Experimental and analytical study on GFRP reinforced concrete deep beams

Abstract

Corrosion of steel in reinforced concrete structures is one of the biggest challenges faced by the civil construction industry today. In reinforced concrete structures, corrosion of steel reinforcement due to harsh environmental conditions considerably reduces the durability and life span of these structures. To overcome this corrosion problem, many new techniques have been tried and found to be either expensive or ineffective. Fiber Reinforced Polymer (FRP) materials in the form of solid bars has been successfully tried as a substitute for steel reinforcement in concrete structures. Considerable research has been carried out to study the flexural and shear behaviour of FRP reinforced slender concrete beams. However, very little effort has been taken to study the behaviour of Reinforced Concrete (RC) deep beams reinforced with FRP rebars. This work is an attempt to study the shear behaviour of RC deep beams reinforced with Glass Fiber Reinforced Polymer (GFRP) web reinforcement. The thirteen deep beams were cast with and without GFRP web reinforcement and were tested in this work. The testing was done in two stages - in the first stage, i.e. in Series-I, nine deep beams were tested with a shear span to effective depth ratio of 0.72 and the results showed a substantial increase in the ultimate shear load carrying capacity for deep beams reinforced with GFRP web reinforcement when compared to those without web reinforcement. Considering this significant increase, four more deep beams were cast in the second stage i.e. Series-II and were tested with a shear span to effective depth ratio of 1.08. Finally, after analysis of the experimental results, a design equation was formulated to predict the shear carrying capacity of GFRP web reinforced deep beams. The results obtained by using this equation were found to be acceptable and so, this equation may be adopted for predicting the shear load capacity of deep beams reinforced with GFRP web reinforcement and loaded within a small shear span to depth ratio.