Development of deflection equations using moment-curvature relationships for reinforced concrete beams strengthened with fibre-reinforced polymer (FRP) plates

This paper presents a rational and relatively simple method for calculating the deflections of reinforced concrete (RC) beams strengthened with fibre-reinforced polymers (FRP) plates. Basically, RC beams strengthened with externally bonded FRP plates to the tension face can display flexural strength several times greater than their original strength. An idealised load-deflection curve for a RC beam strengthened with externally bonded FRP plates can be separated into four different linear stages. Based on these stages, this project is developed from linear elastic theory and analyses of the moment-curvature relationships, which are assumed to be linear An improved analytical procedure for calculating the deflection of the plates strengthened with FRP is developed. The analytical expressions are verified by comparisons with some experimental and American Concrete Institute (ACI) results in the literature. The analytical results correlated well with the experimental results.