The computation of prismatic structures, applied to naval architecture

Abstract In shipbuilding, most long vessels (barges, oil tankers, bulk carriers, etc.) are substantially prismatic in shape in the central region of their structure. These vessels have geometrical characteristics which make their calculation difficult, especially when the shell and plate panels which compose them are heavily stiffened. One of the most challenging aspects of these structures is the computation of stresses and displacements (stress analysis). Consequently, the objective of this study was to develop a tool which allows the computation of such structures, reducing to the greatest extent the simplifications and approximations related to the representation of the structural geometry, the loading and the interdependence of the various elements (such as shell plating, stiffeners, deck beams, web frames and stringers). To analyse the behaviour of each stiffened panel, the stiffened sheathing software L.B.R.-3 is presented, as well as some specific developments required for shipbuilding design. This is a new analytical method using Fourier series expansions to solve the differential equations of orthotropic prismatic shells. Using as an example the stress analysis of a tanker, the L.B.R.-3 software demonstrates its utility and efficiency in giving easily accurate stresses and displacements at every point of the structure.