【摘要】 分别采用窗口滑移、Kameda多重滤波和Nakayama窄带滤波方法得到El Centro NS地震记录的渐进谱,经比较,选择Nakayama方法用于本文的渐进谱研究。分析了有限带宽白噪声、强度非平稳时程与实际地震记录的渐近谱,发现可从渐进谱分布规律的角度解释这些时程的特性差异。在Nakayama方法基础上建立了一个地震动合成模型,指出地震动时程的幅值和频率非平稳应同时与渐进谱和时频非平稳的相位相关。由本文和Kameda模型合成时程与实际地震动记录的渐进谱和相位的对比分析表明,依照本文模型合成时程的渐进谱和相位同时表现为时频非平稳,这与实际地震记录的特性完全相符。更多还原

【Abstract】 The moving window method,Kameda multi-filter and Nakayama narrow band-pass filter were applied to obtained the El Centro NS evolutionary power spectra evaluation.The comparison shows that the Nakayama method is the best in reflecting the non-stationary characteristics of this earthquake wave.The investigation results on the differences among band-limited white noise process,artificial earthquake accelerogram with non-stationary amplitude and actual earthquake record revealed that these differences can be explained from the view point of evolutionary spectra distribution in time-frequency domain.Furthermore,on the basis of Nakayama method a new model for generating earthquake accelerogram was proposed.According to this model,the non-stationary characteristics both in amplitude and frequency of an earthquake accelerogram are related to not only the evolutionary spectrum but also the time-dependent phase angle.The comparison of evolutionary power spectra and time-varying phase angles of actual earthquake record with the artificial accelerograms produced by Kameda model combined with the proposed model demonstrates that the spectra and phase angle are non-stationary both in time and frequency domains,which are essentially identical to the characteristics of actual earthquake record.更多还原