Top-running overhead bridge cranes are frequently supported by welded crane runway beams whose wheel loaded constructional details, such as the welded flange-to-web connections and the continuous double fillet welds to fasten the crane rail, are subject to multiaxial fatigue. The fatigue stressing is composed by normal and shear stresses due to the local wheel load introduction and global bending. As the fatigue stressing exhibits a phase shift between the stress components, it is referred to as nonproportional.
The currently applicable detail category of welded flange-to-web connections according to Part 1-9 of Eurocode 3 is derived theoretically and does not appropriately address the specifics of these connections. A classification of rail welds including a detail-related nominal stress formula is missing.
A design proposal for both constructional details is presented that is based on fatigue tests on girders under traveling and stationarily pulsating wheel loads to simulate the nonproportional fatigue stressing. To derive new detail categories from the test results, a fatigue failure hypothesis is formulated modifying Findley’s critical plane approach for the evaluation of welded constructional details with partial penetration and weld root failure on the basis of notch stresses and accounting for the residual stress state.