考虑截止频率影响的输电塔线体系风振响应分析

Wind-induced dynamic response analysis of transmission tower-line system considering the influence of cut-off frequency

对结构进行风振响应分析时,选用不同截止频率模拟风荷载后得到的结构响应结果有较大区别。文章首先介绍截止频率的选取对风总能量的影响,然后采用谐波合成法进行脉动风的模拟,并将风荷载作用于不同的窄基角钢输电塔及塔线体系上,通过时程分析得到在不同截止频率风荷载作用下结构的加速度响应均方差,对得到的风振响应结果进行功率谱分析并与模态分析得到的结构动力特性进行比较讨论。计算结果表明,4 Hz截止频率下模拟得到的风荷载占到风总能量的90%,当截止频率为2~3阶结构固有频率时,加速度均方根值的误差减小至10%以下。因此对于截止频率的选取,既要满足风总能量的要求,同时也要结合结构自身的动力特性。

When analyzing the wind-induced response of structures, wind loads simulated with different cut-off frequencies will result in significantly different results. The influence of cut-off frequency on the total energy of the wind was introduced and the harmonic superposition method was used to generate fluctuating wind speeds. The wind load was applied to different narrow angle steel transmission towers and tower-line system. The mean squared acceleration responses of the structure for wind loads under different cut-off frequencies were obtained with dynamic response analysis method. The power spectrums of dynamic responses were analyzed and compared with the structural dynamic characteristics obtained with modal analysis. The calculation results show that the wind load for 4 Hz cut-off frequency accounts for 90% of the total wind energy. When the cut-off frequency is equal to the 2 nd to 3 rd order natural frequency of the structures, the dynamic response error of the mean squared acceleration is reduced to less than 10%. Therefore, for the selection of the cut-off frequency, it is necessary to consider the requirements of the total wind energy and the dynamic characteristics of the structure at the same time.