土木工程建筑外文翻译外文文献英文文献欧洲桥梁研究教程文件.docx

土木工程建筑外文翻译外文文献英文文献欧洲桥梁研究教程文件.docx

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土木工程建筑外文翻译外文文献英文文献欧洲桥梁研究教程文件

BridgeresearchinEurope

AbriefoutlineisgivenofthedevelopmentoftheEuropeanUnion,togetherwiththeresearchplatforminEurope.Thespecialcaseofpost-tensionedbridgesintheUKisdiscussed.InordertoillustratethetypeofEuropeanresearchbeingundertaken,anexampleisgivenfromtheUniversityofEdinburghportfolio:

relatingtotheidentificationofvoidsinpost-tensionedconcretebridgesusingdigitalimpulseradar.

Introduction

Thechallengeinanyresearcharenaistoharnessthefindingsofdifferentresearchgroupstoidentifyacoherentmassofdata,whichenablesresearchandpracticetobebetterfocused.AparticularchallengeexistswithrespecttoEuropewherelanguagebarriersareinevitablyverysignificant.TheEuropeanCommunitywasformedinthe1960sbaseduponapoliticalwillwithincontinentalEuropetoavoidtheEuropeancivilwars,whichdevelopedintoWorldWar2from1939to1945.ThestrongpoliticalmotivationformedtheoriginalcommunityofwhichBritainwasnotamember.ManyofthecontinentalcountriessawBritain’sinterestasbeingpurelyeconomic.The1970ssawBritainjoiningwhatwasthentheEuropeanEconomicCommunity（EEC）andthe1990shasseenthewideningofthecommunitytoaEuropeanUnion,EU,withcertainpoliticalgoalstogetherwiththeobjectiveofacommonEuropeancurrency.

Notwithstandingthesefinancialandpoliticaldevelopments,civilengineeringandbridgeengineeringinparticularhavefoundgreatdifficultyinforminganykindofcommonthread.IndeedtheeducationalsystemsforUniversitytrainingarequitedifferentbetweenBritainandtheEuropeancontinentalcountries.TheformationoftheEUfundingschemes—e.g.Socrates,BriteEuramandotherprogramshavehelpedsignificantly.TheSocratesschemeisbasedupontheexchangeofstudentsbetweenUniversitiesindifferentmemberstates.TheBriteEuramschemehasinvolvedtechnicalresearchgrantsgiventoconsortiaofacademicsandindustrialpartnerswithinanumberofthestates—aBriteEurambidwouldnormallybeledbyanindustrialist.

Intermsofdisseminationofknowledge,twoquitedifferentstrandsappeartohaveemerged.TheUKandtheUSAhaveconcentratedprimarilyupondisseminatingbasicresearchinrefereedjournalpublications:

ASCE,ICEandotherjournals.WhereasthecontinentalEuropeanshavefrequentlydisseminatedbasicresearchatconferenceswherethecirculationoftheproceedingsisrestricted.

Additionally,languagebarriershaveprovedtobeverydifficulttobreakdown.IncountrieswhereEnglishisastrongsecondlanguagetherehasbeenenthusiasticparticipationininternationalconferencesbasedwithincontinentalEurope—e.g.Germany,Italy,Belgium,TheNetherlandsandSwitzerland.However,countrieswhereEnglishisnotastrongsecondlanguagehavebeenhesitantparticipants}—e.g.France.

Europeanresearch

ExamplesofresearchrelatingtobridgesinEuropecanbedividedintothreetypesofstructure:

Masonryarchbridges

Britainhasthelargeststockofmasonryarchbridges.IncertainregionsoftheUKupto60%oftheroadbridgesarehistoricstonemasonryarchbridgesoriginallyconstructedforhorsedrawntraffic.ThisislesscommoninotherpartsofEuropeasmanyofthesebridgesweredestroyedduringWorldWar2.

Concretebridges

Alargestockofconcretebridgeswasconstructedduringthe1950s,1960sand1970s.Atthetime,thesestructureswereseenasmaintenancefree.Europealsohasalargenumberofpost-tensionedconcretebridgeswithsteeltendonductspreventingradarinspection.ThisisaparticularprobleminFranceandtheUK.

Steelbridges

SteelbridgeswentoutoffashionintheUKduetotheirneedformaintenanceasperceivedinthe1960sand1970s.However,theyhavebeenusedforlongspanandrailbridges,andtheyarenowreturningtofashionformotorwaywideningschemesintheUK.

ResearchactivityinEurope

ItgivesanindicationcertainareasofexpertiseandworkbeingundertakeninEurope,butisbynomeansexhaustive.

InordertoillustratethetypeofEuropeanresearchbeingundertaken,anexampleisgivenfromtheUniversityofEdinburghportfolio.Theexamplerelatestotheidentificationofvoidsinpost-tensionedconcretebridges,usingdigitalimpulseradar.

Post-tensionedconcreterailbridgeanalysis

OveArupandPartnerscarriedoutaninspectionandassessmentofthesuperstructureofa160mlongpost-tensioned,segmentalrailwaybridgeinManchestertodetermineitsload-carryingcapacitypriortoatransferofownership,foruseintheMetrolinklightrailsystem..

Particularattentionwaspaidtotheintegrityofitspost-tensionedsteelelements.Physicalinspection,non-destructiveradartestingandotherexploratorymethodswereusedtoinvestigateforpossibleweaknessesinthebridge.

