英文原文：ＲｅhabｉlitatｉｏnｏｆrectangｕlarｓｉmplｙｓupporteｄRＣbeamsｗiｔｈｓheaｒｄefiｃiｅncｉeｓusingＣFRＰcoｍpositesAhmｅｄKhaｌifａa，*,AnｔonioNaｎｎｉbaDｅpａrtmｅnｔofSｔｒuctuｒalEｎgiｎeｅｒｉnｇ,ＵnｉversityofAｌexａｎｄria,Aleｘandｒiａ215４4,EgyptbＤeｐａｒtmentofCｉｖilEｎgineｅriｎg，UniverｓｉtyofMｉssoｕrｉatＲｏｌlａ,Roｌｌa,MO６540９，USAReｃｅived28Ａｐril1９99；ｒeceivedinreviｓedform30Ｏcｔoｂer;acceｐteｄ10ＪanuaryAbstracｔThｅpｒeｓeｎtstudｙexａｍｉｎeｓthｅshearpeｒforｍaｎceandmoｄesoｆfaｉｌureofｒｅｃｔａngｕlarｓｉmpｌysｕｐpｏrtedreｉnforceｄconcrete(ＲC）beａｍsｄeｓｉgnedwｉtｈｓheardefｉciｅncｉeｓ.Thesememｂersweresｔrengｔｈenedwitｈｅxterｎallｙｂoｎdｅdｃａrbｏnfibｅrreｉnｆorcｅdpｏｌymｅｒ(CFRP)sｈeetsandeｖaluatedｉｎtｈelａｂoratoｒy．Theexｐｅrｉmeｎtaｌprogramconsisｔedｏftwｅlvefuｌl－ｓｃaleRCbeａmsteｓｔｅdｔｏfaｉｌinsheaｒ．Theｖariaｂｌesinvｅsｔigatedwiｔｈｉnthisprograｍｉｎcluｄedsｔeelstｉｒｒｕps,anｄtheｓhｅaｒspａｎ-to-efｆeｃｔｉｖedeｐｔｈratio,aswｅｌlasａmｏuntaｎdｄｉsｔribｕtiｏnofCFRP.TheｅxperiｍenｔａlreｓultｓiｎdicatedthaｔｔhecｏntrｉｂuｔionofexternａｌｌybondedCFRPtotｈeshearcapacｉtyｗasｓiｇniｆicaｎt．Thｅｓhearｃａｐacitywａsalsoshｏｗntobｅdepｅｎdentuponｔｈeｖariaｂlｅsinvestｉgａｔed.Teｓtreｓultsｗereusedtovaliｄatｅaｓheardｅsigｎapproａcｈ，whichshowｅｄconｓｅrｖaｔiveandacceptａｂｌeｐrediｃｔｉonｓ.eq\o\ac(○,C)EｌsevｉｅrＳｃｉenｃｅLｔd.Ａllriｇhtsｒeservｅd.Keｙｗords:Rehabｉliｔaｔion;Shｅar;Carboｎfibｅrreinforcedpoｌｙmer１．IntｒodｕｃtｉonFｉbeｒrｅｉnｆｏｒcedpolyｍｅr(FRP）compｏsitｅsystｅｍs,composedoffibersembｅｄｄｅdinａpolymｅｒicmａtrix,canbeuseｄforshｅａｒstrengthｅniｎgoｆreinｆorcedcｏn－ｃrete(RC)memberｓ[１–7]．ManｙeｘistinｇRＣｂeamsaredｅｆiｃientandｉｎneｅdofｓtｒｅngthenｉnｇ.TheｓｈeaｒfailureofａnRCbeamiscleａrlydifｆerenｔｆromitsflexuralfailｕｒe．Inｓｈeaｒ,thｅｂeaｍfaｉｌsｓuｄdｅnｌyｗitｈoutｓuffｉcientwarningaｎｄdiaｇoｎalsheａrｃｒacksａｒeconｓｉｄ－eraｂlywｉderthantheｆlｅxuralcｒaｃkｓ［８].Theobjeｃtｉveｓｏfｔhｉsｐrograｍweretｏ:1.IｎｖeｓｔｉｇaｔepeｒformanｃeaｎdmoｄeoffａilurｅofsimplysupportedreｃtａngularRCbeamｓwithｓheａrdeficieｎ-cｉeｓaftersｔrengｔｈeｎiｎgwithexｔｅrnallybｏndedCFRＰsｈｅets.2.Aｄｄｒessthefaｃtorstｈａtinfluｅnceｓheａｒcapaciｔyofstrengthenedbeamｓsｕchaｓ:sｔeelstiｒrｕｐs,ｓheａrｓpａn－to-eｆfｅctivedepthratiｏ(a/dｒａtｉo),ａndａmountａndｄistｒibutiｏｎoｆCFRP.３.Iｎcｒeaｓetｈeeｘperimentaｌdaｔaｂaseonsｈeaｒsｔreｎｇtｈ－ｅningwｉtｈｅxｔernallyｂondeｄFRPrｅiｎforｃeｍent.4．Ｖａｌidatethedesignapproachprｅviouslypropoｓeｄbyｔheautｈors［9]．Fortｈｅseobjectivｅs,12full-scaｌｅ，RCｂeaｍsｄesigｎeｄtoｆaｉlinsheaｒweｒestrengｔｈenｅdｗiｔhdｉffereｎtCFRPscheｍes.Theｓｅmｅmberswereteｓtｅdassimpｌebｅamsusｉｎgafｏur-pointloaｄｉnｇcoｎfiｇurationwitｈtwodｉfferｅｎtａ/ｄratios.2.Expeｒｉmｅntalｐrogrａm2.1.TestspeｃｉmenｓanｄｍateriａlｓTweｌvefｕｌｌ-ｓcalebeａmｓｐecimenｓwｉtｈａtotalspanｏf30５０mm．aｎdarｅctangularcｒｏss-sectionof１5０－mｍ-ｗidｅaｎd3０5-ｍm-dｅeｐwereｔesｔｅｄ.ThｅsｐecｉmenswereｇｒｏupedｉntotwｏmaｉnsｅｒiesｄesiｇnatedSWandSOdepeｎdingonｔhepｒeｓenceｏfｓtｅelstirruｐｓinｔhｅsheａrspanofinterest．SeriesＳＷcoｎsiｓtｅdoｆfourspeｃｉmens.TheｄｅtaｉlsandｄimｅnsioｎsoｆthｅｓpecimensｄesignatedsｅｒiｅsSWarｅｉlluｓtｒａtedｉnＦig.1a.Inｔhisｓｅriｅｓ,ｆoｕｒ３2-mmsｔeelbａｒswｅｒeusedａslｏngｉtudｉnaｌreｉnfｏrcｅmｅnｔwｉtｈtwoaｔtｏpａnｄｔwoaｔboｔtｏmfaｃeofthecroｓs-sｅcｔioｎｔoinｄuｃeashearｆaｉlure.Tｈｅｓpecimenｓwerｅrｅｉnｆｏrcedwｉtｈ１0-mmsteelstiｒrｕｐsｔhroｕgｈouttｈeｉreｎtirespan.Tｈestirrupsspacinｇｉntｈｅshearspaｎｏfintereｓt,righthalf，wassｅlecteｄtoaｌlowfailｕｒｅinｔhatsｐan.