不同循环次数下RC桥墩抗震性能试验研究

Experimental study on the seismic behavior of reinforced concrete bridge piers under varied loading cycles

通过轴压比为0.05和0.15的8个钢筋混凝土(RC)桥墩拟静力试验,研究不同荷载循环次数(同一位移幅值下分别循环3,10,20次)对RC桥墩的抗震性能影响.结果表明:循环往复荷载作用下试件破坏形态为弯剪破坏,主要破坏特征为混凝土斜向明显开裂、纵筋屈曲及箍筋断裂,滞回曲线有明显捏缩;随轴压比从0.05增大到0.15,RC桥墩的屈服荷载和极限荷载增大约50%,而极限位移明显减小,位移延性系数减小约30%;不同轴压比条件下,循环加载次数对试件抗震性能均有影响,在试件达到峰值荷载之前,循环加载次数对其承载能力和变形性能影响较小,而峰值荷载之后影响较大,变形能力明显降低,循环次数的增加会加重试件的累积损伤程度,进而削弱其抗震性能,尤其会在较大程度上降低其延性性能和耗能能力.

Quasi-static displacement loading tests of eight reinforced concrete (RC) bridge piers with axial force ratios of 0.05 and 0.15 were conducted to investigate the effect of loading cycle numbers (3,10,and 20 cycles for a given displacement amplitude) on the seismic behavior of RC bridge piers.Test results demonstrate that the bridge pier specimens subjected to cyclic loading failed in flexural-shear mode,which was evident by the presence of diagonal cracks,buckled longitudinal reinforcement,fractured stirrup,as well as saliently pinched lateral force-displacement hysteretic loops.As the axial force ratio increased from 0.05 to 0.15,there were about 50% increase in their yield and peak strengths,significant decrease in ultimate displacement,and about.30% decrease in the displacement ductility in the RC bridge piers.In addition,the effect of loading cycle numbers on the seismic behavior of the RC bridge pier specimens is explored.Prior to the attainment of peak strength,the variation of loading cycle numbers does not obviously impact the force and deformation responses of the test specimens.The effect of the number of loading cycles on seismic behavior is more significant after the peak load,and the deformation capacity is significantly reduced.Conversely,increasing the loading cycle number during the post-peak loading stage accelerates damage accumulation and impairs the seismic performance of the test specimens due to the substantial reduction of their seismic ductility and energy dissipation capacity.