Semnan University Press Journal of Rehabilitation in Civil Engineering 2345-4415 14 3 2026 08 01 Design Optimization of Strongback Braced Steel Frames Incorporating a Novel Drift Uniformity Constraint 10511 10.22075/jrce.2025.2515 EN Ehsan Jahankhani Ph.D. Candidate, Department of Civil Engineering, Semnan University, Semnan, Iran Omid Rezaifar Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran 0000-0002-4753-7775 Majid Gholhaki Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran Peyman Homami Associate Professor, Faculty of Civil Engineering, kharazmi University, Tehran, Iran Journal Article 2025 11 04 This study investigates the optimal seismic design of a six-story steel frame equipped with three Strongback bracing configurations, characterized by brace-to-beam intersection ratios of , , and  of the span. A Genetic Algorithm (GA) developed in MATLAB was integrated with OpenSees to perform linear static analyses while enforcing a set of design constraints, one of which is a newly introduced drift-uniformity constraint aimed at regulating the distribution of inter-story drifts. A comparative assessment of the three configurations reveals distinct behavioral trends. In the unconstrained optimization, the differences in total structural weight among the configurations remain moderate 0.61% between  and  span, 12.27% between  and , and 11.73% between  and . When the drift-uniformity constraint is included, these differences increase to 4.17%, 25.56%, and 28.55%, respectively, highlighting the pronounced sensitivity of Strongback systems to geometric configuration and showing that brace-to-beam intersection location plays a decisive role in their stiffness-redistribution behavior. The effect of the drift-uniformity constraint varies across the three configurations: it leads to weight reductions of 2.47% and 6.95% in the - and -span arrangements, respectively, while producing a moderate increase of 14.96% for the    span case. Despite this variation, all three systems exhibit improved drift profiles when the constraint is applied. Overall, the findings demonstrate that geometric configuration strongly influences the efficiency of Strongback action, and the proposed drift-uniformity constraint serves as an effective and novel design feature capable of refining drift distribution while maintaining competitive structural weight. https://civiljournal.semnan.ac.ir/article_10511_58072f9a20f4d1766f5366ab463dc080.pdf