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论文2

英文部分：

出处：

Vo1．2lNo．3JournaloIWuhanUniversityofTechnolo~,一Mater．i．EdSept．2006

标题：

CharactersiticsofStress—strainCurveofHighStrengthSteelFiber

ReinforcedConcreteunderUniaxialTension

作者：

YANGMengHUANGChengkuiWANGJizhong

（StateKeyLaboratoryofCoastalandOfshoreEngineering，DepartmentofCivil,Engineering，

DalianUniversityofTechnology，Oalian116023，China）

正文：

Abstract：

Awholeof110specimensdividedinto22groupsweretestedwithvooingthevolumefractionof

steelfibersandthematrixstrengthofthesespecimens．Thestress-strainbehaviorsoffo~typesofsteelfiberrein—

forcedconcrete（SFRC）l~2deruniaxialtensionwerestudiedexperimentally．nthematrixstrengthandthefi—

bercontentincrease，thetensilestressandtensilestrainvarydiferentlyaccordingtothefibertype．Themecha—

nismsofreinforc~ng@ctfordiferenttypesoffiberwereanalyzedandthestress-strainclll't~ofthespecimenswere

plotted．SomeexperimentalfactorsforS~esSorstrainofSFRCweren．Atensiletongh,~sHlo~lasRe05

introducedtoevaluatethetoughnesscharactersofSFRCl~2deruniaxialtension．Moreover，the[ormalaofthe

tensilestress-straincll~ofSFRCwasregressed．Thetheoreticalc11"i~andtheexperimental0，well，which

canbeusedforreferencesinconstruction．

Keywords：

steelfiberreinforcedconcrete；highstrength；uniaxialtension；stress-strainc11"i~：

softencharacteristics

1Introduction

Thetensilepropertiesofconcretecanbeenhanced

substantiallybyincorporatinghighstrengthandsmalldi—

ametershortsteelfibers．whichlcadstothesteelfiberre—

inforcedconcrete（SFRC）．InconventionalSFRC，the

steelfibercontentisusuallywithintherangeof0．2％一

2％byvolume．Atsuchalow6hercontent．thetensile

responseofSFRCwouldassuIneanonhardeningtype．

whichischaracterizedbythewideningofasinglecrack，

similartoanunreinforeedconcrete．econtributionof

tibersis印parentinthepost—crackingresponse，repre—

sentedbyanincreaseinpost—crackingductilityduetothe

workassociatedwithpulloutoffibersbridgingafailure

crack．However，improvementsinsomeotherproperties

areinsignificant．Moreover，thesofteningsegmentof

thestress—straincurveofSFRCthsuchalowfibercont—

entunderuniaxialtensionisdificulttobegotwithnormal

experimentalmethods．Manyworkshavebeendoneto

findasuitableandrelativelyeasywaytoanalyzetheten—

silecharacteristics。

。

．Anditwasreportedthatthewhole

curvecouldbegotonanormaltestingmachinewithstiif_

eningcomponentsadded

Inthisarticle，thestress—strainbehaviorofSFRC

underuniaxialtensionWasanalyzedfordifferenttypesof

fiber．ThetensilecharacteristicsofSFRCinflueneedby

thematrixstrengthandthesteelfibercontentwerestudied

also．Inaddition，thestress—straincurvesofhighstrength

SFRCwithdifferentfactorswerewellacquired．

（Received：

April17，2005；Accepted：

March6，2006）

YANGMeng（杨萌）：

PhDcandidate；E-mail：

yangmeng@stu—

dent．dlut．edu．cn．

*FundedbyRegulationRevisingItemofChinaAssociationforEn—

gineeringCork~tmctionStandardization（CECS15：

2000）

2Experimental

Thespecimensweretestedona60kNuniversaltest—

ingmachine．Fourhighsteelbarswereaddedtoenhance

thestiffnessofthetestingmachine．Inaddition，spheric

hingeswereusedtoabatetheinitialaxialeeeentricityof

thespecimens．．

Itwasensuredthatspecimensshouldbepulled1．113一

deruniaxialtensionbyaajustingthefourhighstrengthbo—

ltswhichconnectthespecimenstotheCroSSbeam．And

thedifferencebetweenthetensilestrainsoftheopposite

sidesofthespecimenshouldbelessthan15％oftheir

meanvalue．Whenthefibercontentwaslow（0and0．

5％byvolume），thecyclic

quirethewholestress—strain

2．1Materials

tensionwaywasusedtoae—

eun，e．

FourtypesofsteelfibersshowninTabk1werecho—

senforthistest．reeofthesefibers（F1，F2andF3）

werehooked—endandtheotherone（F4）wassmoth．

Threeconcretemixtures，showninTable2，werein—

vestigated．WaterreducingagentswereusedinC60and

C80mixes（DK一5madebyDalianStructureResearchIn—

stituteandSikamadeinSwitzerlandrespectively）．e

compressivestrengthsoftheseC30，C60，C80mixeswere

determinedaccordingto“TestMethodsUsedforSteelFi—

berReinforcedConcrete”（CECS13：

89）"83at28days

using150Bin×150Bin×150Bincubes．Averagedre—

suitsfor3specimensaregiveninTable2．0rdinaryPort—

landcement（yieldedbyDalianHuanengOnodaCement

Company）of32．5and52．5（accordingtoChinastaB—

dard）werechosen．Riversand（modulusoffinenessis2．

6）andcrushedlimestonecoarseaggregates（5—20Bin）

wereused．

维普资讯

Vo1．21No．3YANGMeetfzf：

Stud。

nStress-strainCunP（）fHighStrPl1州1SteelFill／eiI1tbrce~t．．．．133

Note：

F忙r——nsijecrackstressofSFRC；f（．r——nsilecrackstressofplainconcretentheSalllemixproportion；fi~UhimatctensilestrengthofSFRC

