矩形高层建筑风荷载气动导纳研究

Aerodynamic admittance of wind loads on rectangular high-rise buildings

摘要:

为探究深宽比对矩形高层建筑风荷载气动导纳的影响,本文对深宽比为0.11～9的矩形高层建筑进行了风洞测压试验,研究了正交风向作用下不同深宽比建筑各立面脉动风压与基底阻力的气动导纳的变化规律,并与基于准定常假定的Vickery模型和Solari模型作了比较；通过拟合分析获得了适用于不同深宽比建筑基底阻力的气动导纳的闭合表达式.结果表明:当建筑深宽比小于0.5时,迎风面脉动风压及基底阻力的气动导纳与Vickery模型较为接近,但随深宽比增大,气动导纳在高频区的衰减速度变缓,Vickery模型和Solari模型较试验值显著偏小；在建筑背风面和侧风面上,因流动分离、再附和旋涡脱落等非定常流动的影响,脉动风压的气动导纳在高频区域会出现大小不等的峰,此时Vickery模型在变化规律和数值大小上均不再吻合.本文获得的幂函数形式的基底阻力气动导纳拟合式可以较准确地预测不同深宽比矩形建筑的基底阻力气动导纳.

Abstract:

To investigate the effects of depth-to-width ratio on the aerodynamic admittance of wind loads on rectangular high-rise buildings, wind tunnel pressure tests for high-rise buildings with depth-to-width ratios of 0.11[WT5,6”BZ〗 — 9 were conducted. Patterns of the aerodynamic admittances for fluctuating wind pressures on each wall and base drag were investigated under the orthogonal wind direction, which were then compared with quasi-steady assumption based Vickerys model and Solaris model. Closed-form expression for the aerodynamic admittance for base drag of buildings with different depth-to-width ratios was obtained through fitting analysis. Results show that when the depth-to-width ratio is lower than 0.5, the aerodynamic admittances for base drag and fluctuating pressures on the windward wall are close to Vickerys model.But as the ratio increases, the decay rate of the aerodynamic admittance becomes lower, and Vickerys model and Solaris model are significantly lower than the measured values.On the leeward and side walls, due to the effects of body-generated turbulence such as flow separation, reattachment, and vortex shedding, peaks with different sizes appear at high frequencies of the aerodynamic admittances for fluctuating pressures, where the varying pattern and magnitudes of Vickerys model no longer match. The fitted formula in power function form that obtained in this paper can well predict the aerodynamic admittance for base drag of rectangular buildings with different depth-to-width ratios.