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Wind

    Wind

    Vo1.18No.2JournalofSouthwestJiaotongUniversity(EnglishEdition)Apr.2010 ;ArticleID:10052429(2010)02-0112-06

    ;WindTunnelTestontheWind-ResistantBehaviorof

    ;aLong--SpanCable--StayedBridgeduringErection

    ;MACunming(马存明),LIAOHaili(廖海黎),TAOQi(陶奇)

    ;ResearchCentreforWindEngineering,So~hwestJiaotongUniversity,Chengdu610031.China ;Abstract

    ;InordertoinvestigatetheaerodynamicbehavioroftheSutongbridgeoverYangtzeRiverduringerection,

    a1:50sectional

    ;modelofthebridgedeck.al:100fullaeroelasticmodelofthefreestandingpylonanda1:125fullaeroelasti

    cmodelforthemaxilll

    ;cantileverconfigurationwerebuilt.Thetestresultsshowthattherewasnoseriousvortexinducedvibra

    tionatthebridgedeck.and

    ;thatthefreestandingtower.themodelscaleandtheturbulenceintensityinfluencedstaticloading.Thebuf

    fetingresponsesduring

    ;themaximumcantileverconfigurationdidnotaffectthesafetyofthebridgeunderconstruction.

    ;KeywordsCablestayedbridge;Erectionstage;Aerodynamicbehavior;Windtunneltest ;Introduction

    ;Long?spancable-stayedbridgesaresusceptibleto

    ;dynamicwindactions,andthustheiraerodynamic

    ;stabilityduringservicinganderectionhasrecentlyre

    ;ceivedconsiderableinterest.Thedesignwindspeed

    ;ofbridgesduringerectionissmallerthanthatafter

    ;bridgeconstruction.Thestiffnesslossofthebridges

    ;intheerectionphasereducesthetorsionalandvertical

    ;naturalfrequencies,andconsequently,theaerody

    ;namicstabilitylimit.Itiscommonlyacknowledged

    ;thaterectionstageisoftenlessfavorabletotheaero

    ;dynamicstabilityoflong-spancable--stayedbridges

    ;comparedtothecompletedstate.

    ;Todate,comprehensiveinvestigations[]have

    ;identifiedsomeimportantfactorsgoverningtheaero

    ;dynamicstabilityofsuspensionbridgesduring

    ;erection,includingdynamiccharacteristics,structural

    ;ReceivedNov.27,2009;revisionacceptedJan.22,2010

    ;FoundationitemsTheNafionalNaturalScienceFoundation

    ;ofChina(Nos.50808148and90815016)

    ;Correspondingauthor.Te1.:+86-28-87601843;Email:

    ;mcm@swjtu.edu.cn

;stiffnessanddamping,finitedecklength,erectionse

    ;quence,theprovisionofeccentricmassandartificial ;dampers,etc.Thewindresistantbehaviorofthesu

    ;perlongcablestayedbridgesduringerection,howev

    ;er,lacksthoroughinvestigation.

    ;Inthispaper,wepresentthemainresultsofwind ;tunneltestsONasectionalmodelandthefullaeroelastic ;modelsoftheSutongBridgeatthefreestandingpylon ;stageandthemaximumcantileverstage. ;1IntroductiontoSutongBridge

    ;TheSutongBridge,locatedatNantong,Jiangsu ;Province,China,istheworld’slongestcable—stayed

    ;bridgewithacenterspanof1088m.Initserec

    ;tionstage,thecantilevermethodwasusedandthe ;girderstretchedasmuchas540matmid?spanside ;beforetheclosingofthecenterspan(seeFig.1). ;Here,thewindresistantpropertiesofthebridge ;inerectionstageincludingvo~exinducedoscillation,

    ;flutter,buffeting,etc.,wereinvestigatedcomprehen

    ;sivelywithan1:50sectionalmodelofthebridge ;deck,an1:100fullaeroelasticmodeloffreestanding ;pylonandan1:125fullaeroelasticmodelforthe ;maximumcantileverstage.

    ;MACunmingeta1./WindTunnelTestontheWindResistantBehaviorofaLongSpanCableStayed...113

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    ;一誊.

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    ;.,;

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    ;Fig.1GeneralviewofSutongBridgeunderconstmcfion(unit:cm)

    ;Thetestsofthebridgedecksectionmodelwere ;conductedintheXNJD.1windtunne1.Thefu11aero

    ;elasticmodelsforfreestandingpylonandthemaxi

    ;mumcantileverstageweretestedintheFL13tunne1.

