不同加载制度下RC框架梁抗震性能试验研究

为了研究不同加载制度下RC框架梁的抗震性能，分别采用4种加载制度对RC框架梁试件进行拟静力试验。结果表明:峰值位移（峰值荷载对应的位移）出现的越早，RC框架梁破坏时剪切变形成分越大，试件的最大裂缝宽度越大，塑性铰转角和延性系数越小，但塑性铰高度基本不变；随着循环位移幅值和循环次数的不同，框架梁的刚度、强度退化也有差异，表现为:在滞回曲线软化段，经历较大位移幅值循环（或较多次循环）后的RC框架梁比经历较小位移幅值循环（或较少次循环）后的RC框架梁刚度和强度退化快；同时，不同加载制度下RC框架梁的耗能能力存在差异，峰值位移出现早的框架梁其耗能能力较差。

EXPERIMENTAL RESEARCH ON SEISMIC BEHAVIOR OF RC FRAME BEAMS UNDER DIFFERENT LOADING PROTOCOLS

To investigate the seismic behavior of RC frame beams under different loading protocols, a pseudo-static experiments of RC frame beam specimens were carried out by four kinds of loading protocols. The results showed that the earlier the peak displacement (the displacement corresponding to the peak load) appeared, the more proportion of shear deformation of the specimens would be brought out in the damage state, and the wider the maximum crack width of the specimens would be. Meanwhile, the rotation of plastic hinge and ductility coefficient of the specimens were smaller, but the plastic hinge height remained the same. With the change of cyclic displacement amplitude and number of cycles, the stiffness and strength degradation of RC frame beams would be different. It showed that the stiffness and strength degradations of RC frame beams with larger displacement amplitude cycle (or more cycles) were faster than that with smaller displacement amplitude cycle (or fewer cycles) in the softening branch of the hysteresis curves. Moreover, the energy dissipation capacities of the RC frame beams were different under different loading protocols. The earlier the peak displacement appeared, the lower the energy dissipation capacity of RC frame beam tends to be.