OPTIMUM DESIGN SENSITIVITY OF REINFORCED CONCRETE FRAMES

This paper presents design optimization of a two bay one storey reinforced concrete plane frame. Direct stiffness method was used for the structural analysis of the frame. The design variables were taken as the area of steel and the cross sectional dimension of the members. The design constraints on dimensions, strength capacities and areas of reinforcement were based on the specifications of Eurocode 2 (1992). A computer program was written using MATLAB to perform the optimization process. The optimal design results in cost savings of an average of 5.1% for the beam and 3.2% for the column. The decrease in cost is due to decrease in cross section as a result of optimization. The saving in cost is lower in the column. This can be attributed to the fewer number of design variables in column optimization. Expressions for computations of span effective depth and reinforcement ratios were obtained. Furthermore beam design charts were plotted for optimum design of reinforced concrete beams. The expressions and design charts based on optimum design concept will be valuable for preliminary and low cost design of reinforced concrete structures.