Flexural behaviour of concrete beams internally reinforced with GFRP rods and steel rebars

Abstract

Use of fibre‐reinforced polymer (FRP) composite rods, in lieu of steel rebars, as the main flexural reinforcements in reinforced concrete (RC) beams have recently been suggested by many researchers. However, the development of FRP RC beam design is still stagnant in the construction industry and this may be attributed to a number of reasons such as the high cost of FRP rods compared to steel rebars and the reduced member ductility due to the brittleness of FRP rods. To resolve these problems, one of the possible methods is to adopt both FRP rods and steel rebars to internally reinforce the concrete members. The effectiveness of this new reinforcing system remains problematic and continued research in this area is needed. An experimental study on the load‐deflection behaviour of concrete beams internally reinforced with glass fibre‐reinforced polymer (GFRP) rods and steel rebars was therefore conducted and some important findings are summarized in this paper.

A design model for fibre reinforced concrete beams pre-stressed with steel and FRP bars

“…A gradual increment is applied to the normalized tensile strain at the concrete bottom fibre ( β ), and corresponding values of the normalized compressive strain at the concrete top fibre ( λ ), and the normalized tensile strain of the steel (ψ ) and FRP (ν ) are obtained from Eqs. (10) to (12).…”

“…In an attempt of overcoming these drawbacks, some researchers [10][11][12][13] proposed a combination of FRP and steel reinforcements for concrete beams. Combining these reinforcement materials and considering the minor concrete cover required for FRP, an effective reinforcement solution in terms of durability is obtained by placing the FRP bars near the outer surface of the tensile zone, and steel bars at an inner level of the tensile zone (Fig.…”

Structural performance and serviceability of concrete beams reinforced with hybrid (GFRP and steel) bars

“…An increase in stiffness was reported for hybrid beams with steel bars placed above the AFRP bars. Leung and Balendran [14] investigated the flexural response of hybrid concrete beams reinforced with glass FRP (GFRP) and steel bars placed at different levels. The authors reported that the hybrid-reinforced beams had higher flexure strength than the steel-or GFRP-reinforced beams.…”

A design model for strain-softening and strain-hardening fiber reinforced elements reinforced longitudinally with steel and FRP bars

“…However, the major obstacles of the application of FRP bars as a reinforcing material for concrete structures are the relatively high initial costs, low modulus of elasticity, lack of ductility (linear stress-strain diagram up to rupture with no discernible yield point), and absence of well-consolidated design guidelines [2][3][4]. Concrete members reinforced with FRP and subjected to bending moments behave linearly up to cracking, and almost linearly after cracking with a significant lower stiffness [5,9]. Deflections and strains of concrete members reinforced with FRP bars are generally larger than the homologous members reinforced with steel bars.…”