大跨屋盖结构风振响应主要参振模态确定方法研究

合理选取主要参振模态是保证大跨屋盖结构风振响应计算精度的关键问题。本文以模态空间分布与风荷载空间分布相关性强弱作为选取主要参振模态的依据,考虑到屋盖结构表面风荷载分布的不确定性,提出了通过低阶主要贡献模态间接寻找风荷载强相关高阶模态的思想,首先实现对高阶参振模态数量的缩减。在此基础上,结合低阶参振模态,通过对模态响应方差矩阵的简化处理,构造了其等效矩阵,根据等效矩阵中对角线元素定义了模态参与系数,通过该系数能够方便的实现对主要参振模态的选取。最后,通过国家体育场屋盖主结构的风振响应分析对所提出方法的有效性进行了验证。

Research on the method for selecting dominant modes of wind-induced response for large-span roofs

Because of the characteristics of multi-mode participant of wind-induced vibration response for large-span roofs, it is an important matter to efficiently select dominant modes. In this paper, taking the correlation of mode and wind load in spatial distribution form as an criterion for selecting dominant modes. considering the uncertainty of wind load around the large-span roofs, according to the lower frequency modes with significant contribution to response, an indirectly way considering correlation of wind load and higher frequency modes is proposed. On the basis of this, the number of higher frequency participant modes are greatly reduced; then, an equivalent matrix of displacement response variance matrix is constructed, the diagonal element of equivalent matrix indicate the extent of contribution to the response of every participant modes. Based on this equivalent matrix, the modes which would participate the final calculation of the wind-induced vibration is further decided. At last, The effectiveness of the proposed method is verified by the wind-induced vibration of National Stadium main roof.