Investigation the behavior and shear ductility of RC deep beam strengthened by FRP

The demand for FRP materials has been increased over the past years for retrofitting or strengthening of reinforced concrete members. Several recent studies focused on the shear strengthening of reinforced concrete deep beams. In deep beams, due to the high ratio of shear span-to-depth and shear deformation, the ultimate strength is generally controlled by shear rather than flexure with lower shear ductility. Shear strengthening with FRP sheets is one of the most effective methods to overcome the weaknesses of deep beams.
In this paper, the behavior of 104 deep beam specimens strengthened with different schemas of FRP sheets which was investigated. Specimens were modelled through the Non Linear finite elements method and analyzed under Push over static loading. The efficiency of FRP installing schema and the effect of some parameters such as shear span-to-depth ratio, compressive strength of concrete and the arrangement and ratio of shear reinforcement were evaluated. The results showed an average increase of shear capacity varied between 15 through 65 percent in each schemas of installed FRP sheets.
Another aim of this study is to define and evaluation of shear ductility index for deep beams. The results show that the shear ductility index depends on the dimensions of the deep beam, compressive strength of concrete and the scheme of installed FRP sheet as using the layers of FRP can increase the shear ductility of strengthened deep beams about 5 to 30 percent.