Deriving seismic fragility curves for sheet-pile wharves using finite element analysis

Seismic fragility curves represent the seismic vulnerability of structures and are used to quickly evaluate structural damage in earthquakes. In this study, seismic fragility analyses for the sheet-pile wharves of Port of Hualien, Taiwan were performed. Representative earthquakes in Taiwan were scaled to various levels of peak ground acceleration (PGA)as the input motions. Nonlinear finite element analyses were performed using PLAXIS 2D for the seismic responses of sheet-pile wharves, and the modelling approach was verified to be satisfactory by simulating a 1-g scale-model shaking table test. According to the thresholds of the displacement of sheet-pile wall for different damage states, the conditional exceedance probabilities of each damage state at various PGA levels, namely, the fragility curves, were obtained. They were approximated by lognormal cumulative distribution function and were parameterized for rapid estimate of earthquake loss. Furthermore, the damage probabilities of the studied sheet-pile wharves during a M_L 6.2 earthquake occurred in Hualien in 2018 were estimated using the parameterized fragility curves, and a realistic result was obtained.