泰山顶部近地层风的方差与谱分析
ANALYSIS OF VARIANCE AND SPECTRUM FOR WIND IN SURFACE LAYER ON SUMMIT OF TAI MOUNTAIN
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摘要: 风在速度与方向上的不稳定性可引发结构振动并可导致损坏。山顶风较少受局地作用影响, 流场较稳定,作为典型风况对山顶风湍流脉动情形进行的观测和分析,对于研究建筑结构风载振动情形有着重要意义。在不同风况下对泰山气象站近地层风的风速和风向进行了同时、逐秒测记,所得样本经检验符合正态分布。计算表明,风向样本方差显著大于风速样本方差。绘制了各风速、风向样本自、互谱密度曲线图。谱图显示诸样本具有红噪声序列特征,不同样本自、互谱密度曲线具有相近形状,而以风速自谱曲线吻合程度最好,谱密度曲线在周期为4秒及2秒处有峰值。此后的研究应结合记录仪器的改进增加采样频率,对周期为2秒以下谱曲线作进一步分析。Abstract: The instability of wind in speed and direction can lead to vibration in the structure and can cause their damage. Wind over the summit of mountain affects less by locate landfrom and its flow pattern is the stability. As wind models, there is an important meaning for research the vibration by wind load on the building construction to the observation and analyses for wind turbulence over the summit of mountain. The changes of wind speed and direction under the various winds flowing through the Tai-mountain Weather Station are observed simultaneously per second. The observed samples are tested and of the normal distribution. A statistical analysis shows that the sample variance of wind direction is obviously more than the sample variance of wind speed. The curve diagrams of own and mutual spectral density of each sample of wind speed and direction are given. The spectrum diagrams show that the samples have the characteristic of red noise sequence, the curves of own and mutual spectral density of different sample have a similar shape, but the own spectral curve of wind speed fits best. There are two peak values in the spectral density curve at the period of 4 and 2 second.
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表 1 样本的均值与方差
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