薄膜结构在动风荷载下的安全性能分析

Safety Analysis of Membrane Structure under Dynamic Wind Load

从理论和实践两方面对薄膜结构在风荷载下的安全性能进行了研究。根据随机过程理论 ,用计算机模拟生成具有空间相关性的风场。发展建立了膜结构几何非线性动力响应问题的有限元公式 ,并以此为基础对一具体的膜结构进行了动力时程响应分析。通过观察膜结构在不同风速下的位移时程曲线 ,笔者发现 :当外界风速小于一定的临界风速时 ,结构的位移响应会逐渐趋于稳态 ,结构的振动逐渐趋于稳定 ,这时结构是安全的 ;当外界风速超过或接近临界风速时 ,结构的振幅会逐渐增大 ,膜结构将可能发生驰振损坏。进而提出了通过增大膜内预应力或提高膜曲面的曲率来防止膜结构风振破坏的方法 ,并指出了在设计和施工中为保证膜结构的风振安全应当采取的措施。

Study on the safety of membrane structure under dynamic wind load was carried out both theoretically and practically. Based on random process theory, wind fields with spatial correlativity were simulated in computer. The finite element formula for geometrically nonlinear dynamic response analysis of membrane structure was also established. On the basis of this dynamic time history response analyses were carried out for a practical membrane project. From its displacement time history curve, it was found that when the wind velocity was under a certain critical wind velocity, the structure vibration was stable, and the structure was safety; otherwise when the wind velocity was beyond the critical wind velocity, the vibration became unstable and the structure might be destroyed. It is pointed out that raising the prestress in membrane or the curvature of membrane surface could effectively avoid structure damage under dynamic wind loads. It is suggested that for the safety of membrane structures under wind load the measures should be taken in the process of design and constructions.