桅杆结构随机风振的离散分析法

DISCRETE RANDOM VIBRATION ANALYSIS OF GUYED MASTS UNDER STOCHASTIC WIND LOAD

风致振动是桅杆结构安全性的控制因素。由于这种结构存在频谱密集的动力特性,不适合采用振型迭加法进行分析。为此本文引入一种新的频域方法计算桅杆结构随机风振响应。基于随机振动的离散分析理论,推导出白噪声激励下结构动力响应的递推公式。经过对风荷载这种有色噪声进行白噪声滤波,桅杆结构的风致振动描述为白噪声激励下的随机振动。于是离散分析理论适用,推导出桅杆结构随机风振响应的递推公式。采用线性化模型时,该方法绝对收敛。计算结果表明,当桅杆结构处于正常使用状态时,采用离散分析理论可以得到满意的精度。

Wind-induced vibration is the controlling factor for the safety of guyed masts. Because of the dense frequency spectrums of guyed masts, model-superposition-method is not applicable. A new spectrum method is introduced to calculate the dynamic response of guyed masts under stochastic wind load. Based on discrete random vibration theory, recurrence formulas are developed to calculate the dynamic response of structures under white noise excitations. After color noise as wind load is generated from white noise filter, wind-induced vibration of guyed masts is described as random vibration under white noise excitations. Thus, discrete random vibration theory is applicable, and recurrence formulas to calculate dynamic response of guyed mast under stochastic wind load are deduced. For linearized model, this method is absolutely convergent. It is shown that satisfactory results can be obtained using the discrete random vibration method when guyed mast is under normal working state.