Use of Conditional Generative Adversarial Nets to Generate Power Spectral Density Function and Its Application for Sampling Seismic Ground Motions

ABSTRACT Simulated ground motions play a crucial role in seismic engineering applications. The present study introduces a novel conditional generative adversarial networks (CGAN) based model to generate the time‐frequency representation of the ground motions and to use the iterative power and amplitude correction (IPAC) algorithm, referred to as the IPAC‐CGAN method, to simulate the nonstationary non‐Gaussian ground motions for scenario events. The proposed CGAN‐based model is trained using time‐frequency representations derived from recorded ground motions originating from strike‐slip fault earthquakes, obtained via the S‐transform. It effectively captures the power distribution in the time‐frequency domain for specific scenario events. Unlike prior GAN‐ or CGAN‐based models in the literature, which assume fixed durations across scenarios and lack control over the marginal probability density function (PDF) of sampled records, our approach innovatively adapts ground motion duration to earthquake magnitude, rupture distance, and site conditions. The IPAC‐CGAN method enables the generation of ground motions with durations that vary according to earthquake magnitude, rupture distance, and site conditions, which were usually fixed for all scenarios in the model developed based on GAN or CGAN in the literature. The combination of the IPAC algorithm and CGAN ensures accurate replication of the nonstationary, non‐Gaussian characteristics observed in actual seismic records, while in the literature, there is no control on the marginal PDF of the sampled record. Validation of the proposed method involves comparing pseudospectral acceleration statistics between simulated and actual ground motions. Predicted values from ground motion models are also considered for comprehensive assessment. Additionally, ductility demand comparisons for single‐degree‐of‐freedom systems using the Bouc–Wen hysteretic model are conducted using simulated and recorded ground motions. In all cases, the results show that the statistics of the linear and nonlinear responses of the simulated ground motions agree well with those of the recorded seismic ground motions. This validation underscores the effectiveness of the proposed method in accurately simulating realistic seismic ground motions.