火灾作用后,由于钢结构材料强度的下降和钢构件刚度的下降,必然导致结构内力重新分布.因此,要正确评定钢结构火灾后的剩余承载力及其整体安全性,就需要对钢结构在火灾作用后的材料性能进行深入研究.对4个足尺栓焊连接节点及其组件进行火灾试验模拟,通过对其火灾前与火灾后若干材料性能试验结果的比较分析,得到火灾后钢构件母材化学成分、显微金相组织和力学性能的变化规律,为火灾后钢结构构件的安全性评定与加固提供科学依据,也为我国钢结构抗火设计规范的修订提供参考.%After fire, exact estimation on the mechanical capability of steel material is essential for the dependable assessment of the remaining load carrying capability and globle safety of steel structures. The strength decrease of steel material and the stiffness decrease of single steel member due to fire will cause the redistribution of internal forces. Therefore, study on material capability of steel materials after fire, which is the essential basis of studying the behavior of a steel member or a whole structure, is very significant and valuable. Experimental study on four full-scale steel flange-welded web-bolted combination connections under simulated natural fire was conducted. The experimental results of the flange-welded web-bolted combination connections after fire were compared with that before fire. Through the comparison, the changes of chemical components, microstructure and mechanical capability of the steel material were concluded. This study can be used as basic reference not only for the inspection and reinforcement of steel structure after fire, but also for the revision of national fire-resistant design code.
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