钢结构英文课件VIP免费

§3.8DesignofHSboltedconnection1.Detaillingrequirements(构造要求)ClassificationBoltinstallationFrictioncoefficient2.Strengthrequirement（受力要求）LoadtransfermechanismStrength1.Aconnectionwithhigh-strengthboltsisclassifiedaseitherabearingorslip-criticalconnection.BearingSlippageacceptableShearandbearingontheconnectorSlip-criticalSlippageunacceptable(Properinstallation)Sufficientshearandbearingstrengthinoverloadthatcausesslip.Usedintheimportantconnection§3.8.1DetailingofHSboltedconnection1)TighteningmethodsA.TurnoftheNut(扭角法)B.Calibratedwrenchtightening(扭矩法)C.Twist-off-typetension-controlbolt（拧断型拉力控制螺栓）D.Directtensionindicator(拉力测量仪)2.BoltinstallationA.TurnoftheNutB.CalibratedwrenchtighteningC.Twist-off-typetension-controlboltD.DirecttensionindicatorThefollowingfactorsareconsideredasReductionofmaterialproperties(0.9)Reductionofovertensioningofbolt(0.9)Reductionofshearwhichwilldecreasetensionstrengthofbolt(1.2)safetyfactor0.9BoltpreloadisuefAP2.19.09.09.0Ae—bolteffectivearea；fu—bolttensionstrength,fu=830N/mm2forgrade8.8andfu=1040N/mm2forgrade10.92）PreloaddesignFrictioncoefficientdependsonthesurfacetreatmentandthesteelgrade.Table7.2forchina3）Frictioncoefficient(1)BehaviorofHSboltHSNδO12341234ordinaryabNN/2N/2§3.8.2StrengthofHSboltedconnectionNδO12341234HSOrdinaryabNN/2N/2PnNfbv9.0where:0.9—reciprocalofresistancefactorγR(γR=1.111)；nf—numberoffrictionsurface；μ--frictioncoefficientP—designvalueofpreload（2）ShearcapacityofsingleboltFortheslip-criticalbolt,NδO12341234HSOrdinarybvevbvfdnN42bcbcftdNbcbvbNNNminminStrengthisShearcapacityisBearingcapacityisForthebearingtypebolt,PNbt8.0btebtebtfdfAN42where:Ae--Effectiveareaofbolt；de--Effectivediameterofbolt；ftb—designvalueofbolttensionstrengthTheresultsisapproximatelyequal（3）TensioncapacityofsingleboltFortheslip-criticalbolt,Forthebearingtypebolt,1bvvbttNNNNbvbtvtNNNN、、（4）CombinedtensionandshearFortheslip-criticalbolt,DesignvalueoftensionandshearloadofsingleboltDesignvalueoftensionandshearcapacityofsingleboltForthebearingtypebolt,122bttbvvNNNNAndtoavoidbearingfailure,shouldalsosatisfyas2.1bcvNN1.2isreductionofbearingcapacityduetothetensionofbolt1)AxialtensionTherequiredboltsis(basedonuniformdistribution)bvNNnbNNnminNNForthebearingtypebolt,Fortheslip-criticalbolt,2ShearcapacityofboltgroupCalculationissimilarasbefore：FTTxyN1TN1TxN1Tyr11F1N1FShearcomponetisnFNF12）CombinedtorsionandshearniniiininiiiTyniniiininiiiTxyxxTrxyxrTNyxyTryyxrTN11221111122111122111112211bvFTyTxNNNN21121Thestrengthof1#boltischeckedasbFTyTxNNNNmin21121TorsioncomponetisbtNNnN2）MomentM3Tensioncapacityofboltgroup1)AxialtensionTherequiredboltsis(basedonuniformdistribution)MM1234y1y2N1N2N3N4Compre.NAnnyNyNyNML2211nnyNyNyNyNL332211niiyyMN1211ThedesignrequirementisbtNN1Thefirmcomtactisassumedas3)EccentricloadingThefirmcomtactisassumedandbothtypesaredesignedbysubstitutingmethodas:btniiMNyyMnNNnNN12111Ne1234M=N·eNy1y2N1N2N3N4N.A.MN1bvvbttNNNN122bttbvvNNNN2.1bcvNNConclusionFortheslip-criticalboltgroup,Forthebearingtypeboltgroup,ShearofsingleboltisNVnVNvTensionofsingleboltisnNNt1234NVNV（4）CombinedtensionandshearMNVPNyyMnNNbtniit8.012111234M=N·eNy1y2N1N2N3N4NAMNVV（4）Combinedtension,shearandmomentFortheslip-criticalboltgroup,nVNNvv1Shearofsingleboltis111bvvbttNNNNPnNfbv9.0PNbt8.0WhereForthesingleslip-criticalbolt,ThestrengthofboltisnVNv1ShearofsingleboltisMax.tensionofsingleboltisniityyMnNN121112121bttbvvNNNN2.1and1bcvNNForthebearingtypeboltgroup,MNV1234M=N·eNy1y2N1N2N3N4N.A.MNVVDesignalapjointshowninthefigure.steelisQ235BandHighstrengthboltisM20withgrade8.8,fayingsurfaceissand-blast(喷砂)andthedesignvalueofaxialloadN=800kN.Example1kNP12545.0kNPnNfbv3.10112545.029.09.09.73.101800bvNNn2/250mmNfbv2/470mmNfbc（1）Slip-criticalconnectionThepreloadofboltischeckedasThefrictioncoefficientisShearcapacityofsingleboltisTherequirednumberisselect9（2）bearingtypeconnectionItischeckedasCapacityofsingleboltisTherequirednumberiskNfdnNbvvbv15725042014.324221.5157800minNNnkNftdNbcbc1884702020select61.Problem12、习题3.6(M20,Q235changetoQ345,sand-blastfayingsurface)3、习题3.8(120changeto130)Assignment