Performance assessment of wind turbines in near-fault mountain regions subjected to physics-based simulated earthquake ground motions

In recent decades, wind turbines (WTs) have experienced unprecedented growth, and their increased installations in mountainous regions has significantly elevated the associated seismic risk. However, the understanding of seismic wave propagation and ground motion attenuations, particularly considering source-path-site effects, remains limited, becoming a key bottleneck in the seismic design of WTs. To address this, this paper assesses the seismic performance of WTs by analyzing the combined effects of seismic source characteristics, wave propagation paths, and local site conditions, and proposes a novel method for assess site effects on WTs in mountainous regions using scenario-based earthquake simulations. In the methodology, the frequency-wavenumber (FK) method is employed for the semi-analytical solution of deep crustal Green's functions, the spectral element (SE) method for efficient large-scale wave field simulations, and the finite element (FE) method for detailed structural modeling of WT responses. The resulting FK-SE-FE approach enables a full-process physics-based simulation from fault rupture to the structural response. Using the Jishishan M_S6.2 earthquake as a case study, near-fault ground motions are synthesized to evaluate the influence of mountainous' terrain on the seismic response of WTs. Results indicate that the presence of the mountain during seismic wave propagation significantly increased the overall seismic response of the structure, with the tower-top displacement of the mountain-top WT being amplified by up to 2.56 times compared to the mountain base. Additionally, the continuous ridge effect led to an increased peak ground acceleration at the mountain base, but the overall amplification effect is more pronounced at the mountain top. These findings provide valuable insights for enhancing seismic design codes and developing risk mitigation strategies for WTs in complex terrains.