INTEGRATED STRENGTH ANALYSIS SYSTEM FOR MAIN STRUCTURAL MEMBERS OF SHIPS

A recent tendency toward an increase in the size and speed of ships has brought about the new problem of structural strength and led to a new design concept different from any hitherto. Thus, it has become necessary to develop a direct structural analysis method by an integrated consistent system which takes in the latest theories in superseding the conventional method based on experiences. The authors have developed an integrated strength analysis system for the main structural members of a ship which involves the following two functions. 1. Hull girder strength analysis: This program is based on refined beam theory and strip method for calculation of seakeeping quality. It enables a statistical prediction of stress. 2. Tanker transverse strength analysis: Three-dimensional frame analysis and two-dimensional finite element methods are combined with a system for external and internal pressure calculation by strip theory. This system is useful for structural arrangement of various types and has a function of calculating fluctuating stresses in a design wave with a specified level of probability. In this report, the authors have applied this system to a 270,000 dwt tanker and a 200 meter container ship and confirmed that the method is sound and practical in designing the main structures of a ship.