基于拉拔试验的GFRP筋与砂浆粘结性能研究

Study on bond performance parameters of GFRP bars based on pull-out test

为了获得玻璃纤维筋与砂浆间的合理粘结性能参数,本文采用室内拉拔试验和数值模拟反演分析相结合的手段开展了相关研究.通过开展不同筋材直径与不同砂浆强度下的筋材拉拔试验,得到了不同工况下的粘结强度-滑移量曲线,探明了筋材直径与砂浆强度对GFRP筋粘结强度的影响规律.基于室内拉拔试验结果,采用有限差分软件FLAC^(3D)模拟再现了GFRP筋拉拔试验,对软件中的粘结性能参数进行了反演分析,修正得到了GFRP筋灌浆体刚度和黏聚强度的计算公式.研究结果表明:GFRP筋与砂浆间的粘结强度与筋材直径成负相关,与砂浆强度成正相关;在缺乏筋材拉拔试验数据时,纤维筋锚杆极限粘结强度宜取灌浆体抗压强度的五分之一,以求得灌浆体黏聚强度;纤维筋锚杆灌浆体刚度可采用普通钢筋锚杆灌浆体刚度计算公式获取,但应乘以位于(1/10,1/15]区间内的折减系数.

To obtain reasonable bond performance parameters of GFRP bars,the indoor pull-out test and numerical simulation are used to study the bond performance between GFRP bars and mortars.Through the pull-out tests of different reinforcement diameters and mortar strengths,the relation curves between bond strength and slip under different working conditions are obtained,and the influence of reinforcement diameter and mortar strength on the bond strength of GFRP bars is revealed.Based on the results of indoor pull-out test,the finite difference software FLAC^(3D)is used to simulate and reproduce the pull-out test of GFRP bars.The back analysis of the bond performance parameters is carried out in FLAC^(3D),and the calculation formulas of the grouting stiffness and grouting cohesion of GFRP bars are modified.The results show that the bond strength between GFRP bars and mortar is negatively correlated with the diameter of bars,while positively correlated with the mortar strength.In the absence of pull-out test data,the ultimate bond strength of GFRP bars should be one fifth of the compressive strength of mortar to obtain the grouting cohesion.The grouting stiffness of GFRP bars can be calculated by formula of ordinary steel bars,but it should be multiplied by the reduction factor in the interval of(1/10,1/15).