Shaking table tests on seismic responses of offshore wind turbines considering fluid-soil coupling

Increasingly more offshore wind turbines (OWTs) have been constructed in coastal regions frequently rocked by earthquakes with the rapid development of offshore wind power generation. Earthquakes pose a severe threat to the safety of OWTs. To reveal the fluid-soil-wind turbine interaction mechanism, soil free field, fluid-soil free field, rigid-foundation wind turbine, fluid-rigid-foundation wind turbine, soil-wind turbine, and fluid-soil-wind turbine models test were conducted on OWTs considering the fluid-soil coupling. The results show that different water depths exert little influence on the amplification factor of the free field under the horizontal seismic action. The fundamental frequency of the rigid-foundation wind turbine decreases while its dynamic responses increase with the increasing water depth. Compared with the rigid-foundation wind turbine, considering the soil-structure interaction (SSI) reduces dynamic responses of the wind turbine. Whether considering SSI or not, the deeper the water, the more significant its influence on the dynamic responses of the wind turbine, which are also more significantly affected by the spectral characteristics of ground motions.