Cracking and deformability of reinforced concrete beams strengthened with externally bonded CFRP sheets

The paper is devoted to the cracking and deformability analysis of steel reinforced concrete beams strengthened with externally bonded carbon Fiber Reinforced Polymers (FRP) sheets. A theoretical nonlinear model, derived from a cracking analysis founded on slip and bond stresses, is adopted. The model takes into account both the tension stiffening effects of the concrete and the force transfer between the concrete and the CFRP sheet at the interface. A local bond-slip law-defined by experimental tests, carried out on concrete specimens strengthened with CFRP sheets- is adopted in the model. The slip between the concrete and the traditional steel bars is also considered. Theoretical predictions, in terms of crack width, curvature and deflections, are compared with available experimental results and predictions of traditional models, usually adopted for design purposes. Obtained results are presented and discussed.