BS_7608_1993

BRITISHSTANDARDBS7608:1993IncorporatingAmendmentNo.1CodeofpracticeforFatiguedesignandassessmentofsteelstructuresLicensedCopy:NanyangTechUniversityLibrary,,WedMay1002:50:21BST2006,UncontrolledCopy,(c)BSIBS7608:1993ThisBritishStandard,havingbeenpreparedunderthedirectionoftheWeldingStandardsPolicyCommittee,waspublishedundertheauthorityoftheStandardsBoardandcomesintoeffecton15April1993©BSI03-1999ThefollowingBSIreferencesrelatetotheworkonthisstandard:CommitteereferenceWEE/44Draftforcomment87/77328DCISBN0580212815CommitteesresponsibleforthisBritishStandardThepreparationofthisBritishStandardwasentrustedbytheWeldingStandardsPolicyCommittee(WEE/-)toTechnicalCommitteeWEE/44,uponwhichthefollowingbodieswererepresented:AEATechnologyAssociationofConsultingEngineersBritishConstructionalSteelworkAssociationLtd.BritishRailwaysBoardDepartmentofTransportDepartmentofTransport(TransportResearchLaboratory)ESDUInternationalLtd.ElectricityAssociationFederationofManufacturersofConstructionEquipmentandCranesInstitutionofCivilEngineersInstitutionofStructuralEngineersMinistryofDefenceProcessPlantAssociationRailwayIndustryAssociationofGreatBritainSocietyofBritishAerospaceCompaniesLimitedUnitedKingdomOffshoreOperatorsAssociationWeldingInstituteAmendmentsissuedsincepublicationAmd.No.DateComments8337February1995IndicatedbyasidelineinthemarginLicensedCopy:NanyangTechUniversityLibrary,,WedMay1002:50:21BST2006,UncontrolledCopy,(c)BSIBS7608:1993©BSI03-1999iContentsPageCommitteesresponsibleInsidefrontcoverForewordivSection1.General1.1Scope11.2References11.3Definitions11.4Symbolsandunits31.5Assessment31.6Designlife31.7Fatigueloading31.8Basisoffatigueanalysis41.9Factorsonfatiguelife41.10Featuresinfluencingfatiguebehaviour51.11Fracturemechanics5Section2.Classificationofdetails2.1General62.2Classificationofdetails62.3Unclassifieddetails242.4Workmanshipandinspection242.5Weldedsteeldecks25Section3.Stresscalculations3.1General273.2Stressrangeinparentmaterial273.3Stressrangeforwelds273.4Effectivestressrangefordetailsinunweldedmembersinwhichthewholeorpartofthestressiscompressive273.5Calculationofstresses273.6Geometricalstressconcentrations283.7Stressesinweldsattachingshearconnectors293.8Axialstressesinbolts303.9Derivationofstressspectra30Section4.Allowablefatiguestresses4.1Tensilestresslimitations314.2S-Ncurves314.3ModificationstobasicS-Ncurves314.4Treatmentoflowstresscycles334.5Treatmentofhighstresscycles344.6Jointssubjectedtosinglestressrange344.7Jointssubjectedtoastressspectrum34AnnexA(normative)Fatiguedesignphilosophy46AnnexB(normative)Explanatorynotesondetailclassification47AnnexC(normative)Guidanceonthecalculationofstressconcentrationfactors51AnnexD(normative)Guidanceontheuseoffracturemechanics61AnnexE(normative)Fatiguetestingandtheuseoftestdatatodefinedesignstresses69AnnexF(normative)Cyclecountingbythereservoirmethod70AnnexG(informative)Backgroundnotesonsourcesofdata71LicensedCopy:NanyangTechUniversityLibrary,,WedMay1002:50:21BST2006,UncontrolledCopy,(c)BSIBS7608:1993ii©BSI03-1999PageAnnexH(informative)Bibliography80Figure1—Weldqualitycategorydeterminedbyadjacentdetail35Figure2—Referencestressinparentmetal36Figure3—Referencestressinweldthroat36Figure4—Typicalexampleofstressconcentrationsduetogeometricaldiscontinuity37Figure5—Typicalexampleofstressconcentrationcausedbyageometricalhardspot38Figure6—Stressconcentrationfactors39Figure7—Exampleofhotspotstressesinanodaljoint40Figure8—Summaryofmean-lineSr-Ncurves41Figure9—SummaryofstandardbasicdesignSr-Ncurves42Figure10—Sr/UTS-Ncurvesforboltswithcutor,groundorrolledthreadsunderaxialloading(classX)43Figure11—Toegrindingtoimprovefatiguestrength44Figure12—Grindingofweldattubularnodaljoint45Figure13—TypicalSr-Nrelationship45FigureB.1—Edgedistance52FigureB.2—Failuremodesatweldends52FigureB.3—FailuremodesincruciformandT-joints53FigureB.4—Failuremodesintransversebuttwelds53FigureB.5—T-junctionoftwoflangeplates53FigureB.6—Cruciformjunctionbetweenflangeplates54FigureB.7—Alternativemethodofjoiningtwoflangeplates54FigureB.8—Localgrindingadjacenttocopeholeintype7.1joint55FigureB.9—Useofcontinuityplatingtoreducestressconcentrationsintype8.1and8.2joints55FigureB.10—Exampleoftype8.3or8.4joint56FigureB.11—Singlefilletcornerweldinbending56FigureB.12—Exampleofathirdmemberslottedthroughamainmember57FigureC.1—Typesofmisalignmentanddistortion61FigureD.1—Flawdimensions63FigureD.2—Transverseload-carryingcruciformjoint64FigureF.1—Exampleofcyclecountingbyreservoirmethod70FigureG.1—ComparisonofproposedS-NcurvesforboltsinaxialloadingwithcurvesfromESDUdatasheets79Table1—Classificationofdetails:plainmaterialfreefromwelding7Table2—Classificationofdetails:boltedorrivetted,splicedorlappedconnections8Table3—Classificationofdetails:fastenersandshearconnectors9Table4—Classificationofdetails:continuousweldedattachmentsessentiallyparalleltothedirectionofappliedstress10Table5—Classificationofdetails:weldedattachmentsonthesurfaceoredgeofastressedmember12Table6—Classificationofdetails:fullpenetrationbuttweldsbetweenco-planarplates13Table7—Cl