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PRECASTCONCRETESHEARWALLCONNECTIONSFORSEISMICZONESK.A.Soudki(l)andS.H.Rizkalla(2)ABSTRACTTheprecastconcreteshearwallsystemisbecomingverypopularinNorthAmericaforlow,medium,andhighriseconstructionduetotheeconomicaladvantagespossiblewiththeeaseandspeedofassembly,andthehighqualityoftheprecastpanels.Theconnectionsbetweenpanelsareextremelyimportantsincetheyaffectboththespeedoferectionandtheoverallintegrityofthestructure.Thispaperpresentstheresultsofthelasttwophasesofasix-yearresearchprogramconductedtoinvestigatethebehaviourandthecapacityoffIfteenconnectionconfigurationsusedforprecastload-bearingshearwallpanelssubjectedtomonotonicshearloadingandlargereversedcyclicloadingconditions.Connectionconfigurationsincludedry-packedplainsurface,dry-packedplainsurfacewithcontinuityreinforcement,dry-packedwithtwotypesofmechanicalshearconnectorsinadditiontothecontinuitybars,dry-packedwithpost-tensioning,andtwotypesofdry-packedmultipleshearkeys.Theresearchalsoincludeconnectionswhichsupporthollow-coreslabwithandwithoutpost-tensioning.Theperformanceofnewinnovativeconnections,suchaspartialorcompletedebondingofthereinforcementcontinuityandtheuseofenergydissipatingmechanicalconnectionsforthecontinuityreinforcement,werealsoexamined.Threedifferentlevelsofloadnormaltotheconnectiontosimulatetheeffectsofgravityloadwereused.Theresearchfmdingsofthisinvestigationwereimplementedinthedesignandconstructionofthree32-storiesapartmentbuildingsinWinnipeg,Manitoba.Theconnectionsconsideredinthisstudyprovidedsignificantsavingsinconstructiontimeandcost.1DoctoralCandidate,CivilEngineeringDepartmeht,UniversityofManitoba2AssociateDeanofEngineeringandProfessor,UniversityofManitobaPRECASTCONCRETESHEARWALLCONNECTIONSFORSEISMICZONESK.A.SoudkiandS.H.RizkallaINTRODUCTIONAtpresent,theprecastconcreteshearwallsystemisbeingdesignedandconstructedinnon-seismiczones.Theuseofsuchasystemisverylimitedinseismicallyactiveregionsduetothelackofknowledgeofhowthistypeofconstructionperformsunderseismicloadingconditions.Thestructuralintegrityoftheprecastwallbuildingisgreatlyinfluencedbythebehaviouroftheconnectionsbetweentheprecastwall-elements.Currentdesigncodesdonotspecificallyaddresstheseismicdesignoftheprecastconnections.Theinformationavailableintheexistingliteratureisnotdirectlyapplicabletoprecastshearwallconnectionsanddoesnotconsiderthecyclicbehaviourofsuchconnections.Therefore,inorderforprecastconcreteshearwallpanelsystemstogainacceptanceandbeacompetitiveconstructionsysteminseismicregions,thecyclicbehaviouroftheconnectionsbetweentheprecastmembersmustbestudied.Thispaperpresentsresultsofanextensiveexperimentalprogramonthecyclicbehaviourofhorizontalconnectionsforprecastconcreteshearwallpanelssubjectedtolargereversedcyclicinelasticdeformations.ThisresearchispartofamultiphaseexperimentalprogramattheUniversityofManitobaonthestaticandcyclicbehaviourofprecastwallconnections.Atotalofforry-threeprototypeprecastconcreteshearwallpanelspecimenswereusedtotestfIfteendifferentconnectionsincludingnewinnovativeconnectionsandconfigurationscurrentlyusedbytheconstructionindustry.TheresultsofearlierphasesonthemonotonicshearbehaviouroftypicalprecastshearwallconnectionswerepublishedbythePCIJournal(Foerster,et.al.,1989,Serrette,et.a!.,1989,Hutchinson,et.al.,1991).Theobjectiveofthecurrentresearchistostudythe.behaviouroftheconnectionunderreversedcyclicpureshearloads(Westet.al.,1993)andcombinedcyclicflexureandshear(Soudki,et.al.,1993).Allspecimensweresubjectedtoaconstantaxialloadnormaltotheconnectiontosimulategravityloads.Thetestresultswereusedtodeterminestiffness,strength,ductilitycapacity,energydissipation,modesoffailure,andcontributionofthedifferentmechanismstotheoverallbehaviour.Basedontheexperimentalresults,designrecommendationsforprecastconnectionsinseismiczones,arepresented.EXPERIMENTALPROGRAMAtotalofseventeenspecimensweretestedincyclicshearandcombinedcyclicshearandflexuralloading.DescriptionsofthespecimenstestedaregiveninTable1.DetailsofthenineconnectionconfigurationsareshowninFigure1.Eachspecimenconsistedoftwoprecastpanelsandaconnectionregion.Thedimensionscorrespondtoaprototypescaleoftheprecastpanelsusedforhighriseconstruction.Allparameters,suchassteeldetailsandconcretematerial,werekeptconstant.Thedrypackmixconsistsof2partsconcretesand,1partnormalportlandcement,andapproximately0.5partswater.Themixwasplacedandcompactedintothe20mmwidejointspacebetweenthetwopanelsandthemultipleshearkeys.ThespecimenssubjectedtopurecyclicshearloadingweretestedasshowninFigure2(a).Thetestsetupusedinthecyclicflexure/shearexperimentalphaseisshowninFigure2(b).Inbothcases,thebottomwallpanelofthespecimenwasfIxedtotherigidfloorofthestructureslabbypost-tensioningagainsttwoabutmentslocatedateachendofthelowerpanel.Thehorizontalcyclicloadwasappliedtothetopconcretepanelusinga1000leNcapacityMTSclosedloopcyclicactuatorbymeansofapush/pull-typeloadingyoke.Theconfigurationofthetoppanelintheshearspecimensandtheloadingyokeallowedapplicationofapureshearloadtotheconnection.Intheflexuralspecimens,theloadingyokewaslocatedacrossthetoppan