:

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Mp,link e ≤ 1 6. (ifR < 0.3)

Vp,link (4.16)

Mp,link e ≤ 1 6. (1.15 − 0.5R)(ifR ≥ 0.3)

Vp,link

where

t (d − 2t )Ed w f R = (4.17) VEd A

inwhichAisthegrossareaofthelink. 4.5.2.7–Toachieveaglobaldissipativebehaviourofthestructure,itshouldbecheckedthat theindividualvaluesoftheratiosWidefinedin4.5.2.1donotexceedtheminimumvalueW resultingfrom4.5.2.1bymorethan25%ofthisminimumvalue. 4.5.2.8–Whenequalmomentsdevelopsimultaneouslyatbothendsofthelink,linksmaybe classifiedaccordingtothelengthe.ForIsections,thecategoriesare:

M p,link Shortlinks:e ≤ e =1 6. s

Vp,link

M p,link Longlinks:e > eL =3 0. (4.18)

Vp,link

Intermediatelinks:es < e < eL

4.5.2.9–Whenonlyoneplastichingedevelopsatoneendofthelink,thevalueofthelength edefinesthecategoriesofthelinks.ForIsectionsthecategoriesare:

M p,link Shortlinks:e ≤ es =0.8(1+α)

Vp,link

Mp,link Longlinks:e > eL =1.5(1+α) (4.19)

Vp,link

Intermediatelinks:es < e < eL

where α is the ratio of the smaller bending moments MEd, at one end of the link in the seismicdesignsituation, to thegreaterbendingmomentsMEd,B at theendwhere theplastic hingedevelops,bothmomentsbeingtakenasabsolutevalues. 4.5.2.10–Thelinkrotationangleθpbetweenthelinkandtheelementoutsideofthelinkas defined in 4.3.4.3 should be consistent with global deformations. It should not exceed the followingvalues:

Shortlinks:θ ≤ θ =0.08radian p pR

Longlinks:θ p ≤ θpR =0.02radian (4.20)

Intermediatelinks:θ p ≤ θpR =byinterpolation

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4.5.2.11–Full=depthwebstiffenersshouldbeprovidedonbothsidesof thelinkwebatthe diagonalbrace endsof the link.These stiffeners shouldhave a combinedwidthofnot less than(bf–2tw)andathicknessnotlessthan0.75twnor10mm,whicheverislarger. 4.5.2.12–Linksshouldbeprovidedwithintermediatewebstiffenersasfollows:

(a) Short links should be provided with intermediate web stiffeners spaced at intervals not exceeding (30tw – d/5) for a link rotation angle θp of 0.08 radians or (52tw – d/5) for link rotationanglesθpof0.02radiansorless.Linearinterpolationshouldbeusedforvaluesofθp between0.08and0.02radians;

(b)Longlinksshouldbeprovidedwithoneintermediatewebstiffenerplacedatadistanceof 1.5timesbfromeachendofthelinkwhereaplastichingewouldform;

(c) Intermediate links should be provided with intermediate web stiffeners meeting the requirementsof(a)and(b)above;

(d)Intermediatewebstiffenersarenotrequiredinlinksoflengthegreaterthan5Mp/Vp;

(e) intermediatewebstiffeners shouldbe fulldepth.For links thatare less than600mmin depthd,stiffenersarerequiredononlyonesideofthelinkweb.Thethicknessofone=sided stiffenersshouldbenotlessthantw or10mm,whicheverislarger,andthewidthshouldbe not less than(b/2)– tw .For linksthatare600mmindepthorgreater, similar intermediate stiffenersshouldbeprovidedonbothsidesoftheweb. 4.5.2.13 – Fillet welds connecting a link stiffener to the link web should have a design strength adequate to resist a force of γov y Ast , where Ast is the area of the stiffener. The designstrengthoffilletweldsfasteningthestiffenertotheflangesshouldbeadequatetoresist aforceofγov yAst/4. 4.5.2.14–Lateralsupportsshouldbeprovidedatboththetopandbottomlinkflangesatthe endsofthelink.Endlateralsupportsoflinksshouldhaveadesignaxialresistancesufficient toprovidelateralsupportforforcesof6%oftheexpectednominalaxialstrengthofthelink flangecomputedas ybtf. 4.5.2.15–Inbeamswhereaseismiclinkispresent,theshearbucklingresistanceoftheweb panelsoutsideofthelinkshouldbecheckedtoconformtoEN1993=1=5:2004,Section5. 4.5.3.Membersnotcontainingseismiclinks The members not containing seismic links, like the columns and diagonal members, if horizontal links in beams are used, and also the beam members, if vertical links are used, shouldbeverifiedincompressionconsideringthemostunfavourablecombinationoftheaxial forceandbendingmoments:

Rd (MEd ,Ed ) ≥ Ed,G +1.1 γ ov Ed,E (4.21)

where Rd(MEd , Ed) is the axial design resistance of the column or diagonal member in accordancewithEN1993,takingintoaccounttheinteractionwiththebendingmomentMEd

andtheshearVEdtakenattheirdesignvalueintheseismicsituation;Ed,Gisthecompression force in the column or diagonal member due to the nonseismic actions included in the combinationofactionsfortheseismicdesignsituation;Ed,Eisthecompressionforceinthe columnordiagonalmemberduetothedesignseismicaction;γovistheoverstrengthfactorW

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isamultiplicativefactorwhichistheminimumofthefollowingvalues:theminimumvalue ofWi=1.5(Vp,link,i/VEd,i)amongallshortlinks;theminimumvalueofWi=1.5(Mp,link,i/MEd,i) amongall intermediateandlonglinks;whereVEd,i ,MEd,i are thedesignvaluesof theshear forceandofthebendingmomentinlinkiintheseismicdesignsituation;Vp,link,i,Mp,link,iare theshearandbendingplasticdesignresistancesoflinkiasin4.5.2.3. 4.5.4.Connectionsofseismiclinks 4.5.4.1–Ifthestructureisdesignedtodissipateenergyintheseismiclinks,theconnections of the linksorof the element containing the links shouldbedesigned for action effects Ed computedasfollows:

E ≥ E +1.1 γ (4.22) d d,G ov d,E

whereEd,Gistheactioneffectintheconnectionduetothenon=seismicactionsincludedinthe combination of actions for the seismic design situation; Ed,E is the action effect in the connection due to the design seismic action; γov is the overstrength factor, Wi is the overstrengthfactorcomputedinaccordancewith4.5.3forthelink. 4.5.4.2–Inthecaseofsemi=rigidand/orpartialstrengthconnections,theenergydissipation maybeassumedtooriginatefromtheconnectionsonly.Thisisallowable,providedthatallof thefollowingconditionsaresatisfied:

(a) the connections have rotation capacity sufficient for the corresponding deformation demands;

(b)membersframingintotheconnectionsaredemonstratedtobestableattheULS;

(c)theeffectofconnectiondeformationsonglobaldriftistakenintoaccount. 4.5.4.3–Whenpartialstrengthconnectionsareusedfortheseismiclinks,thecapacitydesign oftheotherelementsinthestructureshouldbederivedfromtheplasticcapacityofthelinks connections.

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4.6.DESIGRULESFORSTEELBUILDIGSWITHCOCRETECORESOR COCRETEW LLS 4.6.1 – The steel elements shall be verified in accordance with this Chapter and EN 1993, whiletheconcreteelementsshallbedesignedinaccordancewithChapter3. 4.6.2 – The elements in which an interaction between steel and concrete exists shall be verifiedinaccordancewithChapter5.

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4.7.DESIGRULESFORIVERTEDPEDULUMSTRUCTURES

4.7.1–Ininvertedpendulumstructures(definedin4.1.3.1),thecolumnsshouldbeverifiedin compressionconsidering themostunfavourablecombinationof theaxial forceandbending moments. 4.7.2–Inthechecks,Ed,MEd,VEdshouldbecomputedasin4.3.3. 4.7.3–Thenon=dimensionalslendernessofthecolumnsshouldbelimitedto λ ≤1,5.

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CH PTER5 SEISMICDESIGREQUIREMETSFOR

STEEL–COCRETECOMPOSITEBUILDIGS 5.1.SCOPE DDESIGCOCEPTS 5.1.1.Scope 5.1.1.1–ThisChapterappliestotheseismicdesignofelementsofcompositesteel=concrete buildings. 5.1.1.2–TherulesgiveninthisChapterareadditionaltothosegiveninEN1994=1=1:2004. 5.1.1.3–ExceptwheremodifiedbytheprovisionsofthisChapter,theprovisionsofChapters 3and4apply.

5.1.2.DesignConcepts 5.1.2.1–Earthquakeresistantcompositebuildingsshallbedesignedinaccordancewithone ofthefollowingdesignconcepts(seeTable5.1):

(a)Concept :Low=dissipativestructuralbehaviour.

(b)ConceptB:Dissipativestructuralbehaviourwithcompositedissipativezones;

(c)ConceptC:Dissipativestructuralbehaviourwithsteeldissipativezones.

