5 - Shear strengthening of reinforced concrete (RC) beams with fibre-reinforced polymer (FRP) composites

Abstract

This chapter discusses the design of externally bonded Fiber-Reinforced Polymer (FRP) strips and plates for shear strengthening of Reinforced Concrete (RC) beams. Flexural and shear failures are the two main failure modes for normal unstrengthened RC beams. Flexural failure is generally preferred to shear failure as the strength-governing failure mode because the former is ductile, which allows stress redistribution and provides warning to occupants while the latter is brittle and catastrophic. Although the flexural failure mode in an RC beam strengthened with FRP in flexure shows much reduced ductility compared to a normal RC beam, it is still a more ductile mode than shear failure. When an RC member is deficient in shear or when its shear capacity is less than the flexural capacity after flexural strengthening, shear strengthening must be considered. It is important to assess the shear capacity of RC beams, which are intended to be strengthened in flexure, and to ensure that the shear capacity exceeds the flexural capacity.