    ;BothtunnelsarelocatedatChinaAerodynamicsRe ;searchandDevelopmentCene.

    ;2SectionalModel

;Ageometricalscaleof1:50waschosentosimu

    ;(a)

    ;latethedetailsofthegirder.andtoyieldthemaxi

    ;mumblockagelessthan4%.Generally.theblockage ;shouldbelessthan5%forthewindtunneltesting. ;Thelengthofthemode1Lis2.1m.thewidthB

    ;0.6mandthedepthH0.0585m.Theratioof

    ;lengthtowidthis3.5,greaterthan2.5,whichsaris- ;tiestheminimumrequirementE10.Fig.2showsthe

    ;modelinthewindtunne1.

    ;(b)

    ;Fig.2The1:50sectionalmodelinwindtunnel ;2.1Vortex.inducedvibration

    ;Theobjectiveofthevortexinducedvibrationtestis

    ;todeterminetheonsetwindspeedatwhichthevortexin-

    ;ducedvibrationaroundthedeckoccllrsduringerection. ;Table1summarizestheonsetwindspeedforvor- ;texinducedresonanceduringerection.InTable1.UF ;denotesuniformflowandTFturbulentflow.Whenthe ;,vindattackanglewas+3..torsionalvibrationwasob- ;served.Inothercases,novortexvibrationwasfound. ;Thevortex-inducedresponsevaryingwithwind ;speedfordifferentdampinglevelsanddifferentflow ;typesisshowninFig.3.Itwasfoundthatthestruc

    ;turaldampingcallmitigatethevortexresponse,and ;themaximumamplitudesofresponseswerelessthan ;thosedesignedinChinesecode[...Thissuggeststhat ;SutongBridgewasnotaffectedbyanyseriousvortex

    ;inducedvibrationduringerection.

    ;Table1Parametersandonsetwindspeedsm/s ;Note:Theverticalfrequencyis0.3759Hz;thetorsionalfie- ;quencyis0.9814Hz;/ft=2.61;theunitmassis37.86t/m;the ;rotationalinertiaperunitlengthis5338.41t?m./m;thealong.wind

    ;turbulenceintensityis0.055.

    ;建一?Tl_..,......?...000n

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    ;0.025

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    ;JournalofSouthwestJiaotongUniversity(EnglishEdition) ;01O2O3O40

    ;Windspeed/(m’S)

    ;(a)Uniformflow

;OlO2O3040

    ;Windspeed/(m?s-1)

    ;(b)Turbulenceflow

    ;Fig.3Tortionalvortex-inducedresponseduring ;themaximumcantilevererection

    ;2.2Staticforces

    ;Themeanstaticforces,reflectingthesteady ;windeffectsonbridgedecks,areusuallyexpressed ;bydimensionlessforcecoefficients.Thestaticwind ;forcesactingonabridgedecksectioncanbedefined ;inbodycoordinatesystem(xoy)orwindcoordinate ;system(oy)(seeFig.4).

    ;Inthewindcoordinatesystem,threeforcecoef- ;ficients(drag,rift,andmoment)aredefinedas: ;C.()=

    ;CL(O1)=

    ;2FD(O1)

    ;pU2HL’

    ;2FL()

    ;pUZBL’

    ;c)=

    ;whereOtistheattackangleoftheincomingflow;Uis ;thewindspeed;Pistheairdensity;FD(),FL(O/) ;andMz()aredrag,lift,andmomentonthedeck ;inthewindcoordinatesystem,respectively.Trans

    ;formingFH()andFv()inthebodycoordinate ;systemintoFD()andFL(),thedragcoefficient ;CH()andliftcoefficientCv()canbecalculated. ;Notethatthemomentcoefficientskeepunchangedfor ;thebothcoordinatesystem.

    ;Fig.4Definitionofwindloadingandcoordinatesystem ;Toinvestigatethepossibleeffectofwindcharac- ;teristics.b0ththeuniforillflowandturbulentflow ;weretested.ThedragcoefficientsCD,lifccoefficients ;CIandmomentcoefficientsCMvaryingwiththe ;attackanglesaregiveninFig.5,wherethecoeffi

    ;cientstestedinturbulentflowdiffermuchfromthose ;inuniforlTlflow.

