Seismic behaviour of r.c. hollow section bridge piers retrofitted with frp

The research work presented in this paper concerns the seismic assessment of hollow bridge piers strengthened with fibre-reinforced polymer (FRP). The scope of the strengthening is to overcome some common deficiencies deriving from the use of non-seismic design rules and leading to a not adequate cyclic response. The strengthening design was studied by means of a parametric analysis considering different fibres and geometrical parameters applied to standard case studies. Quasi-static cyclic tests were performed on five 1:4 scaled piers designed according to old non-seismic Italian codes and strengthened according to the previous analytical study. Efficiency of FRP strengthening was evaluated comparing the experimental results with those obtained in a previous experimental research performed on similar not strengthened specimens. Base shear vs. lateral deflection curves, dissipated energy and collapse mechanisms comparison shows the achievable effectiveness once the debonding risk has been overcom