ＳeｒiesＳOconsiｓｔedofeigｈtbｅaｍsｐecimｅｎs,whichhadthesameｃroｓs－seｃtｉondimensionanｄlongitudinalsteelrｅinfoｒcementasforｓerｉesSW．Nosｔirrupsｗerｅprovｉdedinthetesthａｌｆspanasｉlｌustｒａtｅd.Eachmainseriｅｓ(i.ｅ.seriｅsSＷandＳＯ）wassｕbdividｅｄｉntoｔwoｓubｇrｏupsacｃoｒｄingtoshｅａrspan-ｔｏ-effｅctiｖｅdｅｐthｒatio．Thiswasseleｃtedｔｏbea/d=3ａnd4，rｅsultiｎginｔｈeｆoｌlowｉngfoursubgroups:ＳＷ３;SW4;ＳO３;anｄＳO４.TｈemechaｎｉｃalｐｒopertieｓofｔheｍateriaｌｓusedfｏrmanufaｃｔurｉngtｈeｔeｓtｓpecｉmensarelistedinTabｌｅ1.ＦａｂriｃatｉonofthespｅcｉmensiｎclｕｄingsurfaｃeｐrｅparatiｏnａndCFＲPinsｔalｌａtiｏｎisｄｅｓcｒibｅdｅlｓewhｅｒe[１0].2.2.SｔｒenｇtheningｓchemesOｎesｐecimenfromeａchserieｓ(SＷ3－1,SW4－１,SO3-1andSO4-1)wasleftwｉthoutsｔrengthenｉngaｓacｏｎｔｒｏlspeｃimｅn,ｗhereasｅigｈｔｂeamｓｐecimｅnsweｒeｓtrengthenedwiｔｈexternaｌlyｂoｎdedCFRPｓheｅtsfolloｗｉngｔhrｅeｄiｆferentｓchemesａsillustrateｄｉnFig.2.InｓeriｅｓSW3,spｅcimenＳW3-2wａsｓｔrengthｅneｄwithtｗoCFRPｐlｉｅsｈａｖingperpenｄicuｌaｒfｉberｄirectionｓ(９0°／0°).ＴｈefｉrstｐｌywaｓattaｃheｄinthefoｒｍofcｏｎtinｕouｓU－wrapｗiththefiberdirectiｏnorieｎtedｐerpｅｎｄiculaｒtｏｔhelｏnｇiｔuｄinａlａｘｉsoｆtｈespecｉmeｎ(９0°)．Theｓｅcｏndplyｗaｓbondｅdonthetwoｓideｓoftｈesｐecimenｗｉtｈtｈefibｅrｄiｒectｉoｎparaｌleltotheｂeａmaxiｓ(0°）.Thｉｓpｌｙ［i.ｅ.０°ｐly］wａsｓelｅctedtoinveｓｔｉgａtetｈeimpaｃtｏfaｄｄitiｏｎalhoｒizｏｎtalrｅｓtｒaintｏnsheａｒsｔrengｔh.InsｅriesSW4,speｃｉｍenSW4-2wasｓtrｅngthenｅdｗiｔhtｗoCFRPpliｅshａｖingperpenｄicuｌaｒｆibｅrdiｒectiｏn（90°/0°)aｓfｏrsｐｅciｍenＳW３-2.FｏｕｒbeamspeｃimeｎswereｓtrengthenedｉnseｒiesSO３.SpeciｍenSO3－2waｓstrｅngthenedwithｏｎe－plｙCFＲPｓtripsinthｅformofU-wｒapｗitｈ９0°-ｆiberoriｅｎtaｔion.Thestrｉpｗiｄｔｈwas５0mｍwiｔhｃeｎteｒ－to-centerspａciｎgof12５mm.SpｅcｉmｅnSO３-3wasstrengｔhｅnｅdinamanｎersiｍilａrtothatofspecimeｎSO3－2,butwiｔhstripwidtｈequalto75ｍm.SpｅcimenSO3-４ｗaｓｓtrengtheneｄwithone-pｌycoｎtiｎuousU－wｒａp(90°).SpｅciｍｅnSＯ3-５wａｓsｔｒｅnｇthenedwithｔｗoCFＲPｐlieｓ(９０°／0°)similartｏｓpｅcimｅnsSW3-2ａndSＷ4-2．InseriｅsＳＯ4,ｔwoｂｅａmsｐecimensweｒestrengｔheｎｅｄ.SpeciｍenＳO4－2ｗasstrengtｈenedwｉthone-ｐlyCFＲPstripsｉnthｅfoｒmｏｆＵ-wrａpsｉｍilartospｅcimeｎSＯ3-２.SpecｉmenSO4-3wａsstｒｅngｔhｅnedwiｔｈonｅ-pｌyｃontinuｏｕsU－ｗrａp(9０°)siｍilartoSO３-4.２.３.Tｅstseｔ-upanｄｉｎstrumeｎtatioｎAllspｅciｍｅnsｗereｔｅstedａｓsimpleｓpanbｅamssubjｅctedtoafoｕr-pｏiｎtlｏａdasillustratedinFig．3．Auniｖersａｌtestｉｎgmacｈineｗiｔｈ1８０0KNｃapacｉtywasｕsｅdinoｒdertoaｐplyacｏncenｔratedloadonasteｅldｉstｒibuｔionbeａmuｓedｔｏgenｅrａｔｅthetｗｏconｃｅｎtｒaｔedloads．Ｔheloａdwａsappliｅdproｇrｅssivelyｉncyclｅs,uｓualｌyｏnecyclebeforeｃrａｃｋｉnｇfollｏwｅｄｂytｈrｅeｃyｃleｓwiｔhｔhelastoｎeuptoultimatｅ．Ｔｈeapplieｄｌoaｄvｓ.ｄeflectｉoncurvｅsshowninthiｓpａｐｅraｒｅtheenｖｅlopｅsofthｅsｅlｏａdｃｙｃｌｅs．Fｏurlineａrvarｉablediffeｒentiaｌｔranｓfｏrｍｅrs(LVＤTs)wｅｒeｕsedfoｒeachtesttomoｎｉtorｖｅｒｔicａlｄｉsplaceｍentsaｔvａrｉousloｃationsaｓshｏwninFig.3．ＴwoLVDTswerｅｌocaｔedatmid-spanoneachsiｄeoｆｔhespecimen.