    ;2.O

    ;1.5

    ;1.O

    ;0.5

    ;0.0

    ;

;0.5

    ;.

    ;1.0

    ;(a)Uniformflow

    ;-

    ;10.50

    ;Attackangleofwind

    ;(b)Turbulentflow

    ;Fig.5Forcescoeffici

    ;Ageometricalscale1:100waschosentosimu

    ;latetherequireddetailsandtoyieldablockageofless ;than1%.Thefullbridgemodelwasdesignedand ;manufacturedusingtheconventionalaeroelasticmodel ;technology.Thus,thestructuralstiffnesswasprovid

    ;edbyametalspineassembly:theexternalshapeby ;claddingelementsandmassbylumpingcomplimenta

    ;ryballastelementsinthecladdingstructure.Withthis ;technology,theexternalstructuraldisplacementswere ;measuredusingdisplacementoraccelerationtransduc

    ;ers,andsectionalforcesweremeasuredusingstrain ;gaugesattachedtothespinestructure. ;Twotypicalerectionstageswereselected:free ;standingpylon(CaseI)andfreestandingpylon ;withaMD3600crane(Case1/),asshownin ;Fig.6.ThemodelparametersarelistedinTable2. ;(a)CaseI

    ;(b)Case1/

    ;Fig.6Fullaeroelasficmodeloffreestand

    ;ingpylon

    ;Table2Parametersoffullaeroelasticmodelforfreestandingpylon

    ;Note:windspeedratiois1:6

    ;Fig.7showsthedynamicdisplacementsatdiffer

    ;entwindspeeds,whereyawanglevariesfrom0.to ;90.andthedamperratiois0.5%.Intests.vortex

    ;inducedvibrationswereidentifiedwhentheincoming ;flowwasalongbridge,yawanglewas0.andtheon- ;setwindspeedwas14.2rn/s.Therewasnoexplicit ;vortexinducedvibrationwhenyawanglesvariedfrom ;15.to90..IftheMD3600cranewasconsidered.the ;vibrationwasreduced.

    ;Fromthewindtunne1tests.theStrouhalnumber ;ofpyloniscalculated

    ;LD0.1498×(9to15)==

    ;l4.20.095to0.158,(2)

    ;where,visthevibrationfrequency;Disthewidthof ;thepyloncolumn(9isthewidthofupperpyloncol

    ;umnand15isthewidthoflowerpyloncolumn). ;ThisvalueisconsistentwiththeStrouhalnumberof ;thesquaresectioninRef.[2].Toinvestigatethe ;effectofwindturbulence,theturbulentwindfield ;wassimulatedwithspires,fencesandroughness ;cubes.Fig.8showsthemeanspeedprofileandturbu

    ;lentintensityprofile.Theturbulenceintensityinthe ;testwas50%ofthatrequiredinthecode~... ;Fig.9showstheeffectofthedamperratioand ;turbulenceintensity.Thevortexvibrationisstrongly ;affectedbythedamperratioandturbulenceintensity. ;4

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    ;400

    ;go0

    ;200

    ;100

    ;0

    ;500

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    ;2oo

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    ;JournalofSouthwestJiaotongUniversity(EnglishEdition) ;Ol0203040506001020304050

    ;Windspeed/(m’S)Windspeed/(m?S.)

    ;(a)CaseI(b)Case1/

    ;Fig.7Dynamicdisplacementsatvaryingwindspeedswithdifferentyawangles

    ;60

    ;8.O8.59.09.510.010.511.011.512.0468101214 ;Windspced/(m?s,)Turb1.nti.”ity/%

    ;(a)(b)

    ;Fig.8Meanwindspeedandturbulenceintensityprofile ;9

    ;300

    ;200

    ;100

    ;0

    ;IOIII2I3I4I5048I2I620

    ;Windspeed/(m.S’)Windspeed/(m?s’)

    ;(a)Uniformflow(b)Turbulentflow

;Fig.9Dynamicdisplacementswithdifferentdamperratios

    ;FullAeroelasticModelTestduring ;MaxinlumCantileverCon

    ;Oneofthemostconcernsforthebridgeduring

    ;erectionisthebuffetingresponseatitsmaximumcantile?

    ;verstage.Fig.10showsthebuffetingresponsewithvar

    ;yingwindspeodatdifferentdampinglevels.