SincethesuddencollapseofYnys-y-GwasBridgeinWales,UKin1985,therehasbeenconcernaboutthelong-termintegrityofsegmental,post-tensionedconcretebridgeswhichmaybeproneto‘brittle’failurewithoutwarning.Thecorrosionprotectionofthepost-tensionedsteelcables,wheretheypassthroughjointsbetweenthesegments,hasbeenidentifiedasamajorfactoraffectingthelong-termdurabilityandconsequentstrengthofthistypeofbridge.Theidentificationofvoidsingroutedtendonductsatvulnerablepositionsisrecognizedasanimportantstepinthedetectionofsuchcorrosion.

Descriptionofbridge

Generalarrangement

Besseso’th’BarnBridgeisa160mlong,threespan,segmental,post-tensionedconcreterailwaybridgebuiltin1969.Themainspanof90mcrossesoverboththeM62motorwayandA665BurytoPrestwickRoad.Minimumheadroomis5.18mfromtheA665andtheM62isclearedbyapprox12.5m.

Thesuperstructureconsistsofacentralhollowtrapezoidalconcreteboxsection6.7mhighand4mwide.Themajorityofthesouthandcentralspansareconstructedusing1.27mlongpre-castconcretetrapezoidalboxunits,post-tensionedtogether.Thisboxsectionsupportstheinsiteconcretetransversecantileverslabsatbottomflangelevel,whichcarrytherailtracksandballast.

Thecenterandsouthspansectionsareofpost-tensionedconstruction.Thesepost-tensionedsectionshavefivetypesofpre-stressing:

1.Longitudinaltendonsingroutedductswithinthetopandbottomflanges.

2.Longitudinalinternaldrapedtendonslocatedalongsidethewebs.Thesearedeflectedatinternaldiaphragmpositionsandareencasedininsiteconcrete.

3.Longitudinalmacalloybarsinthetransversecantileverslabsinthecentralspan.

4.Verticalmacalloybarsinthe229mmwidewebstoenhanceshearcapacity.

5.Transversemacalloybarsthroughthebottomflangetosupportthetransversecantileverslabs.

Segmentalconstruction

Thepre-castsegmentalsystemofconstructionusedforthesouthandcenterspansectionswasanalternativemethodproposedbythecontractor.Currentthinkingsuggeststhatsuchaformofconstructioncanleadto‘brittle’failureoftheentirestructurewithoutwarningduetocorrosionoftendonsacrossaconstructionjoint，Theoriginaldesignconcepthadbeenforinsiteconcreteconstruction.

Inspectionandassessment

Inspection

Inspectionworkwasundertakeninanumberofphasesandwaslinkedwiththetestingrequiredforthestructure.Theinitialinspectionsrecordedanumberofvisibleproblemsincluding:

Defectivewaterproofingontheexposedsurfaceofthetopflange.

Watertrappedintheinternalspaceofthehollowboxwithdepthsupto300mm.

Variousdrainageproblemsatjointsandabutments.

Longitudinalcrackingoftheexposedsoffitofthecentralspan.

Longitudinalcrackingonsidesofthetopflangeofthepre-stressedsections.

Widespreadsaplingonsomeinsiteconcretesurfaceswithexposedrustingreinforcement.

Assessment

Thesubjectofanearlierpaper,theobjectivesoftheassessmentwere:

Estimatethepresentload-carryingcapacity.

Identifyanystructuraldeficienciesintheoriginaldesign.

Determinereasonsforexistingproblemsidentifiedbytheinspection.

Conclusiontotheinspectionandassessment

Followingtheinspectionandtheanalyticalassessmentonemajorelementofdoubtstillexisted.Thisconcernedtheconditionoftheembeddedpre-stressingwires,strands,cablesorbars.Forthepurposeofstructuralanalysistheseelements、hadbeenassumedtobesound.However,duetotheveryhighforcesinvolved,、arisktothestructure,causedbycorrosiontotheseprimaryelements,wasidentified.

Theinitialrecommendationswhichcompletedthefirstphaseoftheassessmentwere:

1.Carryoutdetailedmaterialtestingtodeterminetheconditionofhiddenstructuralelements,inparticular

thegroutedpost-tensionedsteelcables.

2.Conductconcretedurabilitytests.

3.Undertakerepairstodefectivewaterproofingandsurfacedefectsinconcrete.

Testingprocedures

Non-destructiveradartesting

Duringthefirstphaseinvestigationatajointbetweenpre-castdecksegmentstheobservationofavoidinapost-tensionedcableductgaverisetoseriousconcernaboutcorrosionandtheintegrityofthepre-stress.However,theextentofthisproblemwasextremelydifficulttodetermine.Thebridgecontains93jointswithanaverageof24cablespassingthrougheachjoint,i.e.therewereapprox.2200positionswhereinvestigationscouldbecarriedout.Atypicalsectionthroughsuchajointisthatthe24drapedtendonswithinthespinedidnotgiverisetoconcernbecausethesewereprotectedbyinsiteconcretepouredwithoutjointsafterthecableshadbeenstressed.

Asitwasclearlyimpracticaltoconsiderphysicallyexposingalltendon/jointintersections,radarwasusedtoinvestigatealargenumbersoftendonsandhenceloca