瑞利阻尼矩阵对深厚场地地震反应的影响分析

介绍场地时域分析基本理论和几种常见的阻尼矩阵确定方法,并基于有限差分方法,采用实际地震记录,考虑输入地震动强度和频谱特性,分别选择5种不同的瑞利阻尼矩阵形式,比较分析其对深厚场地时域动力反应的影响。结果表明:不同阻尼矩阵对加速度和反应谱均有影响,影响程度和输入地震动的频谱特性有关;当土层基频接近输入地震动卓越频率时,只根据土层基频确定阻尼矩阵是可行的,但当输入地震动卓越频率高于或远高于土层基频时,该方法会严重低估地表加速度峰值和反应谱谱值,时域分析中阻尼的确定应综合考虑土层特性和地震动频谱特性。

Effect of Rayleigh Damping Matrix on SeismicResponse Analysis of Deep Soft Soil

This paper deals with the effect of the Rayleigh damping matrix on site response analysis in the time domain. We introduce the fundamental theory of time domain analysis and summarize several methods for constructing a damping matrix. In our study, we to developed a series of numerical models to simulate wave propagation through an elastic medium after using the finite difference method to consider the intensity and spectral characteristics of the input motions. We adopted a full Rayleigh damping and selected five methods to determine the high frequency. The results show that damping models have a significant influence on acceleration and spectral acceleration, and their degree of influence is related to the frequency characteristics of the input motions. When the fundamental site frequency is close to the predominant frequency of the input motions, it is feasible to determine the damping matrix based on this consideration only. However, the peak ground acceleration and spectral value are underestimated when the predominant frequency of the input motion is high or far higher than the fundamental site frequency. In time domain analysis, damping considerations should include the site frequency and frequency characteristics of the input motions.