多层柱间支撑门式刚架结构的纵向抗震性能研究

Study on longitudinal seismic behavior of multi-tiered steel concentrically braced portal frame structure

当门式刚架结构高度较大时,设置多层柱间支撑可为刚架柱提供侧向支承点以减小柱平面外计算长度,从而减小柱截面并节省钢材,是一种合理的做法,然而对采用多层支撑的门式刚架结构纵向抗震性能研究较少.为研究门式刚架结构采用多层柱间支撑时结构的纵向抗震性能,采用有限元软件ABAQUS对按现行相关规范设计的五个门式刚架结构在纵向地震作用下的抗震性能进行了动力弹塑性时程分析,研究多层柱间支撑门式刚架结构在纵向地震作用下的受力性能、破坏机理.结果表明:多遇地震作用下,结构纵向侧移较小,满足变形要求;罕遇地震作用下,结构纵向存在侧移不均匀、支撑塑性破坏及刚架柱在支撑平面内弯曲等问题,不满足抗震要求.本研究深入分析了产生以上问题的原因,为该结构纵向抗震性能的理论分析和工程实践提供参考.

Multi-tiered bracing configuration, which can provide laterally brace in the plane of the brace at every strut level for column of portal frame structure and also reduces the steel tonnage, is commonly used in tall open single story portal frame structures. However, there are few researches on the longitudinal seismic behavior of portal frame structures with multi-tiered bracing configuration. In order to study the longitudinal seismic performance of multi-tiered steel concentrically braced portal frame structure, a finite element analysis of portal frame structure was performed to simulate the overall elasto-plastic time-history process with FEM program ABAQUS to determine some seismic performances, including mechanical behavior, failure mode etc,. The results show that the structure meet the requirements of structural longitudinal degeneration under frequent earthquakes and may exhibit unsatisfactory seismic response including evenly drift and brace deformation demand under serve earthquake. Study further analyzes the causes of the above problems to provide reference for the future theoretical analysis and engineering practice.