Shear Rehabilitation of RC Deep Beams using NSM CFRP Anchor Bars

Abstract

This paper presents results of an experimental study for the shear strengthening of reinforced concrete (RC) deep beam using near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) anchor bars. To ensure shear failure, five RC deep beam specimens were cast with nominal shear reinforcement. Shear strengthening of the RC deep beams was conducted by inserting 5 mm diameter by 450 mm length of CFRP bars as anchors with spacing of 100 mm and 150 mm centre to centre from the support of the beam. All RC beams were simply supported and subjected to a four-point bending test with shear span to effective depth ratio of 0.864. The results presented include the ultimate load, CFRP contribution to shear, modes of failure and the load-deflection profile. The shear enhancement of the RC deep beams shows an increment of 17.3% up to 25.5% with decreasing mid-span deflection from 6.4% to 15.1%. In addition, using this technique also increases its flexural beam resistance under the same conditions.