A parametric study on the behavior of RC and FRC deep beams with and without CFRP strengthening using ANSYS

Abstract

Deep beams are common elements in concrete structures such as bridges, water tanks, etc. Deep beams were designed by using the strut-and-tie model (STM) method without any web reinforcement using ACI 318-14 with a shear span to depth ratio (a/d =1). RC deep beams show brittle failure by crushing of struts under applied load. Fiber reinforced concrete (FRC) is a better alternative for the reinforced concrete beam without web reinforcement as it contains fibers such as a ramid, steel, etc. The fibers used were steel fibers of 1% volume, and aspect ratio of 60. The use of carbon fiberreinforced polymer (CFRP) for strengthening the deep beams is utilized and a comparison between reinforced concrete(RC) and fiber-reinforced concrete (FRC) deep beams with and without CFRP strengthening is carried out using (Analysis of Systems) ANSYS 18.1. The mid-span deflections were significantly decreased and improved shear strength was observed in CFRP strengthened deep beams and FRC deep beam in comparison of RC deep beam. The ultimate loads for a maximum deflection value were compared in all the deep beams and RC frame with embedded carbonfiber reinforced polymer (RC-CFRP), fiber reinforced concrete carbon-fiber reinforced polymer(FRC-CFRP) and FRC deep beams showed 29.4%, 42.47% and 32.05% improvement, respectively, when compared with the RC deep beam. A total of 43.4% decrease in deflection and 74% decrease in shear stress was observed in FRC deep beam. The deflection and stress values in strengthened beams were comparatively lesser. In this study, deflection was observed to decrease by 74.4% and 82%, and shear stress decreased by 92% and 93.5% in the strengthened RC and FRC deep beam, respectively, compared to the deep beam RC model. It is suggested that strengthened FRC is a better alternative to RC deep beams.