基于保护层劈裂破坏的钢筋屈服后粘结锚固性能研究  

Study on bond⁃anchorage performance of steel bar after yielding based on splitting failure of protective layer

作　　者：易伟建[1,2] 张云慧 YI Weijian;ZHANG Yunhui(College of Civil Engineering,Hunan University,Changsha 410082,China;Hunan Provincial Key Laboratory on Diagnosis for Engineering Structures(Hunan University),Changsha 410082,China)

机构地区：[1]湖南大学土木工程学院,长沙410082 [2]工程结构损伤诊断湖南省重点实验室(湖南大学),长沙410082

出　　处：《建筑结构》2024年第12期58-66,共9页Building Structure

基　　金：国家自然科学基金项目(51878260)。

摘　　要：《混凝土结构设计规范》(GB 50010—2010)要求钢筋拉断先于锚固破坏,但是在地震作用下,结构往往出现锚固破坏。此外,《建筑抗震设计规范》(GB 50011—2010)要求抗震钢筋强屈比不应低于1.25,但是其中抗震锚固长度的修正系数仅考虑了往复荷载对钢筋粘结性能的不利影响,未明确要求钢筋应力达到1.25fy所需的附加锚固长度。主要通过试验研究的方法,探讨混凝土保护层发生劈裂破坏的条件下钢筋屈服后的粘结锚固性能。采用在钢筋表面开槽密贴应变片的方法测量钢筋的应变分布,以混凝土强度、钢筋强度、钢筋直径、保护层厚度等为变量,完成21个梁端式试件锚固试验。结果表明:钢筋屈服后,加载端滑移显著增大,屈服段粘结应力降低;劈裂裂缝的出现会导致粘结应力重分布,由筋端锚固问题向缝间粘结锚固问题转化。基于试验结果,得到了钢筋屈服后锚固强度计算公式以及钢筋应力-滑移的本构模型,能较好地预测钢筋锚固承载力和加载端滑移。Code for design of concrete structures(GB 50010—2010)requires that the tensile failure of steel bars precedes the anchorage failure,but under the action of earthquake,the structure often suffers from anchorage failure.In addition,Code for design of concrete structures(GB 50011—2010)requires that the strength-yield ratio of seismic steel bars should not be less than 125,but the correction coefficient of seismic anchorage length only considers the adverse effect of reciprocating load on the bonding performance of steel bars,and does not explicitly require the additional anchorage length required for steel bar stress to reach 125fy.The bond-anchorage performance of steel bar after yielding under the condition of splitting failure of concrete protective layer was discussed mainly through experimental research method.The strain distribution of the steel bar was measured by slotting on the surface of the steel bar and pasting the strain gauges.The anchorage test of 21 beam-end specimens was completed with the variables of concrete strength,steel bar strength,steel bar diameter and protective layer thickness.The results show that after the steel bar yields,the slip at the loading end increases significantly,and the bond stress at the yield section decreases.The occurrence of splitting cracks will lead to the redistribution of bond stress,which is transformed from the problem of anchorage at the end of steel bar to the problem of bond-anchorage between cracks.Based on the test results,the formula for calculating the anchorage strength after the yield of the steel bar and the constitutive model of the stress-slip of the steel bar were obtained,which can better predict the anchorage bearing capacity of the steel bar and the slip of the loading end.

关 键 词：粘结锚固 滑移 屈服渗透 梁端式试验 

分 类 号：TU375[建筑科学—结构工程]