Table5.1.Designconceptsofcompositebuildings

Designconcept Structural ductilityclass

Behaviour factorq

:Lowdissipativestructuralbehaviour DCL 1.0

BorC:Dissipativestructuralbehaviour DCN ≤5.0 5.1.2.2–Inconcept ,theactioneffectsmaybecalculatedonthebasisofanelasticanalysis withouttakingintoaccountnon=linearmaterialbehaviourbutconsideringthereductioninthe momentof inertiadue to thecrackingofconcrete inpartof thebeamspans, inaccordance withthegeneralstructuralanalysisrulesdefinedin5.2andtothespecificrulesdefinedin5.5 to5.9relatedtoeachstructuraltype.Behaviourfactorshallbetakenasq=1. 5.1.2.3 – In concept the resistance of the members and of the connections should be evaluatedinaccordancewithEN1993andEN1994withoutanyadditionalrequirements. 5.1.2.4– InconceptsBandC, thecapabilityofpartsof the structure (dissipativezones) to resist earthquake actions through inelastic behaviour is taken into account. Behavior factor shallbetakenfromTable5.2.WhenadoptingconceptsBorCtherequirementsgivenin5.2 to5.9shouldbefulfilled. 5.1.2.5–InconceptC,structuresarenotmeanttotakeadvantageofcompositebehaviourin dissipative zones; the application of concept C is conditioned by a strict compliance to measures thatprevent involvementof theconcrete in the resistanceofdissipativezones. In

66

conceptC thecomposite structure isdesigned inaccordancewithEN1994=1=1:2004under non=seismic loads and in accordance with Chapter 4 to resist earthquake action. The measurespreventinginvolvementoftheconcretearegivenin5.5.5. 5.1.2.6 – The design rules for dissipative composite structures (concept B), aim at the developmentofreliablelocalplasticmechanisms(dissipativezones)inthestructureandofa reliable global plastic mechanism dissipating as much energy as possible under the design earthquake action. For each structural element or each structural type considered in this Chapter, rules allowing thisgeneral designobjective tobe achievedaregiven in 5.5 to 5.9 withreferencetowhatarecalledthespecificcriteria.Thesecriteriaaimatthedevelopmentof aglobalmechanicalbehaviourforwhichdesignprovisionscanbegiven. 5.1.2.7–StructuresdesignedinaccordancewithconceptBshallbelongtostructuralductility class identified as ormal Ductility Class (DCN). This ductility class corresponds to increased ability of the structure to dissipate energy in plastic mechanisms, for which compositeseismicdesignrequirementsaregivenintheremainderofChapter5. 5.1.3.StructuraltypesandBehaviourFactors 5.1.3.1 – Composite steel=concrete structures shall be assigned to one of the following structuraltypesaccordingtothebehaviouroftheirprimaryresistingstructureunderseismic actions:

(a)Compositemomentresisting ramesarethosewiththesamedefinitionandlimitationsas in 4.1.3.1(a), but in which beams and columns may be either structural steel or composite steel=concrete.

(b)Compositeconcentricallybraced ramesarethosewiththesamedefinitionandlimitations as in 4.1.3.1(b). Columns and beams may be either structural steel or composite steel= concrete.Bracesshallbestructuralsteel.

(c) Composite eccentrically braced rames are those with the same definition and configurations as in 4.1.3.1(c). The members which do not contain the links may be either structural steel or composite steel=concrete. Other than for the slab, the links shall be structural steel.Energydissipationshalloccuronly through yielding inbendingor shearof theselinks.

(d)Invertedpendulumstructures,havethesamedefinitionandlimitationsasin4.1.3.1(i).

(e) Composite structural systems are those which behave essentially as reinforced concrete walls.Thecompositesystemsmaybelongtooneofthefollowingtypes: − Type 1 corresponds to a steel or composite frame working together with concrete infill panelsconnectedtothesteelstructure; − Type 2 is a reinforced concrete wall in which encased steel sections connected to the concretestructureareusedasverticaledgereinforcement; −Type3, steel or compositebeamsareused to couple twoormore reinforced concreteor compositewalls.

(f)Compositesteelplateshearwallsarethoseconsistingofaverticalsteelplatecontinuous overtheheightof thebuildingwithreinforcedconcreteencasementononeorbothfacesof theplateandofthestructuralsteelorcompositeboundarymembers.

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5.1.3.2–Inalltypesofcompositestructuralsystemstheenergydissipationtakesplaceinthe vertical steel sections and in the vertical reinforcements of the walls. In type 3 composite structuralsystems,energydissipationmayalsotakeplaceinthecouplingbeams. 5.1.3.3–If,incompositestructuralsystemsthewallelementsarenotconnectedtothesteel structure,Chapters3and4apply. 5.1.3.4–ThebehaviourfactorqshallbetakenfromTable4.1orTable5.2as indicatedin thelatter,providedthattherulesin5.3to5.9aremet.

Table5.2.BehaviourFactors(q)forcompositestructuraltypes

Structuraltype q

Compositemomentresistingframesystem

Compositeeccentricallybracedframesystem

Compositeconcentricallybracedframesystem

Frame=dominantdualsystem

Bracedframe=dominantdualsystem(eccentric bracing)

Bracedframe=dominantdualsystem(concentric bracing)

Invertedpendulumsystem

5.0

5.0

3.5

4.0

4.0

3.5 1.5

Compositewalls(Type1andType2)

Compositeorconcretewallscoupledbysteel orcompositebeams(Type3)

3.5

3.5

Compositesteelplatestructuralwalls 3.5

5.1.4.Materialrequirements 5.1.4.1–Indissipativezones,theprescribedconcreteclassshouldnotbelowerthanC20/25. IftheconcreteclassishigherthanC40/50,thedesignisnotwithinthescopeofEN1998=1. 5.1.4.2 – For ductility class DCN the reinforcing steel taken into account in the plastic resistanceofdissipativezonesshallbeofclassBorCinaccordancewithEN1992=1=1:2004 TableC.1. 5.1.4.3–ReinforcingsteelofclassBorC(EN1992=1=1:2004,TableC.1)shallbeusedin highlystressedregionsofnondissipativestructures.Thisrequirementappliestobothbarsand weldedmeshes. 5.1.4.4–Exceptforclosedstirrupsorcrossties,onlyribbedbarsareallowedasreinforcing steelinregionswithhighstresses. 5.1.4.5–Weldedmeshesnotconformingtotherequirementsof5.1.4.2shallnotbeusedin dissipativezones.Ifsuchmeshesareused,ductilereinforcementduplicatingthemeshshould beplacedandtheirresistancecapacityaccountedforinthecapacityanalysis.

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5.1.4.6–Forstructuralsteel,requirementsgivenin4.1.4apply.

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5.2.STRUCTUR L LYSIS 5.2.1.Scope The following rules apply to the analysis of the structure under earthquake action with EquivalentSeismicLoadMethodgiven in2.3 andwith theMulti8ModeResponseSpectrum AnalysisMethodgivenin2.4. 5.2.2.Stiffnessofsections 5.2.2.1–Thestiffnessofcompositesectionsinwhichtheconcreteisincompressionshallbe computedusingamodularrationgiveninEq.(5.1).

E n = a = 7 (5.1)

E cm

5.2.2.2–Forcompositebeamswithslab incompression, thesecondmomentofareaof the section, referred to as I1, shall be computed taking into account the effective width of slab definedin5.4.3. 5.2.2.3 – The stiffness of composite sections in which the concrete is in tension shall be computedassumingthattheconcreteiscrackedandthatonlythesteelpartsofthesectionare active. 5.2.2.4–Forcompositebeamswithslabintension,thesecondmomentofareaofthesection, referredtoasI2,shallbecomputedtakingintoaccounttheeffectivewidthofslabdefinedin 5.4.3 5.2.2.5 – The structure should be analysed taking into account the presence of concrete in compression in some zones and concrete in tension in other zones; the distribution of the zonesisgivenin5.5to5.9forthevariousstructuraltypes.

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5.3.DESIGCRITERI DDET ILIGRULESFORDISSIP TIVE STRUCTUR LBEH VIOURCOMMOTO LLSTRUCTUR LTYPES 5.3.1.Designcriteriafordissipativestructures 5.3.1.1–Dissipativezonesshallhaveadequateductilityandresistance.Theresistanceshall bedeterminedinaccordancewithEN1993=1=1:2004andChapter4forconceptC,andtoEN 1994=1=1:2004 and Chapter 5 for concept B (see 5.1.2.1). Ductility is achieved by compliancetodetailingrules. 5.3.1.2–Dissipativezonesmaybelocatedinthestructuralmembersorintheconnections.

(a)Ifdissipativezonesarelocatedinthestructuralmembers,thenon=dissipativepartsandthe connections of the dissipative parts to the rest of the structure shall have sufficient overstrengthtoallowthedevelopmentofcyclicyieldinginthedissipativeparts.

(b)Whendissipativezonesarelocatedintheconnections,theconnectedmembersshallhave sufficientoverstrengthtoallowthedevelopmentofcyclicyieldingintheconnections. 5.3.2.Plasticresistanceofdissipativezones 5.3.2.1–Twoplasticresistancesofdissipativezonesareusedinthedesignofcompositesteel = concrete structures: a lower bound plastic resistance (index: pl,Rd) and an upper bound plasticresistance(index:U,Rd). 5.3.2.2–Thelowerboundplasticresistanceofdissipativezonesistheonetakenintoaccount in design checks concerning sections of dissipative elements; e.g. MEd< Mpl,Rd . The lower bound plastic resistance of dissipative zones is computed taking into account the concrete componentofthesectionandonlythesteelcomponentsofthesectionwhichareclassifiedas ductile. 5.3.2.3 – The upper bound plastic resistance of dissipative zones is the one used in the capacity design of elements adjacent to the dissipative zone: for instance in the capacity designverificationof4.3.1.2,thedesignvaluesofthemomentsofresistanceofbeamsarethe upperboundplasticresistances,MU,Rd,b ,whereasthoseof thecolumnsarethelowerbound ones,Mpl,Rd,c. 5.3.2.4 – The upper bound plastic resistance is computed taking into account the concrete componentofthesectionandallthesteelcomponentspresentinthesection,includingthose thatarenotclassifiedasductile. 5.3.2.5– ctioneffects,whicharedirectlyrelatedtotheresistanceofdissipativezones,shall bedeterminedon thebasisof theupperbound resistanceofcompositedissipative sections; e.g.thedesignshearforceattheendofadissipativecompositebeamshallbedeterminedon thebasisoftheupperboundplasticmomentofthecompositesection. 5.3.3.Detailingrulesforcompositeconnectionsindissipativezones 5.3.3.1–Forthedesignofweldsandbolts,4.2.3applies.

