Research On The Dynamic Response Of A New Type Of Multi-module Floating Structure Under Wave Action

In contrast with conventional bottom-connected marine structures,floating structures have many superiorities,such as less foundation bearing capacity requirement,easier construction,more efficient in water exchange and space utilization,etc.Consequently,they have attracted widespread attention in the fields of coastal and ocean engineering.At the present stage,it is the urgent need to carry out research on the dynamic response and the wave dissipation capacity of the floating structures,aiming to ensure the structural safety and the water calm within the cover region in rough sea conditions.Summarizing existing multi-module floating structure forms,a new type of multi-module floating structure is proposed.It comprises of a number of serially arranged box-type floating modules.The adjacent modules are connected at top corners using hinge connectors,and rubber fenders are arranged at bottom corners to absorb collision energy.Based on the smoothed particle hydrodynamics(SPH)method,a numerical model for simulating the interaction of nonlinear waves with the proposed multi-module floating structure is then built.Physical experiment in terms of a multi-module floating structure is performed to validate the established numerical model.Within the process of establishing the numerical model for nonlinear waves and the multi-module floating structure interaction,three categories of floating structures are involved.From simple to complex,they are the free-floating structure,the moored floating structure and the multi-module floating structure.In order to improve the computational accuracy of the fluid force,a corrected density calculation approach for the solid boundary particle is developed,which successfully mitigates the pressure fluctuation due to the large density gradient in the vicinity of the solid boundary.With this method,a numerical wave tank is built,and the motion responses of a free-floating structure under nonlinear waves are calculated.Through combining a massless spring model,the numerical model is developed to simulate the interaction of nonlinear waves with a moored floating structure.And further combinations of a newly developed hinge force model and a calculation method of fender force lead to the establishment of nonlinear waves and multi-module floating structure interaction model.Employing the established and validated numerical model,a systematic study concerning the motion response,the structural load and the hydrodynamic performance of the proposed multi-module floating structure is investigated,and parameter studies of gap width,mooring angle and module number are performed.The following main conclusions are drawn:the width of a multi-module floating structure should longer than the incident wavelength;a relatively steady floating platform,which meets the operational requirements,can be formed by increasing the number of floating modules so as to increase the total width of a multi-module floating structure;the multi-module floating structure provides good shelter for the leeside region on condition that it has a relatively long width;decreasing the gap width and increasing the mooring angle both promote the stability of the multi-module floating structure.