A NEW DESIGN APPROACH FOR STIFFENED PlATES TOWARDS WEIGHT AND COST SAVINGS

Abstract

The ship's hull structure is mainly built up of a large number of plate panels stiffened by rolled or built up identical equidistant stiffeners welded to the plate panel from the external side only. The main objective of the designer is to obtain a ship structure having a certain level of safety and reliability with a minimum weight and/or having a minimum total cost therefore, if the weight and cost of these plate panels could be reduced by good design tool this will lead to reduce the total weight of the ship hull and hence will certainly reduce its total cost, i.e, having a more economical design.

For this reason, the author put forward a new design approach for stiffened plates weight and cost saving. The suggested approach is based on designing the plate together with stiffeners using the constraint equation approach based on the failure criteria, i.e failure due to yielding and failure due to buckling. This structural design approach is followed by the cost analysis approach to calculate the total cost elements of building these stiffened plate panels. The author suggests combining the structural and cost analysis approaches in an iterative procedure by changing the thickness of the plate and hence the number of stiffeners to reach a stiffened panel that has a least weight and least total cost. The author developed a computer program to calculate the scantlings of the plate and stiffener as well as their weight and total cost.