Hydrostatic Stiffness as Displacement Boundary Condition of Floating Cylindrical Structural Analysis in Waves

Abstract

Motion analysis is one of the mandatory aspects to predict the performance of a floating structure, as well as how its structural strength under certain wave load. However, in majority of floating body performance prediction, the calculation of motion and strength performance is done separately. Practically, engineers calculate the motion and hydrodynamics forces that work on the structure, then do separate calculations on the structure to predict structure’s strength. These separate calculations often use assumptions that tend to be unrealistic, either over-constrained or under-constrained. This paper provides an alternative to the constraint problem by introducing hydrodynamic stiffness as boundary conditions, instead of using fixed or simply supported boundary conditions, spring boundary conditions are applied with hydrodynamic stiffness of floating body properties. It is expected that this model provides a more realistic constraint to the future analyses. The results achieved are very promising, where the boundary condition resulting a close natural frequency approximation compared with the analytical calculation. This configuration is hoped to be the baseline of more complex structure to be carried out in future research, in order to represent a more realistic structural displacement boundary condition.