碳纤维布加固对腐蚀钢筋与混凝土粘结性能的影响

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1、碳纤维布加固对腐蚀钢筋与混凝土粘结性能的影响邓宗才，万操，李建辉（北京工业大学城市与工程防灾减灾省部共建教育部重点实验室北京100124）摘要：正确评估FRP（FiberReinforcedPolymer）加固对腐蚀钢筋与混凝土粘结性能的影响是确定FRP加固效果的重要问题之一。本文采用外加电流加速腐蚀法对96个预埋钢筋的试件进行腐蚀，腐蚀完成后横向包裹2层单向碳纤维布；通过拉拔试验研究了碳纤维布加固对腐蚀钢筋与混凝土粘结性能的影响规律，探讨了拉拔破坏机理；试验考虑了钢筋种类、保护层厚度、腐蚀率及碳纤维布约束等影响因素。研究表明：①碳纤维布约束使螺纹钢

2、筋试件破坏模式由混凝土劈裂破坏转变为钢筋拔出破坏。②钢筋种类、保护层厚度是影响钢筋峰值粘结强度的主要因素，螺纹钢筋试件的峰值粘结强度约为光圆钢筋的2倍。③当腐蚀率小于5％时，碳纤维布约束对提高钢筋峰值粘结强度作用较小，腐蚀试件峰值粘结强度与未腐蚀试件峰值粘结强度之比（简称比峰值粘结强度）提高约5％～7％,但碳纤维布约束使拉拔全曲线下降段变得平缓，粘结应力维持在较高的水平。④当腐蚀率大于5％时，腐蚀试件的峰值粘结强度随着腐蚀率增大逐步降低。关键词：粘结性能；腐蚀；CFRP；混凝土；加固中图分类号：TU398.9文献标识码：A文章编号：Bondbehav

3、iorofcorrodedreinforcementinconcretestrengthenedwithcarbonfibersheetsDENGZongcai,WANCao,LIJianhui（TheKeyLaboratoryofUrbanSecurityandDisasterEngineering，MinistryofEducation，BeijingUniversityofTechnology，Beijing100124，China）Abstract：Rightevaluationofthebondbehaviorbetweencorroded

4、reinforcementandconcretewrappedwithFRPisachiefproblemtoconfirmtheeffectofFRPconfinement.96testspecimenswithembeddedreinforcingbarswerestrengthenedbytwolayeroftransverseCFRPafteracceleratedcorrosion.ThepullouttestsonthetestspecimenswereconductedtostudytheeffectofconfiningCFRPont

5、hebondbehaviorbetweencorrodedreinforcingbarsandconcrete,consideringthecontributionofdifferentelementsincludingreinforcingbartypes,coverdepths,corrosionrates,andCFRPconfinements.Thefailuremechanismswerestudied.ThetestresultsshowthatCFRPconfinementscanmakethefailuremodeofdeformed

6、reinforcingbarspecimenschangefromconcretesplittingtobarpull-out.Themaininfluencingfactorsoftheultimatebondstrengtharereinforcingbartypesandcoverdepths,andtheultimatebondstrengthofdeformedreinforcingbarspecimensisonetimelargerthanthatofplainreinforcingbarspecimens.Whenthecorrosi

7、onrateislessthan5%,theCFRPconfinementhaslesscontributiononincreasingtheultimatebondstrength,butitiseffectiveonslowingdownthebondstress’sdescendingspeedandmaintainingthebondstrength.Whenthecorrosionrateishigherthan5%,theultimatebondstrengthofcorrodedspecimensdropsgraduallyalongw

8、iththeriseofcorrosionrate.Keywords:bondbehavior;corros