大跨度索穹顶结构抗火性能分析

根据内蒙古伊旗全民健身体育中心工程设计的需要，对大跨度索穹顶结构进行抗火性能分析。以温度-结构耦合为基本方法，基于大空间空气升温模型，考虑高温下材料的非线性，分析了结构在不同火灾工况下的响应，得到火灾下索穹顶结构变形、节点位移、杆件预应力损失的基本规律。研究表明：肋环型索穹顶结构侧向刚度较弱，对偏心火灾敏感，火灾下的挠度超限和侧向变形是导致结构失效和非结构构件提前破坏的主要原因；脊索尤其内脊索是火灾下预应力损失较为严重的杆件，中撑杆侧向位移控制是肋环形索穹顶结构抗火设计的重点。针对肋环形索穹顶结构侧向刚度较弱的缺点，在中撑杆上节点部位加设一道环向杆件进行结构体系的改进，可使结构的抗火性能得到较大改善。

Fire resistance analysis of large-span cable dome structure

To satisfy the need for the design of the National Fitness Center in Ejin Horo Banner,Inner Mongolia,the fire resistance performance of the cable dome structural system is studied in the paper.Considering material nonlinearity under high temperature,the structural response under different fire conditions and the basic laws of structural deformation,node displacement and prestressing force loss were analyzed,based on thermal-structural coupling method and the model of atmosphere temperature ascending in large space.This research indicates that the lateral stiffness of Geiger cable dome structure is weak and it is susceptible to eccentric fire load;the eccessive deflection and lateral deformation are major reasons for structural failure and nonstructural components’ early damage under fire.The pestressing force loss of the ridge cables,especially the inner ridge cables,is more serious,and the struts should be considered as key parts in the fire resistance design.Finally,for the deficiency of plane stiffness in Geiger cable dome structure,the improvement of adding loop rigid rods on the upper node of struts can benefit the fire resistance performance significantly.