Refined Theory Of The Equivalent Static Wind Loads On Large Span Roofs

Large span roofs are widely used in various large public buildings, such as gymnasiums, exhibition pavilions and hangars. When the roofs tend to more flexible and lightweight, they are sensitive to fluctuating wind loads more and more, and the wind loads gradually dominate among all kinds of loads in structural design. At the same time, the study on wind-resistant design of large span roofs is very weak, which restricts the development of these structures. Therefore, it is of vital importance in theory and engineering practice to do systematic researches on the methods of the wind resistance of large span roofs.Based on the study on essential characteristics of wind-induced response of large span roofs, it is demonstrated that the kernel issue of wind-resistant design of large span roofs is to consider multiple distributions of fluctuating wind load, multi-mode vibration and multiple equivalent objectives. According to these characteristics and equivalent static wind loading (ESWL) theory of high-rise buildings and bridges, refined idea to study ESWL of large span roofs is presented. The refined idea can be expressed that ESWL should be studied to reflect the mechanism of wind loading action and rules of wind-induced response, and to relate ESWL to basic characteristics of wind loads and dynamic properties of structures. ESWL obtained by the refined idea possesses more definite physical meanings.Under the direction of the refined idea of ESWL, systematic methods to analyze ESWL are proposed for large span roofs in this paper. Two improved measures are presented: (1) background response and resonant response are defined strictly for structures with many freedom degrees, and the method is presented to analyze the correlation between background response and resonant response. Based on these, it is pointed out that wind-induced response and ESWL can be decomposed into three components as the mean, the background and the resonant component; (2) some refined methods are introduced to describe wind loads and wind-induced response of large span roofs, such as Proper Orthogonal Decomposition method (POD), direct superposition method with Ritz vectors, and Load-Response Correlation method (LRC).