Service-stage analysis of curved composite steel-concrete bridge beams

The long term behavior of composite steel-concrete bridge beams with a circular axis is discussed. The time evolution of strains and stresses arising in the composite section and the main aspects of the structural behavior are investigated, by assuming perfect bond between the steel beam and concrete slab and by considering the sections as thin-walled. The warping theory according to sectorial areas has been adopted for the analysis, extending it to the viscoelastic domain. The problem, governed by a set of sixth-order integrodifferential equations, is solved in a general way recurring to a numerical algorithm carried out by the writers. A significant case study is finally worked out, allowing us to point out the most important prerequisites of the deferred behavior of composite steel-concrete curved bridges, in particular the interaction between the different components of internal actions due both to the curved geometry of the beam and to the delayed deformations of the concrete slab induced by creep.