en Optimal design Optimal design پژوهشي Research <span style="font-size:12pt"><span style="text-justify:inter-ideograph"><span new="" roman="" style="font-family:" times="">Colliding Bodies Optimization (CBO) is a population-based metaheuristic algorithm that complies physics laws of momentum and energy. Due to the stagnation susceptibility of CBO by premature convergence and falling into local optima, some meritorious methodologies based on Sine Cosine Algorithm and a mutation operator were considered to mitigate the shortcomings mentioned earlier. Sine Cosine Algorithm (SCA) is a stochastic optimization method that employs sine and cosine based mathematical models to update a randomly generated initial population. In this paper, we developed a new hybrid approach called hybrid CBO with SCA (HCBOSCA) to obtain reliable structural design optimization of discrete and continuous variable structures, where a memory was defined to intensify the convergence speed of the algorithm. Finally, three structural problems were studied and compared to some state of the art optimization methods. The experimental results confirmed the competence of the proposed algorithm.</span></span></span><br> &nbsp; Colliding Bodies Optimization, Sine Cosine Algorithm, Structural Design, Discrete and Continuous Optimization, Metaheuristic Algorithms. 17 38 http://ijoce.iust.ac.ir/browse.php?a_code=A-10-66-360&slc_lang=en&sid=1 M. Ilchi Ghazaan ilchi@iust.ac.ir 180031947532846002560 180031947532846002560 Yes School of Civil Engineering, Iran University of Science and Technology, P.O. Box 16846-13114, Iran A.H. Salmani Oshnari 180031947532846002561 180031947532846002561 No School of Civil Engineering, Iran University of Science and Technology, P.O. Box 16846-13114, Iran A. M. Salmani Oshnari 180031947532846002562 180031947532846002562 No School of Civil Engineering, Iran University of Science and Technology, P.O. Box 16846-13114, Iran