大跨空间结构连续倒塌分析若干问题探讨

DISCUSSION ON THE PROGRESSIVE COLLAPSE ANALYSIS OF LONG-SPAN SPACE STRUCTURES

为了能利用变换荷载路径法(AP法)分析大跨空间结构抗连续性倒塌性能,在提出了一种AP法中移除构件确定方法的基础上,对连续性倒塌过程中失效构件的模拟方法进行了研究,提出了考虑初始状态的等效荷载瞬时卸载法,该方法可在一个计算过程中同时模拟构件失效前整体结构的初始状态和构件的后续突然失效过程。算例分析表明,该方法可以很好的考虑结构的初始状态及动力效应。然后针对网架结构体系,讨论了利用AP法中静力分析方法的荷载动力放大系数(DIF)。分析结果表明:该文算例空间网架结构的DIF均小于2.0,但是在长边中柱和角柱失效时,其值较为接近2.0。该文最后讨论了大跨空间结构连续倒塌的判断准则。

In order to discuss the progressive collapse-resistance performance of long-span space structures with an alternate load path method （AP method）, a method to evaluate the elements to be removed in the AP method was given. Then the simulation method of elements to be removed was discussed, and the initial condition of a structure before the local damage was considered in an instantaneously unapplied equivalent load method. The numerical example shows that the method is good at considering the initial structural condition and dynamic effect. For a space truss structure, the dynamic increase factor （DIF） for the static analysis of AP method was discussed. It can be concluded that the DIFs of truss structures are smaller than 2.0. However, the value of DIF is close to 2.0 when the middle column of the long side and the corner column are failure. At last, the estimate rule about the progressive collapse of a long-span space structure was discussed.