Revisiting the bearing stresses in webs of crane runway girders under wheel loads

Abstract

This article revisited the problem of local bearing stress in webs of I-section girders supporting overhead cranes. Finite element analysis was carried out to determine the equivalent bearing length. It was found that the moment of inertia of the rail and the web thickness of the girder are the two predominant factors. The equivalent bearing lengths by the finite element analysis were found to be significantly smaller than that predicted by the formula in various codes. Analysis revealed that the differences come from the shear deformation in the rail and the load position on the rail. Closed-form solutions for a Timoshenko’s beam on a semi-infinite plane subjected to a concentrated or distributed load were presented in which the Fourier transform is used. After the shear deformation was considered and a widened load distribution length on the centroid axis of the rail, which considered the load dispersion in an angle of 35°–40° from the top of the rail to the centroid axis, are adopted in the Fourier transform solution, the analytical results are in good agreement with finite element analysis. Formulas of equivalent bearing lengths for two types of rails used in China are recommended for practical use.