90°螺旋型和方形截面高层建筑气弹效应对比研究

Comparative research on the wind-induced responses based on multi-degree -of freedom aero-elastic models of 90° helical and square tall buildings

设计并制作了动力特性基本一致的90°螺旋型和方形截面高层建筑的多自由度气弹模型,对气弹模型进行了风洞试验。运用随机减量法识别了顺、横风向以及多风向角下的气动阻尼;对出现了"拍"现象的工况采用小波方法解耦模态后再进行气动阻尼识别。风洞试验结果表明,方形截面高层建筑顺、横风向气动阻尼比随折算风速的变化规律与相关研究结果类似;螺旋型高层建筑顺风向气动阻尼比随折算风速的变化规律与方形截面高层建筑较为接近,在高折算风速段的阻尼比值相比方形截面高层建筑偏小,横风向气动阻尼比在低折算风速段微弱上升,随后下降,在0值附近波动。对多个风向角的加速度响应进行研究,螺旋型高层建筑均表现出良好的气动性能,尤其在横风向折算风速为12.43时,其加速度均方根为方形截面高层建筑的25.48%。

90° helical and square section models with the same dynamic characteristics have been designed and fabricated, and the dynamic characteristics of two elastic models were identified successfully. Wind tunnel texts were carried out for the elastic models and the various conditions between the along-wind and cross-wind aerodynamic damping ratio were identified by the random decrement technique. Wavelet transform was used to decouple modal to identify aerodynamic damping ratio of the working conditions with the phenomenon of beats. The result indicated that the change regulation between aerodynamic damping ratio and reduced wind velocity of square model in accordance with relevant research results;the cross-wind aerodynamic damping ratio of 90°helical model has a slight rise in the low reduced wind velocity range, being stable in the range of 0 with the increase of reduced wind speed, the along-wind aerodynamic damping ratio of 90°helical model shows the regulation which is similar to square model, but it is smaller at high reduced wind velocity. The acceleration response under multiple wind directions were studied, it was found that the 90°helical model showed better aerodynamic performance in all conditions,especially when the reduced wind velocity arrives at 12.43 in the cross-wind direction, the RMS acceleration of the 90°helical model is 25.48% of that of the square model.