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5.3.3.2 – In fully encased framed web panels of beam/column connections, the panel zone resistance may be computed as the sum of contributions from the concrete and steel shear panel,ifallthefollowingconditionsaresatisfied:

0.6<hb / hc <1.4 (5.2)

V <0.8 V (5.3) wp,Ed wp,Rd

wherehb/hcistheaspectratioofthepanelzone;whereVwp,Edisthedesignshearforceinthe webpanelduetotheactioneffects,takingintoaccounttheplasticresistanceoftheadjacent composite dissipative zones in beams or connections; Vwp,Rd is the shear resistance of the compositesteel=concretewebpanelinaccordancewithEN1994=1=1:2004. 5.3.3.3–Inpartiallyencasedstiffenedwebpanels,anassessmentsimilartothatin5.3.3.2is permitted if, in addition to the requirements of 5.3.3.4, one of the following conditions is fulfilled:

(a)Straight linksof the typedefined in 5.4.5.4 andcomplyingwith 5.4.5.5 and 5.4.5.6 are providedatamaximumspacingsl=cinthepartiallyencasedstiffenedwebpanel;theselinks are oriented perpendicularly to the longest side of the column web panel and no other reinforcementofthewebpanelisrequired;or

(b)Noreinforcementispresent,providedthathb/bb<1,2andhc/bc<1,2. 5.3.3.4 – Whenadissipative steel or composite beam is framing into a reinforced concrete column,verticalcolumnreinforcementwithdesignaxialstrengthat leastequal to theshear strength of the coupling beam should be placed close to the stiffener or face bearing plate adjacenttothedissipativezone.Itispermittedtouseverticalreinforcementplacedforother purposesaspartoftherequiredverticalreinforcement.Thepresenceoffacebearingplatesis required;theyshouldbefulldepthstiffenersofacombinedwidthnotlessthan(bb–2t);their thicknessshouldbenot less than0,75 tor8mm;bband tare respectively thebeamflange widthandthepanelwebthickness. 5.3.3.5 – When a dissipative steel or composite beam is framing into a fully encased composite column, the beam column connection may be designed either as a beam/steel column connection or a beam/composite column connection. In the latter case, vertical column reinforcements may be calculated either as in 5.3.3.4 or by distributing the shear strengthofthebeambetweenthecolumnsteelsectionandthecolumnreinforcement.Inboth instances,thepresenceoffacebearingplatesasdescribedin5.3.3.4isrequired. 5.3.3.6 – The vertical column reinforcement specified in 5.3.3.4 and 5.3.3.5 should be confinedbytransversereinforcementthatmeetstherequirementsformembersdefinedin5.4.

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5.4.RULESFORMEMBERS 5.4.1.General 5.4.1.1 – Composite members, which are primary seismic members, shall conform to EN 1994=1=1:2004andtoadditionalrulesdefinedinthisSection. 5.4.1.2–Fortensionmembersorpartsofmembersintension,theductilityrequirementofEN 1993=1=1:2004,6.2.3(3)shouldbemet. 5.4.1.3 – Sufficient local ductility of members which dissipate energy under compression and/orbendingshouldbeensuredby restricting thewidth=to=thickness ratiosof theirwalls. Steeldissipativezonesandthenotencasedsteelpartsofcompositemembersshouldmeetthe requirements of 4.2.1.1 and Table 4.2. Dissipative zones of encased composite members shouldmeettherequirementsofTable5.3.Thelimitsgivenforflangeoutstandsofpartially or fully encased members may be relaxed if special details are provided as described in 5.4.4.9and5.4.5.4to5.4.5.6.

Table5.3.Limitsofwallslenderness

Sectiontype Wall

slenderness

PartiallyencasedHorIsection FullyencasedHorIsection Flangeoutstandlimitsc/tf:

14ε

Filledrectangularsection h/tlimits:

38ε

Filledcircularsection d/tlimits:

85ε2

whereε=( y/235)

0.5

5.4.1.4–Morespecificdetailingrulesfordissipativecompositemembersaregivenin5.4.2, 5.4.4,5.4.5and5.4.6. 5.4.1.5– Inthedesignofall typesofcompositecolumns, theresistanceof thesteelsection aloneor thecombined resistancesof the steel sectionand theconcreteencasementor infill maybetakenintoaccount. 5.4.1.6–Thedesignofcolumnsinwhichthememberresistanceistakentobeprovidedonly bythesteelsectionmaybecarriedoutinaccordancewiththeprovisionsofChapter4.Inthe case of dissipative columns, the capacity design rules in 5.3.1.2 and 5.3.2.3 should be satisfied. 5.4.1.7–Forfullyencasedcolumnswithcompositebehaviour, theminimumcrosssectional dimensionsb,hordshouldbenotlessthan250mm.

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5.4.1.8 – The resistance, including shear resistance, of non=dissipative composite columns shouldbedeterminedinaccordancewiththerulesofEN1994=1=1:2004. 5.4.1.9–Incolumns,whentheconcreteencasementorinfillareassumedtocontributetothe axialand/orflexuralresistanceofthemember,thedesignrulesin5.4.4to5.4.6apply.These rulesensurefullsheartransferbetweentheconcreteandthesteelpartsinasectionandprotect thedissipativezonesagainstprematureinelasticfailure. 5.4.1.10 – For earthquake=resistant design, the design shear strength given in EN 1994=1= 1:2004,Table6.6,shouldbemultipliedbyareductionfactorof0.5. 5.4.1.11–When, forcapacitydesignpurposes, the fullcomposite resistanceofacolumnis employed,completesheartransferbetweenthesteelandreinforcedconcretepartsshouldbe ensured.Ifinsufficientsheartransferisachievedthroughbondandfriction,shearconnectors shouldbeprovidedtoensurefullcompositeaction. 5.4.1.12–Whereveracompositecolumnissubjectedtopredominatelyaxialforces,sufficient shear transfershouldbeprovided toensure that thesteelandconcretepartsshare the loads appliedtothecolumnatconnectionstobeamsandbracingmembers. 5.4.1.13–Exceptattheirbaseinsomestructuraltypes,columnsaregenerallynotdesignedto bedissipative.However,becauseofuncertaintiesinthebehaviour,confiningreinforcementis requiredinregionscalledcriticalregionsasspecifiedin5.4.4. 5.4.1.14 – 3.5.2.1 and 3.5.3 concerning anchorage and splices in the design of reinforced concretecolumnsapplyalsotothereinforcementsofcompositecolumns. 5.4.2.Steelbeamscompositewithslab 5.4.2.1 – Thedesignobjectiveof this subclause is tomaintain the integrityof the concrete slabduringtheseismicevent,whileyieldingtakesplaceinthebottompartofthesteelsection and/orintherebarsoftheslab. 5.4.2.2–Ifitisnotintendedtotakeadvantageofthecompositecharacterofthebeamsection forenergydissipation,5.5.5shallbeapplied. 5.4.2.3 – Beams intended to behave as composite elements in dissipative zones of the earthquake resistant structure may be designed for full or partial shear connection in accordancewithEN1994=1=1:2004.TheminimumdegreeofconnectionηasdefinedinEN 1994=1=1:2004 6.6.1.2 should be not less than 0.8 and the total resistance of the shear connectors within any hogging moment region not less than the plastic resistance of the reinforcement. 5.4.2.4–Thedesignresistanceofconnectorsindissipativezonesisobtainedfromthedesign resistanceprovidedinEN1994=1=1:2004multipliedbyareductionfactorof0.75. 5.4.2.5–Fullshearconnectionisrequiredwhennon=ductileconnectorsareused. 5.4.2.6–Whenaprofiledsteelsheetingwithribstransversetothesupportingbeamsisused, the reduction factor kt of thedesignshear resistanceofconnectorsgivenbyEN1994=1=1

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shouldbefurtherreducedbymultiplyingitbytheribshapeefficiencyfactorkr=0.8forthe caseofstandardtrapezoidalribs. 5.4.2.7–Toachieveductilityinplastichinges,theratiox/dofthedistancexbetweenthetop concrete compression fibre and the plastic neutral axis, to the depth d of the composite section,shouldconformtothefollowingexpression:

x εcu2 < (5.4) d ε + εcu2 a

whereεcu2 is theultimatecompressivestrainofconcrete (seeEN1992=1=1:2004);εa is the totalstraininsteelatUltimateLimitState. 5.4.2.8–Therule in5.4.2.7 isdeemedtobesatisfiedwhenx/dofasectionis less thanthe limitsgiveninTable5.4.

Table5.4.Limitvaluesx/d for ductilityofbeamswithslabs

fy(MPa) x/d

upperlimit

355 0.27

235 0.36

5.4.3.Effectivewidthofslab 5.4.3.1 – The total effective width beff of concrete flange associated with each steel web should be taken as the sum of the partial effective widths be1 and be2 of the portion of the flangeoneachsideofthecentrelineofthesteelweb.Thepartialeffectivewidthoneachside shouldbetakenasbegiveninTable5.5,butnotgreaterthantheactualavailablewidthsb1 andb2definedin5.4.3.2. 5.4.3.2–Theactualwidthbofeachportionshouldbetakenashalfthedistancefromtheweb totheadjacentweb,exceptthatatafreeedgetheactualwidthisthedistancefromthewebto thefreeedge. 5.4.3.3 – The partial effective width be of the slab to be used in the determination of the elasticandplasticpropertiesofthecompositeTsectionsmadeofasteelsectionconnectedto aslabaredefinedinTable5.5.

