Analysis of a Moored and Articulated Multibody Offshore System in Steep Waves

Abstract

Wave-induced motions and loads on a moored and articulated multibody offshore structure are numerically analyzed, where a coupled mooring–joint–viscous flow solver is used to count for mooring dynamics, joint restrictions, nonlinear rigid body motions, and viscous flow effects. The considered concepts consist of two modular floating structures (MFSs) connected by two types of connections, namely, a rigid joint and a flexible joint, and positioned by four symmetrical catenary mooring lines. The analyzed responses comprised multibody motions as well as associated forces acting in the hinged joints and the mooring lines. Results indicate that surge motions of articulated bodies are almost identical to each other, whereas the effects of the joint on heave motions are not pronounced. However, highly dynamic pitch motions between two hinged MFSs are observed. Apart from motion responses, forces acting on the hinged joint and the mooring lines are estimated. The importance of wave nonlinearity and higher order components is identified by studying waves with different steepness. The coupled mooring–joint–viscous flow solver demonstrates its capability to predict wave-induced motions and loads on a moored multibody offshore structure articulated by various types of joints.