桥梁设计外文翻译文献

桥梁设计外文翻译文献桥梁设计外文翻译文献(文档含中英文对照即英文原文和中文翻译)原文：ABridgeForAllCenturiesAnextremelylong-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-agiftfromthe/doc/e5324711c381e53a580216fc700abb68a982ad21.htmlernmentthatisusedbythePanamaCanalAuthoritytomaintainthecanalgatesandfacilities;Aroadwaywideenoughtocarrysixlanesoftraffic,threeineachdirection;Adeckabletoaccommodatea1.5mwidepedestrianwalkway;AdesignthatwouldadheretotheAmericanAssociationofStateHighwayandTransportationOfficialstandardfora100-yearservicelifeandofferHS-25truckloading;Astructurethatcouldcarrytwo0.6mdianeterwaterlines;Aconstructionmethodthatwouldnotcrossthecanalatanytimeorinterruptcanaloperationainanyway.Becauseofthebridge’slongmainspanandthepotentialforstrongseismicactivityinthearea,nosinglebuildingcodecoveredallaspectsoftheproject.ThereforetheteamfromT.Y.LinInternationaldetermindedwhichportionsofseveralstandardbridgespecificationswereapplicableandwhichwerenot.Thefollowingdesigncodeswereusedindevelopingthedesigncriteriaforthebridge，itisstandardspecificationsforhighwaybridge,16thed,1996Itwasparamountthatthetowersofthecable-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-wascreateusingtheassumedseismicwavevelocityandthedistancebetweenthepiersofthe/doc/e5324711c381e53a580216fc700abb68a982ad21.htmlinganassumedwasvelocityofapproximately2.5km/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-masttowersaswellas“goalpost”towers-thatis,adesigninwhichthetwomastswouldbelinkedtoeachotherbycrossbeams.Ultimatelytheengineersdesigndthebridgetobe34.3mwidewitha420mlongcable-staydmainspan,two200mlongsidespans-oneoneachsideofthemainspan-andapproachstructuresattheendsofthesidespans.Ontheeastsidethereisone46mlongconcreteapproachstructure,whileonthewestsidetherearethree,measuring60,60,and66m,foratotalbridgelengthof1,052m.Thesidespansaresupportedbyfourpiers,referredto,fromwesttoeast,asP1.P2,P3,andP4.Thebridgedeckisacontinuoussingle-cellboxgirderfromabutmenttoabutment;theexpansionjointsarelocatedattheabutmentsonly.Deckmovementsontheorderof400mmareexpectedatthesemodularexpansionjointsMultidirectionalpotbearingsareusedatthepiersandattheabutmentstoaccommodatethesemovements.Thedeckwasfixedtothetwotowerstofacilitatethebalanced-cantilevermethodofconstructionandtoprovidetorsionalrigidityandlateralrestrainttothedeck..Transverseliveloads,seismicloads,andwindloadsareproportionallydistributedtothetowersandthepiersbythefixityofthedecktothetowersandbyreinforced-concreteshearkeyslocatedatthetopofP1,P3,andP4.Thedeckisallowedtomovelongitudinallyovertheabutmentsandpiers.Thelongitudinal,seismic,live,andtemperatureloadsareabsorbedbywhatisknownasportalframestructuralbehavior,wherebythetowersandthedeckformaportal-muchliketheframeofadoorinabuilding-thatactsinproportiontotherelativestiffnessofthetwotowers.Aspreviouslymentioned,thepresenceofcompetentbasaltontheeastsideofthesitemeantthatshallowfoundationscouldbeusedthere;inparticular,spreadfootingsweredesignedfortheeasttower,theeastapproachstructure,andtheeastabutment.Thewesttower,thewestapproachstructure,andthewesternpiers(P2andP3),however,hadtobefoundeddeepwithintheCucarachaFormation.Atotalof48cast-in-drilled-hole(CIDH)shaftswith2mouterdiametersandlengthsrangingfrom25to35mwererequired.Amomentcurvatureanalysiswasperformedtodeterminethecapacityoftheshaftswithdifferentamountsoflongitudinalsteelrebar.Theresultswereplottedagainstthedemands,andonthebasisoftheresultstheamountofrequiredlongitudinalreinforcingsteelwasdeterminedtobe1percentoftheamountofconcreteusedintheshafts.Thedistributionofthelongitudinalreinforcingsteelwasestablishedbyfollowingcoderequirements,withconsiderationalsogiventothelimitationsofconstructingCIDHpileswiththecontractor’spreferredmethod,whichisthewaterorslurrydisplacementmethod.Aminimumamountoftransversesteelhadtobedeterminedforuseintheplasticregionsoftheshaft-thatis,thoseatthetopone-eighthofeighthofeachshaftandwithintheshaftcaps,whichwouldabsorbthehighestseismicdemands.Oncethisamountwasdetermined,itwasusedastheminimumforareasoftheshaftsabovetheirpointsoffixitywherelargelateraldisplacementswereexpectedtooccur.ThelocationsofthetransversesteelwerethenestablishedbyfollowingcoderequirementsandbyconsideringtheconstructionlimitationsofCIDHpiles.Thetransversesteelwasspiralshaped.Eventhoughthieffoundationdesignsdiffered,thetowersthemselvesweredesignedtobeidentical.Eachmeasures185.5mfromthetopofitspilecapandisdesignedasahollowreinforced-concreteshaftwithatruncatedellipticalcrosssection(seefigureopposite).Eachtower’swidthinplanvariesalongitsheight,narrowinguniformlyfrom9.5matthebaseofthetowerto6matthetop.Inthelongitudinaldirection,eachpylontapersfrom9.5matthebasetoabout8mrightbelowthedecklevel,whichisabout87mabovethetowerbase.Abovethedecklevelthetower’ssectionsvaryfrom4.6mjustabovethedeckto4.5matthetop.Eachtowerwasdesignedwitha2by4mopeningforpedestrianpassagealongthedeck,adesignchallengerequiringcarefuldetailing.ThetowersweredesignedinaaccordancewiththelatestprovisionsoftheATCearthquakedesignmanualmentionedpreviously(ATC-32).Owingtotheportalframeactionalongthebridge’slongitudinalaxis,specialseismicdetailingwasimplementedinregionswiththepotentialtodevelopplastichingesintheeventofseismicactivity-specifically,justbelowthedeckandabovethefooting.Specialconfiningforcesandalternatingopenstirrups-with90and135degreehooks-withintheperimeterofthetowershaft.Inthetransversedirection,thetowerbehaveslikeacantilever,requiringconcrete-confiningsteelatitsbase.Specialattentionwasneededatthejointbetweenthetowerandthedeckbecauseofthecentral-planestay-cablearrangement,itwasnecessarytoprovidesufficienttorsionalstiffnessandspecialdetailingatthepier-to-deckintersection.Thisintersectionishighlycongestedwithverticalreinforcingsteel,thecloselyspacedconfiningstirrupsofthetowershaft,andthedeckprestressingandreinforcement.Theapproachstructuresoneithersideofthemainspanaresupportedonhollowreinforced-concretepiersthatmeasure8.28by5minplan.ThedesignanddetailingofthepiersareconsistentwiththelatestversionsoftheATCandAASHTOspecificationsforseismicdesign.Capacitydesignconceptswereappliedtothedesignofthepiers.Thisapproachrequiredtheuseofseismicmodelingwithmomentcurvatureelementstocapturetheinelasticbehaviorofelementsduringseismicexcitation.Pushoveranalysesofthepierswereperformedtocalculatethedisplacementcapacityofthepiersandtocomparethemwiththedeformationscomputedintheseismictime-historyanalyses.Toensureanadequateductilityofthepiers-anessentialfeatureofthecapacitydesignapproach-itwasnecessarytoprovideadequateconcrete-confiningsteelatthoselocationswithinthepierbaseswhereplastichingesareexpectedtoform.Thedeckofthecable-stayedmainspaniscomposedofsingle-cellboxgirdersofcast-in-placeconcretewithinternal,inclinedsteelstrutsandtransverseposttensionedribs,orstiffeningbeams,towardthetops.Eachboxgirdersegmentis4.5mdeepand6mlong.Tofacilitateconstructionandenhancethebridge’selegantdesign,similarsizeswereusedfortheotherbridgespans.Anintegralconcreteoverlaywithathicknessof350mmwasinstalledinsteadofanappliedconcreteoverlayonthedeck.Incontrasttoanappliedoverlay,theintegraloverlaywascastalongwitheachsegmentduringthedeckerection.Diamondgrindingequipmentwasusedtoobtainthedesiredsurfaceprofileandrequiredsmoothness.Theminimumgrindingdepthwas5mm.Atotalof128staycableswereused,thelargestcomprising83monostrands.Allcableswithalengthofmorethan80mwereequippedattheirlowerendswithinternalhydraulicdampers.Corrosionprotectionforthemonostrandsinvolvedgalvanizationofthewiresthroughhotdipping,atighthigh-densitypolyethylene(HDPE)sheathextrudedontoeachstrand,andaspecialtypeofpetroleumwaxthatfillsallofthevoidsbetweenthewires.Thestaysarespaecdevery6mandarearrangedinafanpattern.Theyaredesignedtobestressedfromthetoweronlyandareanchoredinlinewithacontinuousstiffeningbeamatthecenterlineofthedeck.Thedeckanchoragesystemisactuallyacompositesteelframethatencapsulatestwocontinoussteelplatesthatanchorthestaysandtransferthestayforcesinacontinuousandrepetitivesystem-viashearstuds-throuthouttheextentofthecable-supporteddeck(seefigureabove).Asteelframewasdesignedtotransferthestays’horizontalforcestotheboxgirdersthroughconcrete-embeddedlongitudinalsteelplatesandtotransfertheboxes’verticalforcesdirectlythroughtheinternalsteelstruts.Thisinnovativeandelegantloadtransfersystemmaderapidconstructionoftheconcretedecksegments-incyclesofthreetofivedays-possible.Inadditiontothegeotechnicalandseismicanalyses,severalstructuralanalyseswereperformedtoaccuratelycapturethebehaviorofthiscomplexbridge.Fortheservice-loadanalysis,whichincludeslive,temperature,andwindloads,theengineersusedSAP2000,acomputerprogramcreatedandmaintainedbyComputers&Structrures,Inc.(CSI),ofBerkeley,California.Thisprogramwasselectedforitsabilitytoeasilymodeltheserviceloadsandtoaccountfortridimensionaleffects.ForcorrectSAP2000modeling,itwasnecessarytodefineasetofinitialstressesonthecables,deck,andtowerelementstocapturethestateofthestructureattheendofconstruction.Forthecalculationofthoseinitialstresses,aseriesofiterationsonthebasicmodelwereperformedtoobtainthestayforcesinthestructurethatbalanceboththebridges’sself-weightandthesuperimposeddeadloads.Oncethecorrectcablestiffnessandstressdistributionwereobtained,allsubsequentservice-loadanalyseswereperformedtoaccountforthegeometricstiffnessandP-deltaeffects,whichconsiderthemagnitudeofanappliedload(P)versusthedisplacement(delta).TheseismicanalysisofthestructurewasconductedusingtheSADSAPstructuralanalysisprogram,alsoaCSIproduct,basedonthedifferencesinseismicmotionsthatwillbeexperiencedatthedifferentpiersbasedontheirdistancefromoneanother.Thissophisticatedprogramhasthecapabilitytomodelinelasticbehaviorinthatflexuralplastichingescanreadilybesimulated.PlastichingeelementsweremodeledatvarouslocationsalongthestructurewheretheresultsfromapreliminaryresponsespectrumanalysisinSAP2000indicatedthatinelasticbehaviormightbeexpected.Thetime-historyrecordspertainingtothesitewereusedinconjunctionwiththeSADSAPmodeltobotainaperformace-baseddesignofthepiersandtowersandtoverifhthedesignofseveraldeckstctions.Aspreviouslymentioned,theconstructioncontractorwasbroughtonboardearlyintheprocess;thecompany’sbidof$93millionwasacceptedandtheprojectwasawardedinMarch2002.Toguaranteeunimpededcanaltraffic,