Ｔheotheｒtｗｏweｒelocatedatｔhespeｃimensｕpportｓtorecｏｒdsuｐpｏｒtｓettｌemeｎt.FｏｒeachspｅcｉｍenoｆserｉesSW，siｘstraｉｎgａｕgeｓweｒｅatｔachｅdｔothrｅeｓtirｒupstoｍonｉtorthestirｒuｐｓtraiｎdｕrｉngloadingａｓiｌluｓtratｅdｉnFig．1a.ThrｅestraingaugｅswereａttacｈeddirecｔlytｏthｅFRPｓheetｏｎtｈesidｅsoｆeachstrengｔhenedｂｅamtｏmoniｔorsｔrainvａriaｔionintｈeFＲＰ.Thestraiｎgａｕgｅｓｗereorientｅdinthevertiｃaldireｃtiｏnanｄlocateｄａtthesｅctionｍｉd-hｅightwithdistanceｓof17５,300and４２5mm,ｒesｐectively，fromthesuppoｒｔfｏrsｅrｉｅsSW3aｎdSＯ３．ForbｅａmｓpecimensoｆｓeriesSW4andＳＯ4,thesｔraingａuｇesｗｅｒｅlocａｔedａtｄisｔancｅof37５,5０0aｎｄ6２5ｍm,ｒeｓpectivｅｌy,fromtheｓupport.３.ResuｌtsaｎｄdｉscusｓionInｔhefｏllowiｎｇｄiscｕssion,refeｒenceｉｓａlｗaｙsmａdｅtoｗeaksｈｅａrspaｎorｓpaｎoｆｉnｔerest．3.1.SerｉesSW3ＳhearｃｒacksｉnｔheｃontroｌspeｃiｍenSW3-１ｗereobserｖedｃloseｔotｈeｍidｄleofｔｈesheaｒsｐaｎｗhenthｅloadreaｃhedappｒｏｘimatｅly90kN．Ａstheloａｄincｒeaｓed,addiｔｉonalsｈearcrａcksfｏrmeｄｔhrouｇｈｏut，widenｉngａndprｏｐagaｔｉngupｔｏfinalfailuｒeatalｏadoｆ2５3ｋＮIｎsｐecｉｍenSW３-2strengｔhenｅdwithCFRP（９0°/０°),nocrａckｓwerevisibleonｔhesidｅsoｒbｏｔtｏmoｆｔheｔesｔsｐeciｍenduetotheFRPwｒapping.Hｏwｅver，ａlongiｔｕdinaｌsplittiｎgcｒacｋinitｉateｄｏntheｔoｐsurfaｃｅofｔｈebeamaｔａhｉghlｏadofaｐproｘimａｔely３20ｋN.Thecrackinｉｔｉatｅdａtｔhelｏcatiｏnofａppliedlｏadaｎdexｔｅndedtowａｒdstｈesupｐorｔ.Thespecimenｆailedbｙcoｎｃｒetespｌittinｇattoｔalloadof3５4ｋN.Tｈiswasanincｒeａｓｅof40%ｉnultiｍatecａpaｃitｙcompaｒｅdtotｈｅcontrolspecimenＳW３-1.Ｔｈesplittingfaｉｌｕreｗasduetｏtherelativelyhighlongitudinalcｏｍpressivestrｅssdevｅlopedattopofthespｅcimen,whｉcｈcreａtedatrａnsversｅtｅnsion，ledｔｏthesplittiｎgfaiｌurｅ.Iｎaddiｔion,ｔherｅlativelylargeａmountｏｆloｎｇｉtudinaｌsteｅlｒeinforcemｅntｃombineｄwｉthover－sｔrｅngtheｎingforsｈeａrbｙCFＲＰwｒappｒobablycａｕsedthismｏdeoffaｉｌｕｒe.Theloaｄｖｓ.ｍid－spａｎdeflectｉoncｕrvesforsｐecimeｎsSＷ3－1andＳW３-2aｒeilluｓｔratｅd,toｓhｏwtheａdditｉonalｃapacityｇaｉｎedbｙCFRP．ThｅｍaximumCFRPｖｅｒtiｃalstraiｎmｅaｓuredaｔfailurｅｉnspｅcimｅnSＷ3-２wａsａpproximatｅlｙ0.0０2３mm/mm,ｗｈiｃhcｏrｒeｓpｏndedto14%ｏftｈerepｏrtｅdCＦRPulｔｉｍatｅｓｔrain.Ｔhｉsvalueiｓnotａnabsolutebecａuseiｔgreaｔｌydependsonthelocaｔionofthｅsｔraingａugeswｉtｈreｓpecttoａcrack．Howevｅr,ｔｈerecordedstrainｉndicatesthatiｆtheｓplitｔiｎgdidnｏtocｃuｒ,theｓhearｃaｐacitycouldｈａvｅｒｅａchedhiｇheｒload．ＣｏmparisonbetｗeｅnmeａsuｒｅdｌｏｃaｌstiｒrupｓtｒaｉnsinｓｐecｉmensSW３-1aｎdＳW3－2areshowｎinFig．6.Thｅstiｒrups1,２and３weｒｅlocateｄatdｉsｔanceof１75,300aｎd42５mｍfrｏmtｈesuppoｒt，resｐectiveｌｙ.Tｈereｓultsｓhｏweｄthatthｅstirｒupｓ2and3dｉdnoｔyielｄａtultimaｔeｆｏrbothｓpecimens.Thesｔraｉｎｓ(anｄtheforｃes）intｈeｓtｉrrｕpｓofsｐecimｅnＳW3-2wｅre,ingenerａl，smalｌｅrｔhanthoseofspecimenSＷ3-1attｈeｓamｅleｖｅlofloａdingduetｏthｅeffecｔofＣFRP.3.2.SeｒieｓSW4ＩnsｐｅcimenSＷ4-1，thｅfirstdｉａgoｎaｌcｒackwasforｍeｄｉnthemembｅｒatａtoｔalａppliedlｏadof75ｋN．Astｈeloadinｃreased，additioｎaｌshearｃｒacｋｓappeaｒedthrｏughｏｕｔtｈesheａrspａｎ．Ｆaｉｌuｒｅoｆthebeamｏｃｃｕｒreｄwhentheｔotalａｐpｌｉedｌｏadrｅａcｈed２00kN．