土木工程外文翻译钢筋混凝土填充框架结构对拆除两个相邻的柱的响应Word格式文档下载.docx

土木工程外文翻译钢筋混凝土填充框架结构对拆除两个相邻的柱的响应Word格式文档下载.docx

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Acomparativestudyofvarious

commerciallyavailableprograms

inslopestabilityanalysis

文献、资料来源：

ComputersandGeotechnics

文献、资料发表（出版）日期：

2008.8.9

院（部）：

专业：

班级：

姓名：

学号：

指导教师：

翻译日期：

附件一，外文翻译原文及译文

1，文献原文：

Responseofareinforcedconcreteinfilled-framestructuretoremovaloftwoadjacentcolumns

MehrdadSasani_

NortheasternUniversity,400SnellEngineeringCenter,Boston,MA02115,UnitedStates

Received27June2007;

receivedinrevisedform26December2007;

accepted24January2008

Availableonline19March2008

Abstract

TheresponseofHotelSanDiego,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;

Brittlefailure

1.Introduction

Aspartofmitigationprogramstoreducethelikelihoodofmasscasualtiesfollowinglocaldamageinstructures,theGeneralServicesAdministration[1]andtheDepartmentofDefense[2]developedregulationstoevaluateprogressivecollapseresistanceofstructures.ASCE/SEI7[3]definesprogressivecollapseasthespreadofaninitiallocalfailurefromelementtoelementeventuallyresultingincollapseofanentirestructureoradisproportionatelylargepartofit.FollowingtheapproachesproposedbyEllingwoodandLeyendecker[4],ASCE/SEI7[3]definestwogeneralmethodsforstructuraldesignofbuildingstomitigatedamageduetoprogressivecollapse:

indirectanddirectdesignmethods.Generalbuildingcodesandstandards[3,5]useindirectdesignbyincreasingoverallintegrityofstructures.IndirectdesignisalsousedinDOD[2].Althoughtheindirectdesignmethodcanreducetheriskofprogressivecollapse[6,7]estimationofpost-failureperformanceofstructuresdesignedbasedonsuchamethodisnotreadilypossible.Oneapproachbasedondirectdesignmethodstoevaluateprogressivecollapseofstructuresistostudytheeffectsofinstantaneousremovalofload-bearingelements,suchascolumns.GSA[1]andDOD[2]regulationsrequireremovalofoneloadbearingelement.Theseregulationsaremeanttoevaluategeneralintegrityofstructuresandtheircapacityofredistributingtheloadsfollowingseveredamagetoonlyoneelement.Whilesuchanapproachprovidesinsightastotheextenttowhichthestructuresaresusceptibletoprogressivecollapse,inreality,theinitialdamagecanaffectmorethanjustonecolumn.Inthisstudy,usinganalyticalresultsthatareverifiedagainstexperimentaldata,theprogressivecollapseresistanceoftheHotelSanDiegoisevaluated,followingthesimultaneousexplosion（suddenremoval）oftwoadjacentcolumns,oneofwhichwasacornercolumn.Inordertoexplodethecolumns,explosiveswereinsertedintopredrilledholesinthecolumns.Thecolumnswerethenwellwrappedwithafewlayersofprotectivematerials.Therefore,neitherairblastnorflyingfragmentsaffectedthestructure.

2.Buildingcharacteristics

HotelSanDiegowasconstructedin1914withasouthannexaddedin1924.Theannexincludedtwoseparatebuildings.Fig.1showsasouthviewofthehotel.Notethatinthepicture,thefirstandthirdstoriesofthehotelarecoveredwithblackfabric.Thesixstoryhotelhadanon-ductilereinforcedconcrete（RC）framestructurewithhollowclaytileexteriorinfillwalls.Theinfillsintheannexconsistedoftwowythes（layers）ofclaytileswithatotalthicknessofabout8in（203mm）.Theheightofthefirstfloorwasabout190–800（6.00m）.Theheightofotherfloorsandthatofthetopfloorwere100–600（3.20m）and160–1000（5.13m）,respectively.Fig.2showsthesecondfloorofoneoftheannexbuildings.Fig.3showsatypicalplanofthisbuilding,whoseresponsefollowingthesimultaneousremoval（explosion）ofcolumnsA2andA3inthefirst（ground）floorisevaluatedinthispaper.Thefloorsystemconsistedofone-wayjoistsrunninginthelongitudinaldirection（North–South）,asshowninFig.3.Basedoncompressiontestsoftwoconcretesamples,theaverageconcretecompressivestrengthwasestimatedatabout4500psi（31MPa）forastandardconcretecylinder.Themodulusofelasticityofconcretewasestimatedat3820ksi（26300MPa）[5].Also,basedontensiontestsoftwosteelsampleshaving1/2in（12.7mm）squaresections,theyieldandultimatetensilestrengthswerefoundtobe62ksi（427MPa）and87ksi（600MPa）,respectively.Thesteelultimatetensilestrainwasmeasuredat0.17.Themodulusofelasticityofsteelwassetequalto29000ksi（200000MPa）.Thebuildingwasscheduledtobedemolishedbyimplosion.Aspartofthedemolitionprocess,theinfillwallswereremovedfromthefirstandthirdfloors.Therewasnoliveloadinthebuilding.Allnonstructuralelementsincludingpartitions,plumbing,andfurniturewereremovedpriortoimplosion.Onlybeams,columns,joistfloorandinfillwallsontheperipheral

