Modeling the vibration control of floating units by tuned mass damping structures in marine environment using spectral method

Abstract

Civilization in the marine environment has been developing since the ships and harbors were constructed. The dynamic behavior of seas and oceans brings some limitations to constructions in the marine environment. Today's static structures are designed considering the dynamic impacts originating from wind and earthquakes. This dynamic interaction inspires the interaction between water waves and floating structures in the marine environment. Recent studies focus to overcome the stability problem of floating structures against wave action. This thesis analyzes the interaction between water waves and a floating structure. The equation of motion and the Morison equation are combined to represent the behavior of the floating structure under regular and irregular wave conditions. Tuned-mass-damper (TMD) is added to the system to stabilize the wave response of the floating structure. Linear wave theory is used to model water waves, we obtain the initial wave field by spectral transformations starting from Bretschneider-Mitsayusu Spectrum. Using the initial wave field, a realistic linear wave model is obtained by the $4^{th}$ order Runge-Kutta time integrator. Under regular wave conditions, analytical and numerical results of the floating structure without TMD are compared to validate the numerical method. TMD system is solved with numerical iteration. Under regular and irregular wave conditions, the reaction of the floating structure with and without TMD is discussed, while the reaction of the floating structure and TMD is compared for the TMD system. The results show that TMD absorbs the dynamic effect of the waves, reducing the wave response of the floating structure. Therefore, the floating structure becomes more stable.