侧向预应力约束高轴压比混凝土圆柱滞回性能

Hysteretic behavior of circular RC columns confined by lateral pre-stress under high axial compression

为了研究侧向预应力约束高轴压比混凝土圆柱的滞回性能,进行了7根混凝土圆柱的低周反复荷载试验;采用理论分析与回归分析相结合的方法,得出了预应力碳纤维条带约束高轴压比混凝土圆柱的正截面抗弯承载力计算公式;提出了能够考虑轴压比与预应力大小两因素的预应力碳纤维条带约束高轴压混凝土圆柱三折线型恢复力模型及其特征点的计算方法.试验结果表明采用预应力碳纤维条带约束高轴压混凝土圆柱后,柱的滞回性能有显著改善;预应力碳纤维条带提供的环向主动约束力能够有效抑制斜向剪切裂缝的开展,加固后高轴压比圆柱的破坏形态由脆性剪切破坏转变为延性更好的弯曲破坏.采用推荐模型所得计算结果与试验结果吻合较好.

By lateral cyclic loading test,hysteretic behavior of seven circular RC columns confined by lateral pre-stress under high axial compression was studied.Using theoretical analysis and statistic regression analysis,the formula of calculated flexural capacity for columns is proposed.The three line restoring force model of circular RC columns under high axial compression confined by pre-stressed CFRP belts which is capable of considering the pre-stress of CFRP belts and axial load ratio is set up.Test results show that the hysteretic behavior of the columns with high axial load ratio is improved significantly after confined by pre-stressed CFRP belts.The diagonal shear cracks of columns can be effectively confined with the active lateral stress provided by pre-stressed CFRP belts,and the failure mechanism of the columns with high axial load ratio may be changed from shear to flexure with satisfactory ductility.The result of the recommended model shows good agreement with the test result.