土木毕业设计外文翻译近表面埋置加固的钢筋混凝土梁抗弯性能实验研究

ANEXPERIMENTALSTUDYONFLEXURALBEHAVIOROFRCBEAMSSTRENGTHENEDWITHNSMREINFORCEMENTWoo-TaiJUNG1,Young-HwanPARK2,Jong-SupABSTRACT:ThisstudypresentstheresultsofexperimentsperformedonRC(ReinforcedConcrete)beamsstrengthenedwithNSM(NearSurfaceMounted)reinforcement.Atotalof6specimenshavebeentested.ThespecimenscanbeclassifiedintoEBR(ExternallyBondedReinforcement)specimenandNSMreinforcementsspecimens.TwoNSMspecimenswithspacevariableswerestrengthenedwith2CFRP(CarbonFiberReinforcedPolymer)strips.ExperimentalresultsrevealedthatNSMspecimensusedCFRPreinforcementsmoreefficientlythantheEBRspecimens.EvenifCFRPcrosssectionareasofNSMspecimenshave30%,50%ofEBRSpecimen,thestrengtheningeffectofNSMspecimensissuperiortoEBRspecimen.NSMspecimenswithspacevariablesshowedthatthstrengtheningeffectofthespecimenwithnarrowspaceisslightlyincreasedascomparedtothespecimenwithwidespaceuKEYWORDS:carbonfiberreinforcedpolymer,externallybondedCFRPreinforcements,nearsurfacemountedCFRPreinforcements,strengthening1.INTRODUCTIONAmongthevariousstrengtheningtechniquesthathavebeendevelopedandappliedtostrengthendeterioratedRCstructures,anumberofapplicationsusingFRPreinforcementshavesignificantlyincreasedrecently.FRPreinforcementsarebondedtoconcretesurfacesbyadhesivesbutfrequentlyexperiencedebondingfailureattheinterfacebetweenFRPreinforcementsandconcrete.Mostresearch,todate,hasfocusedoninvestigatingthestrengtheningeffectsandfailuremodesofEBRsystemTheproblemofprematurefailureofEBRsystemmaybesolvedbyincreasingtheinterfacebetweenFRPandconcrete.Usingthisprinciple,theNSMsystemhasbeenintroducedrecently.TheNSMsystemforconcretestructureusingsteelreinforcementalreadybeganin1940s.However,thecorrosionofthesteelreinforcementandthepoorbondingperformanceofthegroutingmateriallargelyimpaireditsapplication.ThedevelopmentofimprovedepoxyandtheadoptionofFRPreinforcementofferedtheopportunitytoimplementNSMsystem(HassanandRizkalla2003;TäljstenandCarolin2001).Becauseoftheirlightweight,easeofinstallation,minimallaborcostsandsiteconstraints,highstrength-to-weightratios,anddurability,FRPrepairsystemscanprovideaneconomicallyviablealternativetotraditionalrepairsystemsandmaterials(Mirmiranetal.2004).RizkallaandHassan(2002)havecomparedEBRandNSMsystemintermsofcost,includingcostsofmaterialsandlabor,andstrengtheningeffect.TheyconcludedthattheNSMsystemwasmorecost-effectivethantheEBRsystemusingCFRPstrips.ThisexperimentalstudyinvestigatestheapplicabilityandstrengtheningperformancesofNSMusingCFRPstrips.Forcomparison,flexuraltestsonRCbeamsstrengthenedbyEBRandbyNSMhavebeenperformed.Inaddition,specimenswithspacevariableshavebeentestedtocomparethestrengtheningperformancebycrosssectionwithwideandnarrowspace.2.EXPERIMENTALPROGRAM2.1MANUFACTUREOFSPECIMENSAtotalof6specimensofsimplysupportedRCbeamswithspanof3mhavebeencast.Thedetailsandcross-sectionofthespecimensareillustratedinFigure1.Aconcretewithcompressivestrengthof31.3MPaat28dayshasbeenused.SteelreinforcementsD10(φ9.53mm)ofSD40havebeenarrangedwithsteelratioof0.0041andalayerofthreeD13(φ12.7mm)hasbeenarrangedascompressionreinforcements.ShearreinforcementsofD10havebeenlocatedevery10cmintheshearzonetoavoidshearfailure.Table1summarizesthematerialpropertiesusedforthetestbeams.2.2EXPERIMENTALPARAMETERSTable2liststheexperimentalparameters.Thecontrolspecimen,anunstrengthenedspecimen,hasbeencasttocomparethestrengtheningperformancesofthevarioussystems.CPL-50-BOND,EBRspecimen,hasbeenstrengthenedwithCFRPstrip.Theremaining4specimenswerestrengthenedwithNSMCFRPstrips.AmongthespecimensstrengthenedwithNSMreinforcements,anembedding64depthofNSM-PL-15andNSM-PL-25is15mmand25mm,respectively.AspacebetweengroovesofNSM-PL-25*2andNSM-PL-2Sis60mmand120mm,respectively.Thestrengthenedlengthofallthespecimenshasbeenfixedto2,700mm2.3INSTALLATIONOFTHEFRPREINFORCEMENTSFigure2showsthedetailsofcross-sectionsofthespecimens.ThestrengtheningprocessofEBRspecimen(CPL-50-BOND)wasproceededbythesurfacetreatmentusingagrinder,followedbythebondingoftheCFRPstrip.Thestrengthenedbeamswerecuredatambienttemperaturefor7daysforthecuringofepoxyadhesive.TheprocessforNSMstrengtheningprogressedbycuttingthegroovesatthebottomofthebeamsusingagrinder,cleaningthedebris,andembeddingtheCFRPstripafterapplicationoftheadhesive.Thestrengthenedbeamswerecuredfor3dayssothattheepoxyadhesiveachievesitsdesignstrength.2.4LOADINGANDMEASUREMENTMETHODSAllspecimensweresubjectedto4-pointbendingteststofailurebymeansofUTM(UniversalTestingMachine)withcapacityof980kN.Theloadingwasappliedunderdisplacementcontrolataspeedof0.02mm/secuntilthefirst15mmand0.05mm/secfrom15mmuntilfailure.Themeasurementofalltestdatawasrecordedbyastaticdataloggerandacomputeratintervalsof1second.Electricalresistancestraingaugeswerefixedatmid-spanandL/4tomeasurethestrainofsteelreinforcements.Straingaugestomeasurethestrainofconcretewerelocatedatthetop,5cmand10cmawayfromthetopononesideatmid-span.StraingaugeswerealsoplacedontheFRPreinforcementlocatedatthebottomofthemid-spanandloadedpointstomeasurethestrainaccordingtotheloadingprocess.3.EXPERIMENTALRESULTS3.1FAILUREMODESBeforecracking,allthestrengthenedspecimensexhibitedbendingbehaviorsimilartotheunstrengthenedspecimen.ThisshowsthattheCFRPreinforcementisunabletocontributetotheincreaseofthestiffnessandstrengthintheelasticdomain.However,aftercracking,thebendingstiffnessandstrengthofthestrengthenedspecimenswereseentoincreasesignificantlyuntilfailurecomparedtotheunstrengthenedspecimens.Examiningthefinalfailure,theunstrengthenedcontrolspecimenpresentedtypicalbendingfailuremodewhichproceedsbytheyieldingofsteelreinforcementfollowedbycompressionfailureofconcrete.ThefailureofCPL-50-BOND,EBRspecimen,beganwiththeseparationofCFRPreinforcementandconcreteatmid-spantoexhibitfinallybrittledebondingfailure(Figure3).FailureofNSM-PL-15,NSMspecimen,occurredwiththeruptureoftheFRPreinforcement.FailureoftheremainingNSMspecimens(NSM-PL-25,NSM-PL25*2,andNSM-PL-2S)occurredthroughthesimultaneousseparationoftheCFRPreinforcementandepoxyfromconcrete(Figure4,5,and6).Table3summarizesthefailuremodes.3.2STRENGTHENINGEFFECTFigure7plotedtheload-deflectioncurvesofEBRandNSMspecimens.ThespecimenswithEBR,CPL-50-BOND,presentedultimateloadincreasedby30%comparedtotheunstrengthenedspecimen,whileNSMspecimens(NSM-PL-15,NSM-PL-25)increasedtheultimateloadby40to53%.ObservationofFigure7revealsthatevenifCPL-50-BONDwithrelativelylargecross-sectionalareaofCFRPreinforcementdevelopedlargerinitialstiffness,prematuredebondingfailureoccurredbecauseitsbondingareaismuchsmallerthanNSM-PL-15,NSM-PL-25.EBRspecimenbehavedsimilarlytotheunstrengthenedcontrolspecimenafterdebondingfailure.InFigure7,thestiffnessofNSMspecimensbeforeyieldingofsteelreinforcementwassmallerthanthestiffnessdevelopedbyEBRspecimenbecauseNSMspecimenshavethesmallercross-sectionalareaofCFRPreinforcementthanEBRspecimen.Theultimateloadandyieldloadareseentoincreasewiththecross-sectionalareaofNSMreinforcement.ExaminingtheultimatestrainofFRPsummarizedinTable3,themaximumstrainforEBRspecimenappearstoattain30%oftheultimatestrain,and80to100%forNSMspecimens.ThisprovesthattheNSMsystemisutilizingCFRPreinforcementefficiently（2Swiththesamecross-sectionalareaasCPL-50-Bondresentedultimateloadincreasedby95%,90%comparedtotheunstrengthenedspecimen,respectively.Consideringthesamecross-sectionalarea,thestrengtheningeffectofNSMspecimensissuperiortotheEBRspecimen.InFigure8,NSM-PL-25*2andNSM-PL-2S,NSMspecimenswithspacevariables,showedthatthestrengtheningeffectofthespecimenwithnarrowspaceisslightlyincreasedby2.5%ascomparedtothespecimenwithwidespace.4.CONCLUSIONSPerformancetestshavebeencarriedoutonRCbeamsstrengthenedwithNSMsystems.Thefollowingconclusionswerederivedfromtheexperimentalresults.IthasbeenseenthatNSMspecimensutilizedtheCFRPreinforcementmoreefficientlythantheEBRspecimen.Accordingtothestaticloadingtestresults,thestrengtheningperformanceswereimprovedinNSMspecimenscomparedwithEBRspecimen.However,thespecimensNSM-PL-25,NSM-PL-25*2andNSM-PL-2SfailedbytheseparationoftheCFRPreinforcementsandepoxyadhesivefromtheconcrete.Consequently,itisnecessarytotakesomecountermeasurestopreventdebondingfailureforNSMspecimens.Consideringthesamecross-sectionalarea,thestrengtheningeffectofNSMspecimensissuperiortoEBRspecimen.NSM-PL-25*2andNSM-PL-2S,NSMspecimenswithspacevariables,showedthatthestrengtheningeffectofthespecimenwithnarrowspaceisslightlyincreasedascomparedtothespecimenwithwidespace.5.REFERENCES1.Hassan,T.andRizkalla,S.(2003),InvestigationofBondinConcreteStructuresStrengthenedwithNearSurfaceMountedCarbonFiberReinforcedPolymerStrips”,JournalofCompositesforConstruction,Vol7,No.3,pp.248-2572.Täljsten,B.andCarolin,A.(2001),“ConcreteBeamsStrengthenedwithNearSurfaceMountedCFRPLaminates”,Proceedingofthefifthinternationalconferenceofibre-reinforcedplasticsforreinforcedconcretestructures(FRPRCS-5),Cambridge,UK,16-18July2001,pp.107-1163.Mirmiran,A.,Shahawy,M.,Nanni,A.,andKarbhari,V.(2004),“BondedRepairandRetrofitofConcreteStructuresUsingFRPComposites”,RecommendedConstructionSpecificationsandProcessControlManual,NCHRPReport514,TransportationResearchBoard4.Rizkalla,S.,andHassan,T.(2002),“EffectivenessofFRPforStrengtheningConcreteBridges”,StructuralEngineeringInternational,Vol.12,No.2,pp.89-95近表面埋置加固的钢筋混凝土梁抗弯性能实验研究Woo-TaiJUNG1,Young-HwanPARK2,Jong-SupPARK3摘要：本研究介绍了近表面贴埋置加固钢筋混凝土（RC）实验结果。共有6个试验试件。试件可分为EBR的（外部粘结）和NSM（近表埋置）两种。埋置两片CFRP（碳纤维增强聚合物）的试件埋置间距不同。实验结果表明，用碳纤维增强材料NSM试件比EBR试件更有效。即使NSM试件断面面积是EBR的30％和50％，其效果也优于EBR试件。间距不同的试件结果表明，小间距略比大间距试件效果好。关键词：碳纤维增强复合材料，碳纤维增强材料外贴，近碳纤维增强材料表面安装，加固1．简介在各种不同的技术的开发和应用，加强钢筋混凝土结构的技术越来越多，用玻璃钢增强混凝土的申请项目已显着多起来。玻璃钢加固混凝土表面的粘合胶，但经常在玻璃钢和混凝土界面脱粘导致失败。大多数研究，到今天为止，一直专注于加强调查EBR的影响和破坏模式系统。EBR的系统的过早失效的问题如果得到解决，就会增加玻璃钢和混凝土之间的接口的粘合度。利用这一原则，NSM系统被引进用于钢筋混凝土结构体系是在20世纪40年代开始的。然而，容易受腐蚀的钢筋和灌浆材料的胶合性能较差损害了其应用。提高环氧树脂的发展和采用玻璃钢加固所提供的机会实施NSM（Hassan和Rizkalla2003年;Täljsten和Carolin2001年）。由于其重量轻，安装方便，最小的劳动力成本和场地条件，高强度与重量比，和耐用性，玻璃钢修复系统可以提供一个经济上可行替代传统的修复系统和材料（Mirmiran等。2004年）。Rizkalla和Hassan（2002）EBR和NSM在成本方面的比较，包括原材料和劳动力成本的制度，还有强化作用等​​。他们的结论是，NSM系统在成本效益上更符合要求。为了便于比较，关于钢筋混凝土简支梁的抗弯试验EBR的和NSM开始做了。此外，间距变量试件进行测试，以比较通过加强断面宽和窄的间距影响。2．实验项目

