精品土木工程桥梁外文翻译跨越世纪之桥定.docx
- 文档编号:3958095
- 上传时间:2022-11-26
- 格式:DOCX
- 页数:11
- 大小:30.30KB
精品土木工程桥梁外文翻译跨越世纪之桥定.docx
《精品土木工程桥梁外文翻译跨越世纪之桥定.docx》由会员分享,可在线阅读,更多相关《精品土木工程桥梁外文翻译跨越世纪之桥定.docx(11页珍藏版)》请在冰豆网上搜索。
精品土木工程桥梁外文翻译跨越世纪之桥定
中文4735字
毕业设计
外文翻译
题目跨越世纪之桥
专业土木工程(桥梁)
ABridgeForAllCenturies
Anextremelylong-andrecordsetting-mainspanwasdesignedforthesecondbridgetoacrossthePanamaCanalinordertomeettheowner’srequirementthatnopiersbeplacedinthewater.Becausenodisruptionofcanaltrafficwaspermittedatanytime,thecable-stayedbridgeofcast-in-placecancretewascarefullyconstructedusingthebalanced-cantilevermethod.
In1962,theBridgeofAmericas(PuentedelasAmerica)openedtotraffic,servingastheonlyfixedlinkacrossthePanamaCanal.Thebridgewasdesignedtocarry60,000vehiclesperdayonfourlanes,butithasbeenoperatingaboveitscapacityformanyyears.Toalleviatebottlenecksontheroutethatthebridgecarriesoverthecanal-thePan-AmericanHighway(Inter-AmericanHighway)-andpromotegrowthonthewesternsideofPanama,thecountry’sMinistryofPublicWorks(MinisteriodeObrasPublicas,orMOP)decidedtobuildanewhighwaysystermlinkingthenorthernpartofPanamaCity,ontheeasternsideofthecanal,tothetownofArraijan,locatedonthewesternsideofthecanal.TheCentennialBridge–namedtocommemorate100yearsofPanamanianindependence-hasnoebeenconstructedand,whenopend,willcarrysixlanesoftraffic.Thiscable-stayedbridgeofcast-in-placecancretefeaturesamainspanof420m,thelongestsuchspanforthistypeofbridgeintheWesternHemisphere.
In200theMOPinvitedinternationalbridgedesignfirmstocompeteforthedesignofthecrossing,requestingatwo-packageproposal:
onetechinical,theotherfinancial.AtotalofeightproposalswerereceivedbyDecember2000fromestablishedbridgedesignfirmsallovertheworld.Aftershort-listingthreefirmsonthebasisofthetechnicalmeritsoftheirproposals,theMOPselectedT.Y.LinInternational,ofSanFrancisco,topreparethebridgedesignandprovidefieldconstructionsupportbasedonthefirm’sfinancialpackage.
TheCentennialBridgedesigeprocesswasuniqueandaggressive,incorporatingconceptsfromthetraditionaldesign/build/bidmethod,thedesign/buildmethod,andthesa-calledfast-trackdesignprocess.Tocompletetheconstructionontime-thatis,withinjust27months-thedesignofthebridgewascarriedouttoalevelof30percentbeforeconstructionbiddingbegan,inDecember2001.Theselectedcontractor-theWiesbaden,Germany,officeofBilfingerBerger,AG-wasbroughtonboardimmediatelyafterbeingselectedbytheMOP,justaswouldbethecaseinafast-trackapproach.Thedesigeofthebridgewasthencompletedinconjunctionwithconstruction,aprocessthatidsimilantodesige/build.
Thedesignselectedbytheclientfeaturestwosingle-masttowers,eachsupportingtwosetsofstaycablesthataligninoneverticalplane.Concretewasusedtoconstructboththetowersandtheboxgirderdeck,aswellastheapproachstructures.
TheMOP,inconjunctionwiththePanamaCanalAuthority,establishedthefollowingrequirementsforthebridgedesign:
A420m,theminimumlengthforthemainspantoaccommodatetherecentlywidenedGaillardCut,anarrowportionofthecanalcrossingtheContinentalDividethatwasstraightenedandwidenedto275min2002;
Anavigationalenvelopeconsistingof80mofverticalclearanceand70mofhorizontalclearancetoaccommodatethesafepassageofacraneofWorldWar11vintage-agiftfromtheU.S.governmentthatisusedbythePanamaCanalAuthoritytomaintainthecanalgatesandfacilities;
Aroadwaywideenoughtocarrysixlanesoftraffic,threeineachdirection;
Adeckabletoaccommodatea1.5mwidepedestrianwalkway;
AdesignthatwouldadheretotheAmericanAssociationofStateHighwayandTransportationOfficialstandardfora100-yearservicelifeandofferHS-25truckloading;
Astructurethatcouldcarrytwo0.6mdianeterwaterlines;
Aconstructionmethodthatwouldnotcrossthecanalatanytimeorinterruptcanaloperationainanyway.
