塔冠对超高层建筑风致响应影响研究

Effects of tower crown on wind-induced response of super high-rise building

塔冠是超高建筑中外形变化最丰富的部分,由于其位于高层建筑顶部,其形状的改变对强风作用下高层建筑的基底弯矩、顶部的位移与加速度均有着较大的影响。对大气边界层风向下20种不同形状塔冠的方形截面高层建筑进行了高频天平测力风洞试验,基于随机振动理论,分析了风荷载作用下不同塔冠高层建筑顶部的位移与加速度,对比了不同塔冠结构的风致响应,从减小风致效应的角度给出了塔冠外形的选取建议。研究表明,封闭式的方形开洞型塔冠表现明显优于其它形状的开洞型塔冠;光滑坡面型塔冠横风向响应小于其他类型的坡面型塔冠;棱锥型塔冠对顺风向响应有明显减小作用;阶梯型塔冠大部分情况下对顶部的位移与加速度响应没有明显影响。

Tower crown is the part with the most abundant appearance variation in super-high buildings.Because it is located at top of high-rise buildings,changes of its shape have a larger impact on base moment,top displacement and acceleration of high-rise buildings under strong wind.Here,wind tunnel tests of high-rise buildings with square cross section and 20 different tower crowns were conducted to do high frequency aerodynamic balance measuring in wind direction of atmospheric boundary layer.Based on the random vibration theory,displacement and acceleration at top of high-rise buildings with different tower crowns under wind load were analyzed.Wind-induced responses of structures with different tower crowns were compared,and the suggestion for selection of tower crowns was proposed to reduce wind-induced effect.The study showed that the performance of the closed tower crown with square opening is obviously superior to those of tower crowns with other shape openings;the cross-wind response of the smooth sloping tower crown is less than those of other kinds of sloping tower crown;the pyramid tower crown obviously reduces the downwind response at top of buildings;the stepped tower crown has no obvious effect on displacement and acceleration responses at top of buildings in most cases.