Shear Strengthening of Reinforced Concrete T-Beams using Carbon Fiber Reinforced Polymer (CFRP) Anchored with CFRP Spikes

Abstract

Reinforced Concrete (RC) structures deteriorate over years due to many reasons including corrosion of reinforcing steel, carbonation of concrete, overload on structural members, among others. This may result in flexural or shear deficiency in RC beams. The failure of shear-deficient RC beams is usually brittle, sudden and with little warning, if any. Diagonal shear cracks will form due to load increase that may result in complete fracture of the RC beam. Therefore, deteriorated and shear-deficient RC beams need to be strengthened to avoid such undesirable shear failure. This paper investigates shear strengthening of RC T-Beams using carbon fiber reinforced polymer (CFRP) laminates anchored with spike anchors. The beams have been strengthened in flexure to avoid flexural failure and then strengthened in shear using CFRP sheets that were anchored with CFRP spikes. Six beams were strengthened with CFRP laminates at 45o and at 90o inclination angles and anchored with embedded CFRP spikes with different depths (50 mm and 75 mm) and different diameters (10 mm and 12 mm). Wrapping (U-Wrapped) was also used for anchoring the flexural CFRP laminates. The beams are tested to failure and their capacity were compared with that of an unstrengthen control beam. It is observed that the capacity of the strengthened beams is increased up to 45% compared to that of the control beam. Anchoring with U-wraps enhanced the beam capacity further. The inclination of the CFRP sheets, dowel diameter, and the embedment depth of the spike anchors influenced shear and deformation capacity of the tested RC T-Beams.