Effect of Longitudinal Reinforcement Ratio on the Behaviour of Deep Beams Reinforced with GFRP Headed-End Bars

Abstract

AbstractReinforced concrete (RC) deep beams with small shear span-to-depth ratio (a/d) are common elements in structures. They are usually designed using the Strut-and-Tie Model (STM). To mitigate the corrosion-induced damage, fibre-reinforced polymer (FRP) bars have been used as an alternative to steel bars. Among FRP types, glass FRP (GFRP) reinforcement is of particular interest to the construction industry because of its lower cost and large deformation at failure However, due to its linear-elastic behaviour and relatively low modulus of elasticity compared to steel, GFRP-RC deep beams would be susceptible to deeper and wider cracks, which will adversely affect the capacity of such beams. In addition, GFRP has a different bar surface and bond characteristics compared to steel, which require a longer development length. This paper reports on an experimental study designed to investigate the shear behaviour of GFRP-RC deep beams. In this study, three large-scale, simply supported concrete deep beams reinforced with headed-end GFRP bars were constructed and tested up to failure. The specimens had a rectangular-section of 590-mm high by 250 mm wide, while the length of the specimens were 2,100 mm. The main variable was the longitudinal reinforcement ratio, which varied between 0.6, 1.0 and 1.4%. The specimens were tested in a three-point bending setup over a clear span of 1.38 m with a/d ratio of 1.0. The test results indicated that increasing the longitudinal reinforcement ratio led to increasing the load capacity of such beams.