火灾下钢框架抗连续倒塌动力响应分析

Dynamic Response Analysis of Steel Frame Resisting Continuous Collapse under Fire

为研究钢框架结构在火灾作用下的抗连续倒塌动力响应。通过ABAQUS有限元软件分别对二层四跨平面钢框架瞬间去柱动力试验以及平面钢框架火灾试验进行数值模拟。将数值模拟获取的竖向位移-时程曲线和破坏模态与试验结果对比,验证了有限元模型的准确性,获取的位移-温度曲线也验证了顺序热力耦合方法的适用性。在验证有限元模型有效性的基础上,进一步研究瞬间去柱的钢框架结构在不同受火温度下的抗连续倒塌动力响应。研究表明:不同节点的连接形式对钢框架进行瞬间去柱时,钢框架的破坏模态与结构的稳定性影响显著,当火灾高温下钢框架采用加强型节点时,框架柱更容易发生过度屈曲,从而更容易引发连续倒塌;温度越高,钢框架去柱后中柱节点的峰值位移值和稳定后的竖向位移值均有明显提升,结构动力响应越明显,结构抗连续性倒塌能力也越小。

In order to study the dynamic response of steel frame structures to continuous collapse under fire.Through ABAQUS finite element software,the dynamic test of two story four span plane steel frame with instantaneous column removal and the fire test of plane steel frame were simulated.By comparing the vertical displacement time history curve and failure mode obtained from numerical simulation with the test results,the accuracy of the finite element model was verified,and the displacement temperature curve obtained also verifies the applicability of the sequential thermal mechanical coupling method.On the basis of verifying the validity of the finite element model,the dynamic response of steel frame structures with instantaneous column removal under different fire temperatures against continuous collapse was further studied.The research shows that:when the connection forms of different joints remove the columns instantaneously,the failure mode of the steel frame and the stability of the structure have a significant impact.When the steel frame adopts reinforced joints under high temperature of fire,the frame columns are more prone to excessive buckling,which is more likely to cause continuous collapse.The higher the temperature is,the higher the peak displacement value and the vertical displacement value of the middle column node of the steel frame after removal of the column are.The more obvious the structural dynamic response is,the smaller the structural resistance to continuous collapse is.