A new integrated system of ship structure analysis has been developed. This system consists of five sub-systems of hydrodynamic analysis / automatic load data generation / structural analysis / statistical processing / strength assessment. After a brief introduction of the system outline, special features of each sub-system are described. This integrated system assists ship structural designers in enhancing the structural reliability through "design by analysis" method and will play an active role in designing ship structures with high reliability in accordance with increasing demands among shipping communities.


The recent large-scale oil pollution accidents have brought double hull oil tankers into existence, and the serious casualties in bulk carriers have brought enhanced surveys, structural reinforcements, etc. Today, it is one of increasing demands among shipping communities to enhance the degree of safety and reliability of ship structures. Structural design of conventional ships such as oil tankers and bulk carriers has been, so far, based on "design by rule" method, where nominal strength is assessed in comparison with past experiences and records. Recent remarkable advancement of computer and engineering technology, however, makes it possible to perform "design by analysis", where absolute strength is assessed by simulating actual structural behaviors as close as possible. The newly developed system called MISTRAL (= Mitsui Integrated system of STRuctural And Load analysis) can simulate the structural response by integrated analyses, i.e., direct load analysis of ships in operation, structural response through interface program from the obtained load, statistical processing and strength assessment. History of this kind of integrated computer systems for ship structure analysis goes back to about 20 years before. The first generation (Akita et al., 1974) is direct longitudinal strength analysis system based on beam theory integrating ship motion analysis and statistical processing.

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