Stochastic Simulation of Pulse-Like Ground Motions Using Wavelet Packets

Seismic near-fault ground motions with large amplitudes and long-period velocity pulses can cause significant damage to structures. In this study, a new stochastic model has been developed to simulate pulse-like ground motions for specified earthquake scenarios. Wavelet packet transform is employed to extract and model the velocity pulse. The parameters of the proposed model are fitted to Next Generation Attenuation (NGA)-West2 pulse-like ground-motion database. A group of predictive equations are established to predict occurrence time, frequency content, and total energy of the velocity pulse in terms of earthquake magnitudes, rupture distances, site conditions, and directivity parameters. The correlation relationships among the model parameters are also estimated to jointly simulate pulse and residual components based on specified earthquake scenarios. The model's capacity to stochastically simulate pulse-like motions is demonstrated by systematic comparison with real pulse-like recordings and existing ground-motion prediction equations. The proposed method can find applications in seismic analyses of key infrastructures in the near-field region.