Efficiency of different FRP-based flexural strengthening techniques in beams submitted to fatigue loading

Abstract

Flexural strengthening of reinforced concrete (RC) structures with fiber reinforced polymers (FRP) has been used mostly by two main techniques: Externally Bonded Reinforcement (EBR) and Near-Surface Mounted (NSM). In both strengthening techniques the FRP systems are applied on the cover concrete, which is normally the weakest region of the element to be strengthened. Consequently, the most common problem is the premature failure of the system, which occurs more frequently when using the EBR technique. In an attempt of overcoming this weakness, another flexural strengthening technique, named MF-EBR – Mechanically Fastened and Externally Bonded Reinforcement, is analyzed in the present paper. This technique uses multidirectional carbon fiber laminates that are simultaneously glued and anchored to concrete. To compare the efficiency of NSM, EBR and MF-EBR techniques, four-point bending tests with RC beams were carried out under monotonic and fatigue loading. In this work the tests are described and the obtained results are presented and discussed.