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Modeling of earthquake phase spectrum using a stochastic deferential equation and development of a simulation method of earthquake motion form phase spectrum

使用随机微分方程对地震相位谱进行建模并开发地震运动形式相位谱的模拟方法

基本信息

批准号：
16360230
负责人：
SATO Tadanobu
金额：
$ 9.54万
依托单位：
Kobe Gakuin University (2006)Waseda University (2005)Kyoto University (2004)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Both the amplitude and phase characteristics of earthquake motion provide key information needed to evaluate the aseismic capacity of designed structures. A method to simulate phase spectra is one of challenging topic in the design standard which is used to generate design earthquake motions compatible with the design spectra. We present a simple method for modeling the phase characteristic of earthquake motion based on group delay time and wavelet analysis. First the phase spectra are modeled for near and far source regions. Existing data sets of observed earthquake motions and wavelet analysis are used to calculate the group delay time of each earthquake motion. Regression equations for the mean group delay time and standard deviation of group delay time are obtained as functions of the earthquake's magnitude, epicenter distance and several source parameters. Simulating sample phase spectra assuming Gaussian nature of group delay time, earthquake motions compatible with the design response spectra then are simulated, and their characteristics investigated using ductility demand spectra. Second we develop a method to simulate realistic earthquake motions from phase spectra. The essential requirement of non-stationary time function such as earthquake motion is the causality. Because of this nature of earthquake motion its amplitude and phase cannot be assigned independently to simulate realistic earthquake motions. The restriction to be place on its phase spectra, however, has not been clearly defined to simulate a causal earthquake motion when its Fourier amplitude is given apriori. We develop a method to simulate earthquake motions from a given phase spectrum taking into account the causality restriction. Third we discuss a new method to simulate group delay time using the stochastic differential equation.

地震运动的幅值和相位特征为评价设计结构的抗震能力提供了关键信息。相谱模拟方法是设计标准中的难点之一，用于生成与设计谱相适应的设计地震运动。提出了一种基于群延迟时间和小波分析的地震运动相位特征简单建模方法。首先对近源区和远源区进行了相谱建模。利用已有的地震观测数据集和小波分析计算了每次地震的群延迟时间。得到了群延迟时间均值和群延迟时间标准差随地震震级、震中距离和几个震源参数的回归方程。模拟假定群延迟时间为高斯性质的样品相位谱，模拟符合设计响应谱的地震运动，并利用延性需求谱研究其特性。其次，我们提出了一种用相谱模拟真实地震运动的方法。地震运动等非平稳时间函数的本质要求是因果关系。由于地震运动的这种性质，它的振幅和相位不能独立地赋值来模拟真实的地震运动。然而，当它的傅立叶振幅是先验的时，还没有明确规定对其相谱的限制来模拟因果地震运动。我们开发了一种方法来模拟地震运动从一个给定的相位谱考虑到因果关系的限制。讨论了一种用随机微分方程模拟群延迟时间的新方法。