An improved optimum design method for reinforced concrete frames using integrated genetic algorithm(GA) with direct search method is presented. First, various sets of initially assumed sections are generated using GA, and then, for each resultant design member force condition optimum solutions are selected by regression analysis and direct search within pre-determined design section database. In advance, global optimum solutions are selected from accumulated results through several generations. Proposed algorithm makes up for the weak point in standard genetic algorithm(GA), that is, low efficiency in convergence causing the deterioration of quality of final solutions and shows fast convergence together with improved results. Moreover, for the purpose of elevating economic efficiency, optimum design based on the nonlinear structural analysis is performed and therefore makes all members resist against given loading condition with the nearest resisting capacity. The investigation for the effectiveness of the introduced design procedure is conducted through correlation study for example structures.