Strength investigation of a small size floating dock unit by 3D-FEM models in head design waves

This study is focused on floating docks strength analysis by 3D finite element models, full extended over the dock length. The equilibrium position of the dock in the design equivalent quasi-static waves environment is obtained by own code, based on a non-linear iterative procedure. For the surrounding water and ballast tank water loads we have developed user procedures and functions implemented in the finite element programs. Also the still water conditions are analysed. The numerical study is developed for a small size floating dock, designed for multiple shipyards operation, with 60 m length and two constructive versions, having continuous and non-continuous side ballast tanks. As main operation cases of the small size floating dock are considered: light without docking ship, full ballast at maximum upper deck limit, three docking ship tests, with ship mass uniform, sagging and hogging type distributions, according to the shipbuilding classification societies rules. As assessment criteria, the 3D model yielding stress limit for global and local strength, buckling factor and maximum vertical deflection are considered. Also the freeboard criterion is considered. The results of the study are delivering the operation limits, in terms of design wave height, in order to ensure the strength safety rules requirements.