全高强钢端板节点火灾后性能试验

Experimental Research on Post-fire Behavior of Full High Strength Steel Endplate Connections

为了解Q690高强钢端板节点火灾后的受力性能和失效机理,对2个过火550℃冷却后的Q690高强钢端板节点进行足尺模型试验研究,并将试验结果与常温下高强钢端板节点试验的结果、采用欧洲规范EC3计算的结果进行对比.研究结果表明:节点火灾后的失效模式为端板和螺栓组合破坏;高强钢端板节点火灾后仍具有良好的转动能力;EC3中用于普通钢端板节点承载能力计算和失效模式预测的组件法可直接用于计算和预测高强钢端板节点火灾后的承载能力和失效模式,但转动刚度的计算公式并不适用;过火550°C后冷却至常温,节点可恢复常温下90%以上的承载力.最后,给出判断高强钢节点火灾后失效模式的计算公式.

In order to reveal more information and understanding on behavior and failure mechanisms of high strength steel Q690 endplate connection after fire, a full-scale experimental study has been carried out after cooling down from fire temperature 550℃. Further, their behavior was compared with the provisions of Eurocode 3 and the test results obtained from the experimental study on the high strength steel endplate connections without fire exposure. The research shows that the failure mode of high strength steel Q690 endplate connection after fire is belt failure with yielding of the flange, and their rotation capacity is sufficient. What is more, using accurate post-fire mechanical properties, the component method which Eurocode 3 proposed based on connections made of mild steels can be used to calculate the plastic resistance and to predict the failure mode of high strength steel endplate connections after fire, but it is not suit to predict their stiffness. Furthermore, they can regain more than 90% of its original load bearing capacity after cooling down from fire temperature 550 ℃. Moreover, a series of formulations are presented for judging the failure mode of high strength steel endplate connections post fire.