完整版桥梁毕业设计外文翻译0.docx
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完整版桥梁毕业设计外文翻译0
StructuralRehabilitationofConcreteBridgeswithCFRPComposites-PracticalDetailsandApplications
RiyadS.ABOUTAHA1,andNuttawatCHUTARAT2
ABSTRACT:
Manyoldexistingbridgesarestillactiveinthevariousnetworks,carryingallkindsofenvironments.Water,salt,andwind;andtoextendtheservicelifeofconcretebridgesisbytheuseofcarbonfiberreinforcedpolymer(CFRP)composites.ThereappeartobeverylimitedguidesonrepairofdeterioratedconcretebridgeswithCFRPcomposites.Inthispaper,guidelinesfornondestructiveevaluation(NDE),nondestructivetesting(NDT),andrehabilitationofdeterioratedconcretebridgeswithCFRPcompositesarepresented.TheeffectofdetailingonductilityandbehaviorofCFRPstrengthenedconcretebridgesarealsodiscussedandpresented.
KEYWORDS:
Concretedeterioration,corrosionofsteel,bridgerehabilitation,CFRPcomposites.
1Introduction
Thereareseveraldestructiveexternalenvironmentalfactorsthatlimittheservicelifeofbridges.Thesefactorsincludebutnotlimitedtochemicalattacks,corrosionofreinforcingsteelbars,carbonationofconcrete,andchemicalreactionofaggregate.Ifbridgeswerenotwellmaintained,thesefactorsmayleadtoastructuraldeficiency,whichreducesthemarginofsafety,andmayresultinstructuralfailure.Inordertorehabilitateandorstrengthendeterioratedexistingbridges,thoroughevaluationshouldbeconducted.Thepurposeoftheevaluationistoassesstheactualconditionofanyexistingbridge,andgenerallytoexaminetheremainingstrengthandloadcarrycapacityofthebridge.
1AssociateProfessor,SyracuseUniversity,U.S.A.
2Lecturer,SripatumUniversity,Thailand.
Oneattempttorestoretheoriginalcondition,andtoextendtheservicelifeofconcretebridgesisbytheuseofcarbonfiberreinforcedpolymer(CFRP)composites.
InNorthAmerica,EuropeandJapan,CFRPextensivelyinvestigatedandapplied.SeveraldesignguidesdevelopedforstrengtheningofconcretebridgeswithCFRPcomposites.However,thereappeartobeverylimitedguidesonrepairofdeterioratedconcretebridgeswithCFRPcomposites.Thispaperpresentsguidelinesforrepairofdeterioratedconcretebridges,alongwithproperdetailing.Evaluation,nondestructivetesting,andrehabilitationofdeterioratedconcretebridgeswithCFRPcompositesarepresented.SuccessfulapplicationofCFRPcompositesrequiresgooddetailingastheforcesdevelopedintheCFRPsheetsaretransferredbybondattheconcrete-CFRPinterface.TheeffectofdetailingonductilityandbehaviorofCFRPstrengthenedconcretebridgeswillalsobediscussedandpresented.
2DeterioratedConcreteBridges
Durabilityofbridgesisofmajorconcern.Increasingnumberofbridgesareexperiencingsignificantamountsofdeteriorationpriortoreachingtheirdesignservicelife.Thisprematuredeteriorationconsideredaproblemintermsofthestructuralintegrityandsafetyofthebridge.Inaddition,deteriorationofabridgemanycases,therootofadeteriorationproblemiscausedbycorrosionofsteelreinforcementinconcretestructures.Concretenormallyactstoprovideaagainstcorrosionoftheembeddedreinforcement.However,corrosionwillresultinthosecasesthattypicallyexperiencepoorconcretequality,inadequatedesignorconstruction,and,mayturnintoastrengthproblemleadingtoastructuraldeficiency,asshowninFigure1.
Figure1Corrosionofthesteelbarsisleadingtoastructuraldeficiency
3Non-destructiveTestingofDeterioratedConcreteBridgePiers
Inordertodesignasuccessfulretrofitsystem,theconditionoftheexistingbridgeshouldbethoroughlyevaluated.Evaluationofexistingbridgeelementsorsystemsinvolvesreviewoftheasbuiltdrawings,aswellasaccurateestimateoftheconditionoftheexistingbridge,asshowninFigure2.Dependingonthepurposeofevaluation,non-destructivetestsmayinvolveestimationofstrength,saltcontents,corrosionrates,alkalinityinconcrete,etc.
Figure2Visibleconcretedistressmarkedonanelevationofaconcretebridgepier
Althoughmostofthenon-destructivetestsdonotcauseanydamagetoexistingbridges,someNDTmaycauseminorlocaldamage(e.g.drilled-destructivetesting.
Inordertoselectthemostappropriatenon-destructivetestforaparticularcase,thepurposeofthetestshouldbeidentified.Ingeneral,therearethreetypesofNDTtoinvestigate:
(1)strength,
(2)otherstructuralproperties,and(3)qualityanddurability.Thestrengthmethodsmayinclude;compressivetest(e.g.coretestreboundtest(e.g.Windsorprobe),andpullouttest(anchortest).
Otherstructuraltestmethodsmayinclude;concretecoverthickness(cover-meter),locatingrebars(rebarlocator),rebarsize(somerebarlocatorsrebardatascan),concretemoisture(acquametermoisturemeter),cracking(visualtestimpactechoul