Analysis of Non-stationary Earthquake Ground Motion Energy Changing Based on Orthogonal HHT Theory

It is necessary to describe earthquake ground motion with local spectral density, which is time-dependent and can reflect the non-stationary characteristics. the approach using the orthogonal HHT to estimate local spectral density is provided in the paper as a complementarity of HHT. Comparisons of estimating precision and speed are carried out between orthogonal HHT and HHT. The study shows that orthogonal HHT is a universal method avoiding leakage of energy compared with conventional HHT. Then, the study illustrates that the local power spectra estimated by orthogonal HHT are able to reveal the temporal-frequency energy distribution for earthquake recordings precisely and clearly. It is concluded that the proposed OHHT approach is more aapropriate than the traditional HHT approach for analyzing non-stationary earthquake ground motion.