火灾下门式钢刚架倒塌模式及影响因素

Collapse Mode and Its Influencing Factors of Steel Portal Frame Under Fire

采用火灾下门式钢刚架结构足尺倒塌试验验证有限元模型(FEM),然后对门式钢刚架结构进行二维及三维模拟,并研究构件升温工况、柱脚刚性、跨高比、防火保护、截面温度梯度、荷载比、风荷载及次要构件等因素对火灾下门式钢刚架结构倒塌模式的影响,归纳出四种典型倒塌模式。结果表明:有限元模型能准确预测火灾下门式钢刚架结构的倒塌行为;构件升温工况、柱脚刚性、荷载比及次要构件对倒塌模式影响较大,而风荷载、防火保护、截面温度梯度及跨高比对倒塌模式影响较小。最后,归纳了不均匀火灾下门式钢刚架结构的倒塌规律。

The finite element program,which has been verified by the full-scale collapse test of steel portal frame structure under fire,is used for simulation in this paper.Then two-dimensional and three-dimensional finite element models are established,and the parameter analysis is carried out.The effects of the heating condition of steel member,foot stiff,span-depth ratio,fire protection,section temperature gradient,load ratio,wind load and secondary components on the collapse mode of steel portal frame structure under fire are mainly studied.Four typical collapse modes are summarized.The results show that the finite element model(FEM)can accurately predict the collapse behavior of steel portal frame structure under fire.The heating condition of steel member,the foot stiff,the load ratio and the secondary component have the most significant influence on the collapse mode,while the wind load,the fire protection,the section temperature gradient and the span-depth ratio have little effect on the collapse mode.In addition,the collapse law of steel portal frame structure under nonuniform fire is summarized systematically.