土木工程专业英语 课件 8.2 Concrete-filled Steel Tubular Structure

8.2CompositeStructureConcrete-filledsteeltubularstructureConcrete-filledsteeltubular(CFST)wasthememberwhichwasformedbyconcretefilledintosteeltubular.ClassificationCircularSquareRectangleConcreteInnersteeltubularInnersteeltubularInnersteeltubularConcreteConcreteConcreteExternalsteeltubularInnersteeltubularCirculardouble-skinConcreteExternalsteeltubularInnersteeltubularCircularandsquaredouble-skinConcreteExternalsteeltubularInnersteeltubularSquaredouble-skinSquareandrectangularCircular1+1>2CircularSquareandrectangle1+1>2

Concrete-FilledSHSConcreteCoreSHSNNNN01000200030004000500060007000NsNcNs+NcNsc+....MainadvantagesInteractionbetweensteeltubeandconcreteTheoccurrenceofthelocalbucklingofthesteeltubeisdelayed

ThestrengthofconcreteisincreasedduetotheconfiningeffectprovidedfromthesteeltubularandthestrengthdeteriorationisnotverysevereDryingshrinkageandcreepofconcretearemuchsmallerthanordinaryreinforcedconcrete.

Cross-sectionalpropertiesThesteelratiointheCFSTcrosssectionismuchlargerthanthoseinthereinforcedconcreteandconcreteencasedsteelcrosssections.

SteeloftheCFSTsectioniswellplastifiedunderbendingsinceitislocatedontheoutsidethesection

ConstructionefficiencyFormsandreinforcingbarsareomitted,andconcretecastingisdonebytremietubeorpump-upmethod,whichleadtosavingsofmanpowerandconstructionalcostandtimeConstructionalsiteremainsclean

Fireresistance

Concreteimprovesthefireresistanceperformance,andtheamountoffireproofmaterialcanbereducedoritsusecanbeomitted.

CostperformanceBecauseofthemeritslistedabove,abettercostperformanceisobtainedbyreplacingasteelstructurebyaCFSTstructureEcologyEnvironmentalburdencanbereducedbyomittingtheformwork,andbyreusingsteeltubularsandhigh-qualityconcreteasrecycledaggregates.

Apllication

610mCherryblossomGuarden

No.1Building,LaiwuBaihualijingbuilding

JinanSaigePlaza,Shenzhen(72/292m,1998）YajishaBridge,Guangzhou,200，344mBasicperformanceofCFSTConfiningeffectonconcrete

thecommonopinionisthatinacompositecolumnconsistingofaconcrete-filledhollowsteelsection,compressiveconfiningstressesontheconcretecoreareinducedbypassiveconfinementprovidedbythesteeltubular.Theconfiningpressureisnotconstantasisthecaseforactiveconfinement,andalsodependsonthelateraldeformationoftheconcretecoreunderaxialloadandthestress-strainrelationshipoftheconfiningsteel.

Interactionbetweentheconcretecoreandthesteeltubular

Loadtransfermechanismstheinvestigationsforconcrete-filledsteeltubularshowitisofgreatpracticalandeconomicinterestnottohaveanymechanicalshearconnectorsintheinterfacebetweentheconcretecoreandthesteeltubular.Hence,theloadhastobetransferredinsomewaydirectlyoverthesurfacesoftheconcretecoreandthesteeltubular.FourdifferentmechanismsAdhesionduetochemicalreactionand/orsuctionforcesalongtheinterface,resultingfromcapillaryactionduringthehydrationprocess.Micro-interlockingbetweentheconcreteandthesteelduetosurfaceirregularitiesofthesteeltubular.Fractionbetweentheconcretecoreandthesteeltubularduetonormalforces.Bindingorcurvatureeffectwhichresultsfromimposingcompatibleglobaldeformations.micro-effectsadhesionandmicro-interlockingmacro-effectsfrictionandbindingMicro-effectsAdhesionisanelasticbrittleloadtransfermechanismthatisactivemainlyattheearlystageofloadingwhentherelativedisplacementsaresmall.Thebondmechanismcontributestoatypicalinitialstiffpartoftheload-deflectionrelationshipobtainedfromtest.Surfaceirregularitiesincreasedthebondstrength.Macro-effects

Frictiondevelopsbetweentheconcretecoreandsteeltubularduetonormalforces,forinstancecausedbyvolumetricincreaseoftheconcretecorewhensubjectedtocompressiveloading.Thebindingmechanismmeansthattheloadistransferredbetweentheconcretecoreandthesteeltubularbecausetheyareboundedtogetherbyimposingcompatibleglobaldeformations.Curvatureandvariationsinshapeofthesteeltubularcanbedefinedasbindingmechanisms.Thebettercompactioncouldenhanceboththeeffectofmicro-effectsandmacro-effects,resultinginhigherbondstrength.theultimatebondstrengthwasnotinfluencedbytheconcretestrength,thethicknessofthetubular,thediameterofthetubularorthelengthofconcrete-to－steelinterface.ConnectionCFSTcolumnH-shapedsteelbeam6.4mm1160°CFSTcolumnH-shapedsteelbeamPlatetomatchbeamflangewidthandthickness1-1SimpleconnectionEmbeded

weldabledeformedbars

60°CFSTcolumnH-shapedsteelbeamSteelbarsCFSTcolumnH-shapedsteelbeam111-1CFSTcolumnH-shapedsteelbeam11High-strengthboltsCFSTcolumnH-shapedsteelbeamPlatetomatchbeamflangewidthandthick1-1Headedstubs

Interiorheadedstuds

CFSTcolumnH-shapedsteelbeam11HighstrengthboltsSteeltubecutoutCFSTcolumnH-shapedsteelbeamWebofsteelbeam1-1Headedstubs

Headedstudsonwebplate

CFSTcolumn1-1H-shapedsteelbeamCFSTcolumnH-shapedsteelbeam11

Crosssectioncontinuousthroughsteeltube

(a)Outerdiaphragm(b)Innerdiaphragm(c)Through-typediaphragm(d)RingerstiffenerComparisonofCFSTandSteelsystemsbasedontheresultsoftrialdesignsshowedthatthestructuralcharacteristicsofbothsystemswerealmostthesame,butthetotalsteelconsumptionoftheCFSTsystemforentirebuildingwasabout10%lessthanthatoftheSteelsystem,whichleadtomoreadvantageouscostperformanceoftheCFSTthanSteelsystems.

1.DescribeingredientsusedforconcreteInteractionbetweensteeltubeandconcreteBuckling,strength,dryingshrinkageandcreepofconcreteCross-sectionalpropertiesThesteelratio,wellplastified

ConstructionefficiencysavingsofmanpowerandconstructionalcostandtimeConstructionalsiteremainscleanFireresistanceCostperfor