A study for estimation method of seismic design input motion considering the phase characteristics on scattered wave

本研究的目标是：1)建立一种分析基岩和土层随机介质中散射波影响的数值方法；2)建立一种考虑散射波相位特征的抗震设计估计方法。研究结果总结如下：(1)基于射线理论，提出了一种新的分析路径上各向异性散射的数值方法。该方法得到的能量分布与常规能量粒子法得到的能量分布一致。发现群延迟时间的方差与震源距离的平方成正比。(2)提出了一种基于R/T矩阵法的随机介质中考虑散射波的地面响应分析新方法。结果表明，介质的随机性对散射波的影响小于土层边界的随机性对散射波的影响。(3)基于谱随机有限元法的波在随机介质中传播特性数值分析新方法。该方法的优点是还能给出分布形状。为均值和方差值。该方法的结果与蒙特卡罗方法的结果一致。该方法的计算时间比蒙特卡罗方法要小得多。(4)研究了以群延迟时间定义的非平稳地震动响应特性。结果表明，当幅值傅立叶谱为定值时，可以估计出系统响应值的分布。

The objectives of this research are, 1) to develop a numerical method for analyze the effects of scattered wave occurred in the random media of bedrock and soil layers, and 2) to develop a estimation method for seismic design considering phase characteristics on scattered wave. The results of the research are summarized as follows;(1) A new numerical method is developed to analyze anisotropic scattering on the path based on the ray theory. The energy distribution obtained by the method is consistent with that by the conventional energy particle, method. The variance of the group delay time is found to be proportional to the squared hypocentral distance.(2) A new numerical method is developed to analyze the ground response considering the scattered wave in the random media based on R/T matrices method. The results of the method show that the effect of scattered wave occurred from the randomness of the media is smaller than that form the randomness of the boundary between soil layers.(3) A new numerical method to analyze the characteristics of wave propagation in a random media based on the spectral stochastic finite element method. The advantage of the method is to give the distribution shape as well. as the mean and variance value. The results of the method is consistent with that of Monte Carlo method. The computation time for the method is much smaller than that for the Monte Carlo method.(4) The characteristics of the response against the non-stationary ground motion defined by group delay time are examined. The result show the possibility to estimate the distribution of response value of SDOF system if the amplitude Fourier spectrum have a constant value.