Offshore wind energy offers a huge potential for expansion of renewable energy in the world. However, placement of wind turbines in harsh offshore environments is an engineering challenge, which requires development of suitable foundation to support turbines. Among 4 typical types of offshore foundations, monopile foundation is selected and designed for 2.3 MW offshore wind turbine (OWT) in Weihai, China, considering water depth, soil conditions, foundation cost and other factors. In a three dimensional (3D) finite element model of monopile, the layered seabed soil where the pile is embedded is considered in a soil-structure interaction formulation. Maximum stress and deformation of the monopile are computed under 4 load cases in different operating phases. The natural frequencies of the monopile foundation are given through the modal analysis. Results show that the designed monopile can effectively preclude resonance with the wind turbine. Moreover, the dynamic response of monopile foundation under wave and seismic loads are carried out by transient analysis method, the time histories of the deformation and stress are presented, and dynamic amplification factors (DAF) of maximum stress and deformation are discussed. It is suggested that the dynamic effect must be attached importance in the design.
Recently, wind energy, as the most practical substitute energy to replace the fossil fuel, has been dramatically used, due to its competitive cost of electricity and maturity of technology. Onshore wind energy has grown enormously over the last decade to the point. However, this expansion has not been without problems and the resistance to wind farm developments. One solution, of avoiding landuse disputes and to reduce the noise and visual pollution, is to move the offshore developments. However, placement of wind turbines in harsh offshore environments is an engineering challenge, which requires development of suitable foundation to support turbines.
