Simulation of a Moored Multibody Offshore Structure Articulated by Different Joints in Waves

Abstract

Abstract Within the framework of the Space@Sea project, a modular floating structure (MFS) was developed to serve as building blocks for artificial islands. The modularity was one of the key elements, intended to provide the desired flexibility of additional deck space at sea. Depending on the purpose of a modular floating concept, various articulation techniques, such as hinge, prismatic, cylindrical and screw joints can be applied to connect MFSs. This paper presents numerical simulations of moored and articulated multibody offshore structures in waves, via a coupled mooring-joint-viscous flow solver accounting for mooring dynamics, joint restrictions, nonlinear rigid body motions, and viscous flow effects. The considered concepts consisted of two MFSs connected by two kinds 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 indicated that surge motions of the articulated bodies were almost identical to each other, whereas the effects of the joint on heave motions were not pronounced. However, highly dynamic pitch motions between two hinged MFSs were observed. Apart from motion responses, forces acting on the hinge joint and the mooring lines were considered. The coupled mooring-joint-viscous flow solver demonstrated its ability to predict responses of moored and articulated offshore structures in waves.