Table5.5–I.Partialeffectivewidthbeofslabforelasticanalysis

be Transverseelement beforI(elastic)

tinteriorcolumn Presentornotpresent FornegativeM:0.05l

ForpositiveM:0.0375l texteriorcolumn Present

texteriorcolumn Notpresent,

orrebarsnotanchored

FornegativeM:0 ForpositiveM:0.025l

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Table5.5–II.Partialeffectivewidthbeofslabforevaluationofplasticmoment resistance

Signofbending momentM

Location Transverseelement beforMRd (plastic)

NegativeM Interior column

Seismicre=bars 0.1l

NegativeM Exterior column

lllayoutswithre=barsanchoredtofaçade beamortoconcretecantileveredgestrip

0.1l

NegativeM Exterior column

lllayoutswithre=barsnotanchoredto façadebeamortoconcretecantileveredge strip

0

PositiveM Interior column

Seismicre=bars 0.075l

PositiveM Exterior column

Steeltransversebeamwithconnectors. Concreteslabuptoexteriorfaceofcolumn ofHsectionwithstrongaxisorbeyond (concreteedgestrip).Seismicre=bars

0.075l

PositiveM Exterior column

Nosteeltransversebeamorsteeltransverse beamwithoutconnectors. Concreteslabuptoexteriorfaceofcolumn ofHsectionwithstrongaxisorbeyond (edgestrip).Seismicre=bars

bb/2 +

0.7hc/2

PositiveM Exterior column llotherlayouts.Seismicre=bars bb/2≤be,max

be,max=0.05l

5.4.4.Fullyencasedcompositecolumns 5.4.4.1–Indissipativestructures,criticalregionsarepresentatbothendsofallcolumnclear lengths in moment frames and in the portion of columns adjacent to links in eccentrically bracedframes.Thelengthslcrofthesecriticalregions(inmetres)arespecifiedbyEq.(3.12), withhcintheseexpressionsdenotingthedepthofthecompositesection(inmetres). 5.4.4.2–Tosatisfyplasticrotationdemandsandtocompensateforlossofresistancedueto spalling of cover concrete, the following expression should be satisfied within the critical regionsdefinedabove:

b c α =30 ν ε − 0.035 (5.5) wd ϕ d sy,d b o

inwhichconfinementeffectivenessfactorαisasdefinedin3.3.3.6andthenormaliseddesign axialforceνdisdefinedas:

Ed Ed νd = = (5.6) A + A + A pl,Rd a yd c cd s sd

5.4.4.3 – The spacing, s, (in millimetres) of confining hoops in critical regions should not exceed

s ≤ minb /2 ,260 ,9d (5.7) o bL

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wherebo is theminimumdimensionof theconcrete core (to thecentrelineof thehoops, in millimetres);dbListheminimumdiameterofthelongitudinalrebars(inmillimetres). 5.4.4.4–Thediameterofthehoopsshallbeatleastdbw=6mm. 5.4.4.5–Incriticalregions,thedistancebetweenconsecutivelongitudinalbarsrestrainedby hoopbendsorcross=tiesshouldnotexceed250mm. 5.4.4.6–Inthelowertwostoreysofabuilding,hoopsinaccordancewith5.4.4.3,5.4.4.4and 5.4.4.5shallbeprovidedbeyondthecriticalregionsforanadditionallengthequaltohalfthe lengthofthecriticalregions. 5.4.4.7–Indissipativecompositecolumns,theshearresistanceshouldbedeterminedonthe basisofthestructuralsteelsectionalone. 5.4.4.8 – The relationship between the ductility class of the structure and the allowable slenderness(c/tf)oftheflangeoutstandindissipativezonesisgiveninTable5.3. 5.4.4.9–Confininghoopscandelaylocalbucklinginthedissipativezones.Thelimitsgiven in Table 5.3 for flange slenderness may be increased if the hoops are provided at a longitudinal spacing, s, which is less than the flange outstand: s/c < 1.0. For s/c < 0.5 the limitsgiveninTable5.3maybeincreasedbyupto50%.Forvaluesof0.5<s/c<1.0linear interpolationmaybeused. 5.4.4.10–Thediameterdbwofconfininghoopsusedtopreventflangebucklingshallbenot lessthan

btf ydf dbw = (5.8)

8 ydw

inwhichbandtfarethewidthandthicknessoftheflange,respectively,and ydfand ydware thedesignyieldstrengthsoftheflangeandreinforcement,respectively. 5.4.5.Partiallyencasedmembers 5.4.5.1– Indissipative zoneswhereenergy isdissipatedbyplasticbendingofacomposite section, the longitudinal spacing of the transverse reinforcement, s, should satisfy the requirementsof5.4.4.3overalengthgreaterorequaltolcrfordissipativezonesattheendofa memberand2lcrfordissipativezonesinthemember. 5.4.5.2–Indissipativemembers,theshearresistanceshouldbedeterminedonthebasisofthe structural steel section alone, unless special details are provided to mobilise the shear resistanceoftheconcreteencasement. 5.4.5.3–Theallowableslenderness(c/t)oftheflangeoutstandindissipativezonesisasgiven inTable5.3. 5.4.5.4–Straightlinksweldedtotheinsideoftheflanges,asadditionaltothereinforcements requiredbyEN1994=1=1,candelaylocalbucklinginthedissipativezones.Inthiscase,the limitsgiveninTable5.3forflangeslendernessmaybeincreasedifthesebarsareprovidedat alongitudinalspacing,s1,whichislessthantheflangeoutstand:s1/c<1.0.Fors1/c<0.5the

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limitsgiveninTable5.3maybeincreasedbyupto50%.Forvaluesof0.5<s1/c<1.0linear interpolationmaybeused.Theadditional straight links shouldalsoconform to the rules in 5.4.5.5and5.4.5.6. 5.4.5.5–Thediameter,dbw,oftheadditionalstraightlinksreferredtoin5.4.5.4shouldbeat least6mm.Whentransverselinksareemployedtodelaylocalflangebucklingasdescribedin 5.4.5.4,dbwshouldbenotlessthanthevaluegivenbyEq.(5.8). 5.4.5.6–Theadditionalstraightlinksreferredtoin5.4.5.4shouldbeweldedtotheflangesat bothendsandthecapacityoftheweldsshouldbenotlessthanthetensileyieldstrengthofthe straightlinks. clearconcretecoverofatleast20mm,butnotexceeding40mm,shouldbe providedtotheselinks. 5.4.5.7 – The design of partially=encased composite members may take into account the resistanceof the steel section alone, or the composite resistanceof the steel section andof concreteencasement. 5.4.5.8–Thedesignofpartially=encasedmembersinwhichonlythesteelsectionisassumed tocontribute tomember resistancemaybecarriedout inaccordancewith theprovisionsof Chapter4,butthecapacitydesignprovisionsof5.3.1.2and5.3.2.3shouldbeapplied. 5.4.6.Filledcompositecolumns 5.4.6.1–Theallowableslendernessd/torh/tisasgiveninTable5.3. 5.4.6.2–Theshearresistanceofdissipativecolumnsshouldbedeterminedonthebasisofthe structuralsteelsectionoronthebasisofthereinforcedconcretesectionwiththesteelhollow sectiontakenonlyasshearreinforcement. 5.4.6.3 – In non=dissipative members, the shear resistance of the column should be determinedinaccordancewithEN1994=1=1.

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5.5.DESIG DDET ILIGRULESFORMOMETFR MES 5.5.1.Specificcriteria 5.5.1.1–4.3.1.1applies. 5.5.1.2–Thecompositebeamsshallbedesignedforductilityandsothattheintegrityofthe concreteismaintained. 5.5.1.3 – Dependingon the locationof thedissipative zones, either 5.3.1.2(a) or 5.3.1.2(b) applies. 5.5.1.4 – The required hinge formation pattern should be achieved by observing the rules givenin4.3.1.2,5.5.3,5.5.4and5.5.5. 5.5.2. nalysis 5.5.2.1–Theanalysisofthestructureshallbeperformedonthebasisofthesectionproperties definedin5.2. 5.5.2.2–Inbeams,twodifferentflexuralstiffnessesshouldbetakenintoaccount:EI1forthe partofthespanssubmittedtopositive(sagging)bending(uncrackedsection)andEI2forthe partofthespansubmittedtonegative(hogging)bending(crackedsection). 5.5.2.3–Theanalysismayalternativelybeperformedtakingintoaccountfortheentirebeam anequivalentsecondmomentofareaIeqconstantfortheentirespan:

I =0.6I + 0.4I (5.9) eq 1 2

5.5.2.4–Forcompositecolumns,theflexuralstiffnessisgivenby:

(EI )c =0.9(EI a + 0.5Ecm Ic +EI s ) (5.10)

WhereEandEcmarethemodulusofelasticityforsteelandconcreterespectively;Ia,IcandIs

denote the second moment of area of the steel section, of the concrete and of the rebars respectively. 5.5.3.Rulesforbeamsandcolumns 5.5.3.1 – Composite T beam design shall conform to 5.4.2. Partially encased beams shall conformto5.4.5. 5.5.3.2–Beamsshallbeverifiedforlateralandlateraltorsionalbucklinginaccordancewith EN1994=1=1,assumingtheformationofanegativeplasticmomentatoneendofthebeam. 5.5.3.3–4.3.2.2applies. 5.5.3.4–Compositetrussesshouldnotbeusedasdissipativebeams. 5.5.3.5–4.3.3.1applies.