Ｔhｉswａsaｄecrｅasｅoｆ２0％ｉnsheaｒcapacitｙcｏｍｐaredtothespeｃimｅｎSW3－1ＩｎsｐecimｅｎSW4-2，thｅfailurｅwasｃontroｌleｄbｙcoｎcreｔｅｓplittingsimｉlartotestsｐｅcimｅnSW3-２.Thetotａlappliedｌoaｄａｔuｌtｉmatewaｓ3６1ｋNwithaｎ８0％incｒeaｓeinsｈearcapacitycompａredtｏthｅcontrｏlｓｐecimeｎSＷ４-1.Inadｄition,themｅasuｒedstrａinsｉｎthｅstirrｕpｓｆｏrspｅcimｅｎSW4－2ｗｅｒｅlｅｓsｔhanthoseｏfspeciｍenSW４－1.Tｈｅａpｐliedｌoａdvs.mｉｄ-spandeflｅctioｎcuｒｖｅsforbeamsSW4-１andSW4-２areillｕｓｔrated.IｔmａybeｎoｔeｄtｈatspecｉmenSW4－2rｅｓultediｎgreatｅrdeｆｌectionwhｅｎcoｍparedtosｐｅｃimeｎSW4-１.ＷhｅnｃｏｍpariｎgthｅteｓtresulｔsofｓeriesＳW3specimensｔothatofsｅriｅｓSW４,ｔｈeultimaｔefaｉlureloaｄofsｐeｃimenSW３－2anｄSW4-2wasalmoｓtthesａmｅ.Howｅｖeｒ，ｔhｅenｈancｅdcapacityofspecimenSW3-2(ａ/d=3)duetｏtheaｄditionofthｅCFＲPreinfｏrcｅmentwａs101ｋN,wｈilespｅcimenSＷ4-2(ａ／d＝4)was161kN．ＴｈisinｄicatestｈatthecｏｎtributiｏｎｏfｅxｔerｎaｌＣFRPｒeiｎfｏrceｍeｎtmayｂｅiｎfluenｃeｄbytheａydｒatiｏａndａppeaｒｓtｏdecreasewｉthadecreasingａ/drａtio．Further，ｆｏｒbｏｔｈsｔｒengthｅnｅｄspeｃimeｎs(ＳW3－2ａndSＷ4-2),CFＲＰsｈeetsdiｄnotfractｕreordeｂｏndfｒoｍtheconcｒｅtesurfａceaｔultｉmatｅandtｈｉsｉnｄicatesｔhatCFRＰcoulｄproviｄeadditiｏnａlｓtｒengtｈifthebeamｓｄidnotfaileｄｂyｓplitｔing．3.3．SerｉesＳO３Fｉｇ.8illuｓtrａｔｅstheｆａｉｌｕreｍｏｄeｓfｏrseｒｉｅsSO3specｉmens.Thatdetailsthｅａppliｅdlｏaｄvs.mid-spａｎdefｌｅctiｏｎforthespecimens.ThefaｉluremoｄeofcoｎtｒolspecimeｎSO3-1ｗａｓｓｈearcoｍprｅssion．Faiｌureofthespｅcimenｏccurredａｔaｔotａlappliedｌoadoｆ15４kN．Thisloａdｗasadecrｅaseoｆsheaｒcapacityｂｙ54．5kＮcompａrｅｄtotheｓpecｉmeｎＳW3-１ｄuｅtothｅabsenｔofｔｈesteelstiｒrups.Iｎaddition,ｔheｃrackpaｔternｉnｓpｅcｉmenSW３-1wasdiｆfｅreｎtfromoｆspｅcimｅｎSＯ3-1．IｎspｅcimｅnSW3-１,thｅpreｓenｃeofｓtiｒrupspｒｏvidedａbｅtｔｅrdisｔｒibｕtionofdiagｏｎaｌｃrａckｓthrｏughoutthｅshｅarsｐaｎ.InｓpｅciｍenSO3-2,ｓtｒeｎgtheneｄwith50-mmCFRPｓｔripsｓpａcedat125mm,thefirstdiagｏｎalｓｈearｃｒacｋｗasobsｅrvedaｔanappｌiedloａｄof100ｋN.ThecraｃkproｐａｇａtedasｔheloadincrｅaｓedｉnａsimiｌarmaｎｎertothatofspｅciｍｅｎＳＯ3-１.SuddｅｎfａｉｌuｒｅoccuｒredｄuetoｄeｂoｎdｉngｏｆtheCＦＲＰｓtrｉｐsoveｒthｅdiａgｏnalｓhearcrack,ｗiｔhsｐaｌｌedcoｎcｒeteａtｔacｈedｔoｔheCFRPｓtripｓ.Thetotaｌulｔimaｔeloaｄwａｓ262kNwiｔha70％ｉｎｃｒeａseinsｈｅaｒcaｐaｃiｔyoｖerthｅｃｏnｔroｌｓpeｃｉmenＳO3-1.TｈeｍaxｉmumlocａlCFRPveｒｔicalstrainmeasuredatfailuｒeiｎｓpecｉmeｎＳO３-2ｗａs0.0047ｍm/ｍm(i．e.28％oftheuｌｔimateｓｔrａin)，whichｉndicateｄthａttheCＦＲPdｉdnｏtreacｈitsｕlｔimatｅ.SｐeｃimｅnSO3-3,ｓtrengthｅnedｗith75-ｍｍCFRPstripsfaiｌedaｓaｒｅsｕltｏｆＣFRPdｅbondingatａtoｔalａｐｐｌiedloadof２66ｋN．NosignｉｆicantｉｎｃreaseinｓhearcapacｉtywasｎotedcomｐarｅdtoｓpecimeｎSＯ３-2.Thｅmａｘiｍuｍ-recoｒｄeｄｖerticaｌＣＦRPsｔrainatfailｕreｗａs0.０05２mmymｍ(i.e.31％oｆｔheｕltimａtｅｓtrａiｎ).SpecｉmeｎSO3-４，wｈichwasstｒengthenedwithaｃontinuousCFRPＵ-wrap(908)，faiｌedasaresultofＣＦRPdeboｎdingatanaｐpliedloaｄof２89kN.ＲｅsultsshowthaｔｓpecimｅnSO3-4ｅxhiｂitedｉncreaseinshearcａpacityoｆ8７，10anｄ8.5%oｖerspｅｃiｍeｎsSO３-1,ＳO３-2andSO３－3,respectiｖely．Appliｅdｌoadvｓ.verticalCFRPstrａinｆorsｐeｃimenSO3－４isilｌｕstratediｎFig．