Performance of decommissioned reinforced concrete girders strengthened with fiber-reinforced polymer laminates

Fiber-reinforced polymer (FRP) materials are becoming one of the major innovations in the construction industry. They are widely used as externally bonded reinforcement for flexural and shear strengthening of members because of their durability, ease of installation, low maintenance cost, and excellent performance. This study presents both experimental and analytical investigations of reinforced concrete girders removed from a bridge after 40 years of service. The girders were strengthened with externally bonded FRP sheets and tested, with the principal objective of evaluating performance on real-scale members. Comparisons between the experimental data, an analytical model, and the ACI design guidelines are presented to understand the structural performance, allow for prediction, and address potential weaknesses in the design guidelines. In particular, it appears that the FRP tensile strength reduction coefficients presently adopted may be appropriate only if the member does not present D-regions. In the case of members with disturbances or discontinuities, the interfacial shear stresses may require additional analysis and limitations.