In this paper, hydroelastic responses of the very large floating structure are studied based on linear potential theory. A theoretical method is developed to analyze the hydroelastic responses of very large floating structure(VLFS) using pressure distribution method and modal expansions of structural motion. The singularities are distributed over the structure of a zero draft plate on the free surface and hydrodynamic pressures are evaluated. The integral equation is formulated by the Green function in case of finite water depth. The deflections of structure are approximated by an modal expansion in terms of natural mode functions of free-free beam. The effects of water depth, bending rigidity, relative length of regular waves, and directions of waves on the response of hydrodynamic pressure and deformation of structure are examined. The calculated items are pressure distributions, vertical motions and bending moments over a mat. The calculated results for thin plate of a pontoon type are compared with the experimental ones.
Structures of box-type are surrounded by breakwaters to minimize motions by waves. The typical configuration of the pontoon type is characterized by large horizontal dimensions compared with the draft and incident wave. To analyze dynamic responses of a VLFS, the deflections due to elastic motion must be considered. A number of studies have been made for predicting behaviors of motion of VLFS(Yago & Endo, 1996; Kashiwagi & Furukawa, 1997; Shin et al., 1999). In these studies, the pressure distribution and the source and dipole distribution method were used for calculating hydrodynamic forces. The other method to reduce computing time was proposed based on the velocity potential continuation method for diffraction and radiation problem(Nagata et al., 1997; Ohmatsu, 1998). Also the modal expansion method and finite element method were used to calculate the elastic response.
