Discussion of “Effective Flange Width Definition for Steel–Concrete Composite Bridge Girder” by Methee Chiewanichakorn, Amjad J. Aref, Stuart S. Chen, and II-Sang Ahn

Abstract

This discussion article comments on recent research (Chiewanichakorn et al, 2004) that investigated composite sections (made up of a concrete slab attached to a steel girder by means of shear connectors). The researchers contend that current formulae regarding the effective flange width (as used in national and international design specification) ignore the fact that stresses vary through the thickness. They verify a three dimensional finite-element model of the composite bridge and provide a numerical example illustrating the proposed effective flange width definition. The discussion author maintains that formulas like the one proposed by the researchers tend to produce increasing effective widths with decreasing interaction between beam and slab. It would have been more informative if the researchers had presented their results in the format that has become customary in discussions of effective width. The discusser also points out that the researchers' comparison of interior and exterior beam specimens can be slightly misleading, since all beams were T-shaped. The discusser concludes that the foremost reason for maintaining the present limitations on effective width is that concrete cracks. Composite beams have become notorious for developing longitudinal cracks in the concrete slabs over their steel beam sections.