DESIGN OPTIMIZATION OF BOX TYPE GIRDER OF AN OVERHEAD CRANE

Double bridge girder overhead cranes are used for heavy duty applications in the industry. In this paper a detailed parametric design optimization of the main girder of box type is performed for a 150Ton capacity and 32m long span crane, after its basic design using available design rules. Design optimization is performed using detailed 3D finite element analysis by changing the number, shape and location of horizontal stiffeners along the length of the girder and number and location of stiffeners along the vertical direction to control any possible buckling, with minimum possible weight and for safe stress and deflection. Optimization is performed in two steps. In the first step, keeping plates thickness constant different types and number of stiffeners are added and optimized geometry is found. In the second step, the best geometry of the first step is further optimized for maximum allowable bending stress by changing thickness, height and width of the box girder with minimum possible weight. Effect of added stiffeners is highlighted in controlling its buckling.