Strain Analysis of RC T-beams Strengthened in Shear with Variation of U-wrapped GFRP Sheet and Transverse Steel

The strengthening of concrete structures with fibre reinforced polymer (FRP) composites has existed since last two decade. The most common way to strengthen structures is in bending, shear and retrofitting of columns. FRP offers excellent corrosion resistance to environmental agents as well as the advantages of high stiffness-to-weight ratio and strength-to-weight ratio. This paper presents an experimental investigation on strain analysis of a reinforced concrete (RC) T-beams strengthened in shear with U-wrapped glass fibre reinforced polymer (GFRP) sheet. A total of eighteen (18) full scale simply supported RC T-beams are tested. Nine beams are used as control beam with three different stirrups spacing (transverse steel) without GFRP wrap and rest nine beams are strengthened in shear with one, two, and three layers of GFRP sheet in U-configuration for each type of stirrup spacing. This study focuses on strain analysis of U-wrapped GFRP sheet, transverse steel reinforcement and longitudinal steel reinforcement. It is observed that the strain in the U-wrapped GFRP sheet is higher in the specimens strengthened with one layer of GFRP, as compared to two and three layers in all the series. The stiffness of GFRP sheet is indirectly proportional to the strain.