en Optimal design Optimal design پژوهشي Research <span style="font-size:11.5pt"><span new="" roman="" style="font-family:" times="">In this article, the optimum design of a reinforced concrete solid slab is presented via an efficient hybrid metaheuristic algorithm that is recently developed. This algorithm utilizes the mouth-brooding fish (MBF) algorithm as the main engine and uses the favorable properties of the colliding bodies optimization (CBO) algorithm. The efficiency of this algorithm is compared with mouth-brooding fish (MBF), Neural Dynamic (ND), Cuckoo Search Optimization (COA) and Particle Swarm Optimization (PSO). The cost of the solid slab is considered to be the objective function, and the design is based on the ACI code. The numerical results indicate that this hybrid metaheuristic algorithm can to construct very promising results and has merits in solving challenging optimization problems.</span></span><br> &nbsp; mouth brooding fish, cost optimization, meta-heuristic algorithms, colliding bodies optimization, solid slab, reinforced concrete. 545 555 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-66-354&slc_lang=en&sid=1 D. Sedaghat Shayegan dshayegan@hotmail.com 180031947532846002715 180031947532846002715 Yes Department of civil engineering, Roudehen Branch, Islamic Azad University, Tehran, Iran