Dynamic Analysis of Small Scale Floating Structure by Ship Wave Force

A floating structure has many options for effective ocean space utilization, for instance, the well known floating airport project, called Mega-Float. But after the end of the project, small scale floating structure began to be paid to attention. As the good example of such a kind of floating structure, there is the floating restaurant named “WATERLINE” (Figure 1) in Tokyo Bay. “WATERLINE” is small scale floating structure, and it is moored at the Tennoz Canal that is the closed water area. Therefore, when the ship passes around the floating restaurant, ship wave forces give a great influence on dynamic behavior of floating restaurant. As for ship waves, several studies have been made on the wave resistance and influence on ship handling concerning ship waves, but it is hardly to find papers focused on influence that ship wave forces give to dynamic behavior of small scale floating structure. In this research, dynamic behavior of small scale floating structure by ship wave forces was studied through both theoretical and experimental approach. As for the theoretical analysis, the equations of the Boussinesq type to treat shallow water area were adopted, and ADI (Alternating Direction Implicit) method in a numerical calculation was used for the analysis of these equations. And the floating structure was assumed to be a rigid body, and the displacement responses by ship wave forces were analyzed. With regard to experimental study, dynamic behavior of “WATERLINE” and wave height by the ship wave were actually measured. This measurement data is a profitable basic data for other researchers and engineers in order to analyze a floating structure. In the present paper, the validity of the numerical calculation program for ship wave response analysis was verified by the comparison between calculation results and the measurement results, the characteristics of the displacement response and the wave height were discussed by the numerical results that had been obtained by changing by the ship’s speed and the distance between floating structure and the ship. In addition, the evaluation of habitability in vertical motion of the small scale floating structure at the canal was examined by the diagram proposed from our research results [1], [2]. And, in regard to the ship that passes over around floating structure, ship’s speed limit and minimum distance between the ship and the floating structure were proposed.Copyright © 2009 by ASME