大学本科外文翻译精.docx
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大学本科外文翻译精.docx
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大学本科外文翻译精
大连理工大学外文翻译
受弯钢框架结点周期性行为Cyclicbehaviorofsteelmomentframeconnections
学院(系):
建筑工程学院
专业:
工程管理
学生姓名:
____
学号:
___________
指导教师:
_________
完成日期:
大连理工大学
DalianUniversityofTechnology
受弯钢框架结点周期性行为Cyclicbehaviorofsteelmomentframeconnections
1.Introduction
Aimedatevaluatingthestructuralperformanceofreduced-beamsection(RBS)connectionsunderalternatedaxialloadingandlateraldisplacement,fourfull-scalespecimensweretested.ThesetestswereintendedtoassesstheperformanceofthemomentconnectiondesignfortheMosconeCenterExp-ansionundertheDesignBasisEarthquake(DBE)andtheMaximumConsideredEarthquake(MCE).PreviousresearchconductedonRBSmomentconnections[1,2]showedthatconnectionswithRBSprofilescanachieverotationsinexcessof0.03rad.However,doubtshavebeencastonthequalityoftheseismicperformanceoftheseconnectionsundercombinedaxialandlateralloading.
TheMosconeCenterExpansionisathree-story,71,814m2(773,000ft2)structurewithsteelmomentframesasitsprimarylateralforce-resistingsystem.AthreedimensionalperspectiveillustrationisshowninFig.1.Theoverallheightofthebuilding,atthehighestpointoftheexhibitionroof,isapproxima-tely35.36m(116ft)abovegroundlevel.Theceilingheightattheexhibitionhallis8.23m(27ft),andthetypicalfloor-to-floorheightinthebuildingis11.43m(37.5ft).ThebuildingwasdesignedastypeIaccordingtotherequi-rementsofthe1997UniformBuildingCode.
TheframingsystemconsistsoffourmomentframesintheEast–Westdirect-ion,oneoneithersideofthestairtowers,and
–1–
受弯钢框架结点周期性行为fourframesintheNorth–Southdirection,oneoneithersideofthestairandelevatorcoresintheeastendandtwoatthewestendofthestructure[4].Becauseofthestoryheight,thecon-ceptoftheCoupled-GirderMoment-ResistingFramingSystem(CGMRFS)wasutilized.
Bycouplingthegirders,thelateralload-resistingbehaviorofthemomentframingsystemchangestoonewherestructuraloverturningmomentsareresistedpartiallybyanaxialcompression–tensioncoupleacrossthegirdersystem,ratherthanonlybytheindividualflexuralactionofthegirders.Asaresult,astifferlateralloadresistingsystemisachieved.Theverticalelementthatconnectsthegirdersisreferredtoasacouplinglink.Couplinglinksareanalogoustoandservethesamestructuralroleaslinkbeamsineccentricallybracedframes.Couplinglinksaregenerallyquiteshort,havingalargeshear-to-momentratio.
Underearthquake-typeloading,theCGMRFSsubjectsitsgirderstowariab-bleaxialforcesinadditiontotheirendmoments.TheaxialforcesintheFig.1.MosconeCenterExpansionProjectinSanFrancisco,CAgirdersresultfromtheaccumulatedshearinthelink.
2.AnalyticalmodelofCGMRF
Nonlinearstaticpushoveranalysiswasconductedonatypicalone-baymodeloftheCGMRF.Fig.2showsthedimensionsandthevarioussectionsofthemodel.Thelinkflangeplateswere28.5mm254mm(11/8in10in)andthewebplatewas9.5mm476mm(3/8in183/4in).TheSAP2000computerprogramwasutilized
–2–
受弯钢框架结点周期性行为inthepushoveranalysis[5].Theframewascharacterizedasfullyrestrained(FR).FRmomentframesarethoseframesfor1170whichnomorethan5%ofthelateraldeflectionsarisefromconnectiondeformation[6].The5%valuerefersonlytodeflectionduetobeam–columndeformationandnottoframedeflectionsthatresultfromcolumnpanelzone.
Theanalysiswasperformedusinganexpectedvalueoftheyieldstressandultimatestrength.Thesevalueswereequalto372MPa(54ksi)and518MPa(75ksi),respectively.Theplastichinges’load–deformationbehaviorwasapproximatedbythegeneralizedcurvesuggestedbyNEHRPGuidelinesfortheSeismicRehabilitationofBuildings[6]asshowninFig.
3.△ywascalcu-P–Mhingeload–deformationmodelpointsC,DandEarebasedonTable5.4from[6]for△ywastakenas0.01radperNote3in[6],Table5.8.Shearhingeload-load–deformationmodelpointsC,DandEarebasedonTable5.8[6],LinkBeam,Itema.AstrainhardeningslopebetweenpointsBand
Cof3%oftheelasticslopewasassumedforbothmodels.
Thefollowingrelationshipwasusedtoaccountformoment–axialloadinteraction[6]:
whereMCEistheexpectedmomentstrength,ZRBSistheRBSplasticsectionmodulus(in3),istheexpectedyieldstrengthofthematerial(ksi),Pistheaxialforceinthegirder(kips)andistheexpectedaxialyieldforceoftheRBS,equalto(kips).TheultimateflexuralcapacitiesofthebeamandthelinkofthemodelareshowninTable1.Fig.4showsqualitatively
–3–
受弯钢框架结点周期性行为thedistributionofthebendingmoment,shearforce,andaxialforceintheCGMRFunderlateralload.Theshearandaxialforceinthebeamsarelesssignificanttotheresponseofthebeamsascomparedwiththebendingmoment,althoughtheymustbeconsideredindesign.Thequalita-tivedistributionofinternalforcesillustratedinFig.5isfundamentallythesameforbothelasticandinelasticrangesofbehavior.Thespecificvaluesoftheinternalforceswillchangeaselementsoftheframeyieldandinternalfor-cesareredistributed.ThebasicpatternsillustratedinFig.5,however,remainthesame.
