Seismic performance analysis of concrete dams considering the coupled effects of wavelet asymmetry and incident direction under near-fault ground motions

The seismic performance of concrete gravity dams under near-fault ground motions was investigated in this study by considering the coupled effects of wavelet asymmetry and incident direction. A total of 21 as-recorded near- fault pulse-like motions were analyzed, and their corresponding non-pulse motions were extracted using the wavelet decomposition method for comparison. A typical concrete dam model system was established and used for the nonlinear numerical analyses of 84 trials under both pulse-like and non-pulse motions with two incident directions. Key nonlinear dynamic response indicators, including damage volume ratio, damage distribution, and displacement, were determined and evaluated. Thus, novel dimensionless intensity measure (IM)-based wavelet asymmetry parameters (WAIM) and asymmetric response indices (AREDP) were developed. Quantitative relationships between the IM-based, pulse-based parameters, and AR EDP were described, identifying the optimal index for characterization with and without pulse features. The results showed that acceleration-based parameters correlate more strongly with asymmetric responses than velocity-based parameters, with the optimal wavelet asymmetry index (WAENA) being linked to the energy of the entire acceleration time history. Additionally, a multivariable response prediction model incorporating the proposed WA ENA index and pulse parameters was developed to accurately evaluate the asymmetric responses to various near-fault motion scenarios. These findings provide valuable insights and an effective framework for estimating the potential maximum responses of concrete gravity dams to various seismological parameters of near-fault motion.