高强钢外伸式端板节点火灾性能试验与数值分析

Experimental and numerical analysis on high strength steel extended endplate connections in fire

对1个Q690和2个Q960高强钢外伸式端板连接节点进行高温550℃下的足尺模型试验研究和有限元模拟分析,并将试验结果与采用欧洲现行钢结构设计规范EN 1993-1-8的计算结果及有限元分析结果进行对比.结果表明,550℃时,Q690和Q960高强钢端板连接节点的承载力分别为常温时的45%和46%,初始转动刚度为常温时的57%和65%,但转动能力分别为常温时的1.43倍和1.66倍.EN 1993-1-8中基于普通钢端板连接节点常温力学性能所提出的组件法可直接用于预测高强钢端板连接节点火灾下的失效模式和承载能力,但初始转动刚度的计算公式并不适用,且采用EN 1993-1-8关于保障节点转动能力的相关要求对高强钢端板连接节点进行抗火设计偏于保守.有限元模型可准确模拟该端板连接节点火灾下的弯矩转角关系和失效模式.

The full-scale experimental study and the simulation analysis on the mechanical behaviors of one Q690 and two Q960 high strength steel endplate connections at the elevated temperature 550 ℃w ere carried out. The experimental results were compared with the results calculated according to the current European steel structure design code EN 1993-1-8 and the finite element analysis results. The results show that at 550 ℃,the plastic moment resistance of Q690 and Q960 high strength steel endplate connections are 45% and 46% of those at ambient temperature,and the initial rotational stiffness are 57% and 65% of those at ambient temperature,respectively. How ever,the rotation capacity of Q690 and Q960 high strength steel endplate connections are 1. 43 and 1. 66 times that at ambient temperature. The component method in EN 1993-1-8 proposed based on the connections made of mild steels at ambient temperature can be used to calculate the plastic resistance and predict the failure mode of the high strength steel endplate connections in fire,but it is not suitable to predict the initial rotational stiffness. The suggestion about the rotation capacity of the connections proposed in EN 1993-1-8 is too conservative for high strength steel endplate connections in fire. The finite element models can accurately simulate the moment-rotation relationships and the failure modes of the connections in fire.