任全福英語翻譯

Itissaidthatnecessityisthemotherofallinvention.Ifthatisthecase,thentheneedforstriking,elegantcable-stayedbridgesthatcanspangreaterlengthsandbemoreeasilymaintainedoverthecourseoflongerliveshasyieldedasignificantnewinventionthatmaywellbenefitbridgedesignerstheworldover.Drivenbyadesiretopushthedesignofsingle-planecable-stayedbridgesbeyondtheircurrentlimits—bothinspanlengthandinaestheticappeal—whilestilldeliveringaneconomicsolutionthatiseasytoconstructandmaintain,FIGG,anengineeringfirmbasedinTallahassee,Florida,hascreatedanovelsystemforroutingstaycablesfromoneendofabridgedeck,throughthebridge’spylon,andthendowntotheotherendofthedeckinawaythatprecludesthepossibilityofcable-to-cableinteractions.Theinnovationhasbeenemployedontwonewbridges—theVeterans’GlassCitySkywayBridge,whichcarriesInterstate280acrosstheMaumeeRiverinToledo,Ohio(see“OhioDOTEndorsesDesignforMaumeeRiverCrossing,”CivilEngineering,September2000,page12),andthePenobscotNarrowsBridgeandObservatory,whichcarriesU.S.Route1overthePenobscotRiverinsoutheastern(“downeast”)Mainenearthecoastline(see“ObservatorytoCapMaineCrossing,”CivilEngineering,April2004,pages15–17).Thecradleoffersbenefitsbothduringconstructionandoverthelifeofthebridges.Mostimportantofall,itpermitstheuseofthelargestnumberofstrandswithinasinglestaycableintheworld:156,anincreaseofmorethan70percentoverthesecond-highestnumberknowntohavebeenusedintheUnitedStates.Italsomakesitpossibletoincreasethedistancebetweenstaycablesbyapproximately50percentwhenusedwithprecastdeltaframestofacilitateasingleplaneofstaycables,resultinginaestheticallysuperiordesigns.Thisisaccomplishedbyhavingallthestrandsparallelastheytravelfromtheanchorsatthedecklevelthroughthecradleinthepylonandbacktothedeck.Individualsleevepipeslocatedwithinthecradlesystemenableeachstrandtoactindependentlyofadjacentstrands.Thisalsopermitsthecablestobemuchlargerandtobespacedfartherapart,whichtranslatesintolongerspans.Furthermore,thecradlesystemlowersinitialcostsbyreducingtheamountofmaterialsandlaborneededbecausenoanchoragesinthepylonarerequired.Thissimplifiesconstructionoperationsbyallowingallofthecable-stressingoperationstobeperformedatthebridgedecklevelratherthanwithinthe(oftenrestricted)confinesofthepylon,highabovethebridgedeck.Thesystemalsoincludesremovable“reference”strandsineachstaycablethatprovideasimple,reliablemethodforverifyingtheconditionofthestaycablesinthefuture.Becausethecradlesystemdoesnotrequirestrandstobegrouted,theycanbeindividuallyremoved,inspected,andreplaced,evenwhenthereistrafficonthebridge.Bridgeownerscanthussafelyandaccuratelyassesstheconditionsofthestaycablesatanytimeoverthecourseofthebridge’slife.InthecaseoftheMainebridge,newstrandmaterialscanbetestedside-by-sidewithtraditionalmaterialsinanactualsetting,asopposedtoaprocessofcomputersimulation.Whatismore,thecradlesystemmakespossibletheuseofawidervarietyofpylondesigns—somewithmuchsmallerandmoreelegantcross-sectionalshapes—thatcanbeconstructedmoreeconomically.Engineerscanthusdesignpylonsthatarefarmoreunusualandaestheticallypleasingthanhasbeenthecaseinthepast.Thecradledesignworkswiththenaturalflowofforcesbecausetheforcestransmittedthroughthecradlenaturallycompressthepyloninanefficientmanner,thestressesbeingappliedradiallyalongthecurveofthecradle(seetheillustrationsonpage41).Intraditionalsystems,anchorageswithinthepylonrequiredlargetensiontiestoresistthehighsplittingforcesthatwouldbegenerated.Usingthecradlesystemeliminatesthisrequirementandfurtherenhancestheeleganceofthepylonshapes.Thedevelopmentofthisnewtechniquebeganinearly2000.TheOhioDepartmentofTransportation(ODOT)andtheToledoMetropolitanAreaCouncilofGovernmentshadformedwhatwascalledtheMaumeeRiverCrossingTaskForceDesignCommitteetoassessandcommunicatethecommunities’perspectiveonthedevelopingdesign.Thetaskforcechoseglassasthethemeforthenewcable-stayedbridge.Meetingsinvolvingadiversecrosssectionofthecommunityhadmadethepublic’sviewsclear:thebridgewastofeatureglassinaveryvisibleandstrikingwayinrecognitionofToledo’sindustrialheritageasaleaderintheglassindustry.Manyfamiliesintheareahadworkedinthelocalglassindustryforgenerations,anditwasimportanttothemthatthecrossingbeasymbolofthe“GlassCity,”asToledohascometobeknown.Thepublicwasalsooftheopinionthatthebridgedesignshouldchampionaproductthathadbeenoftheutmostimportancetothearea’seconomy.Thetaskforcefurtherdeterminedthatresidentswantedthebridgedesigntobelight,simple,andelegant.FIGGledtwocommunityworkshops,ordesigncharettes,duringwhichthepublicwaspresentedwithavarietyofaestheticoptions.Communityvotingshowedaclearpreferenceforasingle-pylondesign.Theconsensuswasthatbycreatingasingletallpylon—403ft(123m)—usingglassonthetop196ft(60m)andonallfoursides,thenewbridgewouldbevisuallystunning.Inkeepingwiththisdirective,thetopofthepylontakesonaprismaticshape,itspanelsoftreatedglassreflectingsunlightduringthedayonallfoursides.Behindtheglassarelight-emittingdiodes(LEDS)thatenablethepylontostandasabeaconatnight.(Theledfixturesarecontrolledremotelyandcapableofliterallymillionsofcolorcombinations.Infact,variouscolorschemeshavebeenpreprogrammed,someschemesmarkingmajorholidaysandothersexhibitingteamcolorsforstatewidesportingevents.)有人說需求是一切發(fā)明的母親。如果真的是這樣，那么引人注目的，優(yōu)雅的斜拉橋能夠橫跨更大的距離和使得橋梁在更長的使用壽命中的維護(hù)變得更簡單將是一項(xiàng)可以讓全球橋梁設(shè)計(jì)者都受益的重要的新發(fā)明。在推動(dòng)單面斜拉橋超越現(xiàn)有極限（在跨度和美觀兩方面）的需求的驅(qū)使下，同時(shí)用一種在建造和維護(hù)過程中都經(jīng)濟(jì)的解決方法，F(xiàn)IGG，一家位于Florida首府Tallahassee的工程公司，發(fā)明了一個(gè)新穎的體系。該體系的斜拉索的傳力路徑是將力從橋面板的一端通過橋塔傳下至橋面板的另一端。這種方法就可以排除斜拉索間互相作用的可能性。這種創(chuàng)新的方法被應(yīng)用在兩座新橋上。一座是老兵玻璃城航線大橋，這座大橋連接著280洲際公路橫跨流經(jīng)Toledo,Ohio的Maumee河；另一座是Penobscot紐約灣海峽大橋和天文臺(tái)，這座大橋連接著美國1號(hào)公路橫跨位于靠近海岸線的Maine洲東南面的Penobscot河。這個(gè)支架為橋梁的建造過程和其使用壽命中都帶來了好處。最重要的是，它使得一根拉索中繩的股數(shù)達(dá)到了世界范圍內(nèi)的最大值：156。這個(gè)值比美國境內(nèi)用過的第二多的股數(shù)多了70％。也使得當(dāng)它用于預(yù)制的三角形框架（可使得單面斜拉索更方便）的斜拉索的距離增加大約50％成為了可能。這樣就可以實(shí)現(xiàn)美學(xué)上的非凡設(shè)計(jì)。這是通過在繩股從橋面板水平面的支座穿過橋塔中的支架然后返回到橋面板過程中使得所有的繩股平行來實(shí)現(xiàn)的。位于支架系統(tǒng)內(nèi)的獨(dú)立套管使得每股繩都能不受相鄰繩股的影響而單獨(dú)作用。這也使拉索可以做得比以前大得多并且拉索間的距離也可以更大，也就是說橋梁可以橫跨更大的距離。而且，由于橋塔內(nèi)不需要支座所以材料的用量和人力的使用都減少了，從而支架系統(tǒng)降低了橋梁的初始成本。由于拉索的張拉操作都在橋面板上進(jìn)行而不是在高高的橋塔上那么局限的范圍內(nèi)進(jìn)行所以施工操作也變得簡化了。這個(gè)體系還包括在每個(gè)斜拉索中都有可移動(dòng)的參考繩股，這樣為將來檢驗(yàn)拉索的使用情況提供了一個(gè)簡單可靠的方法。因?yàn)橹Ъ芟到y(tǒng)不要求用水泥漿添塞繩股，所以即使是在橋上有車輛和行人的情況下它們可以被單獨(dú)地移除，檢查和替換。這樣一來橋梁的業(yè)主在橋梁的使用壽命期間隨時(shí)都可以安全地，準(zhǔn)確地對(duì)拉索的