Geometry functions for edge cracks in steel bridge under three- and four- point bending with various span

Abstract

Fatigue cracks are found during the regular structural inspections. To precisely describe/suggest propagation of fatigue cracks throughout structure and it’s designed service life, the knowledge of geometry functions describing the stress situation in front of the crack tip for relative crack lengths are important. The cracks usually propagate/initiated from the edge or the surface of the structural element, where the maximum value of applied load is achieved. The theoretical model of fatigue crack propagation is based on linear fracture mechanics (Paris law). Steel structural elements are subjected to various bending load (three-, four- point bending and pure bending etc.). The geometry functions for the edge cracks are calculated for various span according to real steel bridge elements and appropriate polynomial functions independent on the distance are proposed for three- and four- point bending load.