某拟建838m高楼多自由度气弹模型风洞试验研究

Investigation of the Wind-induced Responses of a Tower 838m High Based on a Multi-degree-of Freedom Aero-elastic Model Wind Tunnel Test

为了考察某拟建超高层建筑(总高838m)在设计风速下的风致响应,对该大厦进行了多自由度气弹模型风洞试验.模型自振特性测试表明,该气弹模型各横截面对两个正交的水平主轴对称,每个轴向1阶和2阶频率误差分别在1%和28%以内,1阶阻尼比约为2%,平动振型与实际结构有限元模型计算结果较为一致.分析不同风速和风向角下风致响应发现,该大厦顶部在100年重现期设计风速下最大动态侧移为0.89m,且动态位移本身并未使结构顶部位移超标,而10年,50年和100年重现期下风致加速度响应超过规范阈值幅度分别为16%,23%和29%.另外,该大厦横风向涡振使得临界风速附近横风向风致响应明显偏大,如果假定风荷载谱为白噪声,则横风向1阶气动阻尼比对总响应的贡献达37%.若欲保证该建筑在百年一遇风速下加速度在允许范围内,则须使其结构阻尼比在2.9%以上.

In order to investigate the wind-induced responses of a tower 838 meters high under the de-signed wind speed,multi-degree-of freedom aero-elastic model wind tunnel tests were carried out.It was found that the first-order and the second-order frequency inaccuracy of the model,which was measured from the free vibration test,were less than 1% and 28%,respectively,the first-order damping ratio was about 2%,and the translational vibration mode shape was consistent with the actual structure.Wind tun-nel test result has shown that the maximum wind-induced dynamic displacement is 0.89m,which is in the standard allowable range.But the wind-induced acceleration of 10 years＇,50 years＇and 100 years＇return pe-riod exceeds the specification threshold with the amplitude of 16%,23%,29%,respectively.What＇s more,the lateral response increases remarkably by first order vortex induced vibration,in which the contri-bution of aerodynamic damping is close to 37%.And in order to ensure acceleration response under one hundred years＇wind speed in the allowable range,the structural damping ratio must be larger than 2.9%.