压型钢板组合楼板课件

Chapter3Compositefloorwithsteelprofiled

压型钢板-混凝土组合楼板

ByProfessorShimingChenLectureNotesforPresentation2019Chapter3Compositefloorwit1OBJECTIVE/SCOPETodescribethedesignofone-wayspanningcompositeslabs,formedusingprofiledsteelsheetingandaconcretetopping,includingconsiderationofultimateandserviceabilitylimitstatedesignforbuildingstructures.压型钢板、压型钢板分类压型钢板-混凝土组合楼板应用范围设计方法构造OBJECTIVE/SCOPE23.1Introduction压型钢板-混凝土组合楼板是指将压型钢板与混凝土通过某种构造措施组合成整体而共同工作的受力构件。Compositeflooringsystemconsistsofacold-formed,profiledsteelsheetwhichacts,notonlyasthepermanentformworkforanin-situcastconcreteslab,butalsoasthetensilereinforcementTheessentialcompositeactionbetweenthesteeldeckandtheconcreteslabisprovidedbysomeformofinterlockingdevice,capableofresistinghorizontalshearandpreventingverticalseparationatthesteel/concreteinterface.

3.1Introduction压型钢板-混凝土组合楼板是指3Compositeslabwithprofiledsteelsheetitprovidesaworkingplatformforconstruction.itactsasformworkfortheconcreteslab.itconstitutesbottomreinforcementfortheslab.Compositeslabwithprofileds4压型钢板组合楼板课件5ProfiledSteelsheeting(apatternof‘embossments’)板面的齿槽与压痕可提供界面粘结力；界面的摩擦粘结等

ProfiledSteelsheeting(apatt6Constructionstage:placetheprofiledsteelsheetingoverthesupportbeamsConstructionstage:placethe7Constructionstage:weldstudsthroughthesteelsheetingwithportableweldinggunConstructionstage:weldstuds8Constructionstage:placethelightsteelreinforcement/steelmeshConstructionstage:placethe9Constructionstage:castconcreteConstructionstage:castconcr10TypesofProfiledSheet

压型钢板类型Re-entranttypes闭口型压型钢板TypesofProfiledSheet

压型钢板类型11Trapezoidaltypes

开口型压型钢板Trapezoidaltypes

开口型压型钢板12

Advantagesidentifiedasthefollows:Thesteeldeckactsaspermanentshutteringforthein-situcastconcreteslab,withaconsequentsavingintimeandlabor.Itonceinposition,immediatelyprovidesaplatformtosupportconstructionloadsandasafe,sturdyworkingsurface.Itactsasthetensilereinforcement.Thesteeldeckgeometrycanresultinareductionoflaborabout30%intheamountofconcretefillrequiredforthefloor,significantreductionindeadweightloads.Advantagesidentifiedast133.2. DESIGNPRINCIPLES设计验算

DesignSituations（设计工况）

Twodistinctstructuralstatesmustbechecked:firstly,thetemporarystateofexecution,whenonlythesheetingresiststheappliedloads（constructionstage施工阶段）;secondly,thepermanentstate,aftertheconcreteisbondedtothesteelgivingcompositeaction（compositestage正常使用阶段）.Relevant

limitstatesand

loadcasesareconsideredforbothdesignsituations.3.2. DESIGNPRINCIPLES设计验算14a) Steeldeckshuttering（施工阶段）

Verificationsattheultimatelimitandserviceabilitylimitstatesarerequired,withrespecttothesafetyandserviceabilityofthesteeldeckactingasformworkforthewetconcrete.Theeffectsofanytemporarypropsusedduringexecution,mustbetakenintoaccountinthisdesignsituation.b) Compositeslabs（正常使用阶段）

