Long-term extreme responses of torsional moments at two-directional hinges for moored very large floating structures

This paper presents an analysis procedure for estimating long-term extreme torsional moments at connections of very large floating structures (VLFS) with two-directional hinges and mooring lines under random waves. This procedure, compared to the common short-term estimation method, can accurately and quickly calculate the extreme response at a certain return period. Applying a coupled frequency-time domain approach, we simulate the hydroelastic response of VLFS with two-directional hinges and vertical mooring lines. In order to validate the proposed approach, numerical simulations are firstly carried out under the action of regular waves. The present approach demonstrates a high level of consistency with experimental data and numerical results from existing studies in terms of vertical displacement, bending moment and shear force. Then, on the basis of the short-term extreme response distribution and environmental model, a procedure for solving long-term extreme responses of the structure is introduced. The long-term extreme response characteristics of the torsional moment at hinges are evaluated and studied in depth using the procedure, providing a reference for the structural design of moored VLFS with two-directional hinges.