Stress Analysis of Linear Elastic Nonprismatic Concrete-Encased Beams with Corrugated Steel Webs

Abstract

The basic mechanical behavior of a nonprismatic concrete-encased beam with corrugated steel webs (CSWs) was investigated through a scale model experiment and finite-element model analysis. Because of the influence of variable cross sections and the concrete encasement, results of this study contradicted the assumption that CSWs bear all of the shear force in a nonprismatic beam. The inclined bottom flange resisted a significant portion of the shear force in the section under longitudinal bending moment. Shear stress in the CSW was uniformly distributed through the cross section when the CSWs were encased in concrete. In addition, the authors made the counterintuitive finding that the average shear stress in the CSW decreased gradually from the free end to the middle support. In other words, the root section near the support did not exhibit the greatest stress concentration, even though this region had the maximum vertical shear force and the largest hogging bending moment. Last, normal strain in concrete flanges and the concrete web approximately obeyed the plane section assumption. The longitudinal bending moment was mainly balanced by the moment from coupled axial forces in the concrete flanges. In general, the CSWs encased in concrete were unable to provide sufficient bending strength.