Comparative Study of Hydroelastic Responses of Semisubmersible Type and Pontoon Type Very Large Floating Structure in Waves

Abstract

The hydroelastic responses of two very large floating structures, semisubmersible type and pontoon type having same displacement and same flexural rigidity, are analyzed and compared in this study. Three dimensional hydrodynamic forces are calculated by using singularity distribution method in which the symmetries of structure were exploited. By combing the mode analysis based on FEM, the deflections are estimated. Some numerical results are compared with experiments and an overall good coincidence has been obtained over wide frequency range.The distribution of hydrodynamic force, vertical displacement and bending moment at different positions are shown. Furthermore, the analysis are also extended to oblique wave conditions, it is found that the two structures have different response each other due to their different characteristics in deformation mode and interaction with fluid. Finally, some investigations are done as for short crested irregular waves, the influence of principal direction and directional distribution of waves are discussed and the significant and maximum value of deflection are shown for both two models.