Becauseofthebridge’slongmainspanandthepotentialforstrongseismicactivityinthearea,nosinglebuildingcodecoveredallaspectsoftheproject.ThereforetheteamfromT.Y.LinInternationaldetermindedwhichportionsofseveralstandardbridgespecificationswereapplicableandwhichwerenot.Thefollowingdesigncodeswereusedindevelopingthedesigncriteriaforthebridge,itisstandardspecificationsforhighwaybridge,16thed,1996
Itwasparamountthatthetowersofthecable-stayedstructucturebeerectedonlandtoavoidpotentialshipcollisionandtheneedtoconstructexpensivedeepfoundationinwater.However,geologicalmapsandboringlogsproducedduringthepreliminarydesignphraserevealedthattheeastandwestbanksofthecanal,wherethetowersweretobelocated,featuredvastlydifferentgeologicalandsoilconditions.Ontheeastsideofthecanal,beneathshallowlayersofoverburdenthatrangsinconsistencyfromsofttohard,liesablockofbasaltrangingfrommediumhardtohardwithverycloselyspacedjoint.Theengineersdeterminedthatthebasaltwouldprovideacompetentplatformfortheconstructionofshallowfoundationfortower,piers,andapproachstructuresonthissideofbridge.Thewestside,however,featuredtheinfamousCucarachaFormation,whichisaheterogeneousconglomerateofclayshalewithinclusionsofsandstone,basalt,andashthatispronetolandslide.AsasudsurfacestratumtheCucarachaFormationisquitestable,butitquicklyerodeswhenexposedtotheelements.Theengineersdeterminedthatdeepfoundationswouldthereforebeneededforthewesternapproachstructure,thewesttower,andthewesternpiers.
Beforeadetaileddesignofthefoundationacouldbedeveloped,athoroughanalysisoftheseismichazardsatthesitewasrequired,Thedesignseismicloadfortheprojectwasdevelopedonthebasisofaprobabilisticseismichazardassessmentthatconsideredtheconditionsatthesite.Suchanassessmentestablishesthereturnperiodforagivenearthquakeandthecorrespondingintensityofgroundshakinginthehorizontaldirecttionintermsofanaccelerationresponsespectrum.ThePSHAdeterminedtwodominantseismicsources:
asubductionsourcezoneassociatedwiththeNorthPanamaDeformedBeltcapableofproducingaseimiceventasstrongas7.7MW,andtheRioGatunFault,capableofproducinganeventasstrongas6.5MW.
The7.7MWNPDBeventwasusedasthesafetyevluationearthquake,thatis,themaximumearthquakethatcouldstrikewithoutputtingthebridgeoutofservice.Thedamagetothebridgewouldbeminorbutwouldrequiresomeclosuresofthebridge.The6.5MWRioGatunFaulteventwasusedasthefoundationalevaluationearthquake,alower-leveltemblorthatwouldcauseminimaldamagetothebridgeandwouldnotrequireclosures.FortheFEEloadcase,theSEEloadingwasscaledbackbytwo-thirds.TheFEEisassumedtohaveapeakaccelerationof0.21gandareturnperiodof500years;theprobabilitythatitwillbeexceededwithin50yearsis10pencentandwithin100years,18persent.TheSEEisassumedtohaveapeakaccelerationof1.33gandareturnperiodof2,500years;theprobabilitythatitwillbeexceededwithin50yearsis2pencentandwithin100years,4persent.
Becauseofuncertaintyaboutthedirectionfromwhichtheseismicwaveswouldapproachthesite,asingleresponsespectrum-acurveshowingthemathematicallycomputedmaximumresponseofasetofsimpledampedharmonicoscillatorsofdifferentnaturalfrequenciestoaparticularearthquakegroundacceleration-wasusedtocharacterizemitionsintwomutuallyorthogonaldirectionsinthehorizontalplane.Toconductatime-historyanalysisofthebridge’smultiplesupports,asetofsyntheticmotionswiththreecomponents-longitudinal,transverse,andvertical-wasdevelopdusinganiterativetechnique.RecordedgroundmotionsfromanearthquakeinChilein1985wereusedas“seed”motionsforthesythesisprocess.
Atimedelayestimate-thatis,anestimateofthetimeitwouldtakeforthemotionsgeneratedbytheSEEandFEEearthquakestotravelfromonepointtothenext-wascreateusingtheassumedseismicwavevelocityandthedistancebetweenthepiersofthebridge.Usinganassumedwasvelocityofapproximately2.5km/s,adelayontheorderofhalfasecondtoasecondisappropriateforabridge1to2kmlong.
Soil-foundationinteractionstudieswereperformedtodeterminethestiffnessofthesoilandfoundationaswellastheseismicexcitationmeasurementthatwouldbeusedinthedynamicanalyses.Thestudieswereconductedbymeansofsoil-pilemodelsusinglinearandnonlinearsoillayeraofvaryingdepths.Theequivalentpilelengthsinthestudies-thatis,thelengthsrepresentingtheportionsofagivenpilethatwouldactuallybeaffectedbyagivenearthquake-inducedgroundmotion-rangedfrom2to10m.Insuchathree-dimensionalmodel,therearesixwaysinwhichthesoilcanresistthemovementofthelpilebecauseofitsstiffness:
thronghaxialforceinthethreedirectionsandthroughbendingmomentsinthreedirections.Becausethebridgesitecontainssomanylayersofvaryingsoiltypes,eachlayerhadtoberepresentedbyadifferentstiffnessmatrixandthenanalyzed.
Oncetheaboveanalyseswerecompleted,theT.Y.LinInternationalengineers-takingintoconsiderationtheprojectrequirementsdevelopedbytheowener-evaluatedseveraldifferentconcretecable-stayeddesigns.Anumberofstructuralsystemswereinvestigated,themainvariables,superstructurecrosssections,andthevaryingsupportconditionsdescribedabove.
Therequirementthattheevevationofthedeckbequitehighstronglyinfluencedthetowerconfiguration.Fortheproposeddeckelevationofmorethan80m,themosteconomicaltowershapesincludedsingle-anddual-masttowers
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 精品 土木工程 桥梁 外文 翻译 跨越 世纪