ACI 408.2R-92 STATE-OF-THE-ART REPORT ON BOND UNDE

ACI408.2R-92STATE-OF-THE-ARTREPORTON(Reapproved1999)BONDUNDERCYCLICLOADSReportedbyACICommittee408DenisMitchellChairmanWilliamC.BlackDavidDarwin*MohammadR.EhsaniRolfEligehausen*FernandoE.FagundoPeterGergely*NarendraK.GosainNeilM.HawkinsJackP.MoehleJames0.Jirsa*KennethH.MurrayDavidW.JohnstonMikaelP.J.OlsenLeRoyA.Lutz*TelvinRezansoff*JohnF.McDermottMorrisSchupackS.AliMirzaPar-vizSoroushian*Member,Sub-CommitteeonRepeatedLoadEffectstChairmanandEditor-Sub-CommitteeonRepeatedLoadEffectsThisstate-of-the-artreportsummarizesthemostrecentresearchonbondbehaviorundercyclicloads.Thereportprovidesabackgroundtobondproblems,discussesthemainvariablesaffectingbondperformance,anddescribesitsbehaviorundercyclicloads.Twogeneraltypesofcyclicloadsareaddressed:high-cycle(fatigue)andlow-cycle(earthquakeandsimilar)loads.Thebehaviorofstraightanchorages,hooksandsplicesisincluded.Designrecommendationsareprovidedforbothhighandlowcyclefatigue,andsuggestionsforfurtherresearcharegiven.Keywords:anchorage;barslip;bond;bondmodels;cyclicloads;designrecommendations;developmentlength;fatigue;seismicloads;hooks;splicesCONTENTSChapterl-Introduction1.l-Bond1.2-Scope1.3-TerminologyChapter2-Bondandanchorage2.l-Bondstresses2.2-Componentsofbondresistance2.3-Failuremodes2.4-BondmechanismsACICommitteeReports,Guides,StandardPractices,andCommentariesareintendedforguidanceindesigning,planning,executing,orinspectingconstructionandinpreparingspecifications.ReferencetothesedocumentsshallnotbemadeintheProjectDocuments.IfitemsfoundinthesedocumentsaredesiredtobepartoftheProjectDocumentstheyshouldbephrasedinmandatorylanguageandincorporatedintotheProjectDocuments.RobertoLeon?Secretary2.5-Factorsaffectingloads2.6--SummaryChapter3-Bondbehavior3.1-Highcyclefatiguebondstrengthundercyclicundercyclicloads3.2-Correlationbetweenfatigueandsustainedloading3.3-Lowcyclefatigue3.4--InfluenceofcrackingonbondstrengthChapter4-Anchorageunderhighcyclefatigue4.1-Straightbaranchorages4.2-Hookedanchorages4.3-SplicesChapter5-Anchoragesunderlowcycleloading5.1-Straightbaranchorages5.2-Hooks5.3-SplicesChapter6-AnalyticalbondmodelsChapter7-Designapproaches7.1-HighcyclefatigueACI408.2R-92becameeffectiveAug.1,1992.Copyright01992,AmericanConcreteInstituteAlrightsreservedincludingrightsofreproductionanduseinanyformorbyanymeans,includingthemakingofcopiesbyanyphotoprocess,orbyanyelectronicormechanicaldevice,printed,written,ororal,orrecordingforsoundorvisualreproductionorforuseinanyknowledgeorretrievalsystemordevice,unlesspermissioninwritingisobtainedfromthecopyrightproprietors.408.2R-1408.2R-2ACICOMMITTEEREPORT7.2-Lowcycleloading7.3-ACI408recommendationsChapter8-Summaryandconclusions,p.408.2-258.l-Summary8.2-Conclusions8.3-RecommendationsforfutureresearchChapter9-References,p.408.2R-26CHAPTERl-GENERALl.l-IntroductionThetransferofforcesacrosstheinterfacebetweenconcreteandsteelbybondstressesisoffundamentalimportancetomanyaspectsofreinforcedconcretebe-havior.Satisfactorybondperformanceisanimportantgoalinthedetailingofreinforcementinstructuralcom-ponents.Manycurrentdetailingprovisionsareaimedatpreventingbondfailures.Bondstressesinreinforcedconcretemembersarisefromtwodistinctsituations.Thefirstisanchorageordevelopmentwherebarsareterminated.Thesecondisflexuralbondorthechangeofforcealongabarduetoachangeinbendingmomentalongthemember.Thebondperformanceunderstaticmonotonicallyincreasingdeformations(tobereferedas“monotonicloading”inthisreport)hasbeensummarizedinpreviousACIre-ports(ACICommittee352,1985;ACICommittee408,1966;ACICommittee408;1970;ACICommittee408,1979).Bondbehaviorundercyclicloadingsreceivedcom-parativelylittleattentionuntildesignforseismicandwaveloadsbecameimportantdesigntopics(ACICom-mittee408,1979).Investigationsintheseareasoverthepast25yearshaveclarifiedsomeoftheimportantpara-metersinfluencingbondbehaviorundercyclicloads.Cl-@dlA--Tl-MlHowever,theinfluenceofmanyoftheseparametersisunderstoodonlyqualitatively.1.2-ScopeTheaimofthisdocumentistoreviewthecurrentstate-of-the-artonbond,withparticularemphasisonbondundercyclicloading.Thereportisintendedtoservebothdesignersandresearchers,andisorganizedaccordingly.Chapters2and3presentbackgroundinfor-mationtotheissueofbondundercyclicloading.Chap-ters4,5,and6dealwithresultsofresearchanddevel-opmentofanalyticalbondmodels,andshouldbeofuseprimarilytoresearchers.Chapters7and8presentare-viewofcurrentdesignguidelines,fromboththeU.S.andabroad,dealingwithbondundercyclicloadsandshouldbeofparticularinteresttodesigners.Thedocumentismeantasasummaryofthestate-of-the-artonbondun-derseismicloads,butshouldalsoservetointroducedesignerstothebasicmechanismsinvolvedinbond,thevariablesthataffectthem,andthedifferencesbetweenbehaviorundercyclicandnon-cyclicloads.Anextensivereferencelistisprovidedforreadersdesiringadditionaldetails.1.3-Terminology“Bondstress”referstothestressesalongthebar-concreteinterfacewhichmodifythesteelstressesalongthelengthofthebarbytransferringloadbetweenbarandthesurroundingconcrete(SeeFig.1.1).Thediffer-enceintensileforcebetweentwosectionsalongamem-berWisg