Recent developments in composite bridges

A review on recent developments in composite bridges is presented and a case study is reported. Conceptual design aspects, to the best use of steel and concrete in composite bridge decks, are discussed. The basic problems in the design of composite bridges, namely time-dependent effects, cracking control of the concrete deck slab and the nonlinear behaviour of the superstructure, due to the post local buckling effects, are considered. Erection schemes and specific technological developments are outlined. The case study presented illustrates the use of a composite plate girder solution for a long railway bridge deck, in which external prestressing cables are adopted to reduce the permanent bending moments in the girders.