Shear Lag and Local Buckling Interaction in Orthotropic Deck of Steel Bridges

Abstract

Abstract The term of shear lag is related to the discrepancies between the approximate theory of the bending of beams and their real behaviour, and it refers to the increases of the bending stresses near the flange-to-web junctions, and the corresponding decreases in the flange stresses away from these junctions. In the case of wide flanges of plated structures, shear lag caused by shear strains, which are neglected in the conventional theory, may be taken into account by a reduced flange width concentrated along the webs of the steel girders. The effects of the shear lag, plate buckling and interaction of both effects should be taken into account at the ultimate, serviceability or fatigue limit states in the design of structures with wide flanges. In EN 1993-1-5, the concept of taking shear lag into account is based on the effectives width of the flange which is defined in order to have the same total normal force in the gross flange subjected to the real transverse stress distribution as the effective flange subjected to a uniform stress. Some aspects concerning the shear lag phenomenon and a design example of effectives width calculation and the shear lag effects for a steel pedestrian bridge deck are presented in this paper.