设置屈曲约束柱的摇摆钢框架结构抗震性能研究

Study on seismic performance of a rocking steel frame structure with buckling-restrained columns

为避免钢框架结构产生损伤集中效应,提高结构的耗能能力,采用屈曲约束支撑(BRB)替换普通钢支撑框架底层边柱,形成设置屈曲约束柱(BRC)的摇摆钢框架(RSFB)。罕遇地震作用下BRC率先屈服耗能,钢框架其余构件保持弹性并绕中柱底部转动以控制结构变形。对1榀RSFB模型进行了拟静力试验,试验现象及分析结果表明:由于平面外约束失效,导致钢框架及BRC伸入段出现较大平面外变形;BRC受压时性能无法充分发挥,结构滞回曲线出现捏缩;但受拉侧BRC仍可正常工作,结构并未完全丧失承载力。建立了多尺度RSFB有限元模型,并通过试验数据进行了验证。在此基础上研究理想平面外约束的RSFB结构(RSFB-FOR)的抗震性能。模拟结果表明:RSFB-FOR结构在往复荷载作用下的滞回曲线饱满,结构层间位移分布均匀,结构塑性变形主要集中于BRC耗能段,表明所提出RSFB结构抗震性能良好。最后,探讨了BRC截面强轴方向对RSFB试验模型抗震性能的影响,结果表明:将BRC截面强轴旋转90°后能提高RSFB结构的稳定性和耗能能力。

To avoid damage localization effect in steel frame structures and enhance the structural energy dissipation capacity,a rocking steel frame with buckling-restrained columns(RSFB)was formed by replacing the side steel columns at the bottom story with buckling-restrained braces(BRBs).The buckling-restrained columns(BRCs)firstly yield to dissipate energy under a rare earthquake,and the rest parts of the steel frame remain elastic and rotate around the base of the middle column to control the deformation of the structure.A pseudo-static test was conducted for an RSFB model,the test phenomena and analysis results show that the larger out-of-plane deformation occurs in the steel frame and embedment portions of BRC due to the failure of the out-of-plane restraints.The capacity of the BRC on the compression side cannot be fully used,and the pinching effect is observed in the structural hysteretic loops.However,the BRC in the tension side can work normally,and the structural lateral carrying capacity is not fully lost.A multi-scale finite element model was established and validated by the test results.The seismic performance of RSFB with full out-of-plane restraints(RSFB-FOR)was investigated based on the validated numerical model.The simulation results show that the hysteretic loops of RSFB-FOR are plump under the cyclic loads,the structural lateral inter-story drift is uniformly distributed,and the plastic deformation is mainly concentrated in the energy dissipating portion of BRCs,showing that the proposed RSFB can achieve good seismic performance.Finally,the influence of the arrangement direction of strong axis of BRC in RSFB on the structural seismic performance was investigated,and the results show that the stability and energy dissipation capacity of RSFB can be enhanced by rotating strong axis of BRC by 90 degrees.