大跨网壳地震反应时Rayleigh阻尼构建方法比较

为研究Rayleigh阻尼系数参考频率选取方法对结构地震反应的影响，以一个长85.2 m，宽61.8 m的网壳为例，对比分析了基于地震波频谱特性选取第二个参考频率的方法、Idriss方法、传统方法、优化方法所得Rayleigh阻尼系数引起顶点位移和基底剪力计算误差.对于地震波的频谱特性，讨论了拟加速度反应谱、拟速度反应谱、位移反应谱的峰值频率和形心点频率的统计范围.数值计算结果表明：基于拟速度反应谱、位移反应谱峰值频率和形心频率以及Fourier谱的峰值频率所得Rayleigh阻尼将使计算结果偏小；用小于基本周期范围内的拟加速度反应谱的峰值频率或形心点频率作为第二个参考频率计算误差较小；当地震波的卓越频率大于基频的结构时，Idriss方法用平滑化Fourier谱的卓越频率计算参考频率效果更好；优化方法可以直接得到Rayleigh阻尼系数，避免了人为选取参考频率的任意性，且计算精度高.
To analyze the effects of Rayleigh damping coefficients reference frequency selection method on structural seismic response, some methods to estimate Rayleigh damping coefficients including the frequency contents-based second reference frequency, IDRISS method, traditional method and the optimization method were compared by the errors of top displacement and base shear with a 85.2 m length, 61.8 m width reticulated shell. As for the frequency contents of earthquake waves, the statistics ranges of the peak and centroid frequencies of pseudo-acceleration-, pseudo-velocity-and displacement response spectrum were discussed. The numerical results show that: the second reference frequency specified by the peak and centroid frequencies of the pseudo-velocity-and displacement response spectrum as well as peak frequency of the Fourier spectrum make the response results smaller than the exact ones. The estimation error is reasonable, which the second reference frequency is equal to the peak and centroid frequencies of the pseudo-acceleration response spectrum in the range below the fundamental frequency. It is suitable that the reference frequency is estimated by the smoothing peak frequency of the Fourier spectrum in the IDRISS method when the predominant frequency of earthquake wave is greater than the fundamental frequency of structure. Optimization method can get the Rayleigh damping coefficient directly, eliminate the arbitrariness of reference frequency and have high calculation accuracy.