Continuous precast concrete girder and slab bridge decks

The availability of powerful means of lifting and transportation, highperformance building materials and refined structural analysis methods, along with the use in the same structure of pre-tensioning, post-tensioning, prefabrication and in situ construction techniques, has led to considerable changes in the design and construction of concrete bridges. Such advances allow engineers to design and build, for example, continuous precast concrete girder bridges, constant or variable in depth and curved or straight in plan, which are comparable to those cast in place, due to their structural efficiency, aesthetic appearance and economical competitiveness. This paper describes the geometric characteristics, conceptual design, analysis and construction of a new type of continuous precast concrete girder bridge. A typical bridge consists of precast prestressed concrete beams with a U cross-section, monolithically interconnected by post-tensioning of the end diaphragms, A cast-in-place reinforced concrete slab, positioned on top, provides longitudinal continuity and shapes the box section with side cantilevers. Particular aspects related to the influence of the segmental construction on the structural behaviour at service of these bridges are discussed. Finally, some actual bridges are presented along with proposals for future applications to long-span bridges.