Inelasticstaticpushoveranalysiswascarriedoutbyapplyingmonotonicallyincreasinglateraldisplacements,atthetopofbothcolumns,asshowninFig.6.AfterthefourRBShaveyieldedsimultaneously,auniformyieldinginthewebandattheendsoftheflangesoftheverticallinkwillform.Thisistheyieldmechanismfortheframe,withplastichingesalsoformingatthebaseofthecolumnsiftheyarefixed.ThebaseshearversusdriftangleofthemodelisshowninFig.7.Thesequenceofinelasticactivityintheframeisshownonthefigure.Anelasticcomponent,alongtransition(consequenceofthebeamplastichingesbeingfosimultaneously)andanarrowyieldplateaucharacterizethepushovercurve.
Theplasticrotationcapacity,qp,isdefinedasthetotalplasticrotationbeyondwhichtheconnectionstrengthstartstodegradebelow80%[7].ThisdefinitionisdifferentfromthatoutlinedinSection9(AppendixS)oftheAISCSeismicProvisions
–4–
受弯钢框架结点周期性行为[8,10].UsingEq.
(2)derivedbyUangandFan[7],anestimateoftheRBSplasticrotationcapacitywasfoundtobe0.037rad:
FyfwassubstitutedforRy•Fy[8],whereRyisusedtoaccountforthediffer-encebetweenthenominalandtheexpectedyieldstrengths(Grade50steel,Fy=345MPaandRy=1.1areused).
3.Experimentalprogram
Theexperimentalset-upforstudyingthebehaviorofaconnectionwasbasedonFig.6(a).Usingtheplasdisplacementdp,plasticrotationgp,andplasticstorydriftangleqpshowninthefigure,fromgeometry,itfollowsthat:
inwhichdandgincludetheelasticcomponents.Approximationsasaboveareusedforlargeinelasticbeamdeformations.ThediagraminFig.6(a)suggestthatasubassemblagewithdisplacementscontrolledinthemannershowninFig.6(b)canrepresenttheinelasticbehaviorofatypicalbeaminaCGMRF.
Thetestset-upshowninFig.8wasconstructedtodevelopthemechanismshowninFig.6(a)and(b).Theaxialactuatorswereattachedtothree2438mm×1219mm×1219mm(8ft×4ft×4ft)RCblocks.Theseblocksweretensionedtothelaboratoryfloorbymeansoftwenty-four32mmdiameterdywidagrods.Thisarrangementpermittedreplacementofthespecimenaftereachtest.
Therefore,theforceappliedbytheaxialactuator,P,canberesolvedintotwoorthogonalcomponents,PaxialandPlateral.Sincetheinclinationangleoftheaxialactuatordoesnotexceed3.0,thereforePaxialisapproximatelyequaltoP[4].However,
–5–
受弯钢框架结点周期性行为thelateralcomponent,Plateral,causesanadditionalmomentatthebeam-tocolumnjoint.Iftheaxialactuatorscompressthespecimen,thenthelateralcomponentswillbeaddingtothelateralactuatorforces,whileiftheaxialactuatorspullthespecimen,thePlateralwillbeanopposingforcetothelateralactuators.Whentheactuatorsundergoaxialactuatorsundergoalateraldisplacement_,theycauseanadditionalmomentatthebeam-to-columnjoint(P-△effect).Therefore,themomentatthebeam-tocolumnjointisequalto:
whereHisthelateralforces,Listhearm,Pistheaxialforceand_isthelateraldisplacement.
Fourfull-scaleexperimentsofbeamcolumnconnectionswereconducted.
AllofthecolumnsandbeamswereofA572Grade50steel(Fy344.5MPa).Theactualmeasuredbeamflangeyieldstressvaluewasequalto372MPa,whiletheultimatestrengthrangedfrom502MPa(72.8ksi)to543MPa(78.7ksi).
Thespecimensweredesignatedasspecimen1throughspecimen
4.TestspecimensdetailsareshowninFig.9throughFig.12.Thefollowingfeatureswereutilizedinthedesignofthebeam–columnconnection:
TheuseofRBSinbeamflanges.Acircularcutoutwasprovided,asillustr-atedinFigs.11and12.Forallspecimens,30%ofthebeamflangewidthwasremoved.Thecutsweremadecarefully,andthengroundsmoothinadirect-tionparalleltothebeamflangetominimizenotches.
–6–
受弯钢框架结点周期性行为Useofafullyweldedwebconnection.Theconnectionbetweenthebeamwebandthecolumnflangewasmadewithacompletejointpenetrationgrooveweld(CJP).AllCJPweldswereperformedaccordingtoAWSD1.1StructuralWeldingCode
UseoftwosideplatesweldedwithCJPtoexteriorsidesoftopandbottombeamflan-ges,fromthefaceofthecolumnflangetothebeginningoftheRBS,asshowninFigs.11and12.TheendofthesideplatewassmoothedtomeetthebeginningoftheRBS.ThesideplateswereweldedwithCJPwiththecolumnflanges.Thesideplatewasadded
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