Strain debonding and design in retrofitting RC structures according to different guidelines

Some experimental results, obtained from a set of RC beams externally strengthened to flexure with CFRP laminate, are presented and analyzed in terms of strength, ductility, material and strain performances. The experimental results, especially the measured strains at debonding , are compared with the theoretical values calculated as per the proposals of some rec ent guidelines such as ACI 440.2R (2008), CAN/CSA S 806 (2002) and CNR-DT 200 (2004). Fur thermore, in order to analyse, compare and highlight wh at the difference is between these guidelines in evaluating, for design purposes, the theoretical maximum FRP strain, a critical ana lysis, with reference to an in - field application , has been carried out. In this intervention, FRP materials were used in a retrofitting operation of a damaged existing RC structure , having t he flexural capacity of the strengthened RC structure evaluated according to the above mentioned guidelines and codes. Th e different design approaches and solutions suggested by the different guidelines are analyzed and commented by highlighting the main structural implications.