土木工程外文翻译-原文

外文原文Responseofareinforcedconcreteinfilled-framestructuretoremovaloftwoadjacentcolumnsMehrdadSasani_NortheasternUniversity,400SnellEngineeringCenter,Boston,MA02115,UnitedStatesReceived27June2007;receivedinrevisedform26December2007;accepted24January2008Availableonline19March2008AbstractTheresponseofHotelSanDiego,asix-storyreinforcedconcreteinfilled-framestructure,isevaluatedfollowingthesimultaneousremovaloftwoadjacentexteriorcolumns.AnalyticalmodelsofthestructureusingtheFiniteElementMethodaswellastheAppliedElementMethodareusedtocalculateglobalandlocaldeformations.Theanalyticalresultsshowgoodagreementwithexperimentaldata.Thestructureresistedprogressivecollapsewithameasuredmaximumverticaldisplacementofonlyonequarterofaninch(6.4mm).Deformationpropagationovertheheightofthestructureandthedynamicloadredistributionfollowingthecolumnremovalareexperimentallyandanalyticallyevaluatedanddescribed.Thedifferencebetweenaxialandflexuralwavepropagationsisdiscussed.Three-dimensionalVierendeel(frame)actionofthetransverseandlongitudinalframeswiththeparticipationofinfillwallsisidentifiedasthemajormechanismforredistributionofloadsinthestructure.Theeffectsoftwopotentialbrittlemodesoffailure(fractureofbeamsectionswithouttensilereinforcementandreinforcingbarpullout)aredescribed.Theresponseofthestructureduetoadditionalgravityloadsandintheabsenceofinfillwallsisanalyticallyevaluated.c2008ElsevierLtd.Allrightsreserved.Keywords:Progressivecollapse;Loadredistribution;Loadresistance;Dynamicresponse;Nonlinearanalysis;Brittlefailure1.IntroductionTheprincipalscopeofspecificationsistoprovidegeneralprinciplesandcomputationalmethodsinordertoverifysafetyofstructures.The“safetyfactor”,whichaccordingtomoderntrendsisindependentofthenatureandcombinationofthematerialsused,canusuallybedefinedastheratiobetweentheconditions.Thisratioisalsoproportionaltotheinverseoftheprobability(risk)offailureofthestructure.Failurehastobeconsiderednotonlyasoverallcollapseofthestructurebutalsoasunserviceabilityor,accordingtoamoreprecise.Commondefinition.Asthereachingofa“limitstate”whichcausestheconstructionnottoaccomplishthetaskitwasdesignedfor.Therearetwocategoriesoflimitstate:(1)Ultimatelimitsate,whichcorrespondstothehighestvalueoftheload-bearingcapacity.Examplesincludelocalbucklingorglobalinstabilityofthestructure;failureofsomesectionsandsubsequenttransformationofthestructureintoamechanism;failurebyfatigue;elasticorplasticdeformationorcreepthatcauseasubstantialchangeofthegeometryofthestructure;andsensitivityofthestructuretoalternatingloads,tofireandtoexplosions.(2)Servicelimitstates,whicharefunctionsoftheuseanddurabilityofthestructure.Examplesincludeexcessivedeformationsanddisplacementswithoutinstability;earlyorexcessivecracks;largevibrations;andcorrosion.Computationalmethodsusedtoverifystructureswithrespecttothedifferentsafetyconditionscanbeseparatedinto:(1)Deterministicmethods,inwhichthemainparametersareconsideredasnonrandomparameters.(2)Probabilisticmethods,inwhichthemainparametersareconsideredasrandomparameters.Alternatively,withrespecttothedifferentuseoffactorsofsafety,computationalmethodscanbeseparatedinto:(1)Allowablestressmethod,inwhichthestressescomputedundermaximumloadsarecomparedwiththestrengthofthematerialreducedbygivensafetyfactors.(2)Limitstatesmethod,inwhichthestructuremaybeproportionedonthebasisofitsmaximumstrength.Thisstrength,asdeterminedbyrationalanalysis,shallnotbelessthanthatrequiredtosupportafactoredloadequaltothesumofthefactoredliveloadanddeadload(ultimatestate).Thestressescorrespondingtoworking(service)conditionswithunfactoredliveanddeadloadsarecomparedwithprescribedvalues(servicelimitstate).Fromthefourpossiblecombinationsofthefirsttwoandsecondtwomethods,wecanobtainsomeusefulcomputationalmethods.Generally,twocombinationsprevail:(1)deterministicmethods,whichmakeuseofallowablestresses.(2)Probabilisticmethods,whichmakeuseoflimitstates.Themainadvantageofprobabilisticapproachesisthat,atleastintheory,itispossibletoscientificallytakeintoaccountallrandomfactorsofsafety,whicharethencombinedtodefinethesafetyfactor.probabilisticapproachesdependupon:(1)Randomdistributionofstrengthofmaterialswithrespecttotheconditionsoffabricationanderection(scatterofthevaluesofmechanicalpropertiesthroughoutthestructure);(2)Uncertaintyofthegeometryofthecross-sectionsandofthestructure(faultsandimperfectionsduetofabricationanderectionofthestructure);(3)Uncertaintyofthepredictedliveloadsanddeadloadsactingonthestructure;(4)Uncertaintyrelatedtotheapproximationofthecomputationalmethodused(deviationoftheactualstressesfromcomputedstresses).Furthermore,probabilistictheoriesmeanthattheallowableriskcanbebasedonseveralfactors,suchas:(1)Importanceoftheconstructionandgravityofthedamagebyitsfailure;(2)Numberofhumanliveswhichcanbethreatenedbythisfailure;(3)Possibilityand/orlikelihoodofrepairingthestructure;(4)Predictedlifeofthestructure.Allthesefactorsarerelatedtoeconomicandsocialconsiderationssuchas：(1)Initialcostoftheconstruction;(2)Amortizationfundsforthedurationoftheconstruction;(3)Costo