Analytical and Numerical Study of FRP Retro tted RC Beams Under Low Velocity Impact

An analytical along with numerical analysis has been carried out to investigate the behavior of concrete simply supported beams strengthened with Fiber-Reinforced Polymer (FRP) unidirectional laminates under impact loading. Concrete beams are reinforced with a minimum ratio of exural and shear steel rebars and nally retro tted with epoxy-bonded high strength carbon FRP laminates in their exure surfaces. The impact force was applied with a solid steel cylinder drop weight. Analytical results showed that composite laminates externally bonded to reinforced concrete beam substrate can signi cantly enhance the performance of theses structural members to resist impact loadings. Also, based on the obtained results, in retro tted beams the crack propagation happens in a desirable mode; an increasing of yielded rebar zones and residual beam sti ness. Retro tted beams were sti er than unretro tted ones in their rst impact response. The residual sti ness of impacted concrete beams depends on their initial sti ness and the impact energy level. The analytical method uses an idealized elastic spring-mass model and exural wave propagation theory to calculate the dynamic response of assumed beams. Analytical responses are adjusted due to an inelastic response, and nally are used for the simpli ed designation of impact resisting reinforced concrete beams retro tting laminates. Keywords: Impact loading; Reinforced concrete beam; Composite laminate; Retro tting; FEM.