An experimental study on the motion and structural characteristics of an interlinked spars' array

Abstract

In this paper, an array of two by two interlinked spars with elastic connectors is studied experimentally in order to identify the motion & structural responses, feasibility of this system. Hywind-OC3 spar is selected as the basic structure and the array is constructed with four floaters with five connectors and five mooring lines. The PVC pipe which outer diameter is 32mm is selected for the experimental model of connectors. Weight and bending stiffness are almost same as the prototype, while the axial stiffness is 5 times higher than that of prototype. Wave 1st motion absorber device is installed at the joint junction of each connector end and floater. Motion responses of floaters are measured by non-contact cameras, while tensions of connector ends, mooring lines are achieved from 1-axis load cell. Strains along the connectors are measured from both FBG sensors and electric resistant strain gauges. These measured results are compared with allowable stresses of ASTM-32 mild steel. Finally, sea-keeping ability and structural reliability of this new conceptual system is summarized. Copyright ？ 2015 by the International Society of Offshore and Polar Engineers (ISOPE).