基于实际火灾场景的钢框架结构倒塌机制分析

采用ABAQUS建立无楼板的多层钢框架模型，采用顺序热-固耦合法，综合考虑实际火灾场景下局部火源位置、火源功率变化、非均匀分布温度场及火灾作用下梁柱失效进行分析，研究了在梁柱的受火形式和失效柱位置两种因素影响下钢框架结构的初始破坏机理与倒塌机制。结果表明：钢框架结构的连续倒塌始于受火柱的屈曲失效，与之相连的梁由于失去竖向支撑挠度增大并产生拉力，使内力重分布柱产生侧移，进而在火灾的持续作用下结构位移不断发展，破坏向周围扩散，最终导致结构发生连续性倒塌；当底层失效柱为角柱和边柱时，结构发生倾覆式连续性倒塌；当底层失效柱主要分布在结构对称轴上时，结构发生下沉式连续性倒塌，该类型倒塌发生较为突然。

The collapse mechanism analysis of steel frame structure based on actual fire

A multi-layer steel frame model without floors was established by ABAQUS.Using sequential heat-solid coupling method,taking into account the location of fire,the power change of fire,non-uniform temperature field and the failure of beams under fire,the initial destruction mechanism and collapse mechanism of the steel frame structure were studied under the influence of 2 factors of the fire form of beam and columns and the location of failure column.The results showed that the continuous collapse of the steel frame structure begins with the failure of the fire column,and the deflection of the beam connected to it increases and the beam produces a pull force due to the loss of support.Then the load distribution columns produce a side shift and the displacement of the structure develop under fire.The destruction spreads to the surrounding and eventually leads to the progressive collapse of the structure.When the bottom failure columns are on the edge,the collapse will be overturn type.When the bottom failure columns are mainly on the structural symmetry axis,the collapse will be sinking type.This type of collapse takes place suddenly.