2.1试样的制造有6组钢筋混凝土简支梁的试件共300次已经实验。具有代表性的试件如图1所示。一个与混凝土抗压强度在28天31.3兆帕斯卡已被使用。钢筋D10中的SD40（φ9.53mm）已安排钢比0.0041和三个D13号层（φ12.7mm）已安排了压缩增援。增援的D10的剪切已经找到剪切带中的每一个10厘米，以避免剪切破坏。表1总结了材料试验梁的属性。图-1试件的细节表示图表-1试验梁的属性材料性能混凝土抗压强度（MPa）31.3张力钢加强

（D10中）

屈服强度（MPa）426拉伸强度（MPa）562直径（毫米）9.53面积（cm2）0.7133压缩钢加固（D13号）

屈服强度（MPa）481拉伸强度（MPa）608直径（毫米）12.7面积（cm2）1.267碳纤维带

（光滑表面）厚度（毫米）1.4拉伸强度（MPa）2452.59（GPA）的弹性模量165.49极限应变（％）1.482.2实验参数表2列出了实验参数。控制试件，一不加强的试件，被拿来比较各系统加强的状态。CPL-50–卷，EBR的试件，加强了与碳纤维带。其余4个试件，加强了与NSM碳纤维带。内嵌加强了试件，嵌入分别为64对NSM-特等-15和NSM-特等-25深度为15mm和25mm，。沟槽之间的一个空间NSM-的PL-25*2和NSM-的PL-2为60mm和120mm，分别为。加强的所有的长度试件已得到修复了二七零零毫米试件碳纤维复合材料试样面积（平方毫米）碳纤维复合材料碳纤维（％）加强

方法控制---不加强CPL-50-BOND70条0.1296EBR1NSM-PL-1521条0.0389NSM2)NSM-PL-2535条0.0648NSM2)NSM-PL-25*270条0.1296NSM-N3)NSM-PL-2S70条0.1296NSM-W4)1）EBR的：外部粘结

2）NSM：近表埋置

3）NSM-N的：2NSM增援;槽空间：60毫米

4）NSM瓦：2NSM增援;槽空间：1202.3安装玻璃钢筋图2显示了跨越部分的试件的细节。EBR的强化过程的试件（cpl-50–粘合剂）是由表面进行研磨处理使用的，其次接合地带的碳纤维。加固梁凝结的7天环境温度环氧树脂胶粘剂的固化。加强对NSM进程在取得进展的沟槽切割底部横梁用粉碎机，清洗碎片，嵌入后的碳纤维带应用的胶粘剂。加固梁的3天凝结，可使环氧胶粘剂达到其设计强度。图-2纤维增强塑料的加强2.4加载和测量方法所有试件受到4点弯曲测试，以衰竭的UTM手段（万能试验机）与980千牛的能力。根据应用的负载量为位移控制在速度0.02毫米/秒，直到第15毫米和0.05毫米/秒，从15毫米到失败。对所有测量测试数据记录静态数据记录器和一个1秒的间隔计算机。电电阻应变计固定在跨中和1/4来衡量钢筋应变。应变计来测量混凝土应变均位于上方，5厘米和10厘米的距离在顶部的一跨中的一面。应变计，存放在位于上玻璃钢加固中期的跨度和负载点底部测量应变根据加载过程。3．实验结果

3.1失效模式开裂前，所有试件展出弯曲性能加强类似的不加强试件。这表明，碳纤维加固是无法作出贡献增加的刚度和强度在弹性域。然而，在开裂，弯曲刚度和强度得到加强的试件被视为显着增加，直到失败相比unstrengthened试件。检查的最后失败，unstrengthened控制试件呈现典型的弯曲破坏模式，由钢筋屈服所得其次是压缩失败混凝土。对于cpl-50–条，EBR的试件，故障开始与碳纤维分离加强和跨中混凝土脆性剥离终于表现出故障（图3）。失败对NSM-特等-15，NSM试件，用玻璃钢加固破裂发生。发生故障其余NSM试件器（NSM-特等-25，NSM-PL25*2，和NSM-特等-2）通过发生同时碳纤维加固的分离，从具体环氧树脂（图4，5和6）。表3总结了失败的模式表-3实验结果试件Py(kN)dy(mm