Flexure and shear behavior of RC beams strengthened by external reinforcement

A novel strengthening technique for Reinforced Concrete (RC) beams based on non-prestressed external reinforcing bars anchored at the supports of simply supported beams or slabs is herein considered. External reinforcement can be easily adopted to retrofit existing reinforced concrete structures. The simplicity of the proposed technique offers advantages in ease of installation, quality control on site and future inspections if comparison to other methods. An analytical and numerical evaluation of the available experimental results as well as a parametric study allows investigation of the effect of different percentages of external reinforcement and of different collapse mechanisms (shear and flexure), in order to optimize the amount of external reinforcement that could provide enough bearing capacity and sufficient ductility prior to collapse. The numerical analyses enable to highlight the collapse phenomena, with emphasis to both the arch and the beam action, the ductility and the stiffness in the cracked stage. © 2009 Taylor & Francis Group.