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5.5.3.6 – In columns where plastic hinges form as stated in 5.5.1.1, theverification should assumethatMpl,Rdisrealisedintheseplastichinges. 5.5.3.7–Thefollowingexpressionshouldapplyforallcompositecolumns:

Ed < 0.30 (5.11) pl,Rd

5.5.3.8–TheresistanceverificationsofthecolumnsshouldbemadeinaccordancewithEN 1994=1=1:2004,4.8. 5.5.3.9–ThecolumnshearforceVEd(fromtheanalysis)shouldbelimitedinaccordancewith thirdexpressioninEq.(4.4). 5.5.4.Beamtocolumnconnections Theprovisionsgivenin4.3.4apply. 5.5.5.Conditionfordisregardingthecompositecharacterofbeamswithslab 5.5.5.1–Theplasticresistanceofabeamsectioncompositewithslab(lowerorupperbound plastic resistance of dissipative zones) may be computed taking into account only the steel section (design in accordance with Concept C as defined in 5.1.2) if the slab is totally disconnectedfromthesteelframeinacircularzonearoundacolumnofdiameter2beff,with beffbeingthelargeroftheeffectivewidthsofthebeamsconnectedtothatcolumn. 5.5.5.2 – For the purposes of 5.5.5.1, totally disconnected means that there is no contact between slab and any vertical side of any steel element (e.g. columns, shear connectors, connectingplates,corrugatedflange,steeldecknailedtoflangeofsteelsection). 5.5.5.3–Inpartiallyencasedbeams,thecontributionofconcretebetweentheflangesofthe steelsectionshouldbetakenintoaccount.

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5.6.DESIG DDET ILIGRULESFORCOMPOSITECOCETRIC LLY BR CEDFR MES 5.6.1.Specificcriteria 5.6.1.1–4.4.1.1applies. 5.6.1.2–Columnsandbeamsshallbeeitherstructuralsteelorcomposite. 5.6.1.3–Bracesshallbestructuralsteel. 5.6.1.4–4.4.1.2applies. 5.6.2. nalysis Theprovisionsgivenin4.4.2apply. 5.6.3.Diagonalmembers Theprovisionsgivenin4.4.3apply. 5.6.4.Beamsandcolumns Theprovisionsgivenin4.4.4apply.

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5.7.DESIG DDET ILIGRULESFORCOMPOSITEECCETRIC LLY BR CEDFR MES 5.7.1.Specificcriteria 5.7.1.1–Compositeframeswitheccentricbracingsshallbedesignedsothat thedissipative action will occur essentially through yielding in bending or shear of the links. ll other membersshallremainelasticandfailureofconnectionsshallbeprevented. 5.7.1.2–Columns,beamsandbracesshallbeeitherstructuralsteelorcomposite. 5.7.1.3–Thebraces,columnsandbeamsegmentsoutsidethelinksegmentsshallbedesigned to remain elasticunder themaximum forces that canbegeneratedby the fully yielded and cyclicallystrain=hardenedbeamlink. 5.7.2. nalysis 5.7.2.1–Theanalysisofthestructureisbasedonthesectionpropertiesdefinedin5.2.2. 5.7.2.2–Inbeams,twodifferentflexuralstiffnessesaretakenintoaccount:EI1forthepartof thespanssubmittedtopositive(sagging)bending(uncrackedsection)andEI2forthepartof thespansubmittedtonegative(hogging)bending(crackedsection). 5.7.3.Seismiclinks 5.7.3.1–Linksshallbemadeofsteelsections,possiblycompositewithslabs.Theymaynot beencased. 5.7.3.2–Therulesonseismiclinksandtheirstiffenersgivenin4.5.2apply.Linksshouldbe ofshortorintermediatelengthwithamaximumlengthe.

(a)Instructureswheretwoplastichingeswouldformatlinkends:

M p,link e = 2 (5.12)

Vp,link

(b)Instructureswhereoneplastichingewouldformatoneendofalink:

M p,link e < (5.13)

Vp,link

ThedefinitionsofMp,linkandVp,linkaregivenin4.5.2.3.ForMp,link,onlythesteelcomponents ofthelinksection,disregardingtheconcreteslab,aretakenintoaccountintheevaluation. 5.7.3.3 – When the seismic link frames into a reinforced concrete column or an encased column, facebearingplates shouldbeprovided onboth sidesof the link at the faceof the columnandintheendsectionofthelink. 5.7.3.4–Connectionsshouldmeettherequirementsoftheconnectionsofeccentricallybraced steelframesasin4.5.4.

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5.7.4.Membersnotcontainingseismiclinks 5.7.4.1 – The members not containing seismic links should conform to the rules in 4.5.3, taking into account the combined resistance of steel and concrete in the case of composite elementsandtherelevantrulesformembersin5.4andinEN1994=1=1:2004. 5.7.4.2 – Where a link is adjacent to a fully encased composite column, transverse reinforcementmeetingtherequirementsof5.4.4shouldbeprovidedaboveandbelowthelink connection. 5.7.4.3–Incaseofacompositebraceundertension,onlythecross=sectionofthestructural steelsectionshouldbetakenintoaccountintheevaluationoftheresistanceofthebrace.

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5.8.DESIG DDET ILIGRULESFORSTRUCTUR LSYSTEMSM DEOF REIFORCEDCOCRETESTRUCTUR LW LLSCOMPOSITEWITH STRUCTUR LSTEELELEMETS 5.8.1.Specificcriteria 5.8.1.1–Theprovisionsinthissubclauseapplytocompositestructuralsystemsbelongingin oneofthethreetypesdefinedin5.1.3.1(e). 5.8.1.2–StructuralsystemTypes1and2shallbedesignedtobehaveasstructuralwallsand dissipate energy in the vertical steel sections and in the vertical reinforcement. The infills shallbetiedtotheboundaryelementstopreventseparation. 5.8.1.3– In structural systemType1, the storey shear forces shallbecarriedbyhorizontal shearinthewallandintheinterfacebetweenthewallandbeams. 5.8.1.4–StructuralsystemType3shallbedesignedtodissipateenergyinthestructuralwalls andinthecouplingbeams. 5.8.2. nalysis 5.8.2.1 – The analysis of the structure shall be based on the section properties defined in Chapter3forconcretewallsandin5.2.2forcompositebeams. 5.8.2.2–InstructuralsystemsofType1orType2,whenverticalfullyencasedorpartially encasedstructuralsteelsectionsactasboundarymembersofreinforcedconcreteinfillpanels, theanalysisshallbemadeassumingthattheseismicactioneffectsintheseverticalboundary elementsareaxialforcesonly. 5.8.2.3–Theseaxialforcesshouldbedeterminedassumingthattheshearforcesarecarried bythereinforcedconcretewallandthattheentiregravityandoverturningforcesarecarried bytheshearwallactingcompositelywiththeverticalboundarymembers. 5.8.2.4– InstructuralsystemofType3, ifcompositecouplingbeamsareused,5.5.2.2and 5.5.2.3apply. 5.8.3.Detailingrulesforcompositewalls 5.8.3.1–ThereinforcedconcreteinfillpanelsinType1andthereinforcedconcretewallsin Types2and3shallmeetthedetailingrequirementsofChapter3. 5.8.3.2 – Partially encased steel sections used as boundary members of reinforced concrete panelsshallbelongtoaclassofcross=sectionindicatedinTable5.3. 5.8.3.3 – Fully encased structural steel sections used as boundary members in reinforced concretepanelsshallbedesignedinaccordancewith5.4.4. 5.8.3.4–Partiallyencasedstructuralsteelsectionsusedasboundarymembersof reinforced concretepanelsshallbedesignedinaccordancewith5.4.5.

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5.8.3.5–Headedshearstudsor tiereinforcement(weldedto,anchoredthroughholes in the steelmembersoranchoredaroundthesteelmember)shouldbeprovidedtotransfervertical and horizontal shear forces between the structural steel of the boundary elements and the reinforcedconcrete. 5.8.4.Detailingrulesforcouplingbeams 5.8.4.1–Couplingbeamsshallhaveanembedment lengthintothereinforcedconcretewall sufficient to resist the most adverse combination of moment and shear generated by the bendingandshearstrengthofthecouplingbeam.Theembedmentlengthleshallbetakento begininsidethefirstlayeroftheconfiningreinforcementinthewallboundarymember.The embedmentlengthleshallbenotlessthan1,5timestheheightofthecouplingbeam. 5.8.4.2 – The vertical wall reinforcements, defined in 5.3.3.4 and 5.3.3.5 with design axial strength equal to the shear strength of the coupling beam, should be placed over the embedment lengthof thebeamwith two=thirdsof thesteel locatedover the firsthalfof the embedmentlength.Thiswallreinforcementshouldextendadistanceofatleastoneanchorage length above and below the flanges of the coupling beam. It is permitted to use vertical reinforcementplacedforotherpurposes,suchasforverticalboundarymembers,aspartofthe requiredverticalreinforcement.Transversereinforcementshouldconformto5.4.

