长耗能梁-偏心支撑机制对中心支撑钢框架结构抗震性能的影响

为研究地震作用下人字形中心支撑钢框架结构因支撑的部分失效导致的长耗能梁-偏心支撑机制对结构抗震性能的影响,基于ABAQUS建立了6层人字形中心支撑钢框架结构数值模型,开展了增量动力分析与易损性分析,对比了考虑与不考虑长耗能梁-偏心支撑机制时结构抗倒塌性能的差异,分析了结构的损伤演化过程。结果表明:长耗能梁-偏心机制改变了结构的失效过程,抑制了薄弱层的产生与发展,对结构抗震性能具有显著影响,算例结构的倒塌富余度提高20%以上; 梁的抗弯刚度对长耗能梁-偏心支撑机制具有一定影响,较大的刚度将不利于该机制的形成,降低了结构的抗倒塌能力; 在人字形中心支撑钢框架结构体系的设计与分析中,宜考虑长耗能梁-偏心支撑机制,否则将低估结构的抗倒塌性能。

Effect of Long-link EBF Mechanism on Seismic Performance of Steel CBF

In order to study the effect of long-link eccentrically braced frame(EBF)mechanism caused by part of braces in chevron concentrically braced frame(CBF)failing in earthquakes on collapse resistance capacity of structure, a 6-story chevron CBF structure was built in ABAQUS. Incremental dynamic analysis(IDA)and vulnerability analysis were carried out to compare the collapse resistance capacity with and without long-link EBF mechanism, and analyzed structural damage evolutionary process. The results show that long-link EBF mechanism changes the failure process and the generation and development of weak story are controlled, which significantly affects structural seismic performance. The collapse margin ratio is raised by 20% of the numerical example models. The flexural stiffness of the beam affects long-link EBF mechanism that large stiffness goes against the formation of the mechanism and reduces collapse resistance capacity. Therefore, long-link EBF mechanism should be considered in seismic design of chevron CBF, or the structural collapse capacity will be underestimated.