Verificationsattheultimatelimitandserviceabilitylimitstatesarerequired,withrespecttothesafetyandtheserviceabilityofthecompositeslabaftercompositebehaviourhascommencedandanypropshavebeenremoved.a) Steeldeckshuttering（施工阶段）15设计考虑因素：Threemajoraspectsidentifiedforconsiderationduringthedesignofacompositeflooringdeck:Thesteeldeckitselfmustbesufficientlystrongandrigidtosupporttheweighttowetconcreteduringcasting-constructionstagebehavior.Thesteeldeckactingcompositelywiththehardenedconcrete,andspanningbetweenthesupportingsteelbeams,mustsupporttheimposedliveloading-compositeslabaction.Thesteelbeams,actingcompositelywiththehardenedconcretethroughthestudshearconnectorsmustsupporttheimposedliveloading-compositebeamaction.设计考虑因素：Threemajoraspects163.2

Criteriaforthedesignofcompositefloors

设计准则Indesign,itisnecessarytoensurethatthestrengthanddeflectionsbothduringconstruction(whentheconcreteisstillgreen)andinservice(whencompositeactionhasbeenachieved)aresatisfactory.Constructionstage:

theprofiledsteeldeckalonewithstandstheweightofwetconcrete,workmanandequipment.Compositeslabstage:thehardenedconcreteslab,actingcompositelywiththeprofiledsteelsheet,spansbetweenthesupportingbeamsandcarriestheimposedliveloads

3.2

Criteriaforthedesign17KeypointsforConstructionstage

-----ProfiledsteelasshutteringInstallationofthesheetingiscarriedoutbylayingoneormorespanlengthsoverthesupportingbeams.Thesheetingbehavesasafoldedplatestructureand,forlowloadlevels,thebehaviorissimilartosimplebeambehavior.Athigherloadlevels,bucklingofthecomponentplatesmayoccur.Thepredictionofbucklingstressesonthecomponentplatescanbeachievedusingclassicalorenergymethods.KeypointsforConstructionst18Thesheetinghastohaveadequatebendingstrengthandstiffness.Thesectionpropertiesofprofiledsheetscanbecomputedbasedontheanalyticalmethodsprovidedbydesigncodes.Manufacturersprefertocarryoutloadtestsontheirproductstoassessfullcapacityandprovideload-spantablesappropriatetoeachprofile.Proppingcandramaticallyreducedeflections.Thesheetinghastohaveadequ19KeypointsforcompositestageThesteeldeckactsastensilereinforcementtotheslabandthedevelopmentofcompositeactiondependsentirelyuponadequatetransferenceofhorizontalshearforcesatthesteel/concreteinterface.Toevaluatetheshearbondresistanceattheinterfacebetweentheconcreteandtheprofileddeck,PorterandEkberg(1976)proposedatestingprogram(shear-bondtest)nowworldwideadoptedindeterminationoftheshearbondresistanceforcompositeslabs.Keypointsforcompositestage203.3BEHAVIORANDANALYSISSteeldeck（混凝土结硬前：压型钢板）Duringexecutionwhentheconcreteiswet,thesteeldeckaloneresiststheexteriorloads.Itsbehavioristhencomparabletothatofprofilesusedforroofdecking.Thesteeldeckissubjectedmainlytobendingandshear;compressionduetobendingmayariseineithertheflangesortheweb;shearoccursessentiallynearthesupports.3.3BEHAVIORANDANALYSISS21Oncetheconcretehashardenedthesteeldeckandconcretecombinetoformasinglestructuralunit,thecompositeslab.Behaviorofacompositeslabisanalogoustothatofaconventionalreinforcedconcreteslab.Thebondbetweenthesteeldeckandconcretemaynotbefullyeffectiveandlongitudinalslipmayoccurbeforethesteeldeckyields.Oncetheconcretehashardened22CompositeslabfailuremodetypesFailuretypeI:弯曲破坏(flexuralfailure)：FailuretypeII:纵向剪切破坏(longitudinalshearfailure,shear-bondfailure.)：FailuretypeIII:垂直剪切破坏(verticalshearfailure)Compositeslabfailuremodety23LoaddeflectionresponseofbrittleandductileslabsThebrittleorductilemodeoffailuredependsonthecharacteristicsofthesteel-concreteinterface.Loaddeflectionresponseofbr24ShearbondfailureBrittlebehaviorinwhichslipcausesasuddendecreaseinloadcarryingcapacityasthesurfacebondisbroken.Theextenttowhichtheloadreducesisdependentontheeffectivenessofthemechanicalembossments.Ductilebehaviorinwhichcasethemechanicalshearconnectioniscapableoftransferringtheshearforceuntilfailureoccurs.Thismaybeflexuralorbylongitudinalshear.ShearbondfailureBrittlebeha25BehaviorofCompositeSlabsBehaviorofCompositeSlabs26

