Seismic fragility of weir structures due to sliding effect

Abstract

The failure of hydraulic systems as flood defence structures can cause extensive catastrophic damage in upstream and downstream areas during an earthquake. Consequently, dams or weir structures as hydraulic systems must remain functional and operational during and after an earthquake. In recent years, in order to mitigate the risk or secure the safety of the hydraulic systems, the Probabilistic Seismic Risk Assessment (PSRA) has been issued as a key area of research. The primary objective of this paper was to evaluate the seismic fragility of weir structures by incorporating a nonlinear Finite Element (FE) model for the contact interfaces among weir-mass concrete-soil foundation in the weir structure. Gangjeong-Goryeon weir, located in Daegu Metropolitan City in the southeastern part of Korea was selected in this study. The seismic fragility of the weir structure corresponding to the sliding Limit State 13 mm (LS I) and 153 mm (LS II) was determined from multiple nonlinear time-history analyses based on Monte-Carol simulation accounting for the uncertainties such as material nonlinearity and ground motions with respect to near field faults and far field faults. The results showed that the sliding failure of the weir structure corresponding to LS I started from 0.1 g, but the weir system under LS II had no failure up to 0.4g. Besides, in the case of LS I and LS II, the weir subjected to both near field faults and far field faults was more fragile than that subjected to far field faults.