Dynamic Response due to Breaking Wave Impact Force on an Offshore Wind Turbine Support Structure

Abstract

Dynamic response due to breaking wave impact force on an offshore wind turbine support structure is investigated, especially the effects of higher modes. From comparison between two representative breaking wave impact force models, i.e. the Goda model and the Wienke model, it is clarified that their impulse response functions in the low-frequency region and high-frequency region reverse their magnitudes. For convenience in the primitive design stage, a procedure for prediction of the dynamic response by a breaking wave impact force acting on a support structure is proposed using the impulse response function. By taking only a few vibration modes, the maximum values of the section forces on the support structure can be estimated without any cumbersome time dependent analyses. Furthermore this paper proposes an approximation of the curling factor in terms of the surf similarity parameter.