预应力碳纤维条带加固混凝土圆形墩柱恢复力模型试验研究

EXPERIMENTAL STUDY ON RESTORING FORCE MODEL OF CIRCULAR RC PIERS STRENGTHENED WITH PRE-STRESSED CFRP BELTS

为了研究预应力碳纤维条带加固钢筋混凝土圆形墩柱的抗震性能,对7根钢筋混凝土圆形墩柱在低周反复荷载作用下的滞回性能进行了试验研究,试验考虑的主要参数为环向预应力大小和轴压比。试验结果表明:预应力纤维条带提供的主动横向约束力能够有效抑制斜向剪切裂缝的开展,将圆形墩柱的破坏形态由剪切破坏转变为延性较好的弯曲破坏。通过分析各工况下被加固圆形墩柱的滞回性能,得出其恢复力模型的滞回规则;采用理论分析与试验数据回归分析相结合的方法,给出预应力碳纤维条带加固混凝土圆形墩柱的正截面抗弯承载力计算公式,得出骨架曲线各特征参数的计算方法,确定了卸载刚度和再加载、反复加载下的强度退化率,最终建立了能够考虑轴压比与环向预应力大小两因素的预应力碳纤维条带加固混凝土圆形墩柱三折线型恢复力模型,计算结果与试验结果吻合较好。

To study seismic behavior of circular RC piers strengthened with pre-stressed CFRP belts, seven circular RC piers were tested with the main experimental parameters being lateral pre-stress level of CFRP belts and axial load ratio. Test results show that the diagonal shear cracks of piers can be effectively confined with the active lateral confined stress provided by pre-stressed CFRP belts, and the failure mechanism of the piers may be changed from shear to flexure with satisfactory ductility. By analyzing the effect on the hysteretic characteristics of the piers strengthened under different conditions, a series of hysteretic rules for piers strengthened are suggested; Using theoretical analysis and statistic regression analysis, the formula for flexural capacity is presented, and the methods to calculate characteristic parameters of skeleton curves are proposed, as well as a series of hysteretic rules for piers. The three-line restoring force model of circular RC piers strengthened with lateral pre-stressed CFRP belts is set up, which is capable of considering lateral pre-stress level of CFRP belts and axial load ratio. The result of the model shows good agreement with the test result.