地震动非平稳性与幅值谱和相位差谱的关系  

ON THE RELATIONSHIP OF EARTHQUAKE GROUND MOTION'S NON - STATIONARITY WITH ITS AMPLITUDE SPECTRUM AND PHASE DIFFERENCES SPECTRUM

作　　者：赵凤新[1] 胡聿贤[1] 

机构地区：[1]国家地震局地球物理研究所

出　　处：《地震工程与工程振动》1994年第2期1-6,共6页Earthquake Engineering and Engineering Dynamics

摘　　要：本文将地震动时程视为非平稳的随机过程,通过将其分解为一系列窄频带波包的方法,讨论了地震动强度及频率非平稳性与幅值谱和相位差谱的关系,并着重分析了相位差谱及其均值和方差对地震动非平稳性作用的机制。An earthquake ground motion time history is a function of its Fourier amplitude and Fourier phase spectrum. For a given Fourier amplitude spectrum, different phase spectrum can produce widely different time histories. For the purpose of simulating design earthquake ground motions which have the properties of non -stationarity of real accelerations in both amplitude and frequency contents,it is very fundamental to make clear the mechanism about how amplitude spectrum and phase spectrum affect the non -stationarity of time history because the influence of non -stationarity on the dynamic response of structures, especially nonlinear structures, can not be neglected. In recent years, the significance of phase differences spectrum in certain properties of envelope functions of earthquake ground motions has been emphasized. In this paper,the relationship between the non - stationarity of earthquake ground motion in both amplitude and frequency contents and the factors such as amplitude spectrum and phase differences spectrum is deduced by means of modeling earthquake ground accelerations as a non - stationary random process and regarding a time history as the addition of a series of narrow band components containing a certain frequency of Fourier spectra. Special attention is paid to the mechanism that the mean value and variance of phase differences spectrum cause the non -stationarity in amplitude and frequency contents of earthquake ground motions. The results indicate that when the mean value of phase differences spectrum approximates constant,the time history is stationary in frequency contents. At this time,amplitude spectrum and phase differences spectrum affect the intensity function of time history independently. Phase differences spectrum is decisive to the shape of intensity function and the influence of amplitude spectrum is negligible. On the other hand,if the mean value of phase differences spectrum is dependent on frequency,the time history will be non -stationary in frequency contents and the influence

关 键 词：地震动 非平稳性 幅值谱 相位差谱 

分 类 号：P315.4[天文地球—地震学]