Longitudinalshearincompositeslabs

Threetypesofshearconnectionbetweenaprofiledsteelsheetandaconcreteslab:(1)naturalbondbetweenthetwo,knownas‘frictionalinterlock’(2)‘mechanicalinterlock’providedbypressingdimplesorribsintothesheet(3)endanchorageprovidedbymeansofshot-firedpins,orbyweldingstudsthroughthesheetingtothesteelflange.Determinationofthelongitudinalshearstrength

Them-korshear-bondtestLongitudinalshearincompos27Mode1brittle(ornon-ductile)behaviorMode2ductilebehaviorMode1brittle(ornon-ductile28EmpiricalmethodforevaluatinglongitudinalshearresistanceEmpiricalmethodforevaluat29Themeritsofusingprofiledsteeldeckcompositefloors:itsefficienciesinconstructionanditshigherloadcarryingcapacityoverthetraditionalsteeldeckasshuttering.Theshear-bondresistanceisessentialtotheinteractionbetweensteelsheetingandconcreteatthesheet-concreteinterface,andgovernsthecompositeslabdesign.Shear-bondtestsmustbecarriedouttocalibratedifferenttypesofsteeldecks.Normally,slabsaretestedwithnoshearconnectors.Themeritsofusingprofileds30Relationshipbetweenfailuremodeandspan

Iflongitudinalshearresistanceoftheslabisnotsufficient,itcanbeincreasedbytheuseofsomeformofendanchorage.Relationshipbetweenfailurem31PartialconnectionmethodThepartialconnectionmethodcanalsobeusedfortheverificationoftheresistancetolongitudinalshear.(slabswithductilebehavior).PartialconnectionmethodThep32压型钢板组合楼板课件33TheverificationprocedureisillustratedintheFigureabovefortwoslabswithdifferenttypesofloadingandspan.ResistantmomentdiagramsanddesignbendingmomentdiagramsareplottedagainstLxonthesameaxissystem.Foranycross-sectionofthespan,thedesignbendingmomentMSdcannotbehigherthanthedesignresistanceMRd.Theverificationprocedureis34Partialconnectionmethod(anotherexpression)Thepartialconnectionmethodcanalsobeusedfortheverificationoftheresistancetolongitudinalshear.Partialconnectionmethod(ano35Thepartial-interactiondesignmethodrequiresthatthemeanultimateshearstressisdetermined.Thepartial-interactiondesign36压型钢板组合楼板课件37

Vl

—designlongitudinalshearforceofthecompositeslabVu—shearbondresistancedeterminedbytests组合楼板前提：压型钢板与混凝土组合作用，要确保界面黏结强度：Shear-bondstrengthrequirement纵向抗剪强度验算Vl—designlongitudinalsh38AnalysisofCompositeSlabs（组合楼板受力分析）linearelastic;linearelasticwithmomentredistribution（线弹性分析、考虑弯矩重分布的线弹性分析）.plasticaccordingtothetheoryofplastichinges（极限状态的塑性分析）.Higherorderanalysistakingintoaccountnon-linearbehaviourandslip（考虑非线性特性以及滑移的高阶分析）.AnalysisofCompositeSla39VerificationofProfiledsteelsheetingasshutteringatultimatelimitstate(ULS)Thesheetingshouldresisttoconstructionandwetconcreteloads.Bendingmomentresistanceofthesectionisthengivenby:Verificationofprofiledsteelsheetingasshutteringatserviceabilitylimitstate(SLS)VerificationofProfiledsteel40Fortheultimatelimitstates(强度极限状态；uncrackedsection)Fortheserviceabilitylimitstates（使用极限状态）• Theslabiscomparabletoacontinuousbeamofconstantinertia,equalinvaluetotheaverageinertiaofthecrackedanduncrackedsection（均匀截面模量）.Long-termloadingeffectsontheconcretearetakenintoaccountusingavariationinthemodularratioEa/Ec（考虑长期、短期效应时引入混凝土模量系数来简化）.Forsimplification.Fortheultimatelimitstates413.4RESISTANCESOFSECTIONSSectionI:ultimatemomentofresistancefailureforpositivebending.SectionII:ultimatemomentofresistancefailurefornegativebending.SectionIII-IV:ultimateresistancetoverticalshearfailure.SectionV:ultimateresistancetolongitudinalshearfailure.3.4RESISTANCESOFSECTIONSSe42Verificationofcompositeslabatultimatelimitstate(ULS)Saggingbendingresistance.Thatfailuremodeisreachedifthesteelsheetingyieldsintensionorifconcreteattainsitsresistanceincompression.Verificationofcompositeslab43compositeslabatultimatelimitstateCase1–PlasticneutralaxisabovethesheetingCase2–Plasticneutralaxisinsteelsheetingcompositeslabatultimatelim44Case1–PlasticneutralaxisabovethesheetingCase1–Plasticneutralaxis45Case2–PlasticneutralaxisinsteelsheetingCase2–Plasticneutralaxis46压型钢板组合楼板课件47VerificationofthehoggingbendingresistanceVerificationofthehoggingbe48Bendingresistanceanddeflection

