Influence of longitudinal stiffeners on the local stresses in crane runway girders: Experimental and numerical investigations

Crane runway girders with slender webs are often strengthened by additional longitudinal stiffeners to avoid local plate buckling of the web. It is expected that this leads to an increase of local vertical bending stresses near the top edge of the web due to eccentric wheel loads. These local stresses have a significant impact on the fatigue design of the flange-to-web connections and the required girder dimensions. However, the current design model in EN 1993-6 for crane supporting structures does not consider this effect. In order to study this behaviour in detail, laboratory tests and numerical finite element calculations are carried out on crane runway girders with longitudinal stiffeners at different positions of the web. It is verified that the local stresses increase with decreasing distance of the stiffeners from the top edge of the web plate. Based on these results and a modified proposal from literature, the design model in EN 1993-6 is extended to also cover additional stiffeners. Finally, the model is validated through a comparison with tests and numerical calculations.