一种新的方式通过和半透过拱桥设计吊带毕业论文外文翻译Word下载.docx
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一种新的方式通过和半透过拱桥设计吊带毕业论文外文翻译Word下载.docx
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Anewwaytodesignsuspendersforthroughandhalf-througharchbridges
R.J.Jiang,Y.Y.Chen,Q.M.Wu,W.M.GaiandD.M.PengShenzhenMunicipalDesign&
ResearchInstitute,Shenzhen,China
1ABSTRACT
Itiswell-knownthat,inthroughandhalf-througharchbridges,thesuspendersareimportantcomponentssincetheyconnectthebridgedecktothearchribs.Thecollapseofbridgedeckorarchribsmaybeinducedonceoneormoresuspendersarebroken.Inthispaper,thetraditionaldesignwayofthesuspendersinthroughandhalf-througharchbridgesisdiscussedfirst.Basedonthediscussion,anewwaytodesignsuspendersforarchbridgesisthenputforward.Thereasonabilityofthisnewwayisprovedbynumericalanalysisexamples.TheimpacteffectoftheremainingcomponentsofthearchbridgeduetothebreakageofoneormoresuspendersisobtainedbyappropriatesimulationusingthecomprehensivecommercialsoftwareANSYS.Itcanbeconcludedfromtheanalysisinthispaperthatthenewwaytodesignthesuspendersforthethroughandhalf-througharchbridgescanassurethesafetyofthebridgeeffectivelyeventhoughoneormoresuspendershappentobreak.
2INTRODUCTION
Withtherapiddevelopmentofnewmaterialsandconstructiontechnologies,themodernarchbridgesarenowenteringanewera.Thespanlengthofthemodernarchbridgesisincreasing,andthefirsttwolongestmodernarchbridgesaretheChaotianmenYangtseRiverBridgeandtheLupubridge,respectively.TheChaotianmenYangtseRiverBridgebuiltin2008isatiedsteeltrussarchbridgewithaspanlengthof552m;
andtheLupuBridgebuiltin2003isasteelboxarchbridgewithacentralspanlengthof550m.Theyarebothhalf-througharchbridgesandrespectivelylocatedinChongqingandShanghai,China.Archbridgescanbeclassifiedintothreecategoriesaccordingtotherelativepositionsbetweenthedeckandthearch:
deck-archbridge,half-througharchbridgeandthrougharchbridge(ChengJ.etal.2003).Forbothhalf-througharchbridgeandthrougharchbridge,thesuspendersaretheimportantcomponentssincetheyconnectthebridgedeckwitharchribsandtransferkindsofloadsfrombridgedecktoarches,andfinallytofoundation.However,atthesametimetheyarethevulnerablememberstobedamagedorruined,becausetheyusuallyworkbothinformidablenaturalenvironmentandunderfatigue-inducedcyclingloads(LiD.S.etal.2007).Itisafactthattheservicelifeofthesuspenderismuchshorterthanthatofthearchbridge,andthesuspendersmustbereplacedtimely(TangH.C.2005).Thedamagetothebridgedeckorarchesmaybeinducedwhenoneormoresuspendersbreak,sometimes,eventhecollapseofthearchbridgemayhappen.Inrecentyears,theaccidentsofarchbridges’collapsecausedseverecasualtiesandhugeeconomicloss(LiD.S.andOuJ.P.2005).Inordertoknowwellaboutthehealthconditionofsuspenders,kindsofrealtimemonitoringanddiagnoseswereconducted(LiD.S.etal.2007).However,boththetechnologiesandthematerialsforstructuralhealthmonitoringanddiagnosearenotfullydevelopeduptonow(LiH.N.etal.2008).Inthispaper,thetraditionaldesignwayofsuspendersinthroughandhalf-througharchbridgesisdiscussedfirst.Basedonthediscussion,anewwaytodesignthesuspendersinthroughandhalf-throughmodernarchbridgesisthenputforward.Withtheapplicationofthisnewway,thearchbridgewillremainsafeeventhoughoneormoresuspendershappentobreak.Thisnewdesignwayisadifferentmethodfromthehealthmonitoringtocontrolthesafetyofthemodernarchbridgesundertheconditionthatthebreakofthesuspenderisuncontrollable.Thereasonabilityandreliabilityofthisnewwayisstudiedandprovedbyanumericalanalysisexamplebasedonarealthrougharchbridge.TheimpacteffectoftheremainingcomponentsofthearchbridgeduetothebreakageofoneormoresuspendersisobtainedbyappropriatesimulationusingthecomprehensivecommercialsoftwareANSYS.Itcanbeconcludedfromtheanalysisinthispaperthatthenewwaytodesignthesuspendersinmodernarchbridgescanassurethesafetyofthebridgeeffectivelyeventhoughoneormoresuspendershappentobreak.
3DISCCUSIONONTRADITONALDESIGNOFARCHBRIDGESUSPENDERS
Forthrough-typeandhalf-through-typearchbridges,thesuspendersareanchoredtoarchribsatoneendandtransversebeamsattheother.Generallyspeaking,inthetraditionalarchbridgedesignthedouble-suspenderanchorage(Fig.1)insteadofthesingle-suspenderanchorageiswidelyadoptedinordertokeepthearchbridgestillsafeandmakethereplacementofthesuspendersmoreconvenientwhenonesuspenderhappenstobreak.
