钢筋混凝土梁抗弯刚度公式修正及研究_英文_

MODIFICATONANDRESEARCHONBENDINGRIGIDITY

FORMULAOFREINFORCEDCONCRETEBEAM

AiJun,ChenJue,ZhangLifang,LiuFang

(CollegeofAerospaceEngineering,NUAA,29YudaoStreet,Nanjing,210016,P.R.China)

Abstract:Beamstiffnessdegradeswithitsageinserviceanditsserviceperformanceisweakened.Accordingtothefundamentalcharacteristicsofthereinforcedconcrete,theinfluenceofstiffnessdegradationcausedbydifferentkindsofdamageisobtained.Amongthem,thecrackisthemostdirectandobviousfactor.Furthermore,accordingtotheanalysisofbendingrigidityformulapresentedincurrentstandard,aninfluenceparameterofcrackdevelopmentonthestiffnessdegradation,i.e.,nonuniformitycoefficientoftensilesteelstrain󰀁,isextracted.Averagecrackdistanceandcrackdeptharetakenascrackstatisticparameters.BasedonanalysisandmodelingwithANSYS,themodifiedbendingrigidityformularelatedtocrackisobtained.Keywords:reinforcedconcrete;beamandgirders;stiffness;crack;ANSYS

CLCnumber:U446　　　Documentcode:A　　ArticleID:1005-1120(2010)04-0299-07

INTRODUCTION

Atpresent,simplediscountedestimationmethodisoftenusedtocharacterizebridgegirderstiffnessinhomeandabroadstandards.Suchmethodsarevalidingeneralbridgedesign,butforservicebridgeassessmenttheyarelimited.Withtheincreasingofserviceages,cracksanddamage,

such

methods

gradually

cannot

characterizetheactualstiffness,andcancauseunnecessaryinterferenceanderrortothebridgeinspection.Soresearchofthemethodthatcanaccuratelycharacterizeactualstiffnessofthebridgebeambythedamageparametersisnecessary.

anddirectlyorindirectlyleadtothedegradationofstructuralstiffness.Amongthem,concretecracksplaythemostdirectandobviousroleinstiffnessdegradation.

Accordingtothebasictheoryofstiffnessanalyticmethod,aformulaofbeamstiffnessinnormalcaseis

EgAgh02

Bs=

1.15󰀁+0.2+6n󰀂

(1)

[1]

whereEg,Ag,h0,n,󰀂areallinvariant,andthosenotkeepinpacewiththechangingofthestructureexternalforce.Nonuniformitycoefficientoftensilesteelstrain󰀁istheonlyvariableaboutstructureexternalloads.Thelawofspecificvariationcanbegivenby

󰀁=1.11-Mcr

M

(2)

1　INFLUENCEOFDAMAGEON

CROSS-SECTIONSTIFFNESS

　　Reinforcedconcreteiscompositematerial.Therearethreecommondamagesinusewhichareconcretecracks,concretecorrosionandsteelcorrosion.Theformationmechanismsofthesedamagesarecomplex,diverseanddifferent,butallofthemhaveaninfluenceonbendingrigidity,

whereMcristhecrackingmomentofmember,andMthemomentvalueofcurrentexternalloads.

Eq.(2)showsthenonuniformitycoefficientoftensilesteelstrain󰀁graduallybecomeslargerfromzerowiththeincreasingoftheexternalloadaftercrack.AndthevalueofthememberstiffnessBswillalsograduallydegradefromthe

　Foundationitem:SupportedbytheCommunicationScientificResearchProjectofJiangsuProvince(06Y21).　Receiveddate:2010-03-05;revisionreceiveddate:2010-04-01　E-mail:aijun0822@nuaa.edu.cn300TransactionsofNanjingUniversityofAeronautics&AstronauticsVol.27

topwiththeincreasingof󰀁untilreachingacertainstablevalue.Itshowsarelationshipbetweenthenonuniformitycoefficientoftensilesteelstrain󰀁andstiffnessdegradationprocesses.Ontheotherhand,fromalargenumberofexperiments,itcanbeseenthatreinforcedconcretemembershavetwomajorchangesinthestiffnessdegradationprocess,whicharethedevelopmentsofcracksandplasticdeformationofconcrete

compression

zone.