10inwhicｈsｔｒaiｎgａugeｓsg1,sg2anｄsｇ3wereｌｏcａtedａｔmｉｄ-ｈｅightwitｈdisｔanｃｅsof175,300aｎd425mmfroｍｔhｅsuppｏｒt,respectively.Fig.10ｓhoｗstｈattheＣFRPstraｉｎｗaｓｚeroprｉortodiａgｏnａlcrａｃkformａtion,tｈenｉnｃｒｅaｓedsｌowｌyunｔｉlthespｅciｍeｎreaｃhedaｌoadintheneｉghｂｏrｈoodｏfthｅultiｍａtesｔrengthofthecontroｌspeｃimen.Attｈispoinｔ,theＣFRＰstrainiｎcreaseｄsignｉfｉｃantｌyuｎtiｌfailure.ThemaximｕmlocalCFＲPveｒticalstｒainmｅasuredａtｆaiｌurewasapproｘi－mately0.0045mm／mｍ.WhencompａrｉｎgｔｈeresulｔｓofbeａmsSＯ3-４ａndSO３-2，ｔheCＦＲPamounｔusedtｏｓｔrengｔheｎｓpｅcｉmenSO3－4was250%ｏｆｔhatｕｓｅｄｆorｓpeciｍenSO3－2.Onｌya１0%inｃｒeａseｉｎsｈeａrcａpaciｔywasacｈievedｆortheaddｉtionaｌａmｏuｎtofCFRPuseｄ.ThismeanｓｔhaｔifaneｎｄanchortocoｎｔｒolFＲPdeｂonｄingｉｓnoｔusｅd,thｅreiｓanｏpｔimumＦＲPquanｔity,ｂｅyｏndwhichｔhesｔrengｔheniｎgeｆfeｃtisｑueｓtioｎａblｅ.Aｐreviousstuｄy［11]sｈowｅdｔｈａｔbyusｉngａｎendanchorsｙｓteｍ,thefａiluremodeofFＲPdｅｂｏndiｎgcｏuldbeａvoided．Ｒepoｒｔedｆinｄｉｎgsareconsistｅntｗithtｈosｅoｆotheｒｒｅｓeａrch[7］,whiｃhwaｓbaｓedonａｒｅviewofｔｈeexperimeｎｔalresｕltsａvailaｂleinｔhelｉtｅrature,andｉndicatedthatthecontｒibｕtionofFRPtoｔheｓhｅａｒcａpａcitｙｉncｒeaseｓａlmostｌｉｎeａrlｙ,wiｔhＦRPaxialrigidityｅxprｅssedby(istheFRPａreaｆｒacｔionaｎdistheFRＰelａｓtｉcmｏdulus)uptｏaｐpｒoxiｍatelｙ0.4GPａ．Beyondtｈiｓvａｌｕe，thｅefｆectｉvｅnessofFRPceasestobepositive.InspeciｍenSＯ3-5,ｔheuseofahorｉｚontａｌpｌｙoｖertｈecｏntinuoｕsU－ｗrap(i.e．90°/０°）rｅsulteｄinaconcretｅsｐliｔtinｇfailuｒｅｒathｅrtｈaｎaＣFRPdｅbondｉnｇｆaiｌuｒe.Tｈefailureoｃcuｒｒedatｔotａlapｐlｉedloadｏｆ339ｋＮwｉtha1２０%inｃｒeａsｅintheshearcapaciｔyｃomparｅdtotheconｔｒolspeciｍｅnSO3-1.Ｔhｅstrengtheningwｉｔhtwopeｒｐｅnｄicｕlaｒｐｌiｅs(i．e.90°/0°)ｒesｕlｔedina17%increaseinsheａrｃapaciｔyｃｏmpａredｔothespｅciｍenwithoｎlｙoneCFRPplyiｎ９0°oｒｉｅnｔation(i.e.sｐecimｅnＳO３-4).ThｅmaximumloｃａｌCＦRPvertｉcalsｔraｉｎmeaｓuredatfａｉlurｅｗaｓ0．0０43mm/mm.ＢycｏmpａringｔhetestｒｅsｕｌｔsofｓｐecimensSW3-２aｎdSO３－5，havinｇthｅｓamea/ｄｒatｉoａndstrｅngtheningscheｍeｓbutwithdiｆfｅrｅntｓｔｅelｓhｅarreｉnforcｅmeｎt,theshearstrength(i．e．177and169.5kNｆoｒspｅcimｅnsSW3－2anｄSO3－5,resｐeｃｔｉvelｙ）,andtheｄｕcｔilityarｅａｌｍosｔidｅｎｔicａl.ＯnemayconcｌｕdｅthaｔthecontｒibutioｎofＣFRPbeｎeｆitstheｂeamcapacityｔｏagreaｔerdegreeforbeamswｉｔhoutstｅelsｈearｒeinｆorcementthanforbeamｓwｉthadeqｕaｔeshearreinforcemenｔ.３．4.ＳeｒiｅｓSO4SeｒiesSO4exｈibitedｔheｌargestincreaseiｎsｈearｃaｐaｃitycoｍparｅdtotheotherserieｓinvｅｓtigaｔedwiththiｓresearchstudｙ.Thｅｅxｐｅriｍentalｒesuｌtｓintermｓｏfapｐlｉedｌoaｄvsmiｄ-spandeflｅctionｆorthｉsseriｅsisｉlｌｕｓｔrateｄｉnFiｇ.１１．TｈecontroｌsｐeｃｉｍeｎSO4-１faiｌedａsaｒeｓｕltoｆsｈeａｒcｏmｐressionatａtoｔalapplｉｅdloａdｏｆ１30ｋN．ＳpecｉｍeｎSO4-2,strengｔｈenedｗitｈCＦＲPstrips,thefaiｌｕrewaｓcontrollｅdbyCFRＰdｅbondiｎgatａtｏtalloadof255kNwｉｔｈ９6％ｉnｃreａseinshearcａｐaciｔｙｏverthecoｎtroｌspeciｍeｎSO4-１.TheｍａximuｍｌocalＣFRPverｔicａlstrainmeaｓuredａtfａｉlurewas0．006２mmymm.WhencomparinｇｔhetestresｕltsofspecimｅnSＯ4-2totｈaｔofspｅcimeｎSＯ3-２,ｔｈeenhａnceｄshearcapacityｏfspecimeｎSO４－2(a/d=4）ｄuｅtoadｄｉtｉｏnofCFRPsｔripswas62.5kN,ｗhilesｐecｉmｅnSO3-2(a/d=３）rｅsｕltediｎaddedｓhearｃaｐaｃitｙｏf54kN.Aｓexｐected,ｔｈｅcｏntriｂuｔionofCFＲPreinforcｅmeｎｔtoｒesisｔtｈesｈearａppｅareｄtodecｒeａsewｉｔhdｅcreasｉnｇa／dratｉｏ．SpecimenＳO４-3,streｎｇthenedwiｔhｃonｔｉnuouｓU-ｗrap，failｅdaｓａresuｌtofｃoncretｅｓplitｔｉnｇａtanａｐplｉedloadof31０kNｗｉtｈａ１3８%incｒeaseiｎsheａrｃapacitｙcompａｒｅdtｏｔｈatofｓｐｅcｉｍｅnSO4－1.ThemaximｕmlｏｃａlＣＦRPｖerｔicaｌstrainmeａsｕｒedatfailurewａs0.0037mm/mm.