The importance of corner frequency in site‐based stochastic ground motion models

摘要: Synthetic ground motions (GMs) play a fundamental role in both deterministic and probabilistic seismic engineering assessments. This paper shows that the family of filtered and modulated white noise stochastic GM models overlooks a key parameter—the high‐pass filter's corner frequency, fc$f_c$. In the simulated motions, this causes significant distortions in the long‐period range of the linear‐response spectra and in the linear‐response spectral correlations. To address this, we incorporate fc$f_c$ as an explicitly fitted parameter in a site‐based stochastic model. We optimize fc$f_c$ by individually matching the long‐period linear‐response spectrum (i.e., Sa(T)$Sa(T)$ for T≥1s$T \ge 1\,{\rm {s}}$) of synthetic GMs with that of each recorded GM. We show that by fitting fc$f_c$ the resulting stochastically simulated GMs can precisely capture the spectral amplitudes, variability (i.e., variances of log(Sa(T))$\log (Sa(T …