Structural Performance of Concrete Beams with Micro-reinforcement Strengthened with GFRP Laminates under Monotonic Loading

Abstract

The behavior of structural elements under different loading conditions decides the performance of the built structures. Fiber-reinforced concrete and fiber-reinforced polymers (FRPs) have received increasing attention in recent years for many structural applications. Steel fibers, when added into concrete as micro-reinforcement, impart a bridging effect, resulting in enhanced mechanical properties. FRPs are most commonly composed of glass, aramid, or carbon fibers in a polymeric matrix and can be tailor-made to provide a large variety of material properties to suit the prerequisites of the engineer. This article presents an experimental investigation of steel fiber reinforced concrete beams externally strengthened with glass fiber reinforced polymer (GFRP) laminates to study their static flexural behavior and failure modes. The experimental program consisted of six concrete beams strengthened with GFRP laminates, and one concrete beam was left unstrengthened to serve as the control beam. The beams were designed for under-reinforced conditions and cast with different fiber volume fractions (Vf) and GFRP laminate thickness (tf). The beams were tested under monotonic loading until failure. The experimental results showed that the strengthened beams exhibit significantly improved performance compared with the control beams in terms of strength, deformation, ductility, and crack resistance under monotonic loads.