小截面建筑干扰下的高层建筑气动力及风致响应研究

Interference effects on aerodynamic and wind-induced responses for an upstream interfering building with small section size

上游来流经小截面施扰建筑可产生频率较高的漩涡,在较低的风速下会使受扰建筑发生涡激共振而受到较大的干扰作用。为此,通过同步测压风洞试验和风振响应计算,详细分析上游施扰建筑与下游受扰主建筑的截面宽度比为0.4时的受扰建筑基底气动弯矩、基底峰值弯矩响应以及结构顶部峰值加速度的干扰效应。结果表明:在B类和C类地貌风场下受扰建筑基底平均和脉动气动弯矩均表现为遮挡效应和弱放大效应,最大干扰系数仅为1.05;顺风向、横风向基底峰值弯矩响应和顶部峰值加速度的干扰效应都较基底平均和脉动气动弯矩的强;结构顶部峰值加速度的干扰效应明显强于基底峰值弯矩响应,其中在B类和C类地貌风场下的横风向峰值加速度均在串列位置(2b, 0)附近处呈现强放大效应,最大包络干扰系数分别为4.7和3.03。进一步对尾流涡激共振的干扰机理研究表明,基底峰值弯矩响应和结构顶部峰值加速度响应的放大效应干扰机理是一致的。对于受小截面施扰建筑影响的情况,仅分析气动力的干扰效应是不够的,必须考虑不同折算风速下的荷载响应包络干扰效应。

An upstream interfering building with a small section size can generate a high-frequency vortex, which might lead to vortex-induced vibration on the downstream principal building in the case of lower approaching velocity. Pressure distributions were measured by a series of wind tunnel experiments and the corresponding wind-induced responses were calculated. Interference effects on aerodynamic moment, base moment response and acceleration response of principal building were detailed investigated when breadth ratio B(B=B/B) equaled 0.4. It is shown that shedding effect is dominant on the mean and fluctuating base aerodynamic moements in both terrain categories B and C, the corresponding maximum interference factor is 1.05. However, interference effects of both base moment response and acceleration response are remarkably greater than those of aerodynamic moment in either along-wind or across-wind direction. Moreover, the interference effect of acceleration is greater than that of base moment response. For the across-wind acceleration response, a remarkable amplification factor occurs at the location(2b, 0) in both B and C terrains, the corresponding maximum interference factors are 4.7 and 3.03, respectively. Then interference mechanism of wake vortex-induced vibration is studied. The interference mechanism of base moment response is the same as that of acceleration response. For the case of an upstream interfering building with a small section size, it is not enough to only consider the interference effect on aerodynamic moment. The envelope interference effect on structural response must be considered in different reduced velocities.