重复荷载作用下钢筋混凝土锚固端黏结性能试验研究

通过对23个钢筋混凝土试件的静载和重复荷载作用下拔出试验，研究了重复荷载作用下钢筋峰值应变和残余应变、自由端和加载端滑移发展特征，得到了重复荷载作用下黏结应力-滑移滞回曲线变化规律。运用试验测定的钢筋应变，计算了静载和重复荷载作用下锚固端黏结应力分布曲线，总结了重复荷载作用下峰值黏结应力、残余黏结应力变化特征，分析了锚固端黏结应力分布机理。研究结果表明：重复荷载作用后黏结强度并不受重复次数影响；重复荷载作用下，自由端、加载端峰值滑移量和残余滑移量发展均符合疲劳破坏的三阶段特征；当滑移量累积到静载作用下破坏时的峰值滑移量时，发生黏结疲劳破坏；随着重复次数的增加，黏结应力沿锚固长度的分布出现明显的双峰现象，最大黏结应力位于距离加载端和自由端约1/4锚固长度位置处。研究结果可为深入研究混凝土结构疲劳性能提供依据。

Test study on bonding performance of reinforced concrete anchorage zone under repeated loads

23 reinforced concrete pull-out specimens were tested under monotonic loading and repeated loading.Rebar’s peak and residual stress,peak slip and residual slip at the loading end and free end were inspected in this test.The bonding stress-slip hysteretic curve was obtained.According to the rebar stress data,the distribution curve in the anchorage was calculated under monotonic loading and repeated loading.Variation characteristics of peak and residual bonding stress under repeated loads were summarized,and bonding stress distribution mechanism was analyzed.Research result shows that bonding strength is not influenced much by repeated loading.The peak slip and residual slip follow the three stage rule of fatigue failure.Bonding fatigue failure occurs when the rebar slippage under repeated loading reaches the maximum slippage under monotonic loading.With the increase of repeating times,the obvious double peak phenomenon was shown in the distribution of bonding stress along the anchorage length.The maximum bonding stress is about one fourth of the anchorage length from the loading end and free end.The results of the present study are expected to be useful for the thorough analysis of concrete structure’s fatigue performance.