A parametric study of a flexible ocean tower

Offshore compliant structures are a valuable and attractive option for conditions involving operation in deep water because of their reduced structural weight. One class of offshore compliant structure is the articulated tower, which does not use guylines or tethers to provide a restoring force; rather, the articulated tower relies on a large buoyancy moment to maintain its orientation. This paper examines a continuous, elastic model of an articulated tower undergoing planar motion. Forces due to gravity, buoyancy, and waves are considered, and the nonlinear governing equations of motion derived using Hamiltonʹs Principle. These equations of motion are discretized using the finite difference method, and solved numerically. A proposed simplification of the derived elastic equations is presented, and the simplified model is shown to provide a good upper bound on the motion and a good picture of the qualitative behavior. A parameter study on the tower system is performed, demonstrating the stability of the tower system in the presence of different environmental loads and under different tower configurations.