Pre-Cracked Concrete Shear Strengthened with External CFRP Strips

Abstract

In reinforced concrete design, there are situations where transfer of shear across a specific plane needs to be considered. Examples of such situation include corbels, bearing shoes, ledger beam bearing, and a host of connection between precast concrete elements. In this study, the shear transfer behavior of reinforced concrete is investigated experimentally by conducting test on 6 precracked push-off specimens. The major parameters considered are the amount of reinforcement and externally bonded fiber reinforced polymer fabrics through the shear plane. External strengthening with Fiber Reinforced Polymer (FRP) fabrics is an effective technique for improving the structural performance and life span of the existing reinforced concrete structures. This paper illustrates the result of shear transfer capacity and modes of failure of the precracked reinforced concrete push-off specimens bonded externally with FRP. An experimental investigation was conducted to study the effectiveness of FRP as an external reinforcement. Based on experimental results, the external FRP reinforcement controls the shear slip along the shear plane and crack width. In the unstrengthened push-off specimens, the pre-existing crack along the shear plane will reduce the ultimate shear transfer capacity and increase of shear slip at all load levels. However in strengthened specimens, the external FRP reinforcement will control the increase of slip and increase the ultimate shear stress transfer capacity along the shear plane.