Hydrodynamic analysis of a hybrid modular floating structure system and its expansibility

Abstract

ABSTRACT This paper reports a hybrid modular floating structure (HMFS) system preliminarily designed for mild marine environment. It is composed of a certain number of inner semi-sub modules and outermost box-type modules. The box-type modules are connected to adjacent semi-sub modules with hinges and additional Power Take-Off (PTO) damping systems. The hydrodynamic characteristics of several representative simplified serially connected HMFS systems under typical sea conditions are compared. The functions of the outermost module, the effects of different outermost module types and the expansibility of the HMFS system are emphatically analysed. The results indicate that compared with the outermost semi-sub module, the outermost box-type module is more effective in reducing the motion responses of inner semi-sub modules, connector forces and mooring forces. The additional PTO damping systems can produce substantial wave energy. The HMFS system shows good expansibility for mild sea zones. Abbreviations: HMFS, Hybrid Modular Floating Structure; VLFS, Very Large Floating Structure; RMFC, Rigid Module and Flexible Connector; MOB, Mobile Offshore Base; FEM, Finite Element Method; PTO, Power Take-Off; MFS, Modular Floating Structure; Ks, Pitch Elastic Stiffness; Kp, Pitch Damping Coefficient; DOF, Degree of Freedom; Fx, Horizontal Force of Connector; Fz, Vertical Shear Force of Connector; My, Pitch Bending Moment of Connector