基于相位差谱的空间相关非平稳地震动场的模拟

地震动的非平稳特性主要是由其相位差谱决定的,相位差谱与相位导数之间存在线性倍数关系。根据相位导数的显式计算公式,从能量的角度解释了相位导数的均值大致决定了时程峰值的发生时刻,相位导数的方差决定了强震段的持续时间。在相关地震动场模拟方法中,首次将相位差谱的统计模型引入空间相关非平稳地震动场的模拟方法之中,利用快速傅立叶变换技术生成地震动场。表示地震动随机特性的随机相位谱利用相位差谱的统计模型生成,生成的地震动场不仅具有空间相关性,而且在时域、频域内均具有非平稳特性。

Phase-difference-based simulation of spatial correlated and non-stationary seismic ground motions

The non-stationary characteristics of an earthquake ground motion are dependent on the phase difference spectrum, which is proportional to the phase derivatives. As viewed from the energy of acceleration time history, the time of PGA is related to the mean value of the phase derivatives while the duration of strong seismic ground motion is related to the variance of the phase derivatives. The empirical model of phase difference spectrum is introduced firstly into the simulation of spatial correlated and non-stationary ground motions. The simulated ground motions are expressed by the power spectra, coherence functions and random phase angles generated according to the empirical model of phase difference spectrum and are synthesized by discrete Fourier transform.