近断层脉冲型地震动的降维模拟

Dimension Reduction Simulation for Near-field Fault Pulse-like Ground Motion

提出一种近断层脉冲型地震动模拟的降维方法,将近断层脉冲型地震动分解为高频和低频2个部分:采用谱表示与随机函数方法生成高频加速度时程,并转化为相应的速度时程;采用Gabor小波模拟低频速度脉冲时程,将高低频的速度时程叠加得到合成的地震动速度时程,并转化得近断层脉冲型地震动的加速度和位移时程。结果表明:用3个基本随机变量模拟的近断层脉冲型地震动时程,可以反映近断层脉冲型地震动的方向性效应、速度大脉冲等特征,进而可为近断层区域工程结构的随机地震反应和抗震可靠度分析提供合理的输入。

A dimension reduction method for the simulation of near-field fault pulse-like ground motions is proposed.The near-field fault pulse-like ground motions are decomposed into two parts,including high-frequency component and low-frequency component.The spectral representation-random function method is used to generate the time-series of high-frequency acceleration,which is then converted to the corresponding velocity time-series.The Gabor wavelet is used to simulate the time-series of low-frequency velocity pulse.And the time-series of high and low frequency velocity are superposed to get the synthetic velocity time-series of ground motion,which are then transformed to obtain the acceleration,displacement time-series of near-field fault pulse-like ground motion.The calculating example shows that the time-series simulated by this method with only three basic random variables can reflect the characteristics of the near-fault pulse-like ground motion,such as directivity effect and large velocity pulse,and thus can provide reasonable input for the random seismic respond and aseismic reliability analysis of engineering structures in the near-field fault region.