Shear Strengthening of Reinforced Concrete Beams with Various Natural and Artificial Fabric Reinforced Composite Systems

Abstract

This article presents the results of an experimental investigation carried out on reinforced concrete (RC) beams strengthened by various fiber-reinforced polymer (FRP) wrapping configurations, by sisal fabric reinforced polymer composite, jute fabric reinforced polymer composite, carbon fabric reinforced polymer composite, and glass fabric reinforced polymer composite. The RC beams were designed such that shear failure occurred before flexural failure. All the strengthened RC beams were wrapped in two techniques, full wrapping (100%) and strip wrapping (50%) techniques. The present study aimed to evaluate the ultimate shear load carrying capacity of the beams and the shear strength contribution provided by the natural FRPs as compared with that of artificial FRPs. To this purpose the article focused on examining the response of the strengthened RC beams using the natural FRP composite sheets, in comparison to un-strengthened beams and artificial FRP strengthened beams, in terms of ultimate shear load carrying capacity, and load deflection behavior and failure modes, etc. From the experimentation, it was concluded that the specimens strengthened with fully wrapped sisal FRP, and fully wrapped jute FRP, the strengthening effect was very noteworthy with one layer itself, providing an increase in the load carrying capacity, and also the strengthening promoted ductile failure without any concrete crushing, and without any FRP rupture or any de-bonding, even at very high loads. Using the full wrapping technique, shear strengthening was obtained by 77% by sisal FRP, 66% by jute FRP, in comparison to 88% by carbon FRP and 83% by glass FRP. This aided us in concluding that the, use of natural sisal and jute fabric reinforced composite system, a very effective shear strengthening of structures could be achieved. The ultimate shear strength of all the strengthened beams increased with the increasing width of the FRP, as strip wrapping showed lesser load carrying capacity than full wrapping. Therefore sisal fabric and jute fabric reinforced polymer composite system, with its various environmental benefits, being a natural fiber, can be used as alternate fabric reinforcements in FRP, for structural shear strengthening purpose.