The evolutionary structural optimization (ESO) method has been under continuous development since 1992. Originally the method was conceived from the engineering perspective that the topology and shape of structures were naturally conservative for safety reasons and therefore contained an excess material. To move from the conservative design to a more optimum design would therefore involve that the low stressed part of the design space is removed by Finite Element Analysis (FEA).The Classical ESO method follows the concept of removing the lightly stressed elements which can be either at the boundary or within the structure. Modified ESO is based on the same concept but removes the elements which are only on the boundaries, modifying only the existing boundaries. By using the Classical ESO and the Modified ESO methods appropriately, the time in the optimization is reduced, and inefficient elements of the structure is removed sensitively. The optimal design by that method is compared to other results by bi-directional evolutionary structural optimization (BESO ). This study deals with several structures, which are box girder, two-bar frame structure, Michell type structure and so forth.
