大开洞对高层建筑风效应的影响研究

在大气边界层风洞中开展了在0.5 H和0.85 H高度设置洞口的高层建筑刚性模型测力试验,获得不同洞口尺寸、高度、位置以及数量时的高层建筑风致基底反力.从基底弯矩系数和基底一阶广义气动力谱研究了不同洞口设置对高层建筑风效应的影响.研究结果表明:1)顺风向开洞能有效地降低顺风向基底平均弯矩,并且上部开洞效果优于下部开洞,开洞率越大效果越明显;横向基底平均弯矩比较小,大开洞提高基底横向平均弯矩,小开洞则相反;开洞对横风向与顺风向的基底脉动弯矩都有较大影响.2)不管是大开洞还是小开洞,在折算频率约为0.12位置处,均出现了与旋涡脱落频率相近的窄带峰值,且不同工况下,低频段的功率谱值差异略大于高频段.

Investigation of the Influence of Openings on the Wind Effect of Tall Buildings

Force tests of tall buildings with openings at its two levels of 0.5H and 0.85H were conducted in the atmospheric boundary layer wind tunnel, and then the wind-induced base forces were obtained with different parameters, such as the dimension, height, location and amount of the openings. The influences on the wind effects of tall buildings with different openings were investigated on the basis of the basement bending moment coefficients and basement first mode aerodynamic force spectrums. The results show that the basement mean bending moment can be reduced efficiently by the opening at along-wind direction, the reduction is more evident for the opening at higher location than that at lower location, and the larger opening also plays more effectual roles for the reduction of basement mean bending moment. The basement mean bending moment at across-wind direction is small, and the value increases in case of large opening, contrary to that for small opening. Furthermore, both of the openings at along-wind and at across-wind directions have influence on the basement fluctuating bending moment. The narrow band frequency with a peak value of 0.12, which is close to the reduced frequency of the vortex shedding, is found for both the cases of large opening and small opening. The difference of power spectrum value is more remarkable in lower-frequency section than that in high-frequency section for different cases.