Analysis and optimization of the main girder of the bridge crane with an asymmetric box cross-section

The presented research deals with the optimal design of the main girder with an asymmetric box cross-section of the double-beam bridge crane. The Moth-Flame Optimization algorithm (MFO) is used for solving this multicriteria optimization problem. This algorithm is a relatively new population-based metaheuristic method. The paper takes the following criteria as the constraint functions: strength, local stability of the girder plates (webs and top flange), local stability of the longitudinal stiffeners, global stability of the main girder, deflections, and period of oscillation. The justification of the proposed procedure is shown in one example of a real solution of the double-beam bridge crane. Significant savings in material were achieved in this research, within the range of 19.42 to 25.49%. The use of this algorithm enables the application of a very large number of variables and constraint functions, whereby the optimal values are obtained in a relatively short period.