An evolutionary power spectrum model of fully nonstationary seismic ground motion

A parametric evolutionary power spectrum model of fully nonstationary seismic ground motion is developed based on the evolutionary spectrum estimation method via generalized harmonic wavelets. The model consists of a frequency-domain energy distribution function and a series of normalized time-dependent envelop functions for different frequencies. The frequency-domain energy distribution function describes the spectral characteristics of the seismic ground motion. The nonstationarity is achieved by the normalized time-dependent envelope functions. For a specific seismic ground motion record, the evolutionary power spectral density (EPSD) is estimated via generalized harmonic wavelets. The parameters are identified by letting the model approximate to the estimated EPSD of the realistic ground motion. By using the spectral representation method, the proposed EPSD model can be used to synthesize the artificial seismic ground motion time histories for engineering purposes.