A NOTE ON THE STATIONARY MODEL OF EARTHQUAKE INDUCED GROUND MOTION WITH A HU SPECTRUM

摘要

The Hu spectral model, a modified Kanai-Tajimi spectral model for the stationary stochastic process of earthquake ground motion, is analyzed. According to the Hu spectral model, the spectral density function of the Kanai-Tajimi spectrum is modified only during the low frequency range and in good accordance with the Kanai-Tajimi spectrum during the moderate and high frequencies. It is proved that the earthquake-induced ground acceleration process with the Hu spectrum is essentially the result of which a filtered Gaussian white noise process on the rock is filtered by the overlaying soil represented by a linear single-freedom-degree system,namely it is a twice filtered white noise process. This shows that the Hu spectral model is not only concise in the mathematical expression but also distinct in physical meaning and reasonable in practice. Furthermore, the low frequency control factor which determines the low frequency contents in Hu spectral model is investigated and evaluated from the observation data of earthquake ground motion.