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5.9.DESIG DDET ILIGRULESFORCOMPOSITESTEELPL TE STRUCTUR LW LLS 5.9.1.Specificcriteria 5.9.1.1 – Composite steel plate shear walls shall be designed to yield through shear of the steelplate. 5.9.1.2 – The steel plate should be stiffened by one or two sided concrete encasement and attachmenttothereinforcedconcreteencasementinordertopreventbucklingofsteel. 5.9.2. nalysis Theanalysisofthestructureshouldbebasedonthematerialsandsectionpropertiesdefined in5.2.2and5.4. 5.9.3.Detailingrules 5.9.3.1–Itshallbecheckedthat

V < V (5.14) Ed Rd

withtheshearresistancegivenby:

yd V = A (5.15) Rd pl

3

where ydisthedesignyieldstrengthoftheplateandAplisthehorizontalareaoftheplate. 5.9.3.2–Theconnectionsbetweentheplateandtheboundarymembers(columnsandbeams), aswellastheconnectionsbetweentheplateandtheconcreteencasement,shallbedesigned suchthatfullyieldstrengthoftheplatecanbedeveloped. 5.9.3.3 – The steel plate shall be continuously connected on all edges to structural steel framingandboundarymemberswithweldsand/orbolts todeveloptheyieldstrengthof the plateinshear. 5.9.3.4–Theboundarymembersshallbedesignedtomeettherequirementsof5.8. 5.9.3.5–Theconcretethicknessshouldbenotlessthan200mmwhenitisprovidedonone sideand100mmoneachsidewhenprovidedonbothsides. 5.9.3.6–Theminimumreinforcementratioinbothdirectionsshallbenotlessthan0,25%. 5.9.3.7–Openingsinthesteelplateshallbestiffenedasrequiredbyanalysis.

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CH PTER6 PERFORM CEB SEDSEISMICDESIGREQUIREMETS

FORT LLBUILDIGS 6.1. LYSISPROCEDURESFORT LLBUILDIGS 6.1.1– In the linearelasticanalysisof tallbuildings requiredfordesignstagesdescribed in 6.3.1and6.3.3,Multi8modeResponseSpectrumAnalysisproceduredescribedin2.4orLinear ResponseHistoryAnalysisproceduredescribedin2.5.1shallbeemployed. 6.1.2–Inthenonlinearanalysisoftallbuildingsrequiredfordesignstagesdescribedin6.3.2 and6.3.4,DirectIntegrationprocedureshallbeemployedinthetimedomain. 6.1.3–Innonlinearanalysis,aminimumsevenearthquakegroundmotionsetsshallbeused inaccordancewith1.2.3andtheaccelerationrecordsinthetwoperpendiculardirectionsshall be applied simultaneously along the principal axes of the structural system. Subsequently directionsofaccelerationrecordsshallbe rotatedby90

oand theanalysisshallbe repeated.

Designbasisseismicdemandsshallbecalculatedastheaverageofresultsobtainedfromthe minimum2*7=14analysis. 6.1.4 – In the linear or nonlinear analysis of tall buildings, damping ratio shall be taken ξ=0.05asamaximum.Secondorder(P–N)effectsshallbetakenintoaccount. 6.1.5–Inthecaseswhereneeded,verticalcomponentoftheearthquakegroundmotionmay beconsideredaswell,subjecttoapprovaloftheIndependentReviewer(s).

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6.2.REQUIREMETSFOR LYSISMODELIG 6.2.1 – Modeling of frame elements shall be made with rame inite elements in linear analysis.Modelinginnonlinearanalysiscanbemadewithplasticsections(plastichinges)in theframeworkof lumpedplasticityapproachor through iberelements in theframeworkof distributedplasticity approach.Regarding theplastichinge length, an appropriate empirical relationship may be selected from the literature, subject to approval of the Independent Reviewer(s).Innonlinearanalysis,alternativemodelingapproachesmaybefolloweduponthe approval of Independent Reviewer(s). In linear and nonlinear models of steel frames, shear deformationinthebeam=columnpanelzoneshallbeconsidered. 6.2.2–Inlinearanalysis,modelingofreinforcedconcretewallsandtheirpartsshallbemade with shell inite elements. In simple walls, frame elements may be used as an alternative. When shell elements are used, elastic modulus (E) of shell elements can be appropriately reducedinbendinginordertobeconsistentwiththee ectivebendingrigiditiesoftheframe elementswithcrackedsections(see6.2.4). 6.2.3 – In modeling reinforced concrete walls and their parts for nonlinear analysis, iber elements or alternative modeling options may be used in the framework of distributed plasticityapproach,subject toapprovalof theIndependentReviewer(s).Shearstiffnessesof reinforcedconcretewallsshallbeconsidered. 6.2.4–Effectivebendingrigiditiesshallbeusedforreinforcedconcreteframeelementswith cracked sections. In the preliminarydesign stagedescribed in 6.3.1, empirical relationships given in the relevant literature may be utilized. In other design and verification stages described in 6.3, effective bending rigidity shall be obtained from the section’s moment=

φ

curvaturerelationshipasfollows:

MY(EI )e = φ' y

M N= φ y

(6.1)

'where M ,representsthestateoffirst=yieldinthesection.Thecorrespondingcurvature Y y representsastatewhereeitherconcretestrainattainsavalueof0.002orsteelstrainreaches the yieldvalue,whicheveroccurs first.Thenominalplasticmoment MN corresponding to effectiveyieldcurvature φ y iscalculatedwithconcretecompressivestrainreaching0.004or steel strain attaining 0.015, whichever occurs first. In calculating the moment strengths of columns,axialforcesduetogravityloadsonlymaybeconsidered. 6.2.5 – In preliminary design stage described in 6.3.1, design strengths, ( d), of concrete, reinforcingsteelandstructuralsteelaredefinedas the relevantcharacteristicstrengths, ( k), divided by material safety factors. In other design and verification stages in 6.3, expected strentghs, ( e ), shall be used as design strengths without any material safety factors. The followingrelationshipsmaybeconsideredbetweentheexpectedandcharacteristicstrengths:

Concrete =1.3 ce ck

Reinforcingsteel =1.17 ye yk

Structuralsteel(S235) =1.5 (6.2) ye yk

Structuralsteel(S275) =1.3 ye yk

Structuralsteel(S355) =1.1 ye yk

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6.2.6 – Bi=linear backbone curves may be considered in hysteretic relationships of plastic sections(plastichinges)offrameelements.Stiffnessandstrengthdegradationeffectsshallbe consideredupontheapprovalofIndependentReviewer(s). 6.2.7– tfloorlevelswhereabruptchanges(inparticulardownwardchanges)occurinlateral stiffness of vertical structural elements, a special care shall be paid for the arrangement of appropriatetrans er loorswithsufficientin=planestiffnessandstrength. 6.2.8–Thestiffnessofthefoundationandthesoilmediumshallbeconsideredbyappropriate modelstobeapprovedbytheIndependentReviewer(s).Whenneeded,nonlinearbehaviourof soil=foundation system may be taken into account in design stages described in 6.3.2 and 6.3.4.

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6.3.PERFORM CEB SEDSEISMICDESIGST GESOFT LLBUILDIGS Performance=baseddesignstagesoftallbuildingsaredescribedinthefollowing. 6.3.1.DesignStage(I– ):PreliminaryDesign(dimensioning)withLinear nalysisfor ControlledDamage/LifeSafetyPerformanceObjectiveunder(E2)Level Earthquake 6.3.1.1–ThisdesignstageaimsatpreliminarydimensioningoftallbuildingforLi eSa ety/ ControlledDamageperformanceobjective(seeTable6.1), 6.3.1.2 – linear analysis shall be performed in the framework of Strength8Based Design approachwithreducedseismicloadsaccordingtoChapter2under(E2)levelearthquakefor ormal Occupancy Buildings according to Table 1.2, and under (E3) level earthquake for SpecialOccupancyBuildings. 6.3.1.3–MinimumbaseshearrequirementgivenbyEq.(2.4)shallbeapplied. 6.3.1.4–PreliminarydesignshallnormallyfollowthedesignrequirementsofChapters3,4 or 5, however deviations from those requirements may be permitted upon the approval of IndependentReviewer(s). 6.3.2.DesignStage(I–B):Designwithonlinear nalysisforLifeSafety/Controlled DamagePerformanceObjectiveunder(E2)LevelEarthquake 6.3.2.1–Thestructuralsystemofa tallbuilding,whichispreliminarilydesignedinDesign Stage (I – ), shall be designed under the same level of earthquake for Li e Sa ety / ControlledDamageperformanceobjective. 6.3.2.2– nonlinearanalysis shallbeperformedaccording to the requirementsof6.2 (see Table6.1). ccidentaleccentricityeffectsneednottobeconsideredinthisanalysis. 6.3.2.3 –The seismicdemandsobtained according to 6.1.3 as the averageof the results of minimum2*7=14analysisshallbecomparedwiththefollowingcapacities:

(a)Interstorydriftratioofeachverticalstructuralelementshallnotexceed0.025ateachstory ineachdirection.

(b)Upper limitsofconcretecompressive strain at theextreme fiber inside theconfinement reinforcement and the reinforcing steel strain are given in the following for reinforced concretesectionssatisfyingtheconfinementrequirements:

ε cg =0.0135;ε s =0.04 (6.3)

(c)Deformationcapacitiesofstructuralsteelframeelementsshallbetakenfrom SCE/SEI 41=06*forLi eSa etyperformanceobjective.

(d) Shear capacities of reinforced concrete structural elements shall be calculated from EN 1992=1=1:2005usingexpectedstrengthsgivenin6.2.5. _________________________ * SCE/SEI41=06:SeismicRehabilitationofExistingBuildings, mericanSocietyofCivil Engineers,1stedition,15/05/2007.

