68Recent development of bridge in China(final vers

RECENTACHIEVEMENTSINBRIDGEENGINEERINGINCHINABaochunChen*，，，，WenjinHuang***CollegeoffCivilEngineering,FuzhouUniversity,523#GongyeRd.,Fuzhou350002,China*E-mail:[e-mail]**E-mail:[e-mail]:Bridgeengineering,achievement,China,lasttenyearsAbstract:BridgeengineeringinChinahasexperiencedarapiddevelopmentsince1980.RecentachievmentsofbridgeengineeringinChinainthelastdecadearepresentedinthispaper,especiallythelong-spanandlargescalebridges.Chinahasavastterritorywithmanyrivers.Throughouthistory,thousandsofbridgeshavebeenbuilterectedandhighprestigehasbeenachieved,suchasstonearchbridgesandsuspensionfootbridges.Since1980,alongwiththeopeningandreforminChina,economicdevelopmentneedstransportationtogrowahead,whichresultslargescaleconstuctionofhighwayandrail,manylong-spanbridgsandlargescalebridgeengineeringshavebeenbuilt1,2.Bytheendoflastyear,Chinahasmorethan320,000highwaybridgeswithatotallengthof13,376km，inwhich717havealengthover1000m.Valuabletechnicalexperiencesandscientificresearchesbringlotsofachievementsinbridgeengineering,suchasdesignthoery,calculationmethods,constructiontechnology,testingmethods,applificationofnewmaterialsandsupportinginstallations.Thispaperbrieflypresentsanoverviewoftheacheivementsinlong-spanbridge--suspensionbridge,cablestayedbridge,archbridgeandlargescalebridgeinthelasttenyears.1.SUSPENSIONBRIDGEAccordingtohistoricalrecords,bamboocablebridgehasappearedin285B.C.inthesouth-westofChina.Theiron-chainbridgeissaidtodateasfarbackastheearlytimeoftheWesternHanDynasty(B.C.206)andbyaclearhistoricalrecord,anironchainscrossedtheYantzeRiverinA.D.280.From1960to1980,someflexiblesuspensionbridgewithnarrowwidthandsmallspansforlightliveloadswerebuiltinmountainousareas.In1995,ShantouBayBridgeinGuangdongProvincewascompletedasthefirstmodernlong-spansuspensionbridgeinChina.Aprestressedconcreteboxgirderservesasboththebridgeroadwayandthestiffeninggirderforthesuspensionsystem.The452mmainspaninthisbridgeisthelongestspanofasuspensionbridgewithprestressedconcretestiffeninggirdersintheworld.The900mlongXilinYangtzeRiverBridge(Fig.1)wasbuiltin1996forthespecialhighway(loadingof78-tontrucks)fortheThreeGorgesDam.Theall-weldedorthotropicsteelboxgirderwasthefirsttimeselectedasastiffeninggirderinsuspensionbridgeinChina.In1997,theHumenBridge(Fig.2)withamainspanof888mwascompleted,whichisthefirstlong-spansuspensionbridgeinthetyphoon-pronezoneinChina.ThesetwobridgeswithsteelstiffeninggirdersisaremarkthecomingofaneraforlongspanmodernsuspensionbridgeinChina.Afterthat,twosuspensionbridgeswithaspanover1000mwereopentotraffic.In1998,TsingmaBridgeinHongKongwasopenwitha1377mlongmainspan,whichisthelongestdoubledeckbridgeforbothhighwayandrailwaytrafficintheworld.Oneyearlater,in1999,JiangyinYangtzeRiverBridgewitha1385mmainspanoverYangtzeRiverwasthelongestbridgeinChinaandthefourthlongestbridgeintheworldatthattime.Figure1:XilinYangtzeRiverBridgeFigure2:HumenBridgeJiangyinYangtzeRiverBridge(Fig.3)locatedinJiangsuProvince,is3,071mintotallengthanddesignedtothestandardofsix-laneexpressway.Themaincablesaremadeofparallelhigh-strengthwires,whicharegalvanizedandwelded.Sag-to-spanratioofthemaincableis1/10.5andthedistanceoftwocentersofmaincablesis32.5m.Thetotalweightofthetwomaincablesis16,800tons.Withalengthof2,200m,thediameterofthemid-spancableis0.86mwhilethatoftheside-span0.89m.Eachcableconsistsof169buncheseachmadeof127steelwires,eachofwhichis0.00535mindiameter.Thetotallengthofsteelwiresis95,000kilometers.Eachhangercablesspaceby16malongthemaincable.Figure3:JiangyinYangtzeRiverBridgeThemaingirderismadeofflatstreamlinesteelboxgirders,joinedbypre-stressedcontinuousconcretegirdersofthesamedepthintwosidespans.Theboxgirderis32.5mwideand3.02mhigh,withatotalgirderwidthof36.9mincludingthetwocantilevers3.Themaintowerformedbytwotowercolumnsandthreetranversebeamsisareinforcedconcretestructurewithaheightof190m.Sincethenorthbankhasasoilcoveringofover80monbedrock,agravitystructure69.51mlongand51mwidewasselectedfortheanchorage.Asthelargestopencaissonintheworld,itgoesasdeepas58mandtook20monthstocomplete.Thesouthtowerisagravitystruturebuiltonbedrock.Duetothegreatsizeandconstructiondepth,theanchorwasanextremelydifficultsubstructurework.Inordertoreducetheunevensettlementofthecaissonduringconstrution,the5mwideconcretemassbehindtheanchoragewasnotpoureduntiltheerectionofthestiffeninggirderswascompleted.(a)Constructionofthecatwalk(b)ErectionofstiffeninggirdersFigure4:ConstructionofJiangyinYangtzeRiverBridgeConstructionofJiangyingBridgebeguninAugust,1994andwascompletedinSeptember,1999.About74,900tonsofsteeland453,000tonsofconcretewereusedinthebridgeandthetotalcostofthebridgewasUSD＄330million.Theheightclearancefornavigationis50mfor50,000-tonnagevessels.Inthelastyear,2005,RunyangYangtzeRiverBridgeEngineeringwascompleted,whichconsistsofsixcomponents,inludingnorthlinkroad,BeichaBridge,ShiyezhouInterchangeBridge,NanchaBridge,southlinkroadandextensionpartengineering.TheNanchaBridgeisasuspensionbridgewithamainspanof1490m,rankingfirstinChinaandthirdintheworld(Fig.