MODELS FOR OPTIMAL-DESIGN OF REINFORCED-CONCRETE BEAMS

This paper outlines the design economics, cost function and modelling of optimal design of reinforced concrete beams for different design conditions. It is shown that there can be large variations in the cost of a beam depending on the unit cost of the materials and shuttering, the beam dimensions and the reinforcement ratio. As there are an infinite number of alternative beam dimensions and reinforcement ratios that yield the same moment of resistance, it becomes difficult to achieve the least-cost design by the conventional methods. This paper presents a geometric programming model which gives the unique least-cost design of a beam, considering the cost of materials and shuttering and the structural requirements. Application of this new design technique is illustrated with example problems.