钢结构英文课件

§3.8

DesignofHSboltedconnectionDetaillingrequirements(构造要求)ClassificationBoltinstallationFrictioncoefficientStrengthrequirement（受力要求）LoadtransfermechanismStrength1.Aconnectionwithhigh-strengthboltsisclassifiedaseitherabearingorslip-criticalconnection.BearingSlippageacceptableShearandbearingontheconnectorSlip-criticalSlippageunacceptable(Properinstallation)Sufficientshearandbearingstrengthinoverloadthatcausesslip.Usedintheimportantconnection§3.8.1

DetailingofHSboltedconnection1)Tightening

methodsA.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-controlbolt

D.Directtensionindicator

ThefollowingfactorsareconsideredasReductionofmaterialproperties(0.9)Reductionofovertensioningofbolt(0.9)Reductionofshearwhichwilldecreasetensionstrengthofbolt(1.2)safetyfactor0.9

BoltpreloadisAe—bolteffectivearea；fu—bolttensionstrength,fu=830N/mm2

forgrade8.8andfu=1040N/mm2

forgrade10.92）

PreloaddesignGradeNominaldiameterM16M20M22M24M27M308.88012515017523028010.9100155190225290355Frictioncoefficientdependsonthesurfacetreatmentandthesteelgrade.

Table7.2forchina3）

Frictioncoefficient(1)

BehaviorofHSbolt

HSNδO12341234ordinaryabNN/2N/2§3.8.2

StrengthofHSboltedconnectionNδO12341234HSOrdinaryabNN/2N/2where:

0.9—reciprocalofresistancefactorγR

(γR=1.111)；nf—numberoffrictionsurface；μ--frictioncoefficientP—designvalueofpreload（2）ShearcapacityofsingleboltFortheslip-criticalbolt,NδO12341234HSOrdinaryStrengthisShearcapacityisBearingcapacityisForthebearingtypebolt,where:Ae--Effectiveareaofbolt；

de--Effectivediameterofbolt；

ftb—designvalueofbolttensionstrengthTheresultsisapproximatelyequal（3）TensioncapacityofsingleboltFortheslip-criticalbolt,Forthebearingtypebolt,（4）CombinedtensionandshearFortheslip-criticalbolt,DesignvalueoftensionandshearloadofsingleboltDesignvalueoftensionandshearcapacityofsingleboltForthebearingtypebolt,Andtoavoidbearingfailure,shouldalsosatisfyas1.2isreductionofbearingcapacityduetothetensionofbolt1)Axialtension

Therequiredboltsis(basedonuniformdistribution)NNForthebearingtypebolt,Fortheslip-criticalbolt,2Shearcapacityofboltgroup

Calculationissimilarasbefore：

FTTxyN1TN1TxN1Tyr11F1N1FShearcomponetis2）Combinedtorsionandshear

Thestrengthof1#boltischeckedasTorsioncomponetis

N2）MomentM3Tensioncapacityofboltgroup

1)Axialtension

Therequiredboltsis(basedonuniformdistribution)MM1234y1y2N1N2N3N4Compre.NAThedesignrequirementisThefirmcomtactisassumedas

3)Eccentricloading

Thefirmcomtactisassumedandbothtypesaredesignedbysubstitutingmethodas:Ne1234M=N·eNy1y2N1N2N3N4N.A.MN

ConclusionFortheslip-criticalboltgroup,Forthebearingtypeboltgroup,

ShearofsingleboltisNVTensionofsingleboltis1234NVNV（4）CombinedtensionandshearMNV1234M=N·eNy1y2N1N2N3N4NAMNVV（4）Combinedtension,shearandmomentFortheslip-criticalboltgroup,ShearofsingleboltisWhereForthesingleslip-criticalbolt,Thestrengthofboltis

Shearofsingleboltis

Max.tensionofsingleboltisForthebearingtypeboltgroup,MNV1234M=N·eNy1y2N1N2N3N4N.A.MNVVDesignalapjointshowninthefigure.steelisQ235BandHighstrengthboltisM20withgrade8.8,fayingsurfaceissand-blast(喷砂)andthedesignvalueofaxialloadN=800kN.Example1（1）Slip-criticalconnection

ThepreloadofboltischeckedasThefrictioncoefficientisShearcapacityofsingleboltisTherequirednumberis

select9