Bridge research in Europe.docx
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1、BridgeresearchinEuropeAbriefoutlineisgivenofthedevelopmentoftheEuropeanUnion,togetherwiththeresearchplatforminEurope.Thespecialcaseofpost-tensionedbridgesintheUKisdiscussed.InordertoillustratethetypeofEuropeanresearchbeingundertaken,anexampleisgivenfromtheUniversityofEdinburghportfolio:relatingtothe
2、identificationofvoidsinpost-tensionedconcretebridgesusingdigitalimpulseradar.IntroductionThechallengeinanyresearcharenaistoharnessthefindingsofdifferentresearchgroupstoidentifyacoherentmassofdata,whichenablesresearchandpracticetobebetterfocused.AparticularchallengeexistswithrespecttoEuropewherelangu
3、agebarriersareinevitablyverysignificant.TheEuropeanCommunitywasformedinthe1960sbaseduponapoliticalwillwithincontinentalEuropetoavoidtheEuropeancivilwars,whichdevelopedintoWorldWar2from1939to1945.ThestrongpoliticalmotivationformedtheoriginalcommunityofwhichBritainwasnotamember.Manyofthecontinentalcou
4、ntriessawBritainsinterestasbeingpurelyeconomic.The1970ssawBritainjoiningwhatwasthentheEuropeanEconomicCommunity(EEC)andthe1990shasseenthewideningofthecommunitytoaEuropeanUnion,EU,withcertainpoliticalgoalstogetherwiththeobjectiveofacommonEuropeancurrency.Notwithstandingthesefinancialandpoliticaldevel
5、opments,civilengineeringandbridgeengineeringinparticularhavefoundgreatdifficultyinforminganykindofcommonthread.IndeedtheeducationalsystemsforUniversitytrainingarequitedifferentbetweenBritainandtheEuropeancontinentalcountries.TheformationoftheEUfundingschemes一e.g.Socrates,BriteEuramandotherprogramsha
6、vehelpedsignificantly.TheSocratesschemeisbasedupontheexchangeofstudentsbetweenUniversitiesindifferentmemberstates.TheBriteEuramschemehasinvolvedtechnicalresearchgrantsgiventoconsortiaofacademicsandindustrialpartnerswithinanumberofthestates一aBriteEurambidwouldnormallybeledbyanindustrialist.Intermsofd
7、isseminationofknowledge,twoquitedifferentstrandsappeartohaveemerged.TheUKandtheUSAhaveconcentratedprimarilyupondisseminatingbasicresearchinrefereedjournalpublications:ASCE,ICEandotherjournals.WhereasthecontinentalEuropeanshavefrequentlydisseminatedbasicresearchatconferenceswherethecirculationofthepr
8、oceedingsisrestricted.Additionally,languagebarriershaveprovedtobeverydifficulttobreakdown.IncountrieswhereEnglishisastrongsecondlanguagetherehasbeenenthusiasticparticipationininternationalconferencesbasedwithincontinentalEurope-e.g.Germany,Italy,Belgium,TheNetherlandsandSwitzerland.However,countries
9、whereEnglishisnotastrongsecondlanguagehavebeenhesitantPartiCiPantS一e.g.France.EuropeanresearchExamplesofresearchrelatingtobridgesinEuropecanbedividedintothreetypesofstructure:MasonryarchbridgesBritainhasthelargeststockofmasonryarchbridges.IncertainregionsoftheUKupto60%oftheroadbridgesarehistoricston
10、emasonryarchbridgesoriginallyconstructedforhorsedrawntraffic.ThisislesscommoninotherpartsofEuropeasmanyofthesebridgesweredestroyedduringWorldWar2.ConcretebridgesAlargestockofconcretebridgeswasconstructedduringthe1950s,1960sand1970s.Atthetime,thesestructureswereseenasmaintenancefree.Europealsohasalar
