钢筋混凝土柱弯剪破坏恢复力模型骨架曲线

为研究弯剪破坏柱的抗震性能，进行了不同设计参数的24根钢筋混凝土（RC）柱的拟静力试验，分析了剪跨比、轴压比及配箍率（箍筋间距）对柱破坏模式及其抗震性能的影响，给出了确定弯剪破坏柱开裂、屈服和破坏时对应荷载及位移的计算方法，并提出了建立弯剪破坏柱恢复力模型骨架曲线的简化方法。研究结果表明：发生弯剪破坏的柱，其变形在2Δy～4Δy前弯曲作用明显，滞回曲线饱满，但之后由于抗剪能力不足会突然丧失承载力；利用弯剪破坏柱的3个特征点（开裂点、屈服点、剪切破坏点）建立其恢复力模型骨架曲线的方法，简化了RC柱的受力分析，可用于计算地震作用下弯剪破坏RC柱的荷载-变形全曲线。建立的恢复力模型骨架曲线与试验曲线吻合较好。

Skeleton curves of restoring force model of reinforced concrete columns failed in flexure-shear

To study the seismic performance of reinforced concrete (RC) columns failed in flexure-shear, cyclic loading tests were carried out on twenty-four RC columns with different design parameters. The effects of shear span ratio, axial load ratio and volumetric stirrup ratio (spacing of transverse reinforcement) on the failure modes and seismic performance of columns were studied. Based on the test data analysis, the calculation formulas for predicting the cracking, yielding and failure loads, as well as corresponding displacements, of RC columns failed in flexure-shear mode were developed, and then the trilinear skeleton curve model of RC columns with flexure-shear failure was established according to three feature points. The study results show that the seismic responses of RC columns failed in flexure-shear mode are dominated by flexure before the displacement reaches 2Δ_y-4Δ_y. The hysteretic loops are plump. But the bearing capacity may be lost suddenly due to shear failure. The skeleton curve model presented in this study is dependent mostly on three feature points of columns with flexure-shear failure, which is simple and computationally efficient. The predicted skeleton curves match the experimental data with adequate accuracy, and the model can be used to simulate the load-deformation curve of RC columns with flexure-shear failure subjected to seismic excitation.