Atconstructionstage:bendingresistanceofthesteeldeckischeckedasthefollowing:

Deflectionofthesteeldeckmustsatisfythedeflectionrequirementas:Bendingresistanceanddeflect49Atcompositeslabstage

Bendingresistance,diagonalshearresistanceandshearbondresistanceshouldbecheckedIfsufficientshearbondisprovidedattheinterfacebetweenconcreteandsteelsheeting,itsbendingresistancenormaltostrongbendingdirectionasthefollowing:Positivebending:

AtcompositeslabstageBendin50Whenacompositeslabspanscontinuouslyoversupportingbeams,withnegativereinforcementovertheinternalsupportregion,thenegativemomentresistanceoftheslabcanbecalculated. Negativebending:Thebendingresistancenormaltoweakbendingdirectionistreatedasreinforcedconcreteslab.

Whenacompositeslabspansco51VerticalshearverificationVerticalshearverification52Verticalandpunchshearresistance

（抗冲切承载力）punchshearresistanceischeckedas

Verticalandpunchshearresis53Longitudinalshearresistance(纵向抗剪承载力）Toenableacompositeslab,thelongitudinalshearbondresistanceattheinterfacebetweentheconcreteandtheprofileddeckshouldbesufficient.

Diagonalshearresistance（斜截面抗剪）Longitudinalshearresistance54

Deflections

组合板挠度，按荷载短期效应组合与荷载长期效应组合计算。Fordeflectionundershorttermload（荷载短期效应）,theareaofconcretesectionisdividedbyaE(aE=Es/Ec);fordeflectionunderlongtermload（荷载长期效应）,dividedby2aE.Deflections55压型钢板组合楼板课件563.5Somedetailingrequirements

（构造要求）DetailingistoensurethatthefullstrengthofcomponentscanbedevelopedunderthemostadverseconditionsTheeffectsofcorrosiononsteelsheetsabout1mmthickaremoreseverethanonthickersections,sothematerialsareusuallygalvanized.Theoveralldepthofacompositeslabshouldnotbelessthan90mm,whilethedistancebetweenthetopsurfaceofconcreteandthetopofthesteelribsshouldnotbelessthan50mm.TheconcretegradeisbetteroverC20.3.5Somedetailingrequirement57Therequiredbearingoverlapsofcompositeslabsoverthedifferent（构造要求）Therequiredbearingoverlaps58Whenshearstudsareweldedthroughsteelprofilestothetopflangeofasteelbeam,thediameterofthestudsshouldbe13to16mmifl<3m,and16to19mmif3m<l<6m.Distributingsteelmeshissuggestedbeusedtocompensateshrinkageandthermalstressinconcrete.Theminimumsteelreinforcementratiointhetwoindividualdirectionsis0.002(rs=As/bhc).Whenshearstudsareweldedth59Negativesteelreinforcementrationotlessthan0.002forcrackwidthcontrolisrequiredinthetoplayerofconcreteslabatthesupportsofasimplysupportedslab,thedistancefromtheedgeofthesupporttothecuttingpointofthereinforcementshouldnotbelessthanl/4,and5re-barsminimumpermeterwidth.Negativesteelreinforcementr603.6Designexample–floorslabAonewaycompositefloorwithprofiledsteelsheeting,theslabspanis2.2m.SteelgradeQ235,t=1mm,As=1700m2/m(weight0.149kN/m2);