４.ＤesignappｒoaｃhTｈedeｓignappｒoａchｆｏrcompｕtｉｎgthｅsｈeａrcaｐacityoｆＲCｂeamssｔrｅnｇｔhenedｗiｔhexternａlｌybｏnｄedCＦRＰreiｎfｏrcemeｎt，exprｅssedinACＩdesigncode［1２]ｆｏrmat，waspｒｏｐｏｓｅdａｎdpuｂlｉｓhedin1998[13].ThedesignmodeldescrｉｂｅdtwopossiｂｌeｆａiｌuremｅchanｉsｍsｏfCＦRＰreinfｏｒcementnａmely:CFRPfｒactｕｒｅ;andCFＲＰdebonｄing.Fｕｒtheｒmore，twolimｉtsonｔｈecｏｎtrｉbｕtionofCＦRPｓheａrｗerepｒｏposed.Ｔhefirstlimiｔｗaｓｓｅｔtoｃontrｏltｈesｈeａrcｒａckwidthanｄlossofaggｒegateintｅrloｃk,anｄｔｈesｅｃondwastｏprecludewebcｒuｓhinｇ．Alｓｏ,thecｏncrｅｔestrengtｈaｎdCＦＲＰwrap－ｐｉngscheｍeｓweｒｅｉncorpｏrａtedaｓdｅsｉgnｐarameters.Ｉｎrecentstudｙ[9,10],ｍodｉfiｃatｉonswereprｏpoｓedｔotｈe１９98desiｇnapproachtｏincｌudeｒeｓｕltｓofanewstｕｄｙonbｏｎｄｍechaｎｉｓmｂeｔweｅnCFRPsheetsandｃoncretesｕrｆace[14].Inadｄiｔioｎ,ｔｈeｍｏdｅlｗasｅxｔenｄedtoprovidethesheardｅsignequatｉｏｎsinＥuｒｏcoｄeasｗellasACIfｏrｍat.Coｍpaｒiｎｇwithａｌltestreｓulｔsavaｉlableinｔhｅｌitｅraturetodate,76tｅsｔs,ｔhedesiｇｎapprｏａｃｈｓhowｅdaｃcｅptaｂleanｄｃoｎservａtｉvｅesｔimａtes［10,１3].Inthisｓｅｃｔion,theｓuｍmaryoftｈedeｓｉgnapproaｃhispresented．Thｅcｏmparｉsｏnbetweenexpｅrimentalｒｅsuｌtsandthecａlculaｔedｆactoredshearｓｔrenｇthdemonsｔrａteｓtｈeａbｉlityoftｈedeｓignaｐproachtopｒedictthｅsheaｒｃaｐacｉｔyｏftｈｅｓtｒｅnｇtheｎｅdbeams.dｅｍｏｎsｔｒatｅstheabｉliｔyoｆthｅｄeｓignａｐpｒoａcｈtoｐredicttｈeｓhｅarｃapaｃitｙofthestｒｅngｔheneｄbeａms．4.1．Ｓｕmmａrｙｏftheｓheardesigｎapproach—ACIfｏrmａtIntraditionaｌｓheardｅsign(ｉnclｕdingtheACＩCode),tｈｅnomｉnaｌsheaｒstｒｅngtｈofanRCｓeｃtioniｓｔhesｕｍofｔhｅnoｍiｎalｓhearｓtrengthsofｃoncrｅteandsteｅlsheaｒrｅinforｃement.ForbeａｍｓｓtｒeｎgｔｈenedwitｈexterｎａｌlyboｎdeｄFＲPｒeiｎfｏrcement，ｔheshearstrenｇtｈmaybeｃoｍｐutｅdbytheaddｉtiｏnｏfathirｄtermtoaccｏuntoftheFRPcontrｉbution.Ｔhiｓiseｘprｅssedaｓｆolｌows:Tｈｅdesｉgｎsheａrｓtreｎｇtｈ，，isobtaiｎedbｙｍultipｌyingthenominalsheaｒｓtrenｇthbyaｓtrenｇthｒeductionfaｃtorforsｈear,.Itｗａｓｓuggeｓtｅdｔｈａttheｒeductionfactor=0.85giveniｎACI［1２]bｅmain-tainedｆｏrtｈecｏｎｃｒeteanｄsｔeeltｅrms.However,aｍorestｒinｇeｎtstrenｇthｒeducｔｉonfａctoｒof0.7fｏｒthｅＣFRＰcoｎtrｉbutionｗａssuｇgestedw10x.Thｉsisduetoｔheｒｅｌatｉvenｏveｌtｙoｆthｉsrｅpaｉrtechniquｅ.Ｔhuｓ,ｔheｄesignｓheaｒstｒengtｈisexｐrｅsｓedaｓfoｌlows.4.2.CoｎtｒibｕｔionoｆCFRPreｉｎforcementtｏtheshearｃaｐacityＴheexprｅssiｏｎusedtocoｍputeｓhearcontributionofCＦRPｒｅinfｏrcｅmentｉｓgiｖeｎiｎEq.(3).ThiｓeｑｕaｔioniｓsimｉlａrｔｏthatforｓheａrcｏntｒibｕtionofsteelstirrupsaｎdｃonsisｔentwｉthｔheＡCＩｆormａt.TheａreaofCＦRＰshｅａｒreinforｃemｅnt,，isｔｈetotalthiｃknessｏfthesheet(ｕsuａllyｏrｓheetsｏnbothsidｅsoftｈｅbeａm)ｔimestheｗidｔｈoｆtheCFRPstrip．ＴhｅdiｍensiｏnｓｕseｄtｏdefinethｅareaofCＦRPinadditiｏnｔothesｐacinｇａnｄthｅefｆecｔivedeptｈofCＦRP,，ａreｓhowninFig．１２．Nｏｔethatforconｔｉnuoｕsvertiｃalsｈeａrreｉnfｏrcｅmｅnt,theｓpacingofthｅsｔrip,,ａndtheｗidｔｈofthｅsｔｒip,,ａreeqｕａl.InEq.(3）,ａneｆfｅctiveaｖeragｅＣＦＲPstress,ｓmalｌerthanｉtsｕltimatestrenｇth,，wａｓusedｔoreplａcethｅyｉｅｌdｓtrｅsｓoｆsteｅl．Attheultiｍatelｉmitstａtｅfｏrtheｍembeｒinshear，itisnｏtpossibｌetoａｔｔａintheｆuｌlstｒｅngthｏftheFRP[7,13］.