Rule-based optimization of midship structures

A rule-based overall design methodology for midship structures of small inland waterways vessels is presented. It is shown how the designer, under conflicting requirements, can select the optimum design by using a combined objective function with priority factors assigned to individual design criteria. The concept of optimization, in large-scale structural design problems, is extended to the local members (the stiffening elements) of the ship structure, so that the stiffeners can be specified by their actual dimensions instead of section moduli. The effects of price-structure (labour rate to material price ratio) and the choice of type of stiffener on design are investigated. Standard sections and optimized fabricated sections are taken as the alternative options for selecting the stiffeners. Conversion of exact mathematical optimum solutions into production-oriented designs is also demonstrated in a series of practical applications of the proposed method.