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(e)Intheeventwhereanyoftherequirementsgivenin(a)through(d)aboveisnotsatisfied, alldesignstagesshallberepeatedwithamodifiedstructuralsystem. 6.3.3.DesignStage(II):DesignVerificationwithLinear nalysisforMinimumDamage/ ImmediateOccupancyPerformanceObjectiveunder(E1)LevelEarthquake 6.3.3.1–Thetallbuildingstructuralsystem,whichispreliminarilydesignedinDesignStage (I– ) andsubsequentlydesigned inDesignStage (I –B), shallbeverified for Immediate Occupancy/MinimumDamageperformanceobjective. 6.3.3.2– linearanalysisshallbeperformedaccording to requirementsgiven in6.2under (E1) levelearthquakeforormalOccupancyBuildingsandunder (E2) levelearthquakefor SpecialOccupancyBuildings(seeTable6.1). ccidentaleccentricityeffectsneednot tobe consideredinthisanalysis. 6.3.3.3 –Verification=basis internal forces shall beobtained as those calculated from linear elasticanalysis(i.e., qR =1.0),irrespectiveofthetypeofthestructuralsystem.Thoseforces shallbeshownnottoexceedthestrengthcapacitiesofcrosssectionscalculatedwithexpected materialstrengthsgivenin6.2.5. 6.3.3.4–Interstorydriftratioofeachverticalstructuralelementobtainedaccordingto2.7.1 shallnotexceed0.01ateachstoryineachdirection. 6.3.3.5– Intheeventwhere6.3.3.3and/or6.3.3.4 isnotsatisfied,alldesignstagesshallbe repeatedwithamodifiedstructuralsystem. 6.3.4.DesignStage(III):DesignVerificationwithonlinear nalysisforExtensive Damage/CollapsePreventionPerformanceObjectiveunder(E3)Level Earthquake 6.3.4.1–Thetallbuildingstructuralsystem,whichispreliminarilydesignedinDesignStage (I – ) and subsequently designed in Design Stage (I – B), shall be verified for Extensive Damage/CollapsePreventionperformanceobjective. 6.3.4.2– nonlinear analysis shallbeperformedunder (E3) level earthquake according to requirements given in 6.2 (see Table 6.1). ccidental eccentricity effects need not to be consideredinthisanalysis. 6.3.4.3 –The seismicdemandsobtained according to 6.1.3 as the averageof the results of minimum2*7=14analysisshallbecomparedwiththefollowingcapacities:

(a)Interstorydriftratioofeachverticalstructuralelementshallnotexceed0.035ateachstory ineachdirection.

(b)Upper limitsofconcretecompressive strain at theextreme fiber inside theconfinement reinforcement and the reinforcing steel strain are given in the following for reinforced concretesectionssatisfyingtheconfinementrequirements:

ε cg =0.018;ε s =0.06 (6.4)

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(c)Deformationcapacitiesofstructuralsteelframeelementsshallbetakenfrom SCE/SEI 41=06*forCollapsePreventionperformanceobjective.

(d) Shear capacities of reinforced concrete structural elements shall be calculated from EN 1992=1=1:2005usingexpectedstrengthsgivenin6.2.5.

(e)Intheeventwhereanyoftherequirementsgivenin(a)through(d)aboveisnotsatisfied, alldesignstagesshallberepeatedwithamodifiedstructuralsystem.

Table5.1.Performancebaseddesignstagesoftallbuildings

Design Stage DesignStage

I– DesignStage

I–B DesignStage

II DesignStage

III

Designtype Prelim.design (dimensioning)

Design Verification Verification

Earthquake

ormalclass buildings

(E2)earthquake

ormalclass buildings

(E2)earthquake

ormalclass buildings

(E1)earthquake ormalclass

buildings (E3)earthquake

Level Specialclass buildings

Specialclass buildings

Specialclass buildings

(E3)earthquake (E3)earthquake (E2)earthquake

Per ormance objective

LifeSafety LifeSafety Immediate Occupancy

Collapse Prevention

Analysistype

3=DLinear Response Spectrum nalysis

3=DNonlinear Time=history nalysis

3=DLinear Response Spectrum nalysis

3=DNonlinear Time=history nalysis

Behaviour Factor

q≤5.0 – q=1.0 –

Storydri t ratiolimit

%2 %2.5 %1 %3.5

Section sti nessinR/C ramemembers

Effective stiffness

Effective stiffness

(frommoment= curvature analysis

Effective stiffness

(frommoment= curvature analysis

Effective stiffness

(frommoment= curvature analysis

Material Design Expected Expected Expected strengths strength strength strength strength

Acceptance Strength& Strains&Story Strength& Strains&Story criteria Storydriftratio driftratio Storydriftratio driftratio

____________________________

* SCE/SEI41=06:SeismicRehabilitationofExistingBuildings, mericanSocietyofCivil Engineers,1stedition,15/05/2007.

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6.4.DESIGREQUIREMETSFOROSTRUCTUR L RCHITECTUR L DMECH IC L/ELECTRIC LELEMETS/COMPOETS 6.4.1.General 6.4.1.1 – Independently responding appendages (balcony, parapet, chimney, etc) that are supportedbythemainstructuralsystemofthetallbuildings,façadeandpartioningelements, architectural components,mechanical and electricalcomponentsand theirconnections shall beanalysedfortheseismiceffectsgiveninthisSection. 6.4.1.2 – Component attachments shall be bolted, welded, or otherwise positively fastened withoutconsiderationoffrictionalresistanceproducedbytheeffectsofgravity. continuous load path of sufficient strength and stiffness between the component and the supporting structure shall be provided. Local elements of the structure including connections shall be designed and constructed for the component forces where they control the design of the elementsortheirconnections. 6.4.1.3–(E3)EarthquakeLevel(see1.2.1)shallbeconsideredforthefollowingnonstructural elementsandtheirattachementstothestructure:

(a)ElementsandcomponentsinbuildingsofSpecialOccupancyClass(Table1.2),

(b)Elementsandcomponents inbuildingsoformalOccupancyClass (Table1.2) thatare requiredtoremainoperationalimmeadiatelyaftertheearthquake,

(c)Elementsandcomponentsrelatedtohazardousmaterial. 6.4.1.4 – (E2)Earthquake Level (see 1.2.1) shall be considered for nonstructural elements andcomponentsotherthanthoseclassifiedin6.4.1.3. 6.4.1.5– If themassof thenonstructuralelementorcomponent is greater than20%of the storeymass, the elementor the component shallbe considered an elementof the structural systemwithitsmassandstiffnesscharacteristics. 6.4.2.EquivalentSeismicLoads 6.4.2.1–Theseismicdesignforce, e,appliedinthehorizontaldirectionshallbecenteredat the component’s center of gravity and distributed relative to the component's mass distributionandshallbedeterminedasfollows:

m A B e e e e = (6.5) qe

where me represents the mass, Ae is the maximum acceleration acting on the element or component,Berepresentstheamplificationfactorandqereferstobehaviourfactordefinedfor the element or component. Be and Re are given for architectural and mechanical/electrical componentsinTable6.2andTable6.3,respectively. 6.4.2.2–Themaximumaccelerationactingontheelementorcomponentshallbedefinedas themaximumvaluetobeobtainedfromthefollowing:

93

(a)MaximumvalueofaveragetotalaccelerationsobtainedfromnonlinearanalysisatStage I=B for ormal Occupancy Class buildings and at Stage III for Special Occupancy Class buildingsmaybedefinedasAe.

(b) In particular cases where mass and stiffness characteristics of component or its attachement is required to be considered, Ae may be calculated as a spectral acceleration corresponding to natural period, Te , of the component from the loor spectrum obtained throughtheanalysisin(b).naturalperiod,Te,maybecalculatedfrom;

m e Te =2π (6.6) k e

where ke represents the effective stiffness coefficient of the nonstructural element or component.Inthiscase,amplificationfactordefinedinEq.(6.5)shallbetakenasBe=1. 6.4.2.3–EquivalentseismicloadcalculatedwithEq.(6.5)shallnotbelessthantheminimum loaddefinedbelow: min =0.3m S (6.7) e e SD

6.4.2.4 – Equivalent seismic load given in Eq.(6.5) shall be applied independently in both horizontal earthquake directions in combination with the dead load, service loads of the elementorcomponentplusaverticalseismicloadequalto ±0.2me SSD 6.4.2.5 – For elements or components suspended from the structural system (with chains, cables,etc),aseismicloadequalto1.4timestheweightoftheelementorcomponentshallbe appliedsimultaneouslyinbothhorizontalandverticaldirections.