ＦailureisgｏｖｅrｎeｄｂyeitherfraｃtuｒeoftheFRＰsheeｔaｔaｖeragesｔrｅｓslevelｓwellbｅlｏwFＲPｕltimａteｃapａcityduetosｔrｅssconcentrａtiｏnｓ，debｏnｄinｇoｆtheFRＰｓheetｆｒomtheｃoncretesurface，ｏrasignifｉcantdecreaseinｔｈepoｓｔ－crackingｃoncreteshearstrengthfromaloｓｓｏfａggｒeｇatｅiｎterloｃｋ.Thus,thｅeｆfectiveaveraｇｅＣFＲPstressiscompuｔｅdｂyapplyingａreductioncoｅffiｃｉent,R,totheCFRPultiｍaｔｅｓｔrｅngthaｓexpreｓｓeｄinＥq.(４).Theｒｅductioncoeｆfiｃiｅntdeｐendsonthepｏsｓiｂlefaｉluremodes(eｉｔｈerCFRPfrａcｔureorCFＲPdｅｂonｄing).Iｎeitherｃａse,anupｐｅrｌｉmｉtfｏrｔhereducｔioｎcoeｆficiｅｎｔisｅsｔａｂlｉshｅdinｏrdertoｃontrolsheaｒcrａｃkwidthａndｌossｏfagｇregatｅｉntｅrｌocｋ.4．3．ＲeｄuctiｏｎcoefｆicｉeｎtｂasｅdｏｎCFRＰsheetfraｃtuｒeｆaｉlureＴhｅpｒopｏsｅｄreｄｕｃtioncoefficｉｅntｗasｃalｉbrａteｄonａｌｌaｖａiｌａbｌetesｔｒeｓｕltsｔｏｄａte,2２tesｔsｗｉtｈfaiｌurecontrolledｂyCFRPｆｒactｕre[１0,13].Ｔherｅｄuｃtioncoefficｉenｔwasｅstａblishedaｓaｆｕncｔionｏf(wｈeｒeisthｅareaｆractiｏnofCFRＰ)ａndeｘｐressｅdｉnEｑ.(5)for0．７GPa.4.4.RｅdｕctiｏnｃoｅfficientｂasｅｄonCFRPdｅｂoｎｄinｇfａilureThesheａrcaｐacｉtygｏvｅｒnedbyCFＲPdebondinｇfromtｈeconcretesuｒｆａcewaspresented[9,10］asafuｎｃtioｎoｆCFＲPaxｉalrigidｉty,ｃoncretesｔrenｇｔh,efｆectivｅdepthofCＦＲＰreinforceｍeｎt,andbonｄedsurfaｃｅconfｉgurａtioｎs.Inｄetｅｒmiｎiｎgtherｅｄuｃtｉoｎｃoｅfficienｔforbｏｎｄ，ｔheeｆfecｔｉveｂonｄleｎgth，,hａｓtobedeｔermiｎeｄfiｒst.Ｂaｓｅdoｎanalｙｔiｃaｌａndｅxperimentaｌｄatafrombｏndtesｔｓ，Ｍiｌlｅr[１４]showeｄthattheeffectivｅbondlｅｎｇthsligｈtlyincｒeａsesasCFRＰａｘialrigｉdity，,ｉnｃreasｅs.Howevｅｒ,heｓｕggesｔedａcｏnｓtantｃonseｒｖativevａｌuｅfoｒequaｌtｏ75ｍm.Ｔｈｅｖaluemａybeｍodifiedwheｎｍoｒｅｂoｎdtｅsｔsｄaｔａbｅｃｏmｅsａvailａble.Aftｅrasheaｒcｒａｃkdｅvelｏｐs,onlythａｔporｔioｎofthewidｔhｏfＣＦRＰｅxtｅndｉngｐastthｅcrａｃkｂｙｔheeffectiveｂonｄedlengthiｓasｓumedtoｂecａｐableoｆcａｒryiｎgsheａr.[１3]Theｅffectｉvewidth，,ｂaｓｅdonｔｈeshｅａrcrackangｌｅof45°,aｎdtｈewｒａｐpingscｈemeiｓexpressedｉｎEｑs．(6ａ)and（６b);ｉftheｓheｅtinｔheformoｆaＵ-wｒaｐ（6ａ)ifthesheeｔisbｏnｄedonlyｔothｅsidｅsofthebeａm.（6b）Thefiｎalｅｘpreｓsioｎｆｏｒthｅreｄｕｃtioncoefficｉeｎt，Ｒ,forｔhemodeoffａｉｌｕreconｔrｏlｌｅdbyCFＲPdebondingisexpｒｅssedinEｑ．(8)Ｅq．(7)iｓaｐplicabｌｅｆorCFRＰaxialrｉｇidity,,ranｇｉngfrｏm20to90mm-ＧPa(kN/mｍ)．Reｓearchｉnｔｏｑuanｔｉfyingthebondchａracterｉsticｓforａｘialrigiｄitiｅsabｏｖe90mm·GPaisbeｉngｃｏnduｃtedaｔｔheUniversityofMｉsｓourｉ,Roｌｌa（UMR).４.5.UｐｐｅｒlimitｏfthｅreducｔioｎcｏeｆｆiｃｉｅntInorｄeｒtｏcontroltheｓhｅａrcrａckwiｄｔhanｄlosｓofagｇregateinｔｅrloｃk,anuｐｐerlｉｍitofrｅductioｎｃoeffｉｃｉent，Ｒ，wassuｇgeｓtedaｎdcａlibratｅdwiｔhａlｌoftheavailabletestresulｔs[10]ｔoｂeequaｌtowhereistheultimatetensｉleＣFRPｓtｒain.ThislimｉtｉssuｃｈthａtｔheaｖｅｒaｇｅeffectｉvｅsｔｒaｉninCFRＰmａtｅrｉaｌsatuｌｔimatecannotｂｅgrｅａtertｈａn0.00６mm/mm（wｉthoutthestrenｇｔheningｒeductioｎfactor,).４.6．ControllinｇreｄｕcｔｉoncoeｆｆicientＴhｅｆｉnalconｔrollinｇreｄｕctioncoefficientfortheCFＲPsysｔｅｍistakenaｓthelｏwesｔvａluedｅｔeｒminedｆｒｏmtｈeｔｗｏpoｓｓibleｍoｄｅsoffａiluｒeａｎdｔhｅｕpｐerｌimｉt.Nｏtethatｉfthｅsｈｅetiswrappedentirelｙaroundｔhｅbeamoraｎeffｅctｉｖeendaｎchｏｒｉsｕsｅｄ,tｈｅfaiｌｕremodeofCFRPｄeｂondinｇｉsnottoｂecoｎsｉdeｒed.ＴheｒｅｄｕctionｃoeｆｆｉcientiｓonlycｏntrｏllｅdｂyＦＲＰfrａcｔureandtｈeupperlｉmｉｔ.4.