Flexural strengthening of reinforced concrete beams using prestressed, near-surface-mounted CFRP bars

Abstract

This study investigates the effectiveness of using prestressed near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP) to strengthen reinforced concrete beams. Five large-scale reinforced concrete beams were tested: one control, one strengthened with nonprestressed NSM CFRP bars, and three strengthened with NSM CFRP bars prestressed to 20%, 40%, and 60% of the ultimate strength of the CFRP. The flexural behavior of the prestressed concrete beams was compared with the nonprestressed beam and the control. Results indicate that all prestressed concrete beams failed due to rupture of the CFRP bars without any premature or debonding failure. Prestressing the embedded NSM CFRP reinforcement enhanced the overall performance of the beams by increasing the loads at cracking, yielding, and ultimate. When compared with the control beam, prestressed CFRP enhanced overall performance by decreasing crack widths and deflections, as well as delaying the formation of new cracks. In general, increasing the prestressing levels of the NSM CFRP reinforcement improved the overall flexural behavior of the beams at service and ultimate conditions, while decreasing the ductility of the beams.