Free transverse vibration of ocean tower

• Dynamic behavior of ocean tower undergoing free transverse vibration is studied.
• It is modeled as non-uniform Timoshenko beam with non-classical end conditions.
• Results are found using Rayleigh Ritz Method and compared with FEM.
• Parametric study is done for different configurations of the tower.

This paper studies a continuous, elastic model of an ocean tower, partially submerged in water, undergoing free transverse vibration in a plane. The tower is modeled as a non-uniform Timoshenko beam which is supported by an eccentric tip mass on one end and a non-classical damped foundation on the other. The foundation is modeled as a combination of translational and rotational springs and dampers. The effect of shear deformation and rotary inertia is included in the analysis. The free vibration equation is derived using Hamilton׳s variational principle based on two approaches, Rayleigh Ritz Method (RRM) and Finite Element Method (FEM), which show a good agreement in results. The computational efficiency of RRM over FEM is shown using a convergence study. Finally, a parametric study is done to demonstrate the dependence of natural frequency on different configurations of the tower.