Most of the time, the resistance structures who have not been statically determined, cut to the right sized, and checked out by the classic methods of the material strength cause the over sizing, because specialists use approximate measurements in order to decrease the number of mathematical calculation. This paper work describes the optimization of the main beam of a resistance structure of a rolling bridge used in metallurgy - by using the OPTSTAR mode that the COSMOS/M calculation software encloses ehich uses finite elements. In order to accomplish the best suited size, we have to perforin both an analytic and experimental study about the performance of the rolling bridge. In order to do that, we analyze the state of the tensions and deformation of the resistance structure by using this calculation software based on Cosmos finite elements. In order to validate the analytic study, we have performed some industrial experiments by using specific devices for measuring the resistance of the electrical tension. Both the analytic and experimental studies have pointed out that we are able to come up with the best sizes in order to reduce the material consumption we used during the production process of the main beam within the resistance structure of the rolling bridge we have analyzed.