Experimental and numerical study on impact resistance of offshore wind turbine CFDST jacket

With the development of large-scale offshore wind turbines (OWT), the jacket foundation widely used to offshore wind turbines are at significant risk of collision damage from vessels and sea ice. In order to improve the impact resistance of hollow steel tube jacket foundation, a new type of concrete-filled double-skin steel tube (CFDST) jacket foundation is proposed. From the analysis of impact force, displacement, acceleration and energy consumption, the peak strain and acceleration of the jacket leg at the impact position are reduced by 57.1 % and 50.4 %, respectively. The deformation mechanism and failure mode of the two foundations under multiple impact loads were obtained by combining LS-DYNA software and test. After two impacts the hollow steel tube jacket was seriously dented and damaged in bending. However, after multiple pendulum impacts on a concrete-filled double-skin steel tube, only the supporting struts were bent, the indentation depth and displacement peak of the jacket leg are reduced by 76.9 % and 72.2 %, respectively, and the entire structure showed excellent impact resistance, overall bending stiffness and energy dissipation capacity. Finally, the experimental basis and theoretical analysis are provided for the application of concrete-filled double-skin steel tube jacket in large offshore wind turbines and the resistance to impact loads.