Local stresses in crane runway girders near transverse stiffeners: Experimental and numerical investigations

In practice, crane runway girders are typically designed with additional transverse stiffeners to improve the buckling resistance of the web and to prevent rotation of the top flange due to eccentric introduction of the vertical wheel loads. This leads to an increase in local vertical stresses in the area of the welds between the transverse stiffener, the web and the top flange. The actual stress field has not yet been researched in detail and is therefore unknown. However, the local stresses have a significant impact on the fatigue design of the crane runway beam and the required girder dimensions. Therefore, this paper sets out to investigate the local stress field in detail. For this purpose, several laboratory tests are carried out on a crane runway girder with crane rail for heavy duty cranes. The vertical wheel loading is applied on the crane rail at different positions near transverse stiffeners, including concentric and eccentric position of the load at the rail. Tests are carried out with and without elastomeric bearing pad beneath the crane rail. The strains in the web and the stiffeners are measured by means of 40 strain gauges. The results of the experimental tests are used to calibrate a numerical finite element model. Thereby it is possible to investigate the whole stress field near transverse stiffeners, also in regions without measuring devices. Based on the investigations described in this study, several observations and conclusions can be made with respect to an improved fatigue verification. Thus, an initial basis is created for designing crane runway beams with transverse stiffeners that are both safer and more resource-efficient in the future.