Finite Element Analysis of Steel Beam to Column co

ThePennsylvaniaStateUniversityTheGraduateSchoolCollegeofEngineeringFiniteElementAnalysisofSteelBeamtoColumnConnectionsSubjectedtoBlastLoadsAThesisProposalinCivilEngineeringByTapanSabuwalaSubmittedinPartialFulfillmentoftheRequirementsfortheDegreeofMasterofScienceAugust2001TapanSabuwala1ABSTRACTTheaimofthisstudyistoanalyzeandassessthebehaviorofsteelconnectionssubjectedtoblastloadsusingfiniteelementanalysis.Threedifferenttypesofconnectionshavingvaryingconnectiondetailswillbeanalyzed.Theseconnectiondetailsarepartofthe8connectiondetailsthathadbeentestedbytheAISCNorthridgeMomentConnectionTestProgram(Engelhardtetal1995).OnthebasisofthesetestsrecommendationswereproposedforimprovingconnectionperformancewhichhavebeenacceptedbytheFederalEmergencyManagementAgency(FEMA)andhavebeenincludedinpartintheRecommendedSeismicDesignCriteriaForNewSteelMomentFrameBuildings(FEMA,2000).Thisstudyaimsatevaluatingtheefficiencyoftheseconnections,whichhavebeendesignedforseismicloads,againstblastloads.ForthisstudythefiniteelementcodeABAQUSwillbeusedtodevelopthevariousconnectionmodels.Thefiniteelementmodelswillbecalibratedusingtestdata.Theverifiedmodelswillthenbesubjectedtosimulatedblastloadsandtheefficiencyandbehavioroftheconnectionswillbeanalyzed.TapanSabuwala21.INTRODUCTION2.PROBLEMSTATEMENT3.OBJECTIVES4.SCOPEOFWORK5.LITERATUREREVIEW6.EXPERIMENTALDATA7.ANALYTICALPROGRAM8.ANTICIPATEDCONCLUSIONS9.REFERENCESTapanSabuwala31.INTRODUCTIONInrecenttimesmanystructureshavebeensubjectedtoblastloadsduetoactsofterrorismandsteelframesformamajorpartofthesetargetedstructures.Hencethebehaviorofstructuralsteelconnectionssubjectedtoblastloadsisofinterest.Forfacilitiessubjectedtoblastloads,theconnectionsdetailshavebeenshowntoplayamajorpartintheresponseofthestructureofsuchhighratedynamicloading.Thusabetterunderstandingofbehaviorofstructuralsteelconnectionsunderblastloadsisveryimportant.Theguidelinescurrentlyusedforthedesignofstructuralsteelconnectionssubjectedtodynamicloadsinducedduringblastsorearthquakeshaveprovedtobeinadequatejudgingfromthepoorperformanceofsteelframesduringthebombingsinrecenttimesandalsoduringseismiceventslikethe1994Northridgeearthquake.Importantdesignmodificationswereintroducedforconnectionssubjectedtoseismicloadsafterextensiveassessmentsoftheobserveddamage(Engelhardtet.al.,1995).Howeverthesemodifieddesigndetailsmightprovetobeinsufficientwhensubjectedtohighratedynamicloadssuchasthosegeneratedduringanexplosion.Thereforeitisimportanttoassessthebehaviorofsuchstructuresunderblastloads.CurrentdesignrecommendationsforblastresistantstructuresinTM-51300(Dept.oftheArmy,1990)includeguidelinesforthesafedesignofblastresistantsteelconnections.Howevertheadequacyofthesedesignproceduresisnotwellunderstoodasnotmuchresearchhasbeendoneinthisfieldleadingtoadearthofinformationregardingthebehaviorofsteelconnectionsubjectedtoblastloads.Theproposedstudyaimsatprovidingabetterunderstandingofthebehaviorofsteelconnectionsunderblastloadsthroughfiniteelementanalysis.TheadequacyofsteelTapanSabuwala4connectionsthatwereproposedforresistanceagainstseismicloadswillbeassessedwhentheseconnectionsaresubjectedtoblastloads.Thisstudyalsoaimsatprovidingabetterunderstandingofthefiniteelementmodelingofsteelconnections.Itisimportanttocorrectlycharacterizetheinteractionofthevariouscomponentsofasteelconnectionsuchasboltsandwelds.Forthisitisimportanttounderstandandadequatelymodelthecontactinteractionbetweenthevariousinteractingpartsoftheconnectionandtocorrectlyspecifytheirconstitutiveproperties.TheproposedstudyaimstoachievethisusingthecapabilityprovidedinthefiniteelementpackageABAQUStomodelvarioustypesofcontactsimulationsandmaterialbehavior,whichmaythenserveasareferenceforfuturefiniteelementmodelsinvolvingsuchinteractions.Threedifferentconnectiondetails,whichhadbeenusedintheAISCNorthridgeMomentConnectionTestProgram(Engelhardtet.al.,1995),havebeenchosenforthestudy.Thefirstspecimenisastandardweldedbeamboltedflangetypeofconnection,whichrepresentsatypicalPre-Northridgeconnection.Theothertwoconnections,Specimens7and8,havebeenmodifiedandstrengthenedbyaddingcoverplatestothebeamflanges,andcontinuityplatesforthecolumntogivebetterperformancewhensubjectedtoseismicloads,andhavebeenselectedfortheirsuperiorperformanceduringtheexperimentalstudy.TheconnectiondetailsforSpecimens7and8aresamebutthematerialpropertiesforthesespecimensaredifferent.Finiteelementmodelsofthese3connectiontestswillbepreparedusingtheFEcodeABAQUS.Thefiniteelementmodelswillbecalibratedusingtheavailableexperimentaldatafromthetests.Oncethemodelshavebeenverified,theywillbesubjectedtosimulatedblastloadsandtheresultsobtainedfromthesesimulationswillbeusedtoanalyzethebehavioroftheseconnectionsunderhighratedynamicloading.TapanSabuwala52.PROBLEMSTATEMENTBlastresistantsteelconnectionsarecurrentlydesignedusingthedesigncriteriadevelopedbytheindustryonthebasisoftheoreticalandexperimentalinvestigations.However,datafromtherecentactsofdomesticterrorismandseismiceventssuggeststhattheperformanceofsteelframesagainstseismicloadsaswellasblastloadsisnot