Behavior of Hollow Tubular-Flange Girder Systems for Curved Bridges

Abstract

This paper describes research results for an innovative curved highway bridge girder system, which uses I-shaped steel girders with hollow rectangular tubes as flanges. The increased torsional stiffness provided by the tubular flanges dramatically improves the structural behavior of the curved girders, resulting in substantially reduced deflection, cross section rotation, and stress compared to conventional curved I-shaped steel plate girders. In this paper, finite-element (FE) models for systems of curved tubular-flange girders are described. The models consider material inelasticity, second-order effects, initial geometric imperfection, and residual stresses. The girder systems are comprised of curved hollow tubular-flange girders (CHTFGs), cross frames between the CHTFGs, and a concrete deck. A parametric study is performed using the FE models to study the effects of web stiffeners, tube diaphragms, geometric imperfection, and residual stresses on the load capacity of three-girder systems with CHTFGs. Then, the results for the CHTFG systems are compared with results for corresponding conventional curved I-girder systems. The effects of the curvature, cross section dimensions, number of cross frames, and a concrete deck are investigated. The results indicate that the CHTFG systems are more structurally efficient than the corresponding curved I-girder systems.