Performance of NSM FRP embedded in concrete under monotonic and fatigue loads: state-of-the-art review

Abstract

ABSTRACTThe use of the near-surface mounted (NSM) fibre reinforced polymer (FRP) strengthening method in civil construction applications has gained considerable popularity worldwide, and can produce confident strengthening and repairing systems for existing concrete structures. The response of concrete structures rehabilitated using the externally bonded (EB) FRP method under monotonic and fatigue loading has been well reported. On the other hand, the monotonic and fatigue response of NSM FRP-rehabilitated concrete structures is less known. This paper reviews current research on concrete members retrofitted using the NSM FRP technique and subjected to monotonic and fatigue loading. It provides an outline of FRP composites and the fatigue behaviour of concrete, steel and FRP materials. In addition, the review focuses on the bond characteristics between NSM FRP, adhesive and concrete substrate, and on the flexure behaviour of NSM FRP-strengthened and repaired reinforced concrete (RC) beams. Furthermore, the paper reviews the failure modes, factors affecting NSM FRP systems, codes and guidelines for the use of FRP in concrete structures, damage accumulation and residual strength, stress limits in steel reinforcement, and the limitations of using epoxy and polymer-based cementitious adhesives for strengthening of concrete members.