Flexural Strengthening of Real-Scale RC and PRC Beams with End-Anchored Pretensioned FRP Laminates

An experimental study on real-scale reinforced concrete (RC) and prestressed reinforced concrete (PRC) beams strengthened in flexure with fiber-reinforced polymer (FRP) laminates, developed at the University of Padova, Padova, Italy, is described in this paper. Externally bonded FRP reinforcement was applied in different ways with different types of end-anchorage devices and, in some beams, prestress transfer. After characterization of the single materials, four-point bending tests were executed and crack pattern and failure modes were studied, with particular attention to the behavior of the anchorages, consisting of two types of mechanical devices. Experimental results in terms of load- deflection response were then compared with the predictions of an analytical model, taking into account prestressing effects due to both internal strands and external FRP laminates, based on trilinear behavior characterized by section flexural crack initiation, steel yielding, and ultimate capacity.