反复荷载下低强度混凝土与光圆钢筋局部黏结性能的试验研究  

Experimental Research on Local Bond Behaviors of Plain Round Bars in Low Strength Concrete under Cyclic Loading

作　　者：洪成[1,2] 周峰 刘凯 HONG Cheng;ZHOU Feng;LIU Kai(School of Civil Engineering and Architecture,Nanchang Institute of Technology,Jiangxi 330099,China;Jiangxi Provincial Engineering Research Center of the Special Reinforcement and Safety Monitoring Technology in Hydraulic & Civil Engineering,Jiangxi 330099,China)

机构地区：[1]南昌工程学院土木与建筑学院,南昌330099 [2]江西省水利土木特种加固安全监控工程研究中心,南昌330099

出　　处：《结构工程师》2019年第1期188-197,共10页Structural Engineers

基　　金：江西省教育厅科技项目(GJJ171009)

摘　　要：通过反复拉拔试验研究了不同加载阶段下光圆钢筋在低强度混凝土中黏结应力沿黏结长度的分布。根据试验中得到的光圆钢筋在低强度混凝土中的局部应力-应变关系及荷载-滑移关系推算出了沿黏结长度拉应力、黏结应力的分布曲线及局部黏结应力-相对滑移关系,并在试验研究基础上,推导了各加载阶段光圆钢筋与低强度混凝土间黏结应力分布的变化机理。试验中采用了3个黏结长度分别为10D、15D、20D(D为钢筋直径)的中心拔出试件。研究结果表明:早期加载阶段,黏结应力起始于加载端,随着荷载增大黏结应力的峰值点由加载端逐渐向自由端移动,并且钢筋表面分布的黏结应力从加载端开始,从由胶结力提供迅速转变为界面摩擦力提供;随着自由端的钢筋滑移量被记录后,分布在钢筋表面的胶结力全部消失;进入卸载阶段至荷载降为0时,由于钢筋黏结段区域存在的残留拉应力,观察到分布的残留黏结应力呈现为反对称形;随后,即使进入反复加载阶段,黏结应力的分布特征基本保持不变。另外,所有试件各测点对应的局部黏结应力-相对滑移曲线与平均黏结应力-滑移曲线的滞回特性基本一致。In this study, the bond stress distributions between low strength concrete and plain round bars along bond length in different loading phases were studied. Based on the experimental results of local stress-strain and load-slip relations between plain round bars and low strength concrete, the tensile stress, the bond stress distributions and the relationship between local bond stress and relative slip were obtained. Variation mechanism was of bond stress distributions between low strength concrete and plain round bars were derived due to the experimental research in different loading phases. Plain round bar was embedded in the center of concrete prism,and three lengths of embedment were prepared at 10D、15D and 20D( D: the diameter of the bar) in this test. From the test results,bond stress started to occur from the loaded end in the early phase. The location of the peak bond stress shifted from the loaded end toward to the unloaded end of the bar with increasing applied load. Bond stress along the bar which was provided by the adhesion force rapidly vanished and the friction force occurred from the loaded end;Adhesive force vanished along the bar when slip at the unloaded end was measured;Distributions of the bond stress along the bar were observed to an anti-symmetric shape due to the residual tensile stress along the bar in the unloaded phase;Subsequently,even though the applied load was reversed,bond stress distribution along the bar was still constant. In addition, the hysteric characteristics of the local bond stress-relative slip curves were almost similar to the hysteric characteristics of the average bond stress-slip curve regardless of the bond length of the specimens.

关 键 词：低强度混凝土 光圆钢筋 反复荷载 黏结长度 局部黏结性能 

分 类 号：TU375[建筑科学—结构工程]