Structural analysis and seismic upgrading of reinforced concrete beams with vertical cracks

The paper proposed by this abstract is inserted in the topic New structural materials. Seismic actions may cause the breakdown of the dowel and aggregate interlocks mechanisms of RC beams, after which the stirrups are the only viable mean of shear resistance. In the zone of the RC beam with vertical cracks, however, also the stirrups do not provide any contribution to the shear capacity. FRP reinforcement epoxy-bonded onto the web is the only viable mean of retrofitting such RC beams, provided that side bonded sheets with diagonal fibers are used. This paper presents a conceptual approach to seismic upgrading. Moreover, this paper presents an analytical model (included all the relevant mathematic) devoted to this special shear state, together with a test (shear failure test of a reinforced beam) and two applications (strengthening of two beams). The model reaches a close expression that predicts the load-carrying capacity of a strengthened beam.