Predicting deflection of retrofitted reinforced concrete beams

To investigate the deflection of preloaded RC beams strengthened with FRP laminates, a total of 18 RC beams, including 16 beams strengthened with CFRP laminate under different preload levels and 2 control beams, were tested. The experimental parameters include rebar ratio, number of plies of CFRP laminates and preload level at the time of strengthening. Based on the assumption that the section of the beam behaves a trilinear moment-curvature response characterized by section flexural crack initiation, yielding and ultimate capacity, the modified equations for calculating the deflection of CFRP-strengthened RC beams are proposed. The parameters of the modified equations are determined by the statistically analyzing the experimental results. Verifications against the similar test results are also performed. The deflections, calculated by the present equations, are compared with the ones calculated by other methods available in the literatures.