基于子结构模型的室内火灾下钢框架结构倒塌分析

Collapse analysis on steel frame structure under compartment fire based on sub-structure model

根据室内火灾下结构的倒塌模式确定钢框架子结构模型的选取范围,采用矩阵分析方法推导出子结构模型的边界条件.基于易损性分析,提出了火灾下钢框架结构抗倒塌性能的简化评估方法,并以结构倒塌时间的可靠指标作为结构抗倒塌性能的定量评估标准,继而研究了起火房间位置以及防火保护对火灾下钢框架结构抗倒塌性能的影响.结果表明,角部房间以及短跨边房间发生火灾对结构倒塌影响最大.在高、中、低3种防火保护条件中,高防火保护条件下结构倒塌时间受随机变量的不确定性影响最大.火灾下结构倒塌时间的可靠指标主要分布在1.0~3.0范围内.为满足目标可靠指标,结构的倒塌时间应除以大于1的分项系数.

The selection region of a steel frame sub-structure model was determined according to the collapse mode of the structure under compartment fire,and the boundary condition of the sub-structure model was derived by the matrix analysis method.A simplified assessment method for the collapse resistance of the steel frame under fire was proposed based on the fragility analysis,and the reliable index of the collapse time was taken as the quantitative evaluation standard.The influence of the fire compartment location and fire protection on the collapse performance of the steel frame structure was studied.The results show that fire in the corner compartment and that in the short-span side compartment have the greatest influence on the structure collapse.Under three different fire protection conditions,the uncertainty of the influencing factors has the greatest impact on the structural collapse time under the high fire protection condition.The reliable indexes of the structure collapse time under fire are 1.0 to 3.0.To meet the target reliability index,the structural collapse time should be divided by the partial coefficient greater than 1.