Optimum Design of Composite Concrete Floors Using a Hybrid Genetic Algorithm

Composite steel–concrete floors are used commonly in bridge decks and as story floors in different kind of buildings. This paper presents optimal design of composite floors consisting of steel joists and a concrete slab on the top of them. The slab thickness, typical joist spacing, and the standard steel section size of joists are considered as design variables. The objective function is the cost of unit area of composite floor including cost of materials and labors for reinforcement, concrete, formwork and steel joists. AISC-ASD89 and EURO-4 (EN 1994) code provisions are considered to define design constraints. A hybrid algorithm based on a modified genetic algorithm is implemented to solve the optimization problem. The effect of many design parameters such as unit cost of materials and characteristic strength of concrete on the optimum solution is investigated using a practical design example.