反复荷载下GFRP筋与混凝土黏结性能

Bonding Behavior Between GFRP Bars and Concrete Under Cyclic Loading Condition

对直径为16mm,埋深分别为4d、5d、8d的玻璃纤维增强(GFRP)筋标准立方体拉拔试件进行静载和反复荷载作用下的拉拔试验,研究了2种不同应力水平(60%Fm、80%Fm)的反复荷载作用下GFRP筋与混凝土之间的黏结滑移关系,埋深与黏结强度关系,黏结刚度、加载端滑移量随循环次数的演变规律,得到了反复荷载下黏结滑移滞回曲线变化规律。结果表明,反复荷载下较少的循环次数对黏结强度和滑移量的影响不大;当反复荷载应力水平不高、循环次数较少时,黏结强度没有显著的退化,反而在一定程度上有所增加;较高应力水平反复荷载下,GFRP筋与混凝土之间的黏结强度退化较显著。

A series of drawing tests were carried out for the standard bonding specimens of GFRP bars with a diameter of 16 mm when embedded in depths of 4d,5d and 8d under the monotonic loading and cyclic loading conditions,and the variations of the bonding-slipping relation,the relationship between embedded depth and bonding strength,and the evolution law of bonding stiffness and slip of loading end with the cycle number.As a result,the evolution law of hysteresis curve under cyclic loading was obtained.The results indicated that fewer cycle times almost had no effect on bonding strength and the amount of slip.The bonding strength did not degenerate significantly but tended to increase to some extent when the test specimen was subjected to cyclic loading with a low stress level and less cycle time.The degradation of bonding strength between GFRP bars and concrete was significant when the test specimen was subjected to cyclic loading under a high stress level.This research result can provide an evidence for further study on fatigue properties of the concrete structures reinforced with GFRP bars.