外文翻译--冷弯型钢框架结构设计方法.doc

PRESCRIPTIVEMETHODFORRESIDENTIALCOLD-FORMEDSTEELFRAMINGSecondEditionPreparedforTheU.S.DepartmentofHousingandUrbanDevelopmentOfficeofPolicyDevelopmentandResearchWashington,DCCo-SponsoredbyTheAmericanIronandSteelInstituteWashington,DCandTheNationalAssociationofHomeBuildersWashington,DCbyNAHBResearchCenter,Inc.400PrinceGeorgesBoulevardUpperMarlboro,MD20774-8731August1997CONTENTS5.0STEELFLOORFRAMING.215.1FloorConstruction.215.2FloortoFoundationorBearingWallConnection.215.3AllowableJoistSpans.215.4JoistBracing.215.5FloorCantilevers.225.6Splicing.225.7FramingofFloorOpenings.225.8FloorTrusses.225.0STEELFLOORFRAMING5.1FloorConstructionCold-formedsteelframingmembersshallcomplywiththeprovisionsofSection2.0.SteelfloorsshallbeconstructedinaccordancewiththissectionandFigure5.1.5.1.1ApplicabilityLimitsTheapplicabilitylimitsofSection1.3andTable1.1shallapply.5.1.2In-LineFraming.Loadbearingsteelfloorframing,wallframing,andceiling/roofframingshallbeconstructedin-linewiththeverticalloadbearingmembers(i.e.studs)locatedbelow.Amaximumtoleranceof3/4inch(19mm)betweenthecenterlinesofthein-linemembersshallbepermittedinaccordancewithFigure1.2.5.2FloortoFoundationorBearingWallConnectionCold-formedsteelfloorframingshallbeanchoredtofoundations,woodsills,orloadbearingwallsinaccordancewithTable5.1andFigures5.1through5.10.FasteningofsteeljoiststootherframingmembersshallbeinaccordancewithTable5.2.5.3AllowableJoistSpansTheclearspanofcold-formedsteelfloorjoistsshallnotexceedthelimitssetforthinTable5.3forsinglespansandTable5.4formultiplespans.Whencontinuousjoistmembersareusedformultiplespans,theinteriorbearingsupportsshallbelocatedwithintwofeet(0.6m)ofmid-spanofthesteeljoists,andtheindividualspansshallnotexceedtheapplicablespansinthetable.Floorjoistsshallhaveabearingsupportlengthofnotlessthan1.5inches(38mm)forexteriorwallsupportsand3.5inches(89mm)forinteriorwallsupports.BearingstiffenersshallbeinstalledateachjoistbearinglocationinaccordancewithSection2.9.Thethicknessofjoisttracksshallbeaminimumof33mils(0.84mm)thickexceptwhenusedaspartoffloorheaderortrimmerinaccordancewithSection5.7.5.4JoistBracingThetopflangesoffloorjoistsshallbelaterallybracedbytheapplicationoffloorfastenedtothejoistsinaccordancewithTable5.2.Floorjoistswithspansthatexceed12feet(3.7m)shallhavethebottomflangeslaterallybracedinaccordancewithoneofthefollowing:1.Gypsumboardinstalledwithminimum#6screwsinaccordancewiththeapplicablebuildingcode,or2.ContinuoussteelstrappinginstalledinaccordancewithFigure5.1and5.2.Steelstrapsshallbeatleast1-1/2inches(38mm)inwidthand33mils(0.84mm)inthickness.Strapsshallbefastenedtothebottomflangeofeachjoistwithatleastone#8screwandshallbefastenedtoblockingwithatleasttwo#8screws.Blockingorbridging(X-bracing)shallbeinstalledbetweenjoistsatamaximumspacingof12feet(3.7m)measuredalongthecontinuousstrapping(perpendiculartothejoistrun).Blockingorbridgingshallalsobelocatedattheterminationofallstraps.5.5FloorCantileversFloorcantileversforthesecondfloorofatwo-storybuildingorthefirstfloorofaone-storybuildingshallnotexceed24inches(610mm)asillustratedinFigure5.1.Cantileversshallsupportinteriorfloorloadingonly.Cantilevers,notexceeding24inches(610mm)andsupportingonefloorandroof(firstfloorofatwostorybuilding),shallbepermittedprovidedthatallcantileveredjoistsaredoubled(nestedorback-to-back).Thedoubledcantileveredjoistsshallextendaminimumof6feet(1.8m)towardtheinsideandshallbefastenedwithaminimumoftwo#8screwsspacedat24inches(610mm)oncenterthroughthewebs(forback-to-back)orflanges(fornestedjoists).Approveddesignisrequiredforcantileveredareassupportinguniformliveloadsgreaterthan40psf(1.92kN/m2).5.6SplicingJoistsandotherstructuralmembersshallnotbesplicedwithoutanapproveddesign.SplicingoftracksshallconformwithFigure5.11.5.7FramingofFloorOpeningsOpeningsinfloorsshallbeframedwithheaderandtrimmerjoists.Headerjoistspansshallnotexceed8feet(2.4m)inlength.Headerandtrimmerjoistsshallbefabricatedfromjoistandtracksections,whichshallbeofaminimumsizeandthicknessastheadjacentfloorjoistsandshallbeinstalledinaccordancewithFigures5.1,5.12,and5.13.Eachheaderjoistshallbeconnectedtotrimmerjoistswithaminimumoffour2inchx2inch(51mmx51mm)clipangles.Eachclipangleshallbefastenedtoboththeheaderandtrimmerjoistswithfour#8screwsevenlyspacedoneachlegoftheclipangle.Theclipanglesshallhaveathicknessnotlessthanthatofthefloorjoist.5.8FloorTrussesCold-formedsteelfloortrussesshallbedesigned,braced,andinstalledinaccordancewithanapproveddesign.Trussme