Estimation of near-fault strong ground motions for key engineering structures

The strong motion database of Western US for different site conditions is reviewed in this paper. A new source spectral model is developed from Brune's ω2model and Atkinson's two-corners model. Associated parameters are estimated by statistical analysis on the Fourier spectra of the recorded strong motions. The spectral differences between small and strong earthquakes are described not only in amplitude and corner periods, but also in the shapes that were revealed by the recordings. Based on this new source spectral model, different ground motion estimation methods including finite-fault method, point-source method, and the method based on random vibration theory are applied to simulate ground motions of the Northridge (Mw= 6.7) earthquake. It is concluded that the finite-fault effect should be considered in the near-source ground motion estimation.