Improved endurance time analysis for seismic responses of concrete dam under near-fault pulse-like ground motions

Abstract

This study aimed to modify the Endurance Time Analysis (ETA) method using a novel prediction model to evaluate the seismic demands of concrete dams subjected to near-fault pulse-like excitations. To this end, a two-dimensional concrete gravity dam–reservoir–foundation system was employed in the numerical model. Twenty as-recorded pulse-like (original) ground motions were decomposed into representative low- and high-frequency components using the continuous wavelet transform method. The contributions of these components toward the dynamic responses under different intensity measures were investigated, based on an Incremental Dynamic Analysis (IDA). The effect of Peak Ground Acceleration (PGA) on the responses was considered, and the response prediction model was further modified, including some dimensionless parameters. Coupled with the response results under residual motion obtained via the ETA method, the estimated response under pulse-like motion can be derived using the proposed ETA prediction method. Based on a comparison of the average results of the IDA and improved ETA methods under pulse-like motion, the average error was found to be approximately 10%. Furthermore, 10 as-recorded earthquakes were used to verify the proposed procedure. The results revealed that the ETA method can be applied to pulse-like motions, which reduces the calculation time and contains pulse properties.