Seismic fragility of arch dams based on damage analysis

Seismic fragility provides a measure for evaluating the safety margin of structures above specific hazard levels. This study investigates the seismic fragility of arch dams using the dynamic damage analysis model of dam-reservoir-foundation systems, in which the radiation damping of semi-unbounded foundation rock, opening of contraction joints, and damage cracking of dam concrete are taken into account. The 210 m-high Dagangshan Dam in Southwest China is analyzed as a case study. Five hundred nonlinear damage analyses are performed using the Monte Carlo simulation technique considering both epistemic and aleatory uncertainties, which are characterized by random material parameters and ground motions, respectively. Three limit states, i.e., slight damage, moderate damage, and severe damage, are proposed according to the calculated damage distribution and joint opening, and seismic fragility curves are subsequently generated using the incremental dynamic analysis approach. Analysis results show that the Dagangshan Dam may be severely damaged by strong earthquakes when uncertainties in material parameters and ground motions are considered.