Abstract: In view of the fatigue damage to the fatigue detail I of the steel crane girder with abrupt right-angled change, an economic, effective, and feasible round steel tube reinforcement method was proposed. Specifically, a round steel tube was welded at the variable section of the crane girder, and a welding connection with the insert plate and the end sealing plate was performed. In order to evaluate the fatigue performance of the reinforced steel crane girder, a three-dimensional crack growth simulation was conducted based on linear elastic fracture mechanics. The results showed that this method could improve the local stress state of the steel crane girder with abrupt right-angled change. Compared with that before reinforcement, the stress amplitude at the fatigue detail I had decreased by nearly 40%, and the fatigue life of the steel crane girder had increased by 2 255 000 times. Through parameter analysis, the influence laws of different outer diameters and wall thicknesses of the round steel tube on the reinforcement effects and economic benefits were further explored, providing a reference basis for the application of crane girder fatigue reinforcement projects.

Key words: abrupt right-angled change, crane girder, round steel tube reinforcement, three-dimensional crack growth, fatigue performance