Study of torsional behavior of reinforced concrete beams strengthened with aramid fiber strips

This paper investigates the strengthening of reinforced concrete (RC) beams for its torsional behavior using aramid fiber strips. Most of the time aramid fiber is used as an externally bonded reinforcement to increase flexural and shear strength of RC beams. An attempt is made to use it for improving torsional moment carrying capacity of RC beam. Torsional failure mostly occurs in earthquake prone areas subjected to rapid failure. Brittle failure of structures occurs due to torsional moment. Different patterns of aramid fiber strips are selected to wrap around RC beams and torsional behavior of these strengthened beams is studied. RC beam of M30 grade of concrete is strengthened with aramid fiber strips and tested for torsional failure using lever arms subjected to torque. The beam size is 150 mm × 300 mm and of 1.3 m in length, designed as per IS456-2000. A total of 21 numbers of reinforced concrete rectangular beams were cast for the experimental study. Three are taken as controlled beams with normal reinforcement, 3 beams are designed with torsional reinforcement and other 15 beams with normal reinforcement have grouped in five sets. These five sets are strengthened using aramid fiber strips of 150 mm width with variable spacing of 100, 125, 150, 175 and 200 mm, respectively. The effect of different configuration of aramid fiber on torsional moment carrying capacity, angle of twist and failure mode of the beams is studied.