    ;Itwasfoundthatthestructuraldampingcanmifi

    ;gatethebuffetingresponse,andthemaxinltlmampli

    ;tudesofresponseswerelessthanthoseprescribedby

    ;codes.ItmeansthatSutongBridgeWasnotaffectedby

    ;seriOUSvibrationduringerection. ;?o

    ;q\?

    ;O5O5O5O

    ;3221lOO

    ;uv

    ;5O5O5O5O

    ;332211OO

    ;m/}{

    ;600

    ;500

    ;400

    ;300

    ;200

    ;1O0

    ;0

    ;300

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    ;0

    ;MACunmingeta1./TunnelTestontheWind?ResistantBehaviorofaLonganCable—Stayed…11

    7

    ;l520253O354O455055

;Windspeed/(m?s-1)

    ;(a)

    ;152O2530354O455O55

    ;Windspeed/(m?s-1)

    ;(b)

    ;l52025303540455O55

    ;Windspeed/(m?s-1)

    ;(c)

    ;Fig.10Buffetingresponseswithdifferentdampinglevelsdur- ;ingthemaximumcantileverconfiguration

    ;(1)Althou~explicitvortexinducedvibrationwas

    ;observedinthesectionmodelatlowwindspeeds,theam- ;plitudeofthevortexinducedvibrationwasverysmal1.Se- ;riousvortexinducedvibrationdidnotoc,curforthebridge. ;(2)Explicitvortexinducedvibrationwasob

    ;servedatthecompletedfreestandingtowerinsmooth ;flow.Structuraldampingandwindturbulencecan ;mitigatethevortexinducedvibration.

    ;(3)Themodelscaleandturbulenceintensity ;hadeffectsonstaticloading.Thedragcoefficients ;decreasedwiththemodelscaleandwiththeincrease ;inturbulenceintensity.

    ;(4)Thebuffetingresponseduringitsmaximum ;cantileverstagedidnotaffectthebridgesafetyduring ;erection.

    ;References

    ;[1]ZhuLD,WangM,WangDL,eta1.Flutterandbuffe

    ;tingperformancesofThirdNanjingBridgeoverYangtze ;Riverunderyawwindviaaeroelasticmodeltest.Journal ;EngineeringandIndustrialAerodynamics,2007, ;95(911):15791606.

    ;[2]ZuoDL,NicholasPJ.Wmdtunneltestingofyawedand ;inclinedcircularcylindersinthecontextoffieldobservations ;ofstaycablevibrations.JournalofWindEngineeringand ;IndustrialAerodynamics,2OO9,97(5-6):219--227. ;[3]NiYQ,WangxY,ChenZQ,eta1.Fieldobservations ;ofrain-?wind??inducedcablevibrationincable-?stayed ;DongtingLakeBridge.JournalofWindEngineeringand ;IndustrialAerodynamics,2007,95(5):303-328. ;[4]BrancaleoniF.Theconstructionphaseanditsaerodynam- ;icissues.AerodynamicsofLargeBridges,Balkema,Rot

    ;terdam,FL,1992:7158.

    ;[5]TanakaH,GimsingNJ.Aerodynamicstabilityofnon- ;symmetricallyerectedsuspensionbridgegirders.Journal

    ;ofWindEngineeringandIndustrialAerodynamics,1999, ;80(1):85104.

    ;[6]LarsenA.Aerodynamicaspectsofthefinaldesignofthe ;l624msuspensionbridgeacrosstheGreatBelt.Journal ;wiEngineeringandIndustrialAerodynamics,1993, ;48(2-3):261-285.

    ;[7]delAreoDC,AparicioAC.Improvingsuspensionbddge ;windstabilitywithaerodynamicappendages.Journalof ;StructuralEngineering,1999,125(12):13671375.

    ;[8]GeYJ,TanakaH.Aerodynamicstabilityoflongspan

    ;suspensionbridgesundererection.JournalofStructural ;Engineering,2000,126(12):14041412.

    ;[9]MaCM,LiaoHL,LiMS.Windtunnelinvestigationon ;windresistantpropertiesofSutongBridgeduringerectionsta- ;ges.Chengdu:ResearchCentreforWmdEngineering,2O06. ;[1O]JTG/T1360-01-2004,Windresistancedesigncodefor ;highwaybridges,2004(inChinese).

    ;(Editor:ZHOUYao)

    ;m/0q1lBl口眦/u0一节【qI8>日叽,g.T_.一馨

    ;

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