Composite Girder Design of Cable-Stayed Bridges

Abstract

The analysis and design of composite girders of cable-stayed bridges are discussed. Cable-stayed bridge girders carrying both axial forces and bending moments are actually beam-columns. The distribution of axial forces along the bridge span and the distribution of axial stresses along the bridge width are not uniform. The “axial force effective width,” which is different from the “bending effective width,” is thus introduced, and its applications in analysis and design are explained. Because the strains of the steel girder and the concrete slab are incompatible at their interface due to the staged construction of composite sections, the AASHTO-factored load design formulas for steel beam-columns are adapted into stress formats to handle these incompatible strains. A numerical example is presented to explain the proposed procedure for the composite section designs of cable-stayed bridge girders.