A STUDY ON THE LOCAL JOINT FLEXIBILITY (LJF) OF TUBULAR K-JOINTS IN JACKET SUBSTRUCTURE OF OFFSHORE WIND TURBINES UNDER AXIAL LOADING

In recent years, there is a strong trend to shift the wind farm activities to offshore. Offshore wind energy utilization has several attractions. A significant advantage of offshore wind energy is the stronger wind spectra which is stronger and steadier than the onshore wind energy (Li and Ren, 2010). Further, in comparison with the onshore wind turbines there is some different ways to installation offshore wind turbines (OWT) that using a jacket foundation is one of them. So because of some shortages in the marine regulations, knowledge of design techniques for jacket foundation has evidently come to sharp focus today. The local joint flexibility (LJF) in the analysis of tubular structures has been recognized as having an effect on the global static and dynamic responses of offshore structures for decades. This local deformation would lower the strength requirement on the joint by redistributing the member-end loads and moments compared with the conventional rigid joint. For this purpose, it is necessary to determine the local joint flexibility for tubular joints with a reliable method (Gao et al. 2013).