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使用作者研发的静态-动态程序研究火灾下二维有支撑体系钢框架结构的连续倒塌机理。对20种不同火灾条件下不同支撑体系的钢框架进行综合分析,总结这些支撑体系的连续倒塌机理,并分析其刚度和强度。结果表明,柱的承载力丧失是连续倒塌的主要原因之一。尽管横向“帽桁架”支撑体系能够直接将屈曲柱的轴向荷载重新分配到邻近柱,它们支承高温楼板的能力仍然有限。另一方面,竖向支撑体系不仅加强了框架的侧向约束,也有效牵制了由局部到整体的倒塌进程。刚度较大的竖向支撑体系能够将屈曲柱的荷载重新分配到邻近柱。“帽桁架”和竖向支撑体系相结合能够尽可能提高框架性能,以防止高温柱屈曲时发生连续倒塌。
A static-dynamic program developed by the author is used to study the mechanism of continuous collapse of steel frame structure with two-dimensional bracing system under fire. The steel frames of different support systems under different fire conditions were comprehensively analyzed, the mechanism of continuous collapse of these support systems was summarized, and their stiffness and strength were analyzed. The results show that the loss of column bearing capacity is one of the main causes of continuous collapse. Although lateral “hat truss” support systems are able to directly redirect axial loading of buckling columns to adjacent columns, their ability to support high temperature floors is still limited. On the other hand, the vertical support system not only strengthens the lateral restraint of the frame, but also effectively restrains the local to entire collapse process. A stiffer vertical support system can redistribute the load on the buckling column to adjacent columns. The combination of “cap truss” and vertical support system can maximize the performance of the frame to prevent the continuous collapse of high temperature column during buckling.