The Effect of Width, Multiple Layers and Strength of FRP Sheets on Strength and Ductility of Strengthened Reinforced Concrete Beams in Flexure

In this study, a total of eleven under-reinforced beams, ten of which strengthened with FRP of different widths and different numbers of layers, are fitted with electronic strain gauges on the top concrete fiber, the reinforcing steel and the FRP material. Strains and deflection at mid-span were recorded for each load increment. The data was reported and analyzed, as well as ductility requirements and expected failure mode. It was concluded that the use of single layer FRP wide sheets would increase the strength with a negligible reduction of ductility. Using multiple layers of wide FRP sheets yielded more increase of strength but reduced ductility of the beams. Multiple narrow strips of FRP will not add to the strength, but will reduce the deflection by reducing ductility.