７.CFＲPｓpａcingｒequiremｅｎtsSimｉlaｒtosteeｌshｅａｒrｅinfoｒcemｅnt,ａｎdconsistｅｎｔwiｔhＡＣIprｏｖisioｎfortheｓｔｉrrupsspａcing[1２]，ｔheｓpacｉｎgofFRPstripｓshouldnotｂesowiｄeasｔoallowｔheformationｏfａｄiaｇonalcｒackwｉthｏutｉｎteｒｃeptingastrｉp.Forｔｈiｓreaｓon,ｉｆstripｓareused,ｔheyshｏuldｎｏtｂｅspaｃedbymｏrｅｔhanthemａximumｇiｖeninＥq.(８).4.８.LimiｔｏｎtoｔalshearreinfoｒceｍentACI31８M-９５[12]１１．５.6.7ａnd11．5.６.8sｅtalｉmｉtoｎtheｔotalｓｈｅarｓtrengthtｈatmaybｅｐrｏvidedbymoｒethanonｅtypeofshｅarｒeinfoｒcementｔoｐrecｌudetｈewｅｂcrｕshing．ＦRPshearreｉnfoｒcemenｔｓｈouｌdbｅｉｎclｕdedｉｎthiｓlimｉt.AmｏdifｉcatiｏｎtoＡCＩ318Ｍ－９5Ｓectiｏn１1．５.6.8ｗassuggestedasfｏllows:4.9．ShearcapacityｏfａＣFRPsｔrenｇthｅnｅdsectiｏｎ—EurｏcoｄeformatTｈeproposeddesｉgneqｕationwEq.(３）ｘfoｒｃomputingthｅconｔribuｔioｎofexternallyｂondedCFRPrｅinfｏrｃｅmeｎtmayｂerewｒittenｉnＥｕrocｏde(EC21992)［１5］foｒmaｔａsEｑ.(10).Inthiseqｕａtiｏn,thepａrtialsafeｔｙfaｃtorｆｏrCＦRPmaterials,,ｗassuｇｇｅｓteｄequalto1.3[１0].５.CoｎcｌuｓionsandfurthｅｒrｅcomｍｅｎdationAnexperｉmentalｉnｖestｉｇaｔionwaｓconductｅdｔoｓｔuｄythｅsｈearbehavioraｎｄthemodesofｆaiｌureoｆｓimplyｓuppｏrｔedrectanguｌａｒｓecｔioｎＲCbeamsｗiｔhｓhｅaｒdefiｃiｅncies,sｔｒeｎgthｅnｅdwiｔhＣFRＰshｅeｔｓ．Ｔhepaｒaｍetｅｒsｉnvｅstｉgａtｅdinthisｐrogramwerｅexｉstｅｎcｅofsｔｅｅｌshearrｅｉｎforcemenｔ,shearsｐan-to－effｅcｔiｖeｄeｐthraｔio（aydｒatio),andＣFRPamｏｕntandｄiｓtribｕtiｏn．TheｒｅｓultｓconｆｉrmｔｈatｔhestrengｔheninｇｔeｃhniｑueｕsingCFRPsheeｔscanbeusｅdtoincｒｅaseｓignifｉcａntlyｓhearcapacity，withefficｉeｎcythatvaｒiｅsdｅpｅndingｏｎｔheｔestｅｄvａｒiａblｅs.Fｏｒｔhｅｂeamｓtesteｄinthispｒｏgram,increａsｅsｉnsｈｅarstｒengthof４０–1３8%wｅreachieｖeｄ.Ｃoｎｃｌｕsioｎｓthatemｅrgｅｄfroｍtｈisstudyｍaybｅsummarizｅdaｓｆollowｓ:TｈecｏntributiｏnofeｘteｒｎａllｙCFRPreｉｎforcemenｔｔotheshｅarｃaｐaｃityisinｆluｅncedbytｈｅa/drａtio.IncreaｓingtheａmｏunｔoｆCＦＲＰmayｎotｒeｓultinaproporｔｉoｎalｉncreaｓｅｉｎthesheａｒｓtｒenｇth.ThｅCFRＰaｍｏuntusｅdｔｏstrengthｅnｓpｅcｉmｅｎSO3－4wａs25０％oｆthaｔusediｎspecｉｍenＳＯ3-2，whicｈresultedｉnaｍinｉmal(1０%)ｉncreaｓeinsheaｒcapａcｉtｙ.AnendanchｏｒｉsreｃommeｎｄedｉｆFRPｄeｂondｉｎgistobｅavoｉded.TheｔestｒeｓultｓindｉcatedthaｔcｏｎｔribｕtiｏnofCFRPｂenｅfｉｔｓtheｓhearcapacｉtyaｔａgreaterdegreefoｒｂeaｍswiｔhouｔsｈeaｒｒeiｎforｃementthaｎｆorｂeamsｗitｈadｅquａteshｅarreinforｃemeｎt.ＴheresulｔsoｆseriesＳO3ｉndicａtedｔhatthe0°plyｉmprovedｔｈeshｅarcａｐacｉｔybyproviｄinｇhorｉzoｎtalrestraint.Thesheardeｓignaｌgoｒｉthmsprovｉdｅdacceptablｅandｃoｎseｒｖａｔiveｅstimatesｆortｈｅｓtrｅnｇtｈeｎedbeams.Ｒecｏｍmｅｎdａtioｎｓfoｒfuｔｕrereseaｒchａreａsfollows：ExpeｒimentalandanａlｙｔｉcaliｎvｅsｔigaｔionsaｒerequiｒedｔｏliｎkｔhｅｓhｅaｒcｏntribｕtionofFRPwiｔhthｅloadcondｉtion.Tｈｅｓｅsｔudieshaveｔocｏnsidｅrboththｅlongitudinalｓteeｌreｉnfoｒcementｒatｉoaｎdｔheconｃretestreｎｇthasｐaｒamｅtｅrs.Laｂorａtoryｓpecimenssｈouldmaｉntainpracｔｉｃａldimenｓioｎs．ThesｔrengtheｎingeｆfecｔivｅｎessoｆFRPhａｓｔoｂeaｄdresｓｅｄinthecasesofsｈｏrｔandｖerysｈorｔsｈearｓpａnsｉｎｗhｉｃｈarchａctionｇovernｓfailure.TheintｅraｃtioｎbｅtweenｔｈeconｔributionoｆexｔｅrnａlFＲPａndinteｒnalsｔeeｌsheaｒｒｅinｆorｃeｍｅnthastobｅiｎvｅstigatｅd.Tooｐtimizｅdesignalｇｏritｈmｓ,additionaｌｓｐeｃimｅnsnｅedtobｅｔeｓｔedwithdifferentCFＲＰamｏuntａndconfiguｒaｔioｎstocｒｅａteaｌaｒｇｅdaｔａbaｓeofinformatｉｏn．Sheardesignalgoritｈmsneedｔo