11、genumberofpost-tensionedconcretebridgeswithsteeltendonductspreventingradarinspection.ThisisaparticularprobleminFranceandtheUK.SteelbridgesSteelbridgeswentoutoffashionintheUKduetotheirneedformaintenanceasperceivedinthe1960sand1970s.However,theyhavebeenusedforlongspanandrailbridges,andtheyarenowreturn
12、ingtofashionformotorwaywideningschemesintheUK.ResearchactivityinEuropeItgivesanindicationcertainareasofexpertiseandworkbeingundertakeninEurope,butisbynomeansexhaustive.InordertoillustratethetypeofEuropeanresearchbeingundertaken,anexampleisgivenfromtheUniversityofEdinburghportfolio.Theexamplerelatest
13、otheidentificationofvoidsinpost-tensionedconcretebridges,usingdigitalimpulseradar.PosttensionedconcreterailbridgeanalysisOveArupandPartnerscarriedoutaninspectionandassessmentofthesuperstructureofa160mlongpost-tensioned,segmentalrailwaybridgeinManchestertodetermineitsload-carryingcapacitypriortoatran
14、sferofownership,foruseintheMetrolinklightrailsystem.Particularattentionwaspaidtotheintegrityofitspost-tensionedsteelelements.Physicalinspection,non-destructiveradartestingandotherexploratorymethodswereusedtoinvestigateforpossibleweaknessesinthebridge.SincethesuddencollapseofYnys-y-GwasBridgeinWales,
15、UKin1985,therehasbeenconcernaboutthelong-termintegrityofsegmental,post-tensionedconcretebridgeswhichmaybepronetobrittle5failurewithoutwarning.Thecorrosionprotectionofthepost-tensionedsteelcables,wheretheypassthroughjointsbetweenthesegments,hasbeenidentifiedasamajorfactoraffectingthelong-termdurabili
16、tyandconsequentstrengthofthistypeofbridge.Theidentificationofvoidsingroutedtendonductsatvulnerablepositionsisrecognizedasanimportantstepinthedetectionofsuchcorrosion.DescriptionofbridgeGeneralarrangementBesseso,th,BamBridgeisa160mlong,threespan,segmental,post-tensionedconcreterailwaybridgebuiltin196
17、9.Themainspanof90mcrossesoverboththeM62motorwayandA665BurytoPrestwickRoad.Minimumheadroomis5.18mfromtheA665andtheM62isclearedbyapprox12.5m.Thesuperstructureconsistsofacentralhollowtrapezoidalconcreteboxsection6.7mhighand4mwide.Themajorityofthesouthandcentralspansareconstructedusing1.27mlongpre-castc
18、oncretetrapezoidalboxunits,post-tensionedtogether.Thisboxsectionsupportstheinsiteconcretetransversecantileverslabsatbottomflangelevel,whichcarrytherailtracksandballast.Thecenterandsouthspansectionsareofpost-tensionedconstruction.Thesepost-tensionedsectionshavefivetypesofpre-stressing:1. Longitudinal
19、tendonsingroutedductswithinthetopandbottomflanges.2. Longitudinalinternaldrapedtendonslocatedalongsidethewebs.Thesearedeflectedatinternaldiaphragmpositionsandareencasedininsiteconcrete.3. Longitudinalmacalloybarsinthetransversecantileverslabsinthecentralspan.4. Verticalmacalloybarsinthe229mmwidewebs
20、toenhanceshearcapacity.5. Transversemacalloybarsthroughthebottomflangetosupportthetransversecantileverslabs.SegmentalconstructionThepre-castsegmentalsystemofconstructionusedforthesouthandcenterspansectionswasanalternativemethodproposedbythecontractor.Currentthinkingsuggeststhatsuchaformofconstructio
21、ncanleadto4brittle,failureoftheentirestructurewithoutwarningduetocorrosionoftendonsacrossaconstructionjoint,Theoriginaldesignconcepthadbeenforinsiteconcreteconstruction.InspectionandassessmentInspectionInspectionworkwasundertakeninanumberofphasesandwaslinkedwiththetestingrequiredforthestructure.Thei
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