Simulating nonstationary and non-Gaussian vector ground motions with time- and frequency-dependent lagged coherence

Seismic ground motions at multiple sites are nonstationary and non-Gaussian with potentially time- and frequency-dependent coherence, although the nonstationarity or non-Gaussian or time-dependent coherence aspects are often neglected because of lack of algorithm or method to take all these aspects into account to simulate synthetic ground motion records at multiple sites. In the present study, an iterative power and amplitude correction algorithm is proposed to simulate the nonstationary and non-Gaussian vector process and takes into account time- and frequency-dependent coherence. The algorithm usually converges within 10 iterations. It can be viewed as the extension of the well-known iterative amplitude adjust Fourier transform algorithm for generating a vector of surrogates. The proposed algorithm uses the S-transform and discrete orthonormal S-transform rather than the ordinary Fourier transform. The adequacy of the proposed algorithm is validated numerically by using simulated ground motions.

Automated summary

An iterative algorithm is proposed in this study to simulate nonstationary and non-Gaussian seismic ground motions, considering time- and frequency-dependent coherence, and its adequacy is numerically validated using simulated ground motions.