不同跨受火时两层两跨钢框架火灾行为试验

为对不同跨受火时的两榀两层两跨钢框架足尺结构进行试验研究.受火工况有一层两跨梁柱同时受火,节点被保护不受火和一层两跨梁单独受火,节点被保护不受火两种形式.分析宏观试验现象、温度场以及变形情况,得出钢框架各个构件的温度场分布和变形规律,并在此基础上对钢框架的整体变形全过程进行全面分析,考虑了内力重分布的影响.结果表明:钢框架各构件在火灾作用下的破坏特征与单个构件在火灾行为下的破坏特征有所不同;框架柱的变形对不同跨的组合梁挠度变化有着不同的影响,有些影响是有利的,而有些影响却是负面的;内力重分布和造成内力重分布的各种因素所起的作用时时刻刻发生着变化,当两种不同的因素交替起主导作用时,便发生位移拐点现象.

Experimental study of two-storey and two-bay composite-beam steel frame subjected to fire in different spans

The experiments of two two-storey and two-bay frames under two different fire modes were conducted. One of the fire modes is that the whole columns and beams of the first floor are under fire and the beam-to-column joints are protected. The other is that the whole columns and joints are protected and the beams are under fire. Temperature distribution and deformation modes of members of the frames were obtained through analyzing experimental phenomena. The deformation progress of the overall frames was analyzed comprehensively considering the influence of internal force redistribution. The experimental results show that the destructive characteristics of a steel frame are different from those of a single structural member. Distortions of the columns have different influences on different spans,favorable or unfavorable. Internal force redistribution and the function of affecting factors change momently during the experiments. Inflexion will occur due to the alternate domination of two different factors.