强风作用楔形超高层建筑的局部气动抗风措施研究

Study on local aerodynamic strategy to reduce wind load on tapered super-tall buildings under strong wind action

在边界层风洞中对4栋缩尺比为1∶600、高546 m的等截面、沿高度渐缩和切角的正方形平面高层建筑模型,以及对这些建筑的3个不同高度设备层角区进行敞开处理(局部气动措施)后的瞬态风压分布进行同步测压试验。对结构表面脉动风压场的分布特性、气动荷载沿高度分布、频域相干性、基底气动弯矩功率谱密度以及基底弯矩响应等进行详细分析比较。结果显示:局部气动措施可以显著消减横风向漩涡脱落频率附近的气动弯矩功率谱密度值,且对于平面切角后气动弯矩谱和漩涡脱落有关的残余能量部分同样有较为显著的消减效果,所采取的局部气动措施宜选在脉动风压场分布较强的结构中上部位置,建议选在0.6~0.8倍结构高度之间。风振计算结果显示在3个设备层角区均敞开的情况下可以分别使4栋建筑的100年重现期的横风向风致峰值基底弯矩减少25.7%、21.0%、24.9%和15.5%,且在结构实际自振周期与有限元分析得到的自振周期之比在0.60~1.35范围内时,所采取措施对建筑结构风致荷载消减效果在10%~32%之间。

The wind pressures on four 546 m height super-tall buildings,one basic building model with a square crosssection,one with tapered elevation,one with corner cut and one with open corner area of the equipment floors at three different heights( local aerodynamic strategy,LAS),were synchronously measured in a boundary layer wind tunnel. The distribution characteristics of fluctuating pressure,cross wind aerodynamic force( CWAF) and coherence of CWAF between different building height spacing,power spectrum density( PSD) of cross wind aerodynamic base bending moment( CWABBM) and wind induced response( WIR) were analyzed in detail. The results show that the LAS can significantly reduce the PSD of CWABBM near the vortex shedding frequency,and for the corner cut building model LAS can also effectively reduce remainder energy of vortex shedding that is reduced by corner cut on the corresponding without corner cut building. The appropriate position for LAS is 0. 6 ~ 0. 8 times building height range where the distribution of fluctuating wind pressure is stronger. The results show that across wind induced peak base bending moment( BBM) of 100 year return period of four buildings are reduced by 25. 7%,21. 0%,24. 9% and 15. 5% when the corner of the three equipment floors of the buildings are opened. And the LAS can make a reduction of 10% ~ 23% in wind induced peak BBM over a wide range of structural period ratio that varies from 0. 60 to 1. 35.