Deep embedment and NSM techniques for shear strengthening of reinforced concrete slender beams with cFRP ropes

Abstract

Shear failure is catastrophic and occurs usually without advance warning, thus it is desirable that the beam fails in flexure rather than in shear. Many existing reinforced concrete beams are found to be deficient in shear strength and need to be strengthened. Reinforced concrete beams can be strengthened against shear failure by using polymer composites reinforced with fibres in many different techniques. This study aims to the most efficient shear strengthening of beams with carbon fibre reinforced polymer (cFRP) between near-surface mounted (NSM) technique and the deep embedment (DE) technique. Reinforced concrete beams with dimensions 15x15x70 cm, with the use of classified C30/37 concrete were constructed, each of which was reinforced with 3Ø10 B500c steel bars, only under bending. The specimens were tested in shear under two-point bending loading conditions, after having been strengthened with NSM or DE technique with cFRP rope by various reinforcing arrangements. As main conclusion, it appears that the NSM strengthening technique gives lower values than DE strengthening technique in correspondingly schemes.