不同火灾下单层钢框架梁柱结构性能分析

Analysis of behaviors of beam-column of one-story steel framed structure under different fires

采用理论分析与有限元分析相结合的方法,对单层钢框架结构在火灾下的热、结构性能进行模拟,并与试验结果进行比较.在验证模型正确性的基础上,研究结构在"短热"和"长冷"火灾下的响应,分析火灾模型对结构性能的影响.结果发现:升降温速率越小(长冷模型),构件长时间处于高温区,组合梁截面温度梯度小,但平均温度高,易使结构产生较大的变形,出现悬链线效应,梁屈服时对应的温度高;初始降温时变形恢复快,但残余变形较大,对结构抗火不利.

Thermal and structural coupling behaviors of one-story steel framed structure in fire were investigated by both theory and finite element methods.The results acquired from numerical simulation are compared with ones of experiment.Based on this model,the structure response in two different fire models of ＂short-hot＂ and ＂long-cool＂ were studied.Fire model effect on structure behaviors was discussed.It is found that when the temperature rise and descenting rate is smaller（for ＂long-cooling＂ fire）,the structure is in high temperature for long; the temperature gradient of the cross-section of the composite beam is small; the even temperature is higher; and the deformation is large.The yield temperature of the beam is high.The deformation recover is fast at beginning of temperature descent; but residual deformation is larger.Those are disadvantageous to fire resistance of the structure.