鋼筋混凝土梁抗彎加固實(shí)驗(yàn)研究 鋼筋混凝土的特點(diǎn)

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ReinforcedconcretebeambendingreinforcementexperimentalstudyEngzihouse

(lanzhoujiaotonguniversity,ingansu,civilengineeringcollegelanzhou730070)

Abstract:carbonfiberbecauseofitslightweight,highstrength,corrosionresistance,anti-fatigueperformanceandsoonissuperiorperformance,soCFRPreinforcementinconcretehasextensiveapplications,inrecentyearsinacademicandengineeringcausedwideinterest.Basedoncarbonfibercompositereinforcingsteelreinforcedconcretebeamofexperimentaldata,makeaseriesofanalysis,theresearchoftheexperimentalbeamspreloadingcharacteristicsofloadandtheinfluenceoftherigidity.

Keywords:reinforcedconcretebeam;CFRP;Reinforcement;Preloading;Loadcharacteristics;stiffness

1..Experimentscheme

Theexperimentwere18rootbeam,accordingtothelongitudinalreinforcementrateintoA,Btwogroups.Thesizeofthebeamfor150mmwide,high250mmlong,2500,sectionalshape,sizeandreinforcementisshowninfigure1below.ThisexperimentisthedesignofconcretestrengthforC25,concretecompressivestrengthis23MPa,longitudinalreinforcementyieldstrengthfor360MPa,elasticmodulusfor200GPa,CFRPtensilestrengthfor3550MPa,elasticmodulusfor235GPa,,thesingleCFRPthicknessof0.111mm.

Theexperimenttestcontentincludes:displacement(cross,thedistributionoftwosupportbeamposition),carbonfiberstrain,beamlongitudinalreinforcementstrain,thestrainofconcreteandcrackdevelopmentsituation.

Theexperimentprocess:thesimplysupported;Thelengthof2000mm,purebendinglengthfor500mm;CFRPpastelengthof1800mm,widthis120mm,noadditionalanchormeasures.Loadingmethod:thehydraulicjackreversetwosymmetricloading.

2.Theexperimentalresults

2.1thefailureprocess

16thebeamsappearedtwokindsoffailuremode:(1)CFRPplatetensile;(2)themiddlecausedcracksCFRPplatedetachment.

2.2CFRPdissectionofthefailureprocess

Fromtheexperimentphenomenonsee(figure3),longitudinalreinforcementyieldincreasedwithloadafter,distributionoftheLordnearloadingbeambendingshearfractures(figure4a)widthincreasequickly.WhentheLordcurvedshearfracturestoacertainwidth(usuallyina1.0mmorso),theinterfacecracksonbothsidesformedthefreesurfaceconcrete,concretecrackbetweenbothsideslostinteraction,theLordcurvedshearfracturestoendarangeofconcretewascracking(figure4b,thecrackformationcalledtimeinclinedcracks).Whenloadingtocertaindegree.Timewiththemaindiagonalcrackbendingshearfracturesfellowshipformatriangleprismformconcreteblock.Whenthetimeofthediagonalcrackwidthtoacertainextent,fiberclothfromthecracksintheconcretecoverandattheendoftheinterfacestartdetachment(figure4c).Withtheloadincrease,intheperiodofpurebendingconcretecoveryieldmorealongthelongitudinalreinforcementofapproximationofhorizontalcrack,concretecoverhasbeenstrippedofthetendency;CutsectionbendinginconcretecoverdepthwithinthescopeofTheTimesdiagonalcrackalsosignificantlyincreased,localalsoappearedalongthelongitudinalreinforcementofhorizontalcrack.FRPsheetmaterialfinallydetachment,formthetriangleprismformofblockisstillattachedtotheconcreteinfibersheetmaterial(figure4d).

Tosumup.CFRPplatecanpeeldividedintothreephases:theinitialstage,stablestrippingstagestrippedcompletelystrippedandstage.(1)theinitialstrippingstage:theLordbendingshearfracturestosetthewidthofthe-thedegree,intheaftformaTiaoCiinclinedcracks,CFRPplatestartstripping;(2)thestablestrippingstage:CFRPplateafterstartstripping,withtheloadincreasingCFRPplatetotheplatetopeelrangeattheendofthepassagedirection;(3)completedetachmentstage:whenstrippinggoesontorangefromsheetmaterialendsabout200mm,innotloadcases,whenthefiberclothinafewminutesoftimecontinuousdetachment.Wheneventuallystripped.Becauseofelasticfiberclothcanreleaseinamoment,intheperiodofpurebendingandloadingtheconcretecoverhappenedneardifferentdegreeoffalloff,tensilesteelexposed.

