Experimental behavior of prestressed concrete beams under simultaneous sustained loading and corrosion

The paper presents an experimental study for the evaluation of the flexural response and failure mode of a prestressed concrete (PC) beam subjected to simultaneous sustained loads and corrosion. The obtained results are judged and discussed also through a comparison with the experimental outcomes on a reference sound PC beam, and a companion specimen subjected to artificial corrosion first, and then tested in bending. The three specimens are characterized by a 200 x 300 mm rectangular cross section, a total length of 3700 mm, and a clear span of 2700 mm. The value of the sustained load, applied with a simultaneous accelerated corrosion process of the strands, was chosen, based on the result of the uncorroded reference beam, to achieve a scenario that can occur in a real structure in situ. The flexural response of the tested element was monitored over a period of 70 days, up to failure, and showed to be highly dependent on the localization of the corrosion phenomena affecting the strands, especially when coinciding with the maximum bending moment position. The obtained results are finally compared with the ones obtained on a PC beam with the same geometry and material properties, first subjected to corrosion and then tested in bending. The differences in corrosion morphology and location and in the failure mode of the strand confirm the importance of accounting for the combined effect of reinforcement corrosion and loading when assessing the structural performance of PC beams.