小振幅振动屋盖风压特性研究

Wind pressure analysis of small-amplitude vibrating roof

风荷载作用下,大跨度屋盖通常会出现不同频率的小振幅振动。为描述这类小振幅振动屋盖的风荷载分布情况,采用准定常理论,构造基于时间离散的准定常风压统计方法,并由此给出相应的平均风压统计表达式。采用计算流体力学方法,对不同振动频率的屋盖进行风压分布模拟,结合准定常风压统计方法分析屋盖表面平均风压和脉动风压分布特性,并与相关风洞试验数据进行对比。研究结果表明:对于二阶振型振动的小振幅平屋盖,在不同振动频率条件下,屋盖表面平均风压的分布与静态平屋盖的形态接近;而脉动风压的特性与静态平屋盖的情况差别较大。

With incident flow over large-span roofs,small-amplitude vibrations always occur with various frequencies.To describe the wind loading distribution on these kinds of vibration roofs,quasi-steady theory is applied to construct a set of discrete-time quasi-steady pressure expressions by statistical methods,and thereby gives the statistical formula of the mean wind pressure.Numerical simulation cases are carried out to approve the wind loading distribution along the vibrating roof surface under different frequencies and amplitudes.The mean pressure and fluctuating pressure distribution are compared with the same model of steady roof,with corresponding wind tunnel data adopted as benchmark cases and comparison.The results show that the mean wind pressure distribution and values of the vibrating roof are similar to those of the steady roof,while the fluctuation pressure distribution and magnitudes of the vibrating roof are different from those of the steady roof.