应变率对光圆钢筋与混凝土“粘结-滑移”行为影响的实验研究

An experimental study of dynamic bond-slip behaviors of plain steel bars in concrete at different strain rates

为研究应变率对钢筋与混凝土界面粘结性能的影响,利用高速拉伸试验机进行了光圆钢筋的动态拔出实验。通过合理设计加载夹具和测试方法,得到不同应变率下光圆钢筋的“粘结-滑移”全程曲线。实验结果表明:随着应变率的增大,钢筋-混凝土界面的粘结强度显著提高,且界面失效形式由拔出失效为主转变为混凝土试件的破裂破坏为主;粘结强度的动态增强因子(fDIF)随应变率的增长斜率明显可以分为低应变率和高应变率两个区段。低应变率下,fDIF 增长较为缓慢;而高应变率下,fDIF快速增长;转变应变率约为33 s^-1。

To investigate the effect of strain rate on the bond-slip behaviors of smooth steel bars in concrete, we conducted plain steel bar pullout tests from quasi-static to impact loading using a high-speed tensile test machine and obtained the whole bond-slip curves of the plane steel bar at different strain rate with reasonable designed stop devices and testing methods. The test results show that the bond strength increased obviously, and the failure mode transferred from pullout to splitting with the increase of the strain rate, that the dynamic increase factor(DIF) curve can be divided into two parts, those of the low and high strain rates, and that the DIF increased slowly with the increase of the strain rate at low strain rates, but increased sharply at high strain rates.