采用时频滤波技术的近断层脉冲地震人工模拟

利用现代时频分析工具S变换的时频滤波特点,把反映场地局部特征的实际远场地震波或人工合成的远场地震波在等效速度脉冲的发生时间段实行时频滤波,再与等效速度脉冲叠加,生成既能反映场地局部特征又能反映近断层脉冲地震特点的人工近断层脉冲地震时程.通过数值算例,得到的人工近断层地震波与原始波有相似的时频特征,而功率谱密度函数在高频段与建筑抗震规范相容的目标功率谱一致,该波的峰值加速度还与抗震规范中相应烈度的峰值一致,可供近断层地区结构抗震分析使用.

Generation of artificial near-fault ground motions based on time-frequency filtering

S transform is one of the effective modern time-frequency analysis techniques.A new method of applying S transform to generates artificial near-fault ground motions is presented.The artificial near-fault ground motions are simulated by combining filtered real or artificial far-fault ground motions by time-frequency filter with equivalent pulse,which can reflect the local characteristics of site and the pulse characteristics of near-fault ground motions.Numerical analysis shows the time-frequency characteristics of artificial near-fault ground motions are similar to that of parents ground motions,and the power spectrum density(PSD) in high frequency range is compatible with a target PSD of code for seismic design of buildings of China.The peak ground acceleration(PGA) of artificial near-fault ground motions are identical to the PGA corresponding to earthquake intensity in this code.So the artificial near-fault ground motions presented in the paper can be used for seismic analysis of the structures in near-fault seismic zone.