震损后圆钢管混凝土柱-钢梁节点耐火性能数值分析

Numerical analysis on fire resistance of the connections with steel beam to concrete filled steel tubular column after earthquake damage

钢管混凝土结构已广泛应用于抗震设防地区,钢管混凝土柱-钢梁外环板式节点作为目前工程中最常用的节点形式,该类节点在经历地震损伤后耐火性能的研究对灾后工程加固具有重要意义,采用低周往复加载方式模拟地震作用,通过合理选取地震损伤指数,建立了节点在经历不同损伤后下部柱单独受火和下部柱及刚梁下翼缘同时受火2种工况下的有限元模型。分析了节点在震损后的损伤积累、温度传递以及损伤指数和受火方式对节点耐火极限和破坏模态的影响。结果表明:随着震损程度的增大,耐火极限逐渐降低;不同受火方式对节点温度传导和破坏模态有较大影响。

Concrete-filled steel tube structure has been widely used in seismic fortification areas. The outer ring plate connection as the most commonly used connection type in current engineering. The study of fire resistance performance for concrete-filled steel tubular column-steel beam with ring plate connection is of great significance for post-disaster engineering reinforcement. In this paper, the seismic action is simulated by the low-cycle reciprocating loading method. And selecting the earthquake damage index rationally, the finite element model for the connection under two conditions is established. One condition is that the connection is damaged by the fire at lower column, the other is that the connection is damaged by the fire at both the lower column and the lower flange of the steel beam. The damage accumulation, temperature transmission after the damage are analyzed. Meanwhile, the influence of damage index and fire mode on fire resistance and failure mode are investigated. The results show that with the increase of earthquake damage, the fire resistance decreases gradually. Different fire modes have great influence on temperature conduction and failure mode.