Figure1:
Double-suspenderanchoragetraditionallydesigned:
(a)Paralleldouble-suspenderanchorage,(b)Inclineddouble-suspenderanchorage
However,thetwosuspendersatthesameanchorageareusuallydesignedasthesamebothinmaterialandcrosssections;
i.e.,,E1=E2,A1=A2andθ1=θ2,whereE,Aandθaretheelasticmodulus,crosssectionareaandinclinedanglesofthesuspender,respectively.Thatmeanstheyhavethesameorsimilarstressandvariationofstressinservice.Theyarealsounderthesameorsimilarcorrosionenvironmentsincetheyarelocatedatthesameanchorage.Hereby,itcanbeconcludedthatthetwosuspendersatthesameanchoragewillfailatthesameorsimilartimebecauseofthealmostequallevelofbothfatigueloadandcorrosionenvironment.Basedonthediscussionabove,itcanbeseenthatthedouble-suspendersystemdesignedinthetraditionalwaywillnotimproveboththesafetyofthearchbridgeandtheconvenienceofsuspendersreplacementcomparedtothesingle-suspendersystem.
4ANEWWAYTODESIGNARCHBRIDGESUSPENDERS
Inordertokeeptheremainingstructureofarchbridgestillsafewhenonesuspenderhappenstobreak,thedouble-suspendersmustbedesignedwithdifferentservicelife.Theonlywaytoachievethisaimistodesignthetwosuspendersatthesameanchoragewithdifferenteithermaterialorcrosssectionareassincetheycarrythesamefatigueloadsandareunderthesamecorrosionenvironment.Ifthetwosuspendersatthesameanchoragearedesignedwithdifferentmaterials,theextrainconveniencebothindesignandconstructionofthearchbridgewillbeinduced.ThebetterwayistomakethetwosuspenderswithdifferentcrosssectionareasAFandAS(Fig.2)respectively.Withdifferentcrosssectionareas,thetwosuspendersatthesameanchoragewillhavedifferentstresslevelsandvariationofstresses,thatistosay,thereareσF,max≠σS,max,σF,a≠σF,a.Σmaxandσaarethemaximumstressandamplitudeofthestressofthesuspenders,respectively.Basedonthebasictheoriesofthematerialfatigue,thematerialormemberhasdifferentserviceliveswithdifferentmaximumstressandstressamplitude.
Figure2:
Double-suspenderanchoragedesignedinnewway:
Thereupon,thetwosuspendersatthesameanchoragemayhavedifferentservicelivesiftheyareappropriatelydesignedwithdifferentcrosssectionareaseventhoughtheyaremadeofthesamematerialandunderthesamefatigueloadsandcorrosionenvironment.Duringtheservicelifeofthearchbridge,thesuspenderwiththelargercrosssectionwillstillkeepthearchbridgesafewhenthesuspenderwiththesmallercrosssectionatthesameanchoragehappenstobreak.Thereasonabilityandreliabilityofthisnewwaytoconsiderthesuspenderdesignwillbeprovedbynumericalcomparisonstudyonatrough-typemodernarchbridge,ShenzhenNorthRailwayStationBridge,usingcomprehensivecommercialsoftwareANSYSinthefollowingsectioninthispaper.
5NUMERICALANALYSISEXAMPLE
5.1DescriptionofShenzhenNorthRailwayStationBridge
ShenzhenNorthRailwayStationBridgewithaspanlengthof150misathrough-typemodernconcrete-filledsteeltubulararchbridge.Itwasbuiltin2000andlocatedattheShenzhenNorthRailwayStation,spanningallrailwaysatthatstation.Rise-to-spanratioofthisbridgeis1/4.5.TheelevationviewofthebridgeisshowninFig.3.Thewidthofthegeneralbridgedeckis23.5mexceptattheendofthearchribswithabridgedeckwidthof28m.Horizontalcablesinthesteelboxgirdersofthebridgedeckareadoptedtobalancethehorizontalforceofthearchribs.Thisbridgehastwoverticalarchribsandeacharchribiscomposedoffourconcrete-filledsteeltubesandthushasatrusscrosssectionof2.0minwidthand3.0minheight.ThematerialpropertiesofthebridgearelistedinTable1.ThemoredetailsaboutthisbridgeisfoundinLietal.(2002).
5.2Finiteelementmodeloftheexamplebridge
Adetailedfiniteelementmodel(Fig.4)oftheexamplebridgewasdevelopedusingthecomprehensivecommercialsoftwareANSYS.Inthis3dimensional(3D)finiteelementmodel,everycomponentisappropriatelymodelled.
Asmentionedabove,eacharchribiscomposedoffourconcrete-filledsteeltubes.Theseconcrete-filledsteeltubesaremodelledbyBEAM4element.Sincetheconcrete-filledsteeltubeisacompositemember,theequivalentcrosssectionalpropertiesandmaterialpropertiesareobtainedfirstbyeditinganAPDLfilebasedonsomeequivalencerules,andthenassigntheseequivalentcrosssectionalpropertiesandmaterialpropertiestothecorrespondingbeamelements.Theequivalentcrosssectionalpropertiesandmaterialpropertiesoftheconcrete-filledsteeltubesarelistedinTable2.
TheBEAM4elementisalsoadoptedtomodelthearchribbracings,thelongitudinalsteelboxgirders,thesteeltubesconnectingthefourconcrete-filledsteeltu
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