**2. Optimization**

The optimization process is used to achieve the best solution to a problem. This process is a clear alternative to designs based on experience. Optimization methods can be categorized into exact methods and heuristic methods. On one hand, the exact methods are based on mathematical algorithms that make it possible to obtain the global optimal solution [19]. On the other hand, the heuristic methods, which include a large number of algorithms [20], obtain an optimal solution starting from an initial solution. The exact methods are very useful in problems where there are a small number of variables, because the computing time becomes unworkable for a large number of variables. Structural optimization problems are defined for a large number of design variables and thus the heuristic method is the most useful for structural optimization. There are a large number of works that use heuristic algorithms for the optimization of different kinds of structures [8,9,21].
