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Strengthening of reinforced concrete beams with FRP reinforced systems (FRP plate or strips) have been utilize from around 1980s. FRP systems can be used for increasing shear strength of reinforced concrete beams by completely or partially wrapping FRP systems around reinforced concrete member. Since, most of reinforced concrete beams are constructed monolithically with other continuous members such as slabs or walls, therefore complete wrapping of FRP plates is not possible in most cases. Directing FRP fibers perpendicular to potential shear cracks is effective in providing extra shear strength. Moreover, enhancing shear strength might lead to flexural failure which is more ductile failure hence more desired compare with brittle shear failure. The additional shear strength achieved by applying FRP plates or strips depends on number of factors such as beam geometry, existing concrete strength, and applied wrapping scheme. There are three main types of FRP systems which includes Aramid, Glass, and Carbon FRPs. The Carbon Fiber Reinforced Polymer plate which is a high quality but expensive type of FRP plate, is shown in Figure-1. Externally bonding of FRP systems have been applied successfully for strengthening reinforced concrete beams in shear and for improving bridges especially in the United States of America. Shear design procedures provided by Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-08) is used in this article.
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