拟合D-V-A联合谱及各项峰值的人造地震动

An Artificial Earthquake Ground Motion′s Generation Method for Matching Combined D-V-A Spectrum and Target Peak Values

结合D-V-A联合谱的宽频带特点及传统人造地震动方法在拟合各项峰值方面的局限性,提出了一种可同时拟合D-V-A联合谱及各项峰值的人造地震动新方法。根据小波变换的原理,在时-频域将天然地震波加速度时程进行分解,确定对峰值加速度(peak values of acceleration,简称PGA)和峰值位移(peak values of displacement,简称PGD)贡献最大的小波分量,对其初步调整后拟合D-V-A联合谱及PGA,PGD值;在此基础上,通过在时域叠加小波函数对加速度时程进行小幅度修正,提高D-V-A联合谱的拟合精度,同时对峰值速度(peak values of velocity,简称PGV)贡献最大的小波分量进行振幅调整,拟合PGV值;循环执行多次后,生成的人造地震动可同时拟合D-V-A联合谱及PGA,PGV和PGD值。算例结果表明,该方法得到的地震动加速度、速度和位移时程不仅对目标反应谱及各项峰值均具有较高的拟合精度,且对天然地震波的改动较小,可用于生成高质量的人工地震波。

According to the broad-band characteristics of a combined D-V-A spectrum and the limitations of traditional methods in artificially generating earthquake ground motion on the fitting of peak values, this paper proposes a new method for matching a combined D-V-A spectrum and all the peak ground values. Based on wavelet principles, a natural ground motion record was discomposed into wavelet components in a time-frequency domain. The wavelet components that mostly affected the peak values of acceleration (PGA) and peak values of displacement (PGD) were identified to modify the natural ground motion's peak values and preliminarily match the combined D-V-A spectrum. Then, the time domain wavelet synthesizing method was applied to modify the generated artificial ground motion to match the combined D-V-A spectrum with the peak values of velocity (PGV). After iteration, the artificial ground motion precisely matched the combined D-V-A spectrum with the target PGA, PGV and PGD values. The results of a numerical example showed that the generated ground motion, which includes acceleration, velocity and displacement time histories, well fit the target spectrum and every peak value with little impact on the natural earthquake ground motion. This suggests that the proposed method can be used to generate high-quality artificial earthquake ground motion. © 2016, Editorial Department of JVMD. All right reserved.