When

the

developmentstendtobestable,

thebeam

stiffnesswillalsoremainrelativelystable.Thisindicatesthatthereisacloserelationshipbetweenthe

plastic

deformationofconcretecompressionzone,andthememberstiffnessBs.Therefore,thenonuniformitycoefficientoftensilesteelstrain󰀁,andthedevelopmentsofcracksandplasticdeformationofconcretecompressionzonehaveacloseconnection.

Nonuniformitycoefficientoftensilesteelstrain󰀁characterizestheinfluencedegreeofthetensileconcretebetweenthecracksonthelongitudinaltensionsteelstrain.Afterfirstcrackappeares,thesteelintheun-crackedzoneandconcretestillkeepacertainrelationshipofdeformationcoordinationbecauseofcohesiveactionbetweentheconcreteandthesteel.Butthecapacityoftensileconcretedeformationislimited,sosteelstrainintheun-crackedzoneismuchsmallerthanthatinthecrackedzone.Then,deformationenergycausedbyexternalforcesinthetensilezoneismainlyconsumedbysteelstrain.Withtheloadincreasing,tensileconcretebetweenthecracksgraduallywithdraw.Largestrainappearsintheoriginalun-crackedregionofreinforcedconcreteandnewcracksappear,whichmeansthatthecrackspacingdecreases.Then,moreconcretesareoutofwork,resultingintheincreasingofthecoefficientoftensionsteelstrain.Ontheotherhand,thebeamcurvaturecorrespondinglybecomeslargerwiththefurtherincreasesoftheload.Tipstressofcrackontheactionofbendingtensilestressofitstwo-sidedconcretegraduallyincreases.Indevelopments

of

cracks

and

addition,theproblemsofcracktipstressconcentrationstillexist,whichmakethetipconcreteconstantlyfractureandwithdrawfromworkingandleadtotheincreaseinheightofcrackandnonuniformitycoefficientoftensilesteelstrain󰀁.Soitissurethatthereisacloserelationshipbetweentheheightofcrackandnonuniformitycoefficientoftensilesteelstrain󰀁,andthedevelopmentofcrackisthemainfactorfor󰀁.

Thestructuredestroyedbyconcretecorrosionismainlyconcretecrackingandspalling,soitsinfluenceonthestiffnessdegradationcanbestudiedtogetherwithconcretecracks.

Themaininfluenceofsteelcorrosiononthestiffnessdegradationhasthreeaspects,andtheyaretheweakeningofsteelsections,thedamageofagglutinateforcebetweenconcreteandsteel,andthecrackingcausedbyconcretecorrosion.Thefirstfactorcanbeconsideredbyusingthepracticalreinforcingsteelarea.Thesecondisthemostimportantfactorthatthecorrosioneffectsonstiffnessdegradation.Becausetheinfluenceisrelativelyindependentanddoesnotinterferewitheachother,itcanbesolvedbytheindependentcoefficientofstiffnessdegradation.Thethirdfactorisanindirectinfluenceonstiffnessthroughcrack,soitcanalsobeanalyzedandresearchedtogetherwithcracks[2-8].

Thus,thedamageinfluenceonstiffnessisbasedonthecracks,anditisalsothechiefcontentofthispaper.ScholarsinDalianUniversityofTechnologycarriedoutmanyexperimentsaboutbeamcrackdevelopmentfor

[9-10]

.Inthispaper,indicatingcrackcharacteristics

finiteelementsimulationmethodisusedtofindtherelationshipbetweenbeamstiffnessandcracks.

2　MODELANALYSISOFREINFORCED

CONCRETEBEAM

2.1　Basicideasofmodelanalysis

　　Thepaperistostudytherelationshipbetweencrackdevelopmentanddegradationofstructuralstiffnessthroughadjustingthecrackingparametersofconcreteunitandcontrollingartificiallythespecificlocationandheightofthecracks.Specifically,concreteunitispermittedtoNo.4AiJun,etal.ModificatonandResearchonBendingRigidityFormulaof…301

thecrackintheareathatisallowedtothecrack,whileinotherareas,itisnotpermittedtothecrack.Thesetwokindsofconcreteunitshavethesameparametervaluesexcepttheoptionsofcracks.Themodelaccordingtothiswayisanartificialidealizedone.Althoughthelargerworkload

of

modeling,

it

can

suppress

interferenceoftheplasticmaterialdevelopmenttothecracks,anditalsocananalyzeanddiscusstheinfluenceof

independently.

different

crack

parameters

isabout50—4cmintheprocessofreinforcedconcretefromcrackingtodestructingcompletely.Therefore,thevaluesofthesetwovariableparametersareamongthesetworanges.Inaddition,thepapermainlyresearchesthestructurerelationshipbetweenthecrackdevelopmentandstiffnessdegradationunderthenormalservicecondition.Anditisgenerallythoughtthataveragecrackheightreachesonlyabout0.5hinthisstate.Sotheselectionofparameterbetween0.1hand0.5hcanbeencrypted.ThespecificvaluesofthevariableparametersareshowninTable2.

