Seismic fragility of offshore wind turbine considering scour depth

The geological conditions in the eastern coastal areas of China are complex, and the saturated soft clay around the offshore wind turbine foundation may be affected by the local erosion and dynamic water pressure conditions around the pile under the cyclic action of earthquake and waves. In this study, a nonlinear dynamic model of offshore wind turbine considering earthquake hydraulic pressure and scour effects was established. A total of 34 earthquake records were selected based on the site target response spectrum. Based on the multi-band analysis method, the seismic vulnerability curves of offshore wind turbine under various working conditions were obtained, and the influence of earthquake hydro-dynamic pressure and scour depth on the seismic vulnerability of offshore wind turbines was discussed further. The results indicate that under the seismic fortification intensity, the scour depth has a significant impact on the normal operation of offshore wind turbine under seismic load, but has marginal effect on the permanent failure of wind turbine. By comparison, the hydrodynamic pressure has little effect on the seismic vulnerability under different limit states. The vulnerability analysis of offshore wind turbine can serve as a guidance for the seismic design of offshore wind turbine.