Is=0.96×106mm4/m.Thedepthofconcreteabovethetopribsis80mm,ConcretegradeC20,deadload:gk1=0.29kN/m2,liveload:qk=2kN/m2.Checkbendingstrength,diagonalshearstrengthanddeflectionoftheslab3.6Designexample–floorsla61Solution:

CalculationsofloadandinternalforcesTaketheunitwidthb=1m.Deadload(themeandepthoftheconcreteslab101mm)gk=0.101×25+0.149+0.29=2.964kN/mg

=1.2×2.964=3.56kN/mLiveload

qk=2×1=2kN/m

q=1.4×2=2.8kN/mSolution:62

M=(g+q)l02/8=(3.56+2.8)×2.22/8=3.85kN·m

V=(g+q)l0/2=(3.56+2.8)×2.2/2=7.0kNCalculationofmomentresistancefsy=205N/mm2,Es=2.06×105N/mm2fc=9.6N/mm2,h0=150–70/2=115mm

mm=0.8×1700×205×(115–36.3/2)=27.0kN·m>M

M=(g+q)l02/8=(3.56+63Diagonalshearstrength

Takeonewavelength(200mm)asacheckingunit,subjectedtoshearforceas:

V1=V×200/1000=7.0×200/1000=1.4kNft=1.10N/mm2(C20)0.7f

tbbm

h0=0.7×1.10×(70+50)/2×115=5.31kN>V1

CalculationofdeflectionTakeonewavelength(200mm)asacheckingunit.Elasticmodulusofconcrete:Ec=2.55×104N/mm2

aE=E

s/E

c=2.06×105/2.55×104=8.08DeflectionundershorttermloadingEquivalentwidthofconcreteslab:

DiagonalshearstrengthTak64Equivalentwidthofrib:

secondmomentofareaofthetransformedsectionofonewavelengthofcompositeslab

Equivalentwidthofrib:65secondmomentofareapermeterofslab:Isk=5Isk’=5×475×104=0.238×108mm4

pk=gk+qk=2.954+2=4.964kN/mDeflectionunderlongtermloadingsecondmomentofareapermete66SteelDeckP3623SteelDeckP362367压型钢板组合楼板课件68压型钢板组合楼板课件69压型钢板组合楼板课件703.7AdvancedcompositefloorsystemsanumberoftrendsinmodernconstructionhaveledtothedevelopmentofmoreadvancedformsofcompositeconstructionFabricatedbeamswithtappedwebs3.7Advancedcompositefloors71

HaunchedbeamsHaunchedbeams72Compositetrusses

Compositetrusses73StubgirdersStubgirders74ParallelbeamgrillagesystemParallelbeamgrillagesystem75BeamwithsinglewebopeningsBeamwithsinglewebopenings76BeamswithwebopeningsCellularandcastellatedbeams

