Ductility of torsionally strengthened reinforced concrete beams

Fibre Reinforced Polymers (FRP) are understood to be brittle materials deforming linearly up until failure without much pre-failure deformation warnings. What follows from this naturally is that when FRPs are used to strengthen concrete structures for example, the structure will be less ductile or even completely brittle. While this is true in many applications, there are a number of cases in which a FRP strengthening scheme may in fact enhance the ductility of the system. Torsional strengthening is such a case. In this paper, this phenomenon is explained through a discussion on the results of the experiments performed by the authors of the current paper and the limited results available in the literature. The authors' experiments are performed on 12 reinforced concrete beams wrapped by carbon and glass fibres of different configurations. The results exhibit interesting enhanced ductIlity behaviour in some cases