InTable2,thevaluesofaveragecrackheighthcraretherelativeheightofsection.ItisthesameinTables3,4.Becauseoftheinfluenceofreinforcementcover,itappearssmallunitof5mmlengthofsideaccordingto0.1hofmodeling,anditisdifficultforthemodeltoconstringe.Sothemodelof0.1hisusedtoreplacethemodelof0.08h.Inordertochecktheaccuracyoftheoreticalanalysis,twobeamsofL-crackandL-non-crackareusedtobecheckedinaddition.Accordingtotheprincipleofreinforcedconcretestructuredesignand\"StrengthEvaluationofExistingConcreteBridge\",theprooftestvalueofmid-spanconcentratedloadofmodelbeamPsis25547.98N.

2.2　ANSYSfiniteelementmodeling

　　ThebeammodelisanalyzedbyusingANSYS.Solid65andLink8elementisusedtosimulateconcreteandsteel.TheconstitutivelawofconcreteinChinaStandardGBJ0010-2002isadopted.Andbilinearidealelastic-plasticcurveisusedassteelbarconstitutivelaw.

GeometricparametersandmaterialparametersofconcretemodelareshowninTable1andFig.1.

Twocrackparametersofaveragecrackdevelopedheighthcrandaveragecrackspacinglcrarechosentostudy.Atthesametime,accordingtoreference,thevariationrangeofaveragedevelopedheighthcrisabout0.1h—0.8h(histhedepthofsection)andtheveragecrackspacinglcr

Table1　Geometricandmaterialparametersofbeammodel

Geometricparameter

ItemBeamdepthBeamlengthBeambreadthCalculatedlengthofbeam

Parametervalue/mm

2502500

1502300

Materialparameter

Item

ConcretegradeTensilesteelHangerstirrup

Steel

Parametervalue

C20

HRB335(2 12)R235(2 8)R235( 6@150)

Fig.1　Geometricparameterandarrangementofreinforcementofsimulatedbeam302TransactionsofNanjingUniversityofAeronautics&AstronauticsTable2　Valuesoftwovariableparametersandnumbersofsimulatedbeam

4

0.08L4-0.080.20L4-0.200.25L4-0.250.30L4-0.300.35L4-0.350.40L4-0.400.45L4-0.450.50L4-0.500.60L4-0.600.70L4-0.700.80L4-0.80Collationofadditional

beamhcr

50.L5-L5-0.L5-0.0.L5-L5-0.0.L5-L5-0.L5-0.0.L5-L5-0.0.L5-10

0.08L10-L10-0.20L10-0.250.30L10-L10-0.350.40L10-L10-0.45L10-0.500.60L10-L10-0.700.80L10-L-crack

lcr/cm

15L15-0.08L15-0.20L15-0.25L15-0.30L15-0.35L15-0.40L15-0.45L15-0.50L15-0.60L15-0.70L15-0.80

20L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.L20-0.

25L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.L25-0.

500.L50-L50-0.L50-0.0.L50-L50-0.0.L50-L50-0.L50-0.0.L50-L50-0.0.L50-

Vol.27

08

20253035404550607080082025303540455060708008202530354045506070800820253035404550607080

L-non-crack

Table3　Calculatedresultsofmid-spandeflectionofmodelbeam

hcr0.080.200.250.300.350.400.450.500.600.700.80

4

2.59E-033.26E-033.57E-033.84E-034.12E-034.37E-034.60E-034.78E-034.96E-035.02E-035.02E-03

5

2.56E-033.06E-033.26E-033.48E-033.71E-033.93E-034.07E-034.22E-034.37E-034.40E-034.40E-03

102.45E-032.85E-033.01E-033.18E-033.39E-033.57E-033.69E-033.83E-033.93E-033.95E-033.95E-03L-crack5.09E-03

lcr/cm152.38E-032.70E-032.83E-032.96E-033.15E-033.31E-033.39E-033.51E-033.61E-033.64E-033.64E-03