3.Theresultanalysis

3.1load-deflectionrelationship

A1,A2,B1andB2,fourgroupsofload-deflectioncurvesarerespectivelyasshowninfigure5tofigure8shows.Thefigureofthegods.and

Commonreinforcedconcretebeamsimilar,CFRPreinforcementofcutting-Hollywoodderived.adeflectioncurveisdividedintothreestages,namelyelasticstage,withcrackstageandyieldstage.Eachphaseofthecorrespondingcharacteristicsrespectivelyload,loadcrackingyieldloadandlimitload.

Andcommonreinforcedconcretebeamdifferentis,CFRPreinforcedbeamswilldestroydissectionoccurred,testrecordstheCFRPplatestrippingtheinitialwhenload().Thischargeiscuttingthroughtestingthephenomenonofobservationcertain.InCFRPplatebeforedeparturegeneralwillappearthefollowingthreefeatures:(1)longitudinalreinforcementhappenyield;(2)theloadbendingcutnearcrackwidthincreasequickly;(3)whenloadingtoacertainload,CFRPplatewillsendoutaclearandcrispsound.Butnowcan"tjudgeinwhichspecificlocaldissectionoccurred,reload2-3levelwillintimeattheendoftheinclinedcracksappeararoundthroughoutthepasteofthewidthofthedissection,atthispointintheregionbyhandorothergoodthingstrikingtheCFRPplatewillfindemptydrumsound,resultswillCFRPplateappearthefullwidthalongthecrosssectionofstrippingbeforeloadlevelasstrippingload().

3.2CFRPplatestraincurve

From9to12figurecanbeseen,theCFRPplateshowedgoodlinearelasticproperties,andthiswiththematerialitselfistheperformanceofthematch.Inthelongitudinalreinforcementyieldbefore,withthespecimensunderpreloadingreinforcement,CFRPplateload-theslopeofthesamebasicstraincurve.Thisshowsthatthetestoftheepoxyresinwithalmostthesameproportionandthedosage,strengtheningqualityisreliable,thetestschemeandtestrightloading.Fromthestraincurvetosee,inthesameleveloftheload,ingoodconditionofreinforcementspecimens(inadditiontotheindividualspecimenoutside)thefiberstrainaretobehigherthanunderpreloadingthereinforcementofspecimens.

4.Experimentresults

4.1preloadingfeaturetheeffectofload

Fromthefigure13andfigure14cansee,preloadingsizeontheinfluenceoftheloadcharacteristicsarenotobvious.Inaddition,thetestdatafromtable1statisticalanalysisfoundthat:thegroupwithintactforcomparisonspecimensbeams,eachgroupincertainspecimensunderpreloadingthereinforcementofspecimensitsyieldloadsandloadsofgoodbeamyieldratioof0.98forthemeanrespectivelyA1,A2group0.98,1.02groupB1,B2group1.06,thevariationcoefficientwere0.02,0.03,0.04and0.05;Eachgroupmustbeshowninthispaper.thetopspecimensofthereinforcementofultimateloadandintactbeamlimitloadofthemeanvalueratiorespectively1.01groupA1,A2group1.01,1.11groupB1,B2group1.13,thevariationcoefficientwere0.01,0.04,0.01and0.02.

Sofromtheaboveanalysis,wecanfindthat,inthisexperiment,thespecimensstrengtheningpreloadingthereinforcementofthesizeoftheloadcharacteristicsafterthelittleinfluence.

4.2theinfluenceoftherigidityofpreloading

Fromthegraph5tofigure8andtable1cansee,preloadingsizeofgroupAandBgroupofreinforcedbeamtangentstiffnessinfluenceeacharenotidentical:groupBofthetangentstiffnessofreinforcedbeamslinebypreloadingsignificantlygreaterthantheeffectofgroupAspecimen,figure15tofigure16intwogroupsoftangentstiffnessspecimensbypreloadingsizecomparisonofinfluencemoredirectl