基于实用大空间火灾空气温升模型和张弦梁结构三维整体有限元模型,对火灾下整体结构的抗火性能进行了模拟分析.研究对比了不同火源面积和高度下结构的温度场分布、位移和应力特征、钢索的应力变化和结构破坏模式,得到了不同火灾下张弦梁结构的极限耐火时间.分析结果表明:在火灾作用下由于张弦梁结构局部构件变形过大不能继续承载,导致整体结构失稳和倒塌;结构的抗火薄弱区域位于结构中心附近,结构变形不对称;火灾下引起张弦梁结构破坏的主要因素为较大的初始应力以及高温下结构刚度和强度的降低. Based on the practical large space fire air temperature model and the three-dimensional finite element model of the beam string structure, the fire resistance performance of the fire structure under fire is simulated.The temperature field distribution, displacement and temperature distribution under different fire source area and height Stress characteristics, the stress changes of steel cables and the failure mode of structure, the ultimate fire-resistant time of the beam string structure under different fires is obtained.The analysis results show that the overall structure is not stable due to excessive deformation of the local components of the beam string structure under fire And collapsed. The weak area of ​​fire resistance of the structure is located near the center of the structure and the structure is not symmetrical. The main factors causing the damage of the beam string under fire are the large initial stress and the decrease of the structural rigidity and strength under high temperature.