en Optimal design Optimal design پژوهشي Research <span style="font-size:11.5pt"><span new="" roman="" style="font-family:" times="">This study presents a cost optimization approach for simply supported one-way ribbed slabs, with the primary objective of minimizing concrete and reinforcement costs. A Genetic Algorithm (GA), implemented in MATLAB, is utilized to address this optimization problem. The optimization model incorporates seven discrete design variables: rib dimensions (spacing, bottom/top width, and height), topping slab thickness, flexural reinforcement diameter, and concrete compressive strength. For validation, an initial optimization based on ACI 318-08 with six variables demonstrated a 3% cost reduction compared to established algorithms. To ensure practical relevance, subsequent optimizations incorporated actual market conditions utilizing the 2025 Iranian Building Construction Price List. Transitioning to ACI 318-19 resulted in a 10% increase in optimal cost relative to ACI 318-08, primarily due to stricter shear strength provisions. To mitigate this increase and enhance design efficiency, concrete compressive strength was introduced as a seventh design variable. This expanded optimization was evaluated across spans ranging from 5 to 8 meters, yielding a further 4.4% cost reduction for a 6-meter span. Conclusively, the results demonstrate that the strategic application of higher-strength concrete, informed by real-world market prices, significantly reduces the overall cost of one-way ribbed slab construction.</span></span> Optimization, Optimal design, Ribbed slab, Genetic algorithm, ACI 318-19 573 594 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-6463-41&slc_lang=en&sid=1 A. Sheikhalishahi 180031947532846002874 180031947532846002874 No Department of Civil Engineering, Yazd University, Yazd, Iran B. Ahmadi-Nedushan Behrooz.Ahmadi@yazd.ac.ir 180031947532846002875 180031947532846002875 Yes Department of Civil Engineering, Yazd University, Yazd, Iran