中文摘要：

强地面运动作为复杂的非平稳信号由多个不同频率信号组成,它的频谱中有多个交叉项。正交化HHT（Hilbert-Huang Transform）法的局部时频特性使它成为非平稳信号局部谱估计的一种好方法。本文针对近断层脉冲型地震动和远场软土层场地类谐和地震动这两类特殊的长周期地震动,分别选取1999年台湾集集地震TCU068台站的NS分量地震动和ILA056台站的EW分量地震动进行了正交化HHT分析,同时选用工程界广泛使用的El-Centro波NS分量进行比较。通过对二条典型的特殊长周期地震动时程以及El-Centro波NS分量时程的局部谱密度、频率局部特性、能量分布和峰值系数的分析与比较,得到了有应用价值的结果。

英文摘要：

As a complex non-stationary signal,the strong ground motion is composite with lots of different frequency signals and its frequency spectrum has many cross terms.The orthogonal Hilbert-huang Transform（HHT） becomes a good method to estimate the local spectral density of non-stationary signal because of its local time-frequency characteristics.The special long-period seismic wave TCU068-NS was selected to analyze the characteristic of near-fault pulse type long-period ground motion,and the seismic wave ILA056-EW was selected to analyze the characteristic of harmonic-like type long-period ground motion.The two special long-period seismic waves are from 1999 Taiwan chi-chi seismic records,and the general seismic wave El Centro-NS was selected to comparative study.The orthogonal HHT method was adopted to study the local spectral density,frequency local characteristic,energy distribution and peak coefficient of the two special long-period seismic waves and the general El Centro-NS wave.A significant conclusion is drawn on the energy distribution of special long-period ground motion and its variation.