Shear Strengthening of RC Elements by Means of EBR FRP Systems

In this chapter, a thorough review of some typical models adopted to represent the effect of EBR FRP systems on the shear capacity of RC elements is carried out, by comparing their advantages, their accuracy and also by highlighting their possible weaknesses. Then, more light is shed upon the so-called “variable angle strut model”, commonly adopted in RC structures, but whose application in the FRP field raises some concerns. Along the same line, the formulations provided by current Codes for the evaluation of the shear capacity of FRP-RC elements are widely discussed and proved to overestimate the actual shear capacity. Having assessed some of the shortcomings of such models, an alternative approach is proposed. The final outcome is a revised model for EBR FRP shear-strengthening that accounts for the actual contribution of steel stirrups and FRP strips/sheets to the shear capacity, while at the same time checking the stress in concrete.