| Offshore wind power is always concerned in the new energy field currently. Seismic analysis of an offshore wind turbine plays an important part for its design. And finite element method is a complicated process involving many respects. As there are few researches about seismic dynamic response of an offshore wind turbine as so far, it is necessary to explore an effective method for the dynamic calculations of it.In this paper, under the background of a project, seismic dynamic response is analyzed of a system consisted of a bucket foundation wind turbine structure and soil foundation. A finite-infinite element coupled model is built, consisted of blade, nacelle, tower, bucket foundation and soil foundation. Using infinite element boundary simulates infinite soil foundation and eliminates wave reflection at the boundary and contact element simulates SSI effects(soil-structure interaction). Static analysis is carried out before dynamic calculation. And take the stress field from the static calculation as an initial condition for dynamic calculation. In order to understand the dynamic characteristics of the wind turbine, the model analysis for the wind turbine structure is carried out and the effects of SSI for vibration characteristics are summarized. Under the coupled loads of seismic, wind loads and wave loads, the dynamic calculation for the finite element model was carried out through time domain analysis, in which the equivalent linear dynamic constitutive model which can reflect dynamic characteristics of soil is implemented. And the dynamic response of acceleration, displacement, stress, internal forces and contact forces is analyzed after the dynamic calculation. At last, transient liquefaction of the soil foundation is determined through anti-liquefaction shear stress method.The results are more real as take the offshore wind turbine structure and the soil foundation as a whole model. Solutions for soil dynamic constitutive model and SSI effects are proposed. An effective method of seismic response analysis for offshore wind turbine is explored. So this paper can be a reference for seismic design and research about offshore wind turbine. |
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