Wavelet packets-based simulation of non-stationary multivariate ground motions

This study proposes a novel approach to simulate non-stationary multivariate earthquake accelerograms for the seismic analysis of extended structures. This approach is based on an extension of the traditional stochastic decomposition technique applied to the wavelet packet theory using the spectral representation method. Using the advantages of a wavelet packet to identify the time and frequency characteristics of ground motion effectively, the generated recordings successfully reflected the non-stationarity in both the time and frequency domains. Accordingly, the spatial correlation trend was consistent with the selected coherence function. Compared to the ground motions observed using the traditional method, the proposed approach was exemplified by simulating ensembles of ground motions at three points spaced 200 m apart. The multivariate ground motions simulated by different methods were applied as multi-support excitations for the dynamic time-history analysis of a 190 m continuous rigid-frame box girder bridge. Notable variations in structural response were observed when considering the non-stationarity of the frequency domain, contrasting with the cases where it was not taken into account. This study provides an effective approach for generating non-stationary multivariate earthquake accelerograms, which is of great significance for structural response analysis in engineering applications.