Research on an improved dynamic analysis method for performance-based probabilistic hazard analysis of structural demand parameters in high arch dams

Abstract

The influence of ground motion selection and dynamic analysis methods on the seismic fragility and risk analysis of high arch dams has not been sufficiently investigated in existing studies. The widely adopted Incremental Dynamic Analysis (IDA) method often fails to adequately capture the variations in ground motion characteristics across different seismic intensity levels, which can result in significant discrepancies in the arch dam's responses. Additionally, due to complex damage patterns under strong seismic events and insufficient empirical data, inconsistencies persist in evaluating seismic damage indices for high arch dams. To address these issues, an improved IDA method that considers hazard consistency is proposed. The robust Multiple Stripe Analysis (MSA) was used as a benchmark to refine the IDA method, incorporating hazard consistency and improving analytical efficiency. The correlation between residual displacement gradient (RDG) indices and the overall and localized damage indices was further analyzed, enabling unified quantification of damage thresholds for the Baihetan arch dam at various limit states. The improved IDA method proved effective in assessing seismic risk within a defined scaling range, but it was observed to overestimate seismic demands at low exceedance probability levels and in severe damage states. Establishing unified performance levels and objectives for high arch dams is recommended to provide a more reliable foundation for identifying damage states and making informed reinforcement decisions under strong earthquakes.