拟合多维能量反应谱及峰值速度的地震动调整方法

基于小波变换原理提出了一种以设计用多维能量反应谱及峰值速度为目标的实测地震动调整方法.该方法首先依据多维能量反应谱与伪加速度谱之间的近似转换关系,在时域内叠加小波函数实现对实测地震动记录的初步调整,保留原始地震动的强度、频率非平稳特性;再应用二阶基数B-样条小波函数模拟上述调整后的多维地震动场,通过循环调整拟合精度较低频段的小波系数和对峰值速度贡献最大的小波分量,实现对设计用能量反应谱及各向峰值速度的同时拟合.算例分析结果表明,该方法具有较高的拟合精度,对初始地震动的能量分布改变较小,为建筑结构基于能量平衡设计时的多维动力反应分析提供了一种新的地震波合成方法.

A Modification Method of Earthquake Ground Motions for Matching Multi dimensional Energy Input Spectra and Peak Velocity

The paper presents a modification method for the recorded earthquake ground motions to match multi-dimensional design input energy spectra with wavelet.According to the approximate relationships between input energy spectra and pseudo acceleration response spectra,the recorded earthquake ground motions are modified to match the target response spectra preliminarily by synthesizing wavelets in time domain.In this process,the non-stationary intensity and frequency characteristics of real records have retained.Then the second cardinal B-spline wavelet is used to simulate the multi-dimensional accelerograms.By modifying the amplitudes of special wavelets of low fitting accuracy and the wavelets affecting peak values of velocity mostly,the target input energy spectra and peak ground values of velocity can be matched by iterations.The numerical example demonstrates this method is of high-fitting precision with few changes to the original energy distribution,which is a new artificial ground motions’ generating method for dynamic analysis of structures designed by energy balance.