Behavior of Concrete Beams Strengthened in Shear with Carbon-Fiber Sheets

Abstract

This paper presents the results of a test program for shear strengthening characteristics of continuous unidirectional flexible carbon-fiber polymer sheets bonded to reinforced concrete (RC) beams. A total of eight $150\mathrm{mm}\times 200\mathrm{mm}\times 2\text{,}600\mathrm{mm}$ concrete beams were tested. Various sheet configurations and layouts were studied to determine their effects on ultimate shear strength of the beams. From the tests, it was found that the externally adhesive bonded flexible carbon-fiber sheets are effective in strengthening RC beams in shear. Further, it was observed that the strength increases with the number of sheet layers and the depth of sheets across the beam section. Among the various schemes of wrapping studied, vertical U-wrap of sheet provided the most effective strengthening for concrete beam. Beam strengthened using this scheme showed 119% increase in shear capacity as compared to the control beam without any strengthening. Two prediction models available in literature for computing the shear contribution of carbon-fiber tow sheets to the shear capacity of fiber reinforced polymers bonded beams were compared with the experimental results.