Beamswithwebopenings77SlimfloorsystemSlimfloorsystem783.8 CONCLUDINGSUMMARYThedesignofacompositeslabmustconsidertheperformanceoftheprofiledsteelsheeting,whenitactsasshutteringforthewetconcreteduringexecution,aswellasthecompositeperformanceofthesteelandhardenedconcreteundertheimposedfloorloading.Attheexecutionstage,theprofiledsteelsheetingactsasathin-walledmember.Itsdesignmusttakeintoaccountthepossibilityoflocalbuckling.Thedesignofthecompositeslabmustconsidertheresistancetopositiveandnegativemomentsandalsotoverticalandlongitudinalshear.3.8 CONCLUDINGSUMMARY79Theresistancetolongitudinalshearatthesteel/concreteinterfaceislargelyderivedfromembossmentsinthesteelsheetorfromconnectorsplacedattheendsofthespans.Empiricalmethodsareusedtoensureadequateshearresistance.shallowfloorsystems,whichcombinethefloorandslabinthesameverticalspace,offeracompetitivealternativetoconcreteflatslabconstruction.Inseekinganeconomicdesign,considerationshouldbegiventooverallprojectcostsandflexibilityforfuturechangesinbuildinguseandservices.Theresistancetolongitudinal80Reviewpoints:Whatisthelongitudinalshear?Whicharegoverningfactorsindesignofacompositeslab?Determinationofthelongitudinalshearbyshearbondtestsanddefectsofthem-kmethod.简述压型钢板-混凝土组合板在施工阶段和使用阶段有哪些破坏模式。FurtherreadingofdesignmethodsforresistancetofireReviewpoints:81Fireresistance

（抗火性能）Thecompositefloormustprovidesatisfactoryperformanceintermsofstability,integrityandinsulationintheeventoffire.Thethicknessoftheslabisdirectlyrelatedtoitsinsulationcapacity.Integrityisensuredbythesheetingwhichactsasashieldtoconcreteandhelpstocontainspalling.Stabilityofthestructuredependsuponconventionalreinforcementprovidedfortheslab.Asmallamountofadditionalreinforcementmaybeneededdependingupontheextentoffireresistanceneeded.Fireresistance（抗火性能）Thecomp82Basedonalargenumberoffiretests,manycarriedoutinassociationwithBritishSCI,adesignguidehasbeenpublished,whichprovidespracticalassistanceinassessingfireresistanceofcompositeslabs.抗火评定：fire-proofrating:1hr,2hr,etc.Basedonalargenumberoffir83谢谢！谢谢！84Chapter3Compositefloorwithsteelprofiled

压型钢板-混凝土组合楼板

ByProfessorShimingChenLectureNotesforPresentation2019Chapter3Compositefloorwit85OBJECTIVE/SCOPETodescribethedesignofone-wayspanningcompositeslabs,formedusingprofiledsteelsheetingandaconcretetopping,includingconsiderationofultimateandserviceabilitylimitstatedesignforbuildingstructures.压型钢板、压型钢板分类压型钢板-混凝土组合楼板应用范围设计方法构造OBJECTIVE/SCOPE863.1Introduction压型钢板-混凝土组合楼板是指将压型钢板与混凝土通过某种构造措施组合成整体而共同工作的受力构件。Compositeflooringsystemconsistsofacold-formed,profiledsteelsheetwhichacts,notonlyasthepermanentformworkforanin-situcastconcreteslab,butalsoasthetensilereinforcementTheessentialcompositeactionbetweenthesteeldeckandtheconcreteslabisprovidedbysomeformofinterlockingdevice,capableofresistinghorizontalshearandpreventingverticalseparationatthesteel/concreteinterface.

3.1Introduction压型钢板-混凝土组合楼板是指87Compositeslabwithprofiledsteelsheetitprovidesaworkingplatformforconstruction.itactsasformworkfortheconcreteslab.itconstitutesbottomreinforcementfortheslab.Compositeslabwithprofileds88压型钢板组合楼板课件89ProfiledSteelsheeting(apatternof‘embossments’)板面的齿槽与压痕可提供界面粘结力；界面的摩擦粘结等

ProfiledSteelsheeting(apatt90Constructionstage:placetheprofiledsteelsheetingoverthesupportbeamsConstructionstage:placethe91Constructionstage:weldstudsthroughthesteelsheetingwithportableweldinggunConstructionstage:weldstuds92Constructionstage:placethelightsteelreinforcement/steelmeshConstructionstage:placethe93Constructionstage:castconcreteConstructionstage:castconcr94TypesofProfiledSheet