beamswerepresent.

3.Sensors

Concreteandsteelstraingageswereusedtomeasurechangesinstrainsofbeamsandcolumns.Linearpotentiometerswereusedtomeasureglobalandlocaldeformations.Theconcretestraingageswere3.5in（90mm）longhavingamaximumstrainlimitof±

0.02.Thesteelstraingagescouldmeasureuptoastrainof±

0.20.ThestraingagescouldoperateuptoaseveralhundredkHzsamplingrate.Thesamplingrateusedintheexperimentwas1000Hz.Potentiometerswereusedtocapturerotation（integralofcurvatureoveralength）ofthebeamendregionsandglobaldisplacementinthebuilding,asdescribedlater.Thepotentiometershadaresolutionofabout0.0004in（0.01mm）andamaximumoperationalspeedofabout40in/s（1.0m/s）,whilethemaximumrecordedspeedintheexperimentwasabout14in/s（0.35m/s）.

4.Finiteelementmodel

Usingthefiniteelementmethod（FEM）,amodelofthebuildingwasdevelopedintheSAP2000[8]computerprogram.ThebeamsandcolumnsaremodeledwithBernoullibeamelements.BeamshaveTorLsectionswitheffectiveflangewidthoneachsideofthewebequaltofourtimestheslabthickness[5].Plastichingesareassignedtoallpossiblelocationswheresteelbaryieldingcanoccur,includingtheendsofelementsaswellasthereinforcingbarcut-offandbendlocations.Thecharacteristicsoftheplastichingesareobtainedusingsectionanalysesofthebeamsandcolumnsandassumingaplastichingelengthequaltohalfofthesectiondepth.ThecurrentversionofSAP2000[8]isnotabletotrackformationofcracksintheelements.Inordertofindtheproperflexuralstiffnessofsections,aniterativeprocedureisusedasfollows.First,thebuildingisanalyzedassumingallelementsareuncracked.Then,momentdemandsintheelementsarecomparedwiththeircrackingbendingmoments,Mcr.Themomentofinertiaofbeamandslabsegmentsarereducedbyacoefficientof0.35[5],wherethedemandexceedstheMcr.Theexteriorbeamcrackingbendingmomentsundernegativeandpositivemoments,are516kin（58.2kNm）and336kin（37.9kNm）,respectively.Notethatnocrackswereformedinthecolumns.Thenthebuildingisreanalyzedandmomentdiagramsarere-evaluated.Thisprocedureisrepeateduntilallofthecrackedregionsareproperlyidentifiedandmodeled.

Thebeamsinthebuildingdidnothavetopreinforcingbarsexceptattheendregions（seeFig.4）.Forinstance,notopreinforcementwasprovidedbeyondthebendinbeamA1–A2,12inchesawayfromthefaceofcolumnA1（seeFigs.4and5）.Tomodelthepotentiallossofflexuralstrengthinthosesections,localizedcrackhingeswereassignedatthecriticallocationswherenotoprebarwaspresent.FlexuralstrengthsofthehingesweresetequaltoMcr.SuchsectionswereassumedtolosetheirflexuralstrengthwhentheimposedbendingmomentsreachedMcr.

Thefloorsystemconsistedofjoistsinthelongitudinaldirection（North–South）.Fig.6showsthecrosssectionofatypicalfloor.Inordertoaccountforpotentialnonlinearresponseofslabsandjoists,floorsaremoldedbybeamelements.JoistsaremodeledwithT-sections,havingeffectiveflangewidthoneachsideofthewebequaltofourtimestheslabthickness[5].Giventhelargejoistspacingbetweenaxes2and3,tworectangularbeamelementswith20-inchwidesectionsareusedbetweenthejoistandthelongitudinalbeamsofaxes2and3tomodeltheslabinthelongitudinaldirection.Tomodelthebehavioroftheslabinthetransversedirection,equallyspacedparallelbeamswith20-inchwiderectangular