202.34E-032.59E-032.70E-032.79E-032.94E-033.04E-033.12E-033.19E-033.28E-033.31E-033.31E-03

252.31E-032.52E-032.60E-032.68E-2.80E-2.89E-2.94E-3.01E-3.08E-3.09E-3.10E-0303030303030303

mm

502.27E-032.37E-032.42E-032.46E-032.51E-032.57E-032.60E-032.64E-032.68E-032.69E-032.69E-03

Collationofadditional

beamDeflection

L-non-crack2.25E-03

Table4　Nonuniformitycoefficientoftensilesteelstrain󰀁ofsimulatedbeam

hcr0.080.200.250.300.350.400.450.500.600.70

40.10940.32550.42590.51370.60580.68550.75970.81830.87600.8961

50.09970.26070.32580.39610.47190.54450.58890.63560.68420.69450.6945

100.06340.19400.24480.29960.36830.42690.46450.51020.54290.55040.5504L-crack0.9197

lcr/cm150.04170.14540.18750.22730.28890.34070.36890.40680.43890.44960.4496

200.02710.10870.14340.17450.22340.25620.28050.30440.33330.34270.3427

250.01930.08610.11200.13790.17680.20500.22380.24450.26780.27240.2733L-non-crack0.0002

500.00440.03840.05270.06560.08310.10230.11230.12530.13850.14180.1418

0.800.8961Collationofadditional

beam󰀁

No.4AiJun,etal.ModificatonandResearchonBendingRigidityFormulaof…303

2.3　CalculatedresultsofANSYSfiniteelement　　ThroughtheANSYSfiniteelementanalysis,wecanobtaincalculatedresultsofmid-spandeflectionineachgroupbeam,asshowninTable3.

Accordingtothegeometricparametersandmaterialparametersofthesimulatedbeam,aswellasEq.(1),wecanobtainthevalueofnonuniformitycoefficientoftensilesteelstrain󰀁ofthecorrespondingsimulatedbeamthroughmid-spandeflection.ConcreteresultsareshowninTable4.

Table4showsthatwhenthebeamdeformsaccordingtothewayofnaturallycrackingcompletely,thevalueof󰀁is0.9197.Basedontheformulasgivenbythespecification.󰀁specification=1.1

Mcr

=0.9006M

Fig.2　Scatterdiagramofhcr-󰀁ofdifferentcrack

heights

linearcorrelationcoefficientsofthecurveareover0.9946onaverage,andlinearrelativityissky-high.Itshowsthatthevalueof󰀁changeslinearlywiththeincreasingofhcr.Inotherwords,hcrand󰀁havealinearrelationshipandcanbeexpressedby󰀁=khcr+C.3.2　Relationshipbetweenaveragecrackspacing

and󰀁　　Fromthecalculatedvalues󰀁throughfiniteelementinTable4,wecanobtainlcr-󰀁curveatdifferentcrackheights.Besides,fromtheaboveanalysiswecanseethatthecrackaverageheightsareabout0.5h—0.6hundercheckingload.Sowecanonlypickupsplattersofhcr≤0.5htoanalyzeandfit.ThespecificcurveisshowninFig.3.

Fig.3showsthat󰀁decreaseswiththeincreasingoflcr,butitishardtogettheconcretecurvefromthisfigure.Sothispapermakesaequivalentchange

N=100/lcr

(3)

　　ThephysicalmeaningofNisaveragequantityofcrackspermeteralongwiththebeam.

ThroughtheequivalentchangeofEq.(3),wecanobtainscatterdiagramofN-󰀁,asshowninFig.4.

N-󰀁curveshowsthatNobtainslargerwith

.Itsincreasingspeedslowstheincreasingof󰀁

downatfirst,andthengoesup,andhasaclearinflectionpointintherangeofN∈(10,20).Thatistosay,N-󰀁isatypicalcubiccurve.So,thepaperusescubicpolynomialtofit.Itisdiscoveredthatthefittingdegreeofcurveisover0.9984ontheaverageundercubicpolynomial,andthefittingeffectsareexcellent.Therefore,the　　Therelativeerrorbetweenthemisonly2.12%.Consideringtheinfluenceofconvergenterrorcausedbynon-linearcalculation,theerrorvaluemeetstherequirementsofthelimitedvalueoferrorcompletely.Atthesametime,italsoshowsthatthesimulateddegreeandsimulatedresultsofthemodelarehigherandbetterinthepaper.

