Challenges for local strain measurements in crane runway girders near transverse stiffeners

Abstract

This paper presents both laboratory tests and finite element (FE) calculations to investigate in detail the local stresses in crane runway girders near transverse stiffeners. Six different girder geometries (i.e. flange thickness 20, 30 and 40 mm; web thickness 10, 15 and 20 mm; thickness of transverse stiffeners 10, 15 and 20 mm) and two rail types (i.e., A 75 and A 100) are tested with three load eccentricities each (i.e. e = 0 and e = ± k/4, where k is the width of the rail head). Two different types of rail bedding are investigated (with or without an elastomeric bearing pad between the rail and the top flange). Thus, all geometric parameters that affect the local stresses below the concentrated load are investigated. Based on test results and numerical calculations, the significant influence of geometric imperfections on the local stresses in crane runway girders is highlighted. To reproduce the measured strains using FE calculations, it is essential to account for geometric imperfections at the flange top surface and the rail bottom surface. It was found that simulations with plane, nominal contact surfaces between the rail and the flange are unable to accurately determine the local stress fields. The findings within this paper highlight the sensitivity of measured local strains in crane runway girders to geometric imperfections.