摘要：A discrete optimization problem for minimizing the sum of fabrication cost and steel material cost of sf^el frames under constraints based on Japanese seismic code is set up. Enhancements of the genetic algorithm for the above-mentioned problem are proposed, which are combined with a 1D （one-dimensional） search or a 2D （two-dimensional） search. After the proposed methods are described, they are applied to a five-story frame. A comparison with an exact solution obtained by a revised enumeration algorithm demonstrates the effectiveness of the proposed methods.