3　DATAANALYSISOFFINITE

ELEMENTANDRIGIDITYMODIFIEDFORMULA

3.1　Relationshipbetweenaveragecrackheight

and󰀁

　　Table4showsthatthecalculatedvaluesofnonuniformitycoefficientoftensilesteelstrain󰀁throughfiniteelement,andwecanobtainhcr-󰀁curveindifferentcrackspacingsituations.ThespecificcurveisshowninFig.2.

　　Fig.2showsthatwhenhcr≤0.5h,thecurveislinear.Andwhenhcr>0.5h,thecurveslopesgently.Especially,whenhcr>0.6h,thevalueof󰀁hasbarelychanged.Thatistosay,thecrackaverageheightsareoftenabout0.5h—0.6hundercheckingload.So,wecanpickupthesplatteringofhcr≤0.5h,andlinearlyfitthem.Afterfitting,304TransactionsofNanjingUniversityofAeronautics&AstronauticsVol.27

󰀁=C1hcrN3+C2hcrN2+C3hcrN+C4hcr+C5N3+

C6N+C7N+C8

2

(6)

　　Inordertoobtainthehigherandmorereasonableformula,thepaperusesUDFfunctionsinTableCurve3DsoftwaretofitEqs.(5-6).

Throughfittingandanalyzing,thefittedresultsofthetwoformulasareshowninTable5.

Fig.3　Scatterdiagramoflcr-󰀁ofdifferentcrack

heights

Table5　Fittedresultsofabsolutetermandfitteddegree

ofEqs.(4-5)

　Parameter

C1

Independentparameterofcoefficientofequation

C2C3C4C5C6C1C2

Correlationparameterofcoefficientofequation

C3C4C5C6C7C8

Fittedresult7.9479603E-3-1.0952218E-43.6316459E-2-1.651516828.232651-21.6789413.3363163E-4-1.494702E-20.23797617-0.1508862-2.1690431E-58.5738818E-4-8.1391593E-3-5.5829987E-3

0.997144870.9962044FitteddegreeR2

Fig.4　ScatterdiagramofN-󰀁ofdifferentcrackheights

relationshipbetweenNand󰀁canbecharacterizedbycubicpolynomial,thatis

󰀁=a1N3+a2N2+a3N+a4(4)3.3　Fittingtwo-dimensionalformulaand

modifyingrigidityformula

　　According

totheabovedescription,

nonuniformitycoefficientoftensilesteelstrain󰀁

isabinaryfunctionthatisaboutcrackheightandquantityofcracksperunitlength.Ittakeslargevolumesofworkloadandcannotensureaccuratelytouseordinarydataprocessingsoftwaretofitsuchabinaryfunction.Sothepaperusestheautomaticcurvefittingofsoftwaretofit.

three-dimensional

Table5showsthatthefittedeffectsofthetwoformulasaregood,andthediversitiesarenotobvious.Comparatively,Eq.(6)fitsbetter,sothepaperusesEq.(6)asthetheoreticalcalculatedformulaof󰀁.

AndbecauseN=100/lcr,Eq.(6)canbewrittenas

󰀁=C1hcrlcr-3+C2hcrlcr-2+C3hcrlcr-1+C4hcr+

C5lcr-3+C6lcr-2+C7lcr-1+C8

(7)

wherehcrisrelativeheightofsection,andtheunitoflcriscm.ThevaluesofcoefficientareshowninTable6.

Table6　ValuesofcoefficientinEq.(6)Coefficient

C1

C2C3C4C5

Value333.631631-149.470223.797617-0.1508862-21.6904318.5738818-0.81391593-5.5829987E-3Because󰀁andhcrarelinearrelationship,andwithNarethecubicfunctionrelationship.IfhcrandNareuncorrelatedindependentvariables,󰀁canbeexpressedby

󰀁=(C1hcr+C2)(C3N3+C4N2+C5N+C6)

(5)

　　IfhcrandNarerelatedvariables,󰀁canbeexpressedasC6C7C8No.4AiJun,etal.ModificatonandResearchonBendingRigidityFormulaof…305

Eq.(7)isarelationalexpressionofnonuniformitycoefficientoftensilesteelstrain󰀁aboutstatisticalparameterofcrackhcrandlcr.Astheabovestated,theinfluenceofcrackonthestiffnessdegradationismainlythroughthe

.So,Eq.(7)isthemeaningofthechangesof󰀁

rigiditymodifiedformulaaboutstatisticalparameterofcrack.BytakingcrackparametersinEq.(7),󰀁canbecalculated,Then,thedegradationstiffnesscanbecalculatedbyEq.(1).

