AbstractAn optimal drift design model for the steel moment frames under the seismic load is presented. The objective function of the proposed drift design model is to minimize the differences of the inter-story drifts so that the interstory drifts of the structure could be reduced. This model uses a constraint condition not to change the weight of the structure before and after the application of the presented method. This method resizes all or partial structural members consisting of the structure according to the values of displacement participation factors of the corresponding member. The efficiency of this algorithm is demonstrated by the application to a 3-story steel moment frame. It is concluded that the proposed method can determine the sectional properties of structural members to reduce the interstory drifts of the structure without the iterative structural analysis.