双层马鞍型空间网壳屋盖风振系数非线性模态叠加法计算

Calculation of Wind Load Factors for Double-Layer Saddle-Type Spatial Reticulated Shells by Using Nonlinear Mode Superposition Method

非线性模态叠加法将非线性项作为外部荷载处理,结合与荷载相关的Ritz向量后可快速、准确求解简化的模态方程组。以一大跨度马鞍型屋盖刚性模型风洞试验为例,利用非线性模态叠加法计算风振响应时程,进而求得相应风振系数,并与直接时程积分计算结果比较,表明在选择一定数量参振振型后该方法准确、可靠。分析表明该屋盖风振系数受风向影响显著,在0°1、80°风向角下由于大拱曲边涡脱效应出现风振系数极值。

Nonlinear mode superposition method, combined with load dependent Ritz vectors and by treating nonlinear forces as external loads, could be employed to solve mode equations quickly and exactly. Rigid model wind tunnel test of a long-span roof shell was taken as an example. Wind induced vibration time history and wind load factors were calculated by using the nonlinear mode superposition method. Compared with direct time history integral, the nonlinear mode superposition method is efficient and accurate on condition that enough modes are selected. Furthermore, analysis shows that the wind load factors are influenced prominently by wind direction angles. Because of the vortex-shedding in arch border of 0 degree or 180 degree, the wind load factors achieve extreme.