Flexural behavior of slender long-span precast prestressed high-strength concrete girders

摘要

The flexural behavior of slender (1/40) long-span precast high-strength concrete girders was experimentally investigated as a competing solution to steel alternatives for highway overpasses. Half-scale specimens were produced using an economical and high-strength (120 MPa) concrete mixture, non-fiber reinforced, designed only with conventional raw materials, currently available at Portuguese precast companies. Two girder specimens were subjected to quasi-static short-term loading up to structural failure in bending. Results have shown the typical behavior of conventional reinforced concrete members in bending, despite the brittle behavior of non-fiber-reinforced high strength concretes. Results also showed acceptable ductility (2.6) and the ability of the girder specimens to experience large deformation without significant softening. An analytical approach, based on plane sections and short-term stress-strain constitutive model recommended by the Eurocode 2 for concrete up to the C90/105 strength class, showed to predict accurately the behavior of girders in bending, both to ultimate and serviceability limit states, including cracking, yielding, maximum loads, and ultimate deflections.