桥梁毕业设计外文翻译

外文资料TheTenthEastAsia-PacificConferenceonStructuralEngineeringandConstructionAugust3-5,2006,BangkokStructuralRehabilitationofConcreteBridgeswithCFRPComposites-PracticalDetailsandApplicationsRiyadS.ABOUTAHA1,andNuttawatCHUTARAT2ABSTRACT:Manyoldexistingbridgesarestillactiveinthevarioushighwaytransportationnetworks,carryingheavierandfastertrucks,inallkindsofenvironments.Water,salt,andwindhavecauseddamagetotheseoldbridges,andscarcityofmaintenancefundshasaggravatedtheirconditions.Oneattempttorestoretheoriginalcondition;andtoextendtheservicelifeofconcretebridgesisbytheuseofcarbonfiberreinforcedpolymer(CFRP)composites.ThereappeartobeverylimitedguidesonrepairofdeterioratedconcretebridgeswithCFRPcomposites.Inthispaper,guidelinesfornondestructiveevaluation(NDE),nondestructivetesting(NDT),andrehabilitationofdeterioratedconcretebridgeswithCFRPcompositesarepresented.TheeffectofdetailingonductilityandbehaviorofCFRPstrengthenedconcretebridgesarealsodiscussedandpresented.KEYWORDS:Concretedeterioration,corrosionofsteel,bridgerehabilitation,CFRPcomposites.1IntroductionThereareseveraldestructiveexternalenvironmentalfactorsthatlimittheservicelifeofbridges.Thesefactorsincludebutnotlimitedtochemicalattacks,corrosionofreinforcingsteelbars,carbonationofconcrete,andchemicalreactionofaggregate.Ifbridgeswerenotwellmaintained,thesefactorsmayleadtoastructuraldeficiency,whichreducesthemarginofsafety,andmayresultinstructuralfailure.Inordertorehabilitateand/orstrengthendeterioratedexistingbridges,thoroughevaluationshouldbeconducted.Thepurposeoftheevaluationistoassesstheactualconditionofanyexistingbridge,andgenerallytoexaminetheremainingstrengthandloadcarrycapacityofthebridge.1AssociateProfessor,SyracuseUniversity2Lecturer,SripatumUniversity,Oneattempttorestoretheoriginalcondition,andtoextendtheservicelifeofconcretebridgesisbytheuseofcarbonfiberreinforcedpolymer(CFRP)composites.InNorthAmerica,EuropeandJapan,CFRPhasbeenextensivelyinvestigatedandapplied.SeveraldesignguideshavebeendevelopedforstrengtheningofconcretebridgeswithCFRPcomposites.However,thereappeartobeverylimitedguidesonrepairofdeterioratedconcretebridgeswithCFRPcomposites.Thispaperpresentsguidelinesforrepairofdeterioratedconcretebridges,alongwithproperdetailing.Evaluation,nondestructivetesting,andrehabilitationofdeterioratedconcretebridgeswithCFRPcompositesarepresented.SuccessfulapplicationofCFRPcompositesrequiresgooddetailingastheforcesdevelopedintheCFRPsheetsaretransferredbybondattheconcrete-CFRPinterface.TheeffectofdetailingonductilityandbehaviorofCFRPstrengthenedconcretebridgeswillalsobediscussedandpresented.2DeterioratedConcreteBridgesDurabilityofbridgesisofmajorconcern.Increasingnumberofbridgesareexperiencingsignificantamountsofdeteriorationpriortoreachingtheirdesignservicelife.Thisprematuredeteriorationconsideredaproblemintermsofthestructuralintegrityandsafetyofthebridge.Inaddition,deteriorationofabridgehasaconsiderablemagnitudeofcostsassociatedwithit.Inmanycases,therootofadeteriorationproblemiscausedbycorrosionofsteelreinforcementinconcretestructures.Concretenormallyactstoprovideahighdegreeofprotectionagainstcorrosionoftheembeddedreinforcement.However,corrosionwillresultinthosecasesthattypicallyexperiencepoorconcretequality,inadequatedesignorconstruction,andharshenvironmentalconditions.Ifnottreatedadurabilityproblem,e.g.corrosion,mayturnintoastrengthproblemleadingtoastructuraldeficiency,asshowninFigure1.Figure1Corrosionofthesteelbarsisleadingtoastructuraldeficiency3Non-destructiveTestingofDeterioratedConcreteInordertodesignasuccessfulretrofitsystem,theconditionoftheexistingbridgeshouldbethoroughlyevaluated.Evaluationofexistingbridgeelementsorsystemsinvolvesreviewoftheasbuiltdrawings,aswellasaccurateestimateoftheconditionoftheexistingbridge,asshowninFigure2.Dependingonthepurposeofevaluation,non-destructivetestsmayinvolveestimationofstrength,saltcontents,corrosionrates,alkalinityinconcrete,etc.Figure2VisibleconcretedistressmarkedonanelevationofaconcretebridgepierAlthoughmostofthenon-destructivetestsdonotcauseanydamagetoexistingbridges,someNDTmaycauseminorlocaldamage(e.g.drilledholes&coring)thatshouldberepairedrightaftertheNDT.Thesetestsarealsoreferredtoaspartialdestructivetestsbutfallundernon-destructivetesting.Inordertoselectthemostappropriatenon-destructivetestforaparticularcase,thepurposeofthetestshouldbeidentified.Ingeneral,therearethreetypesofNDTtoinvestigate:(1)strength,(2)otherstructuralproperties,and(3)qualityanddurability.Thestrengthmethodsmayinclude;compressivetest(e.g.coretest/reboundhammer/ultrasonicpulsevelocity),surfacehardnesstest(e.g.reboundhammer),penetrationtest(e.g.Windsorprobe),andpullouttest(anchortest).Otherstructuraltestmethodsmayinclude;concretecoverthickness(cover-meter),locatingrebars(rebarlocator),rebarsize(somerebarlocators/rebardatascan),concretemoisture(acquameter/moisturemeter),cracking(visualtest/impactecho/ultrasonicpulsevelocity),delamination(hammertest/ultrasonicpulsevelocity/impactecho),flawsandinternalcracking(ultrasonicpulsevelocity/impactecho),dynamicmodulusofelasticity(ultrasonicpulsevelocity),Possion’sratio(ultrasonicpulsevelocity),thicknessofconcreteslaborwall(ultrasonicpulsevelocity),CFRPdebonding(hammertest/infraredthermographictechnique),andstainonconcretesurface(visualinspection).Qualityanddurabilitytestmethodsmayinclude;rebarcorrosionrate–fieldtest,chlorideprofilefieldtest,rebarcorrosionanalysis,rebarresistivitytest,alkali-silicareactivityfieldtest,concretealkalinitytest(carbonationfieldtest),concretepermeability(fieldtestforpermeability).4Non-destructiveEvaluationofDeterioratedConcreteTheprocessofevaluatingthestructuralconditionofanexistingconcretebridgeconsistsofcollectinginformation,e.g.drawingsandconstruction&inspectionrecords,analyzingNDTdata,andstructuralanalysisofthebridge.Theevaluationprocesscanbesummarizedasfollows:(1)Planningfortheassessment,(2)Preliminaryassessment,whichinvolvesexaminationofavailabledocuments,siteinspection,materialsassessment,andpreliminaryanalysis,(3)Preliminaryevaluation,thisinvolves:examinationphase,andjudgmentalphase,andfinally(4)thecost-impactstudy.Iftheinformationisinsufficienttoconductevaluationtoaspecificrequiredlevel,thenadetailedevaluationmaybeconductedfollowingsimilarstepsfortheabove-mentionedpreliminaryassessment,butin-depthassessment.Successfulanalyticalevaluationofanexistingdeterioratedconcretebridgeshouldconsidertheactualconditionofthebridgeandlevelofdeteriorationofvariouselements.Factors,e.g.actualconcretestrength,levelofdamage/deterioration,actualsizeofcorrodedrebars,lossofbondbetweensteelandconcrete,etc.shouldbemodeledintoadetailedanalysis.Ifsuchdetailedanalysisisdifficulttoaccomplishwithinareasonableperiodoftime,thenevaluationbyfieldloadtestingoftheactualbridgeinquestionmayberequired.5BridgeRehabilitationwithCFRPCompositesApplicationofCFRPcompositematerialsisbecomingincreasinglyattractivetoextendtheservicelifeofexistingconcretebridges.ThetechnologyofstrengtheningexistingbridgeswithexternallybondedCFRPcompositeswasdevelopedprimarilyinJapan(FRPsheets),andEurope(laminates).Theuseofthesematerialsforstrengtheningexistingconcretebridgesstartedinthe1980s,firstasasubstitutetobondedsteelplates,andthenasasubstituteforsteeljacketsforseismicretrofitofbridgecolumns.CFRPCompositematerialsarecomposedoffiberreinforcementbondedtogetherwitharesinmatrix.Thefibersprovidethecompositewithitsuniquestructuralproperties.Theresinmatrixsupportsthefibers,protectthem,andtransfertheappliedloadtothefibersthroughshearingstresses.MostofthecommerciallyavailableCFRPsystemsintheconstructionmarketconsistofuniaxialfibersembeddedinaresinmatrix,typicallyepoxy.Carbonfibershavelimitedultimatestrain,whichmaylimitthedeformabilityofstrengthenedmembers.However,undertrafficloads,localdebondingbetweenFRPsheetsandconcretesubstratewouldallowforacceptablelevelofglobaldeformationsbeforefailure.CFRPcompositescouldbeusedtoincreasetheflexuralandshearstrengthofbridgegirdersincludingpiercapbeams,asshowninFigure3.InordertoincreasetheductilityofCFRPstrengthenedconcretegirders,thelongitudinalCFRPcompositesheetsusedforflexuralstrengtheningshouldbeanchoredwithtransverse/diagonalCFRPanchorstopreventprematuredelaminationofthelongitudinalsheetsduetolocalizeddebondingattheconcretesurface-CFRPsheetinterface.InordertopreventstressconcentrationandprematurefractureoftheCFRPsheetsatthecornersofconcretemembers,thecornersshouldberoundedat50mm(2.0inch)radius,asshowninFigure3.Deteriorationofconcretebridgemembersduetocorrosionofsteelbarsusuallyleadsinlossofsteelsectionanddelaminationofconcretecover.Asaresult,suchdeteriorationmayleadtostructuraldeficiencythatrequiresimmediateattention.Figure4showsrehabilitationofstructurallydeficientconcretebridgepierusingCFRPcomposites.Figure3FlexuralandshearstrengtheningofconcretebridgepierwithFRPcompositesFigure4RehabilitationofdeterioratedconcretebridgepierwithCFRPcomposites6SummaryandConclusionsEvaluation,non-destructivetestingandrehabilitationofdeterioratedconcretebridgeswerepresented.Deteriorationofconcretebridgecomponentsduetocorrosionmayleadtostructuraldeficiencies,e.g.flexuraland/orshearfailures.ApplicationofCFRPcompositematerialsisbecomingincreasinglyattractivesolutiontoextendtheservicelifeofexistingconcretebridges.CFRPcompositescouldbeutilizedforflexuralandshearstrengthening,aswellasforrestorationofdeterioratedconcretebridgecomponents.TheCFRPcompositesheetsshouldbewelldetailedtopreventstressconcentrationandprematurefractureordelamination.Forsuccessfulrehabilitationofconcretebridgesincorrosiveenvironments,acorrosionprotectionsystemshouldbeusedalongwiththeCFRPsystem.第十届东亚太结构工程设计与施工会议2006年8月3-5号，曼谷，泰国碳纤维复合材料修复混凝土桥梁结构的详述及应用RiyadS.ABOUTAHA1,andNuttawatCHUTARAT2摘要：在各式各样的公路交通网络中，许多现有的古老桥梁，在各种恶劣的环境下，如更重的荷载和更快的车辆等条件下，依然在被使用着。冲刷、腐蚀和风化对这些古老的桥梁已经造成了破坏，而维修资金短缺更加剧了它们的损坏。一个利用碳纤维增强复合材料〔CFRP〕来延长混凝土桥梁的使用寿命的想法使桥梁恢复了原有的状态。然而，采用碳纤维复合材料修复受损混凝土桥梁的指导和标准还非常有限。在本文中对无损探伤、无损检测和利用碳纤维复合材料修复已遭侵蚀的桥梁的方法进行了介绍。此设计对碳纤维增强混凝土桥的延性，及其应用后效果也进行了讨论和介绍。关键词:混凝土腐蚀，钢筋锈蚀，桥梁修复，碳纤维复合材料1简介在这里存在几个有害的外部环境因素影响着桥梁的耐久性。这些因素包括但又不仅限于化学物的侵蚀，受力钢筋的锈蚀，混凝土的碳化，化学物质的聚合反响。如果桥梁维护不好，这些因素可能导致结构的受损，如结构边缘不稳定或结构损毁。为了修复日渐恶化的现存桥梁，应当对其作彻底的评估。目的是通过大致检测剩余耐久度和承载力，评定出所有现存桥梁的真实情况。应用碳纤维复合材料可以恢复混凝土桥梁最初的状况并延长其使用年限。在北美、欧洲和日本，碳纤维复合材料应经得到深入的研究和广泛的应用。碳纤维复合材料的几个设计指南也已经被应用于强化混凝土桥梁。然而，采用碳纤维复合材料修复损坏的混凝土桥梁的指导和标准还非常有限。本文通过适宜的例子给出了修复受损混凝土梁桥的准那么，列出了评估、无损检测、碳纤维复合材料复原受损混凝土桥梁。碳纤维复合材料的成功应用由于良好的细节设计，它主要考虑了集中力在碳纤维复合材料中依靠混凝土与碳纤维复合材料接触面间的粘合剂转移。此设计对碳纤维增强混凝土桥的延性和反响的效果也进行了讨论和介绍。2混凝土桥梁的损坏桥梁的使用年限应该给予极大地关注。越来越多的桥梁在到达设计使用年限之前出现令人侧目的破损。这些过早出现的损坏使得桥梁的结构可靠性和平安性成为1副教授，雪城大学，美国2讲师，斯巴顿大学，泰国了值得考虑的问题。总的来说，桥梁的损坏与考虑它的花费多少是紧密相关的。在很多情况下，损坏问题的根源是混凝土结构中受力钢筋的腐蚀。通常由混凝土保护层预防受力筋的腐蚀。然而，这些具有代表性的问题，如混凝土质量差、不适当的设计或施工和周围恶劣的环境导致了钢筋的腐蚀。如果不及时处理像钢筋腐蚀这种耐久性问题，可能会引起受力不均问题，进而导致结构失稳，如图1所示。图1钢筋的锈蚀导致的结构失稳3损坏的混凝土梁桥墩柱的无损检测为了设计一个成功的新式系统，应该对桥梁现有的情况作彻底评估。评价现有桥梁的元素或体系需要翻看asbuilt图纸，才能准确的评估出现有桥梁的状况，如图2所示。根据评估的目的，无损测试应该包括的内容：强度的检测，盐度，腐蚀率，混凝土中碱含量等等。虽然大多数的无损测试对现有桥梁不会造成任何损坏，一些无损检测可能导致的轻微局部损伤〔如钻洞取芯〕，在无损检测完毕后应予以修复。这些测试也被叫作局部破坏性测试,但属于无损检测。裸露的钢筋裸露的钢筋裂缝平行于锈蚀的钢筋剥离〔敲击有空心声音〕弯剪/剪切裂缝图2混凝土桥墩可见缺陷正面图为了针对特殊情况选择最适宜的无损检测，应该明确测试的目的。一般来说,有三种类型的无损检测进行调查：〔1〕强度；〔2〕其他结构性质；〔3〕质量及耐久性。强度测试的方法可能包括：抗压测试〔如轴心抗压、反弹测试仪、超声波脉冲速度检测〕；外表硬度测试〔如反弹仪测试〕；贯入度试验〔如温莎探针〕；拉拔试验〔锚索抗拔试验〕。其它结构测试方法还包括：混凝土保护层厚度〔保护层测量〕；定位钢筋位置〔钢筋定位器〕；钢筋尺寸〔某些钢筋定位器、钢筋数据扫描仪〕；混凝土的湿度〔含水量测试仪、水分测定仪〕；混凝土裂缝检查〔外观鉴定、回音法、超声波脉冲回波速度检查法〕；混凝土分层剥离〔锤击试验、超声波脉冲回波速度检查法、回音法〕；缺陷和内部开裂〔超声波脉冲回波速度检查法、回音法〕；动态弹性模量〔超声波脉冲回波速度检查法〕；泊松比〔超声波脉冲回波速度检查法〕；混凝土板或墙的厚度〔超声波脉冲回波速度检查法〕；碳纤维复合材料剥离〔锤击