多层混凝土框架火灾连续倒塌数值分析

NUMERICAL ANALYSIS OF FIRE-INDUCED PROGRESSIVE COLLAPSE OF A MULTI-STOREY REINFORCED CONCRETE FRAME

常规的结构抗火设计主要针对构件,但实际结构系统中的构件受力更为复杂。为分析整体结构在火灾下的破坏和倒塌,基于纤维梁模型和简化楼板建模方法,建立了一个8层混凝土框架整体结构数值模型。分析不同结构位置处3开间发生火灾时的整体结构力学响应。结果表明:框架柱在压弯组合作用下更易发生破坏。当结构短边受火作用时,由于结构内力重分布能力不足,柱破坏会触发结构连续倒塌。而其他结构部位受火时,周边结构能够有效分担受火区域的荷载,从而抵抗连续倒塌的发生。

The conventional structural fire resistance design is mainly aimed at independent members,but the mechanical behavior of the members in a structural system is more complex. In order to analyze the damage and collapse of the whole structure under fire,an eight-storey reinforced concrete（ RC） frame model was built based on the beam fiber model and simplified modeling method for RC slabs. The mechanical responses of the whole frame structure under non-spread 3-bay-fire in different locations of the structure were analyzed. The results indicated that the frame columns were vulnerable to fire under the combining action of compression and bending. And due to the limited ability of the short side of the structure redistributing the internal force,the progressive collapse was triggered by the damage of columns when the short side was exposed to fire. On the other hand,the structure was capable to resist progressive collapse when the other areas were subjected to fire because the unbalanced loads could be transferred to the remaining structure effectively.