屈曲约束支撑核芯板在常幅加载下的高阶屈曲演化研究

High⁃order Buckling Evolution of Buckling⁃restrained Brace Core Plate Under Constant Amplitude Loading

屈曲约束支撑(BRB)因具有稳定滞回曲线、优异耗能效果、造价低等优点,近年来在抗震设计中的应用越来越多。通过对3组全尺寸一字形钢芯BRB进行不同加载制度下的拟静力试验,得到相应滞回曲线和骨架曲线。通过试验结果对比BRB在不同加载制度下的基本力学参数及低周疲劳寿命,评估其累积滞回性能。对核芯板参数对BRB累积滞回性能的影响进行研究。首先通过对屈曲约束支撑核芯板高阶屈曲演化过程的研究,发现屈曲半波数随着加载幅值逐渐增大后趋于恒定值,该恒定值与核芯板厚度成负相关。然后通过对核芯板耗能机理、局部应力应变集中现象进行理论分析,得出间隙与核芯板厚度之比与应变集中成正相关的结论。

Buckling-restrained brace(BRB)has been used more and more in seismic design in recent years due to its advantages of stable hysteresis curve,excellent energy dissipation and low cost.In this paper,three BRBS were subjected to quasi-static tests under different loading regimes,and the corresponding hysteresis curves and skeleton curves were obtained.The basic mechanical parameters and cumulative plastic deformation of BRB were calculated by the experimental results,and the cumulative hysteresis performance of BRB is evaluated.Then,the influence of core plate parameters on the cumulative hysteretic performance of BRB is studied.Firstly,the high-order buckling evolution of buckling-restrained brace core plate constraint is studied.It is found that the buckling wave number tends to a constant value with the increasing amplitude loading,and the constant value is negatively correlated with the thickness of core plate.Then through the theoretical analysis of the energy dissipation mechanism of the core plate and the phenomenon of local stress and strain concentration,it is concluded that the ratio of gap to core plate thickness is positively correlated with strain concentration.