Analysis of Offshore Structure with Concrete Piles

In the scope of this study, structural behavior of the offshore platform whose substructure is modeled by piles is determined according to different fluid-structure interaction analysis methods. Bilateral fluid-structure interaction is primarily performed in the analyses. Flow around the structure is modeled by Stokes 5 wave theory which is an example of nonlinear wave theories. Velocity profile of Stokes 5 wave theory is modeled by using Abaqus/CFD solver in the bilateral fluid-structure interaction. While the marine environment of the fluid is modeled by Abaqus/CFD solver, the platform is modeled by Abaqus/Explicit solver. Fluid-structure interaction (FSI) is provided by the interaction of two solvers. Sensitivity analysis that determines number of nodes and elements in the finite elements model is performed through modal analysis. Displacement and stress values are obtained as well as the modal behavior of the structure by finite elements analysis. Wave velocity profiles are determined by both numerically and visually by bilateral interaction analysis and flow structure around the structure is observed. Secondarily, unidirectional fluid-structure interaction analysis is performed in the study. In this analysis, the structure is modeled as semi analytical multi degree of freedom (MDOF) system. Wave velocities are calculated by Stokes 5 wave theory same as in the case of the first method. Wave forces are numerically determined by Morrison equation. These forces constitute the external force in the equation of motion. Displacement and natural frequency values of the structure are determined by the equation of motion. The compatibility between the results of both analyses is observed.