varying profiles of cfrp ropes for strengthening concrete beams

The efficacy of flexural strengthening of concrete beams using near-surface mounted (nsm) carbon fiber reinforced polymer (cfrp) ropes at varying profiles along the beams’ opposite-side covers is investigated in this work. seven reinforced concrete beams (150 × 250 × 1400 mm3) were prepared then cured until matured before later retrofitted using straight, trapezoidal, and parabolic profiles of cfrp ropes; the eighth was designated as control. another beam was strengthened using a single trapezoidal rope (equivalent to two ropes) inserted in an internal hole (20-mm-in-diameter) along the beam’s span. use of variable instead of straight rope profiles imparted higher increases in load capacity, stiffness, and toughness of strengthened beams reaching 56, 37, and 33%, respectively, with a reduced loss in rotational ductility in the range of 7–10%. the cfrp rope with an internal trapezoidal profile of 20° inclination imparts the best enhancement on structural performance. the strain induced in the cfrp ropes at failure point at (72–99%) of their ultimate strain capacity spurs adopting the present technique for practical applications. a comparison in performance between concrete beams with cfrp ropes and those with cfrp strips indicates a higher advantage of strengthening with the former composites. © 2021, iran university of science and technology.