——UfinlHfetensilestrengthofplainconcretewiththesanlemixingproportion．

2．2Spc~imem

Thetensilespecimenwasbondedtosteelpadding

platesatbothendsbytygoweld．Atotalof110specimens

weredividedinto22groupsaccordingtocertainparame—

ters．TheparametersofthesespecimensareshowninTa—

ble3．

2．3Items

Attheageof28days．plainconcreteandsteelfiber

concretespecimensweretestedfortensilestrength，

resqectively．Thetensilestress—straincurveswereac。

quired．Manyothertensilecharactersofthehighstrength

steelfiberconcretesuchastensilework，etcwerecalcu—

latedalso

3ResultsandDiscussion

3．1Crackstressandultimatetensilestrength

Thecrackstressandultimatetensilestrengthofdifferent

specimensarelistedinTable3．Theadditionof

steelfibersintoconcreteincreaseditscracks[ressandultimate

tensilestrength．AndtheratiosofthesetwoparaiTl~

etersofSFRCtothoseofplainconcreue（withthesame

mixproportion）aregiveninTable3，too．

3．1．1Effectofmatrixstrengthan（1fibertype

FH）mFable3．it（·anbeseenthattheeffectsofsteel

fibers0ncrackstressarelittleinfluencedbythematsix

strength．TI1atish）sav．whenthenlatr／xstrengthi11{7‘reas-

维普资讯

134JournalofWuhanUniversityofTechnology．

一Mater．Sei．EdSept．2006

es，theratiosofcrackstressesofSFRC（ththesame

typeoffiberscontained）tothoseofplaioconcreteones

withthesamemixproportionareinvariable．

However，theconditionforultimatetensilestrength

isdifferent．Whenthematrixstrengthincreases．thesera—

ticsofultimatetensilestrengths（showninTable3）vary

dissimilarlyaccordingtothetypeofsteelfiber．Moreover．

theincrementsarebiggerthanthoseofcrackstress．

TheheighteningefficiencyoffiberF1forultimate

tensilestrengthrisesasmatrixstrengthincreases．Itis

becausethatthestrengthofthiskindoffiberisveryhigh

（>1100MPa）．Nofiberbrokenwasobservedduringthe

testandthehooked—endsofthefiberswerestraightened

whenthematrixstrengthwashigh（C80）．Thehigherthe

matrixstrength．thiskindofsteelfibertakesonits

strengtheningeffectmoreeficientlyfortheincreasingof

bondstress．ThestrengthsoffibersF2andF3aremid—

high（>700MPa）．Thevallhavebokedendsandboth

oftheirsurfacesarecoarse．enthematrixstrengthwas

high（C80）．fiberbreakingoccurredinthetest．Andthis

phenomenonimpairedtheheighteningeficiencyofthese

twokindsofsteelfiber．Sotheyshouldbeusedinmiddle

strengthconcretetoexerttheirstrengtheningefectmore

eficiently．FiberF4issmooth．anditsbondstresswith

matrixiscomparativelylow．T}1erefore．itsstrengthening

effectis1essnotablethanthoseofotherkindsoffiber．

Becauseofthelowbondstress．nofiberbrokenwasfound

duringthetestanditsheighteningeficiencyforultimate

tensilestrengthrisesasmatrixstrengthincreases．

3．1．2Effectoffibercontent

Theeffectoffibercontentonthecrackstressandu1．

timatetensilestrengthwasinvestigatedforSFRCcon—

tainedfiberF3．Andthefibercontentvariedfrom0．5％

to1．5％byvolume（showninTable3）．Itcanbeseen

fromFig．1andFig．2thatasthefibercontentincreases．

thecrackstressandultimatetensilestrengthofSFRCim．

proveobviously．Moreover．therisingtrendsofthecurves

inthesetwofiguresarestupendouslysimilar．Inother

words，theeffectoffibercontentonthecharactersoften．

silestressofSFRCispositiveandconsistent．

Table4Fjbertvaefactors

Fibercoded．

Fl

F2

F3

F4

O．642

O．862

0．794

0．589

ThetensilestrengthofSFRCcanbecalculatedwith

thefollowformula：

=×（1+a）

（1）

where，istheultimatetensilestrengthofsFRc；the

ultimatetensilestrengthofplainconcretewiththe

samemixingproportion；a，thefibertypefactor，

whichisSh。

Ⅵ1inTable4；，：

告，isIhe—

bercontent0fv。

l愀aI1d吾istheaspectrali。

0f

steelfibers

3．2Tensilestrainandtoue．hnesscharacters

3．2．1Crackstrainandthestrainatpeaktensilelcad

Thetensilestrainswel'~acquiredbyaveragingthe

readingsofthefourdisplacementsensorsfixedaroundthe

specimen．Inaddition，thespecimenswhosedifference

betweenthetensilestrainsofitsoppositesidesislarger

than15％oftheirmeanvaluewereblankedout．

Thecrackstrainorthestrainsatpeaktensilelcadof

SFRCaremuchbigerthanthoseofplainconcrete（as

showninTable5）．Andtheincrementsgoupasthema—

trixstrengthorthefibercontentincreases．Comparedto

thatoncrackstrain．theincrescenteffectofsteelfiberon

thestrainatpeaktensilelcadismoreremarkable．

3．2．2Tensileworkandtoughnessmodulus

Thetensileworkwasdefinedastheareaunder

theload-displacementcurvefrom0to0．5rain．More—

over，atensile