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Table6.2. mplificationandBehaviourFactorsforarchitecturalcomponents

rchitecturalelementorcomponent

Be qe

Nonstructuralplainmasonryinternalwallsandpartitions 1.0 1.5 Nonstructuralotherinternalwallsandpartitions 1.0 2.5 Cantileverelementsunbracedorbracedbelowtheircentresofgravity (parapets,cantileverinternalwalls,laterallysupportedchimneys,etc)

2.5 2.5

Cantileverelementsbracedabovethecentreofgravity(cantilever internalwalls,chimneys,etc)

1.0 2.5

Externalwallsandconnections 1.0 2.5 Woodpanels 1.0 1.5 Penthousesindependentfromstructuralsystem 2.5 3.5 Suspendedceilings 1.0 2.5 Storagecabinetsandlaboratoryequipment 1.0 2.5 ccessfloors 1.0 1.5 Signsandbillboards 2.5 2.5 Otherrigidcomponents 1.0 2.5 Otherflexiblecomponents 2.5 2.5

Table6.3. mplificationandBehaviourFactorsformechanical/electricalcomponents

Mechanical/electricalelementorcomponent

Be Re

BoilersandFurnaces Pressurevesselsonskirtsandfree=standing Stacks Cantileveredchimneys Other

1.0 2.5 2.5 2.5 1.0

2.5 2.5 2.5 2.5 2.5

PipingSystems Highdeformabilityelementsandattachments Limiteddeformabilityelementsandattachments Lowdeformabilityelementsandattachments

1.0 1.0 1.0

3.5 2.5 1.5

HV CSystemComponent Vibrationisolated Non=vibrationisolated Mountedin=linewithductwork Other

2.5 1.0 1.0 1.0

2.5 2.5 2.5 2.5

ElevatorComponents 1.0 2.5 EscalatorComponents 1.0 2.5 GeneralElectrical Distributionsystems(busducts,conduit,cabletray) Equipment

2.5 1.0

4.0 2.5

LightingFixtures 1.0 1.5

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6.4.3.Limitationofdisplacements 6.4.3.1– Incaseswherenonstructuralelementsorcomponentsareattachedtotwodifferent pointsofthesamestructureexperiencingdifferentdisplacements,orattachedtotwodifferent structural systems, the effects of relative displacements between the points of attachement shallbeconsidered.Relativedisplacementsshallbecalculatedfromtheresultsofnonlinear analysisofthestructuralsystematDesignStageI=BforormalOccupancyClassbuildings (see6.3.2)oratDesignStageIIIforSpecialOccupancyClassbuildings(see6.3.4). 6.4.3.2 – Relative displacements of nonstructural elements or components, δe , shall not be morethanthevaluegiveninEq.(6.8).

(δ )i max δ ≤ (h − h ) (6.8) e x y hi

where hx and hy represent the vertical distances of top and bottom attachement points, respectively, of the nonstructural element or component measured from the relevant floor level. (δi)max /hi is theallowable storeydrift ratio specified in6.3.2 forormalOccupancy Classbuildingsandin6.3.4forSpecialOccupancyClassbuildings. 6.4.3.3 – Relative displacements of nonstructural elements or components attached to two differentstructuralsystemsshallbecalculatedas theabsolutesumof themaximumrelative displacements at points of attachement and it shall not be more than the value given in Eq.(6.9).

(δ (δ i )max iB )max δ ≤ h +h (6.9) e x yh hi iB

where(δi )max /hi ve(δiB)max/hiBrepresenttheallowablestoreydriftratiosofthefirstand second structural systems, respectively, specified in 6.3.2 for ormal Occupancy Class buildingsandin6.3.4forSpecialOccupancyClassbuildings. 6.4.4.onstructuralfaçadeelementsandconnections Glassorcurtainwallfaçadeelementsoftallbuildingsshallbesubjectedtostaticanddynamic testsdescribedinthefollowingstandards:

(a) “RecommendedStaticTestMethod orEvaluatingCurtainWall and Store rontSystems Subjected to Seismic and Wind Induced Story Dri ts”, M 501.4=00, merican rchitecturalManufacturing ssociation,Schaumburg,Illinois,2001.

(b)“RecommendedDynamicTestMethod orDetermining theSeismicDri tCausingGlass Fallout rom a Wall System”, M 501.6=01, merican rchitectural Manufacturing ssociation,Schaumburg,Illinois,2001. 6.5.IDEPEDETDESIGREVIEW Design of tall buildings according to this Code shall be peer reviewed and endorsed by independentreviewersinalldesignstages,startingfromthestructuralsysteminceptionstage. Theadministrativestructureoftheindependentdesignreviewprocesswillbeestablishedby DubaiMunicipality.

96

CH PTER7 STRUCTUR LHE LTHMOITORIGSYSTEMS

FORT LLBUILDIGS Healthmonitoringsystemsshallbeestablishedinalltallbuildingsinordertomonitorthereal behaviouroftallbuildingstructuralsystems,toimprovetheexistingseismicandwindcodes andtopredictthelevelofseismicdamageinatallbuildingimmediatelyaftertheocurrenceof an earthquake. typical health monitoring system shall have a minimum 8 acceleration sensorsdistributedinthebuilding,asshowninFig.7.1.

(a) cceleration sensors shall be syncronized and connected to a 24=bit digital recording system equipped with a GPS card. Recording system shall record the building vibrations continuouslyandtransferthedatainrealtimetoaprescribedcentreviainternet,modemor similarchannels.Sufficientbatteryanddiskcapacityshallbeprovidedagainstelectricityand communication shortages, which will help the system operate and store data for at least a periodofoneweek.

(b) Technical specification of sensors and recording systems shall be provided by Dubai Municipality.

(c) Vibration records shall be transferred in real time to the Structural Health Monitoring Centre of Dubai Municipality. The records shall be stored at this centre as well as by the buildingowner.

Recordbox (atanystorey)

Horizontalsensors Verticalsensors

Figure7.1

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EX SOILCL SSIFIC TIOFOR

SPECIFIC TIOOFSEISMICGROUDMOTIO

.1.Soilclassificationprocedure .1.1 – For the purpose of specifying elastic response spectrum, the site soil shall be classified according to Table .1. Where the soil properties given in Table .1 are not known in sufficient detail to determine the soil class, it shall be permitted to assume Soil ClassDunlessDubaiMunicipalitydeterminesthatSoilClassEorFcouldapplyatthesiteor intheeventthatSiteClassEorFisestablishedbygeotechnicaldata.

Table .1.Soilclassificationparameters

SoilClass v (m/s) s or ch s (kPa) u

.Hardrock >1500 N N B.Rock 760–1500 N N C.Verydensesoilandsoftrock 360–760 >50 100 D.Stiffsoil 180–360 15–50 50–100 E.Softclaysoil <180 <15 <50 oranyprofilewithmorethan3mofsoilwith

Plasticityindex:PI>20 Moisturecontent:w≥40% Undrainedshearstrength: s <25kPa u

F.Soilsrequiringsiteresponse analysis

1.Soilsvulnerabletopotentialfailureorcollapse underseismicloadingsuchasliquefiablesoils, quickandhighlysensitiveclays,collapsible weaklycementedsoils 2.Peatand/orhighlyorganicclayswithmore than3m. 3.Veryhighplasticityclayswithmorethan7.5m andPI>75 4.Verythick,soft/mediumstiffclayswithmore than35mandsu<50kPa

.1.2–TheparametersusedinTable .1todefinetheSoilClassarebasedontheupper30 m of the site profile. Profiles containing distinctly different soil and rock layers shall be subdivided into those layersdesignatedby anumber that ranges from1 to n at thebottom wherethereareatotalofndistinctlayersintheupper30m.Thesymbolithenreferstoany one of the layers between 1 and n. Parameters characterizing upper 30 m is defined as follows:

n

d∑ i

(a) v s = i=1 n d i∑

( .1)

i=1 vsi wherevsi=shearwavevelocityinm/s

98

di=thicknessofanylayer(between0and30m). ∑ n

di isequalto30m. i=1

∑ n

id i=1 (b) = n ( .2) di ∑ i=1 i

where i = Standard Penetration Resistance as directly, measured in the field without corrections,andshallnotbetakengreaterthan100blows/ft.Whererefusalismetforarock layer, i shall be taken as 100 blows/ft. i and di in Eq.( .2) are for cohesionless soil, cohesivesoilandrocklayers.

d (c) ch = s ( .3)

m di ∑ i=1 i

whereianddiinEq.( .3)areforcohesionlesssoillayersonly.

m

ds=totalthicknessofcohesionlesssoillayersinthetop30m. ∑di = ds i=1

d

(d) su = k

c ( .4) di ∑ si=1 ui

wheresui=undrainedshearstrengthinkPa,andshallnotbetakengreaterthan250kPa.

k

dc=totalthicknessofcohesivesoillayersinthetop30m. ∑di = dc i=1

.2.StepsforclassifyingSoilClassesC,D,E,F Step1:CheckforthefourcategoriesofSoilClassF(seeTable .1)requiringsite=specific evaluation.Ifthesitecorrespondstoanyofthesecategories,classifythesiteasSoilClassF andconductasite=specificevaluation. Step2:Checkfortheexistenceofatotalthicknessofsoftclay>3mwhereasoftclaylayer isdefinedbysu<25kPa,w≥40%andPI>20.Ifthesecriteriaaresatisfied,classifythesite asSoilClassE. Step 3: Categorize the site using one of the following three methods with vs , and su

computedinallcasesasspecifiedin .1.2: (a) vs forthetop30m( vs method)

(b) forthetop30m( method) (c) ch forcohesionlesssoillayers(PI<20)inthetop30mandaverage su forcohesivesoil

layers(PI>20)inthetop30m( su method)

99

If s methodisusedand, and s criteriadiffer,thecategorywiththesoftersoilsshallbe u ch u

selected(forexample,useSoilClassEinsteadofD). .3.ClassifyingSoilClasses ,B .3.1– ssignmentofSoilClassBshallbebasedontheshearwavevelocityforrock.For competent rock with moderate fracturing and weathering, estimation of this shear wave velocity shall be permitted. For more highly fractured and weathered rock, the shear wave velocityshallbedirectlymeasuredorthesiteshallbeassignedtoSoilClassC. .3.2 – ssignment of Soil Class shall be supported by either shear wave velocity measurementsonsiteorshearwavevelocitymeasurementsonprofilesofthesamerocktype in the same formationwithanequalorgreaterdegreeofweatheringand fracturing.Where hard rock conditions are known to be continuous to a depth of 30 m, surficial shear wave velocitymeasurementsmaybeextrapolatedtoassess vs .

.3.3–SoilClasses andBshallnotbeusedwherethereismorethan3mofsoilbetween therocksurfaceandthebottomofthespreadfootingormatfoundation.

100