Shear Design Equations for Concrete Girders Strengthened with FRP

Fiber Reinforced Polymer (FRP) systems have emerged as one of the most promising and widely accepted methods of strengthening concrete structures. FRP strengthening systems may consist of carbon (CFRP), glass (GFRP), or aramid (AFRP) fibers. The acceptance and utilization of such strengthening techniques depends on the availability of reliable design guidelines. Shear strengthening with externally bonded FRP is still under investigation and the results obtained thus far