大跨度可开合空间网架屋盖风致效应

大跨度屋盖结构作为风敏感性较强的结构，风荷载是其控制荷载之一，可开合屋盖由于外形和结构的多变性，其风致效应更为复杂。以某大跨度可开合空间网架屋盖结构为研究对象，利用刚性测压风洞试验实测了屋盖内外表面的风压系数，对比了开合状态下屋盖表面风压的分布特征。基于本征正交分解(POD)及瞬态动力有限元分析，得到屋面节点的位移响应时程，分析了屋盖开合状态下的位移响应和风振系数分布特征，研究了结构阻尼比对风振系数的影响。研究表明：屋盖翻转开启形成的悬挑结构会强化流动分离，使得屋盖整体最小净风压较闭合状态进一步减小。闭合状态下风振位移响应中背景响应占主导，背景响应和共振响应之间的相关性较小；开启状态则反之。对于对称的屋盖结构，在对称的屋盖分区上，风振系数会呈现与位移均值相反的分布特征。风振系数与结构阻尼比呈现明显的非线性关系，阻尼比越小，风振系数越大，且对阻尼比越敏感；风振系数随阻尼比演变趋势依赖结构风致平均响应及脉动响应共振分量占比。

Wind-induced effect of a large-span openable truss roof

Large span roof structures are wind-sensitive structures, and wind load is one of the governing design loads. The wind-induced effect of openable roofs is more complicated due to the variability of shape and structure. Taking a large-span openable truss roof as the focus of this research, its wind pressure distribution was measured by the pressure measurement of wind tunnel test with rigid model and the wind pressure distribution of closed and open roof states were compared. The roof displacement response was subsequently calculated through transient dynamic analysis based on wind pressure reconstruction by the proper orthogonal decomposition (POD) method. The characteristics of the displacement response and wind vibration factors were analyzed for both closed and open states. The influence of structural damping on wind vibration factors was also clarified. The results show that the cantilever structure formed by the opening of the roof will enhance the flow separation so that the minimum net pressure of the open roof is lower than that of the closed roof. In the closed roof state, the background response dominates the wind-induced vibration, and the correlation between the background and resonant response is rather weak. For the open state, however, the results were the opposite. For symmetrical roof structures, the wind vibration factor for symmetrical roof area presents a tendency opposite to the mean displacement response. The wind vibration factors show the obvious nonlinear relationship with the structural damping ratio. When the damping ratio decreases, the wind vibration factors increase and become more sensitive to the damping ratio. The sensitivity of the wind vibration factors to the damping ratio is closely related to both the mean displacement response and the ratio of resonant component.