高强钢平齐式端板连接节点火灾后力学性能试验研究

Experimental Study on Mechanical Behaviour of High Strength Steel Flush Endplate Connections after Fire

火灾后,钢构件残余应力和变形的重新分布,导致钢结构整体在火灾后可能比火灾高温作用下更加危险.节点对钢结构整体安全性至关重要,为研究高强钢平齐式端板连接节点火灾后的力学性能,采用稳态试验方法对经历550℃的火灾高温并冷却至常温的7个端板连接节点进行试验,得到节点火灾后的变形状态、弯矩-转角关系曲线以及失效模式等.同时,将试验结果与普通钢端板连接节点过火后的力学性能进行对比分析.此外,将试验结果同现行欧洲钢结构设计规范Eurocode3中相应条文进行比较.研究表明:通过合理的节点设计,与采用较厚普通钢端板的节点相比,采用较薄高强钢端板的节点可实现相同的节点失效模式、相近的剩余承载力以及更高的(至少是相当的)节点转动能力;同时,欧洲钢结构规范Eurocode3中有关节点塑性抗弯承载力的条文适用于高强钢平齐式端板连接节点火灾后塑性抗弯承载力的预测.

After fire,residual forces and deformations are re-developed inevitably in steel structures,and it may cause more dangerous consequence than that in fire condition.Beam-column connections are very important parts for the whole structure.In order to reveal more information about high strength steel flush endplate connection,an experimental study on mechanical behaviour of high strength steel flush endplate connections was carried out.Seven flush endplate connections were tested after cooling down from 550℃.The final deformation,moment-rotation curves and failure mode of high strength steel flush endplate connections were obtained and compared with those of mild steel flush endplate connections.Moreover,the provisions of Eurocode 3 were validated with the test results.It is found that a thinner high strength steel endplate can achieve similar residual load-bearing capacity and comparable or even higher rotation capacity after fire,in comparison with a connection with thicker mild steel endplate.Meanwhile,the provisions of Eurocode 3 for plastic flexural resistance of endplate connections are applicable when used to predict the behavior of high strength steel flush endplate connection after fire.