References:

[1]　XiangHaifan.Highertheoryforbridgestructure

[M].Beijing:ChinaCommunicationPress,2001.[2]　SunBin,NiuDitao,WangQinglin.Analysisand

calculationofflexuralrigidityofcorrodedreinforcedconcretebeam[J].BuildingStructure,2004,34(10):42-45.[3]　ZhaoYuxi,

Teststudyonbond

behaviorofcorrodedsteelbarsandconcrete[J].JournalofZhejiangUniversity:EngineeringScience,

JinWeliang.

4　CONCLUSIONS

　　Accordingtothefundamentalcharacteristicsofreinforcedconcrete,theinfluenceofstiffnessdegradationcausedbydifferentkindsofinjuriesisobtainedinthepaper.Itisalsoconsideredthattheinfluenceofstiffnessdegradationcausedbycrackisthemostdirectandobvious.Furthermore,accordingtotheanalysisofbendingrigidityformulapresentedincurrentstandard,aninfluenceparameterofcrackdevelopmentonthestiffnessdegradation,nonuniformitycoefficientof

,isextracted.Then,basedtensilesteelstrain󰀁

onanalysisandmodelingbyusingANSYS,theinfluenceoflcrandhcron󰀁isdiscussed,andthefollowingconclusionsareachieved.

(1)Thereisanobviousrelationshipbetween󰀁andhcr,and󰀁getslargerwiththeincreasingofhcr;

(2)Thereisatypicalrelationshipofcubicfunctionbetween󰀁andhcr,and󰀁getslargerwiththeincreasingofN;

(3)Thereisacertaincorrelationbetweenhcr

andN;

(4)Thetheoreticallycalculatingformulaof,statisticalcrackparametershcrandlcris󰀁

obtainedwhichcontributestodegradationstiffness.

2002,36(4):352-356.(inChinese)

[4]　ZhangJianren,ChenZhaoquan,WangLei,etal.

Studyonthebendingrigidityofrectangularbeamof

reinforcedconcrete[J].JournalofChina&Foreign

78.Highway,2007,27(3):74-[5]　YiMeiying.

Loadbearingcapacityofcorroded

reinforcedconcretebeamsunderrepeatedloading

[D].Shanghai:SchoolofNanvalArchitecture,OceanandCivilEngineering,ShanghaiJiaotongUniversity,2008.

[6]　XingJingzhong,LiJun.Nonlinearanalysisof

reinforcedconcretebeambaseonANSYS[J].Coal

Engineering,2006,10:27-29.

[7]　HaoWenhua.AppliedexamplesofANSYSincivil

engineeringexamples[M].Beijing:ChinaWaterpowerPress,2005.[8]　TrafficStandard.Identificationmethodsofcarrying

capacityoftheoldhighwaybridge(trial)[S].

Beijing:ChinaCommunicationPress,1988.[9]　LiXiaoke,Guanjunfeng,Zhaoshunbo,etal.

SimilituderatioandcalculationmethodofcrackofRCbeams[J].JournalofYangtzeRiverScientificResearchInstitute.2010,27(6):62-65.(inChinese)

[10]ZhangLimei,ZhaoShunbo,HuangChengkui.

Experimentalstudyoncrackingwidthandstrengthofprestressedhigh-strengthconcretebeams[J].

BuildingStructure,2004(8):45-48.

钢筋混凝土梁抗弯刚度公式修正及研究

艾　军　陈　珏　张丽芳　刘　芳

(南京航空航天大学航空宇航学院,南京,210016,中国)

摘要:使用过程中梁的刚度会发生退化,从而影响其使用性能。根据钢筋混凝土的基本性能,分析了各种损伤对刚度退化的影响因素,认为裂缝对刚度的影响最为直接也最为明显。进而从数学角度、物理意义角度对现行规范刚度公式进行分析,并提取出裂缝对刚度退化的影响参数——受

　基金项目:

拉钢筋应变不均匀系数󰀁。选择裂缝平均间距和裂缝开展高

度作为裂缝统计参数,通过ANSYS有限元软件模拟和分析,建立了关于裂缝统计参数的抗弯刚度修正公式。关键词:钢筋混凝土;梁;刚度;裂缝;ANSYS中图分类号:U446

江苏省交通科学研究计划(06Y21)资助项目。