Fourier amplitude spectrum model for strong ground motion

Three kinds of Fourier amplitude spectrum models for earthquake accelerogram are proposed in this paper, which can be widely used in acclerogram synthesis. Model I can be deduced from the equation of motion of the SDOF system with bandlimited white-noise input. The shape of this model is similar to the Kanal-Tajimi spectrum model. Model II originates from Model I, but an additional filter is added before the input, hence Model II is similar to the Clough-Penzien spectrum model. The same derivation method is used in Model III as Model I, but the inertia force is depicted by the pseudo acceleration, of which the treatment was first used in the power spectral density (PSD) of earthquake ground accelerations by S. Matsuda and K. Asano. All the above models have been applied to earthquake acceleration's Fourier amplitude spectrum analysis. The investigations demonstrate that Model III is superior to the other two models for the better fitness and narrow coefficients' confidence interval.