Dynamic Analysis of Offshore Monopile Wind Turbine Including the Effect of Scour

An engineering approach to dynamic analysis of an offshore monopile wind turbine is presented in this paper. The interactions between the foundation and the soil are simulated by nonlinear springs, which stiffnesses are obtained from the axial load transfer (t-z) curve, the tip load-displacement (Q-z) curve and the lateral load-deflection (p-y) curve. Three types of soil conditions are considered in the simulations; 100% sand layer, 50% sand layer (top) and 50% clay layer (bottom), as well as 100% clay layer. Wind, wave and current loads on the wind turbine in operational conditions are taken into account. The variation of the dynamic responses of the wind turbine due to the effect of scour is investigated by comparing the results between the cases with and without scour.