压型钢板类型Re-entranttypes闭口型压型钢板TypesofProfiledSheet

压型钢板类型95Trapezoidaltypes

开口型压型钢板Trapezoidaltypes

开口型压型钢板96

Advantagesidentifiedasthefollows:Thesteeldeckactsaspermanentshutteringforthein-situcastconcreteslab,withaconsequentsavingintimeandlabor.Itonceinposition,immediatelyprovidesaplatformtosupportconstructionloadsandasafe,sturdyworkingsurface.Itactsasthetensilereinforcement.Thesteeldeckgeometrycanresultinareductionoflaborabout30%intheamountofconcretefillrequiredforthefloor,significantreductionindeadweightloads.Advantagesidentifiedast973.2. DESIGNPRINCIPLES设计验算

DesignSituations（设计工况）

Twodistinctstructuralstatesmustbechecked:firstly,thetemporarystateofexecution,whenonlythesheetingresiststheappliedloads（constructionstage施工阶段）;secondly,thepermanentstate,aftertheconcreteisbondedtothesteelgivingcompositeaction（compositestage正常使用阶段）.Relevant

limitstatesand

loadcasesareconsideredforbothdesignsituations.3.2. DESIGNPRINCIPLES设计验算98a) Steeldeckshuttering（施工阶段）

Verificationsattheultimatelimitandserviceabilitylimitstatesarerequired,withrespecttothesafetyandserviceabilityofthesteeldeckactingasformworkforthewetconcrete.Theeffectsofanytemporarypropsusedduringexecution,mustbetakenintoaccountinthisdesignsituation.b) Compositeslabs（正常使用阶段）

Verificationsattheultimatelimitandserviceabilitylimitstatesarerequired,withrespecttothesafetyandtheserviceabilityofthecompositeslabaftercompositebehaviourhascommencedandanypropshavebeenremoved.a) Steeldeckshuttering（施工阶段）99设计考虑因素：Threemajoraspectsidentifiedforconsiderationduringthedesignofacompositeflooringdeck:Thesteeldeckitselfmustbesufficientlystrongandrigidtosupporttheweighttowetconcreteduringcasting-constructionstagebehavior.Thesteeldeckactingcompositelywiththehardenedconcrete,andspanningbetweenthesupportingsteelbeams,mustsupporttheimposedliveloading-compositeslabaction.Thesteelbeams,actingcompositelywiththehardenedconcretethroughthestudshearconnectorsmustsupporttheimposedliveloading-compositebeamaction.设计考虑因素：Threemajoraspects1003.2

Criteriaforthedesignofcompositefloors

设计准则Indesign,itisnecessarytoensurethatthestrengthanddeflectionsbothduringconstruction(whentheconcreteisstillgreen)andinservice(whencompositeactionhasbeenachieved)aresatisfactory.Constructionstage:

theprofiledsteeldeckalonewithstandstheweightofwetconcrete,workmanandequipment.Compositeslabstage:thehardenedconcreteslab,actingcompositelywiththeprofiledsteelsheet,spansbetweenthesupportingbeamsandcarriestheimposedliveloads

3.2

Criteriaforthedesign101KeypointsforConstructionstage

-----ProfiledsteelasshutteringInstallationofthesheetingiscarriedoutbylayingoneormorespanlengthsoverthesupportingbeams.Thesheetingbehavesasafoldedplatestructureand,forlowloadlevels,thebehaviorissimilartosimplebeambehavior.Athigherloadlevels,bucklingofthecomponentplatesmayoccur.Thepredictionofbucklingstressesonthecomponentplatescanbeachievedusingclassicalorenergymethods.KeypointsforConstructionst102Thesheetinghastohaveadequatebendingstrengthandstiffness.Thesectionpropertiesofprofiledsheetscanbecomputedbasedontheanalyticalmethodsprovidedbydesigncodes.Manufacturersprefertocarryoutloadtestsontheirproductstoassessfullcapacityandprovideload-spantablesappropriatetoeachprofile.Proppingcandramaticallyreducedeflections.Thesheetinghastohaveadequ103KeypointsforcompositestageThesteeldeckactsastensilereinforcementtotheslabandthedevelopmentofcompositeactiondependsentirelyuponadequatetransferenceofhorizontalshearforcesatthesteel/concreteinterface.Toevaluatetheshearbondresistanceattheinterfacebetweentheconcreteandtheprofileddeck,Porter