强台风作用下不同退台方式对超高层建筑横风向风效应的影响

Effects of different setback measures on across wind effects of super-tall buildings under strong typhoon

在边界层风洞模拟的台风风场中，针对考虑立面旋转影响的一系列退台外形超高层建筑模型进行同步测压试验，分析了不同退台方式对建筑的横风向气动力、气动弯矩功率谱密度和风致响应的影响。结果表明：采用退台方式可使建筑侧立面由等截面方式的频率相同的整体漩涡变成若干个频率不同的局部漩涡，从而有效减少了作用在结构上的横风向气动力和风致响应，进一步采用旋转退台方式则可以更好地抑制漩涡的整体性、削减结构横风向气动力并最终降低结构的横风向风致响应;作用于结构的基底气动弯矩取决于经过模态加权处理的气动力的分布，方形截面模型对气动弯矩影响最大的气动力出现在结构高度的80%处;对于不同退台方式的模型，对气动弯矩产生主要影响的仍然是结构顶部的气动荷载，其最大影响高度位于结构高度的80%一90%范围内。与方形等截面结构相比，不同退台方式可以有效降低作用在结构上的横风向风荷载，其降幅为75. 0%一79.2%;采用退台旋转方式对横风向荷载的减少量可达91%。

The wind pressures on several setback and rotating setback building models were synchronously measured and recorded under the simulated boundary layers representing typhoon wind field by the synchronous multi-pressure scanning system in wind tunnel. The effects of different setback on across wind aerodynamic forces, the power spectrum density for base aerodynamic moment and the characteristics of wind-induced response were analyzed. The results show that for the buildings with uniform square cross-section, the vortex sheds at the same constant frequency along height, but for the setback buildings, the vortex sheds at different frequency along height. That is effective to reduce the across-wind aerodynamic forces and responses. Rotating setback step suppresses the vortex shedding and leads to the further reduction of across-wind aerodynamic forces and wind-induced responses. The base aerodynamic moment MA is mainly affected by the distribution of modal-weighted aerodynamic force Fm . For the square cross section model, the most influencing F~ occurs at 80% of building height. For the setback models, the aerodynamic loads that make a greater contribution to MA still occur at the top of building and the crucial height locates at the rang from 80% - 90% of building height. Compared with the square cross section model, different setback shape measures can reduce the wind-induced load by 75.0%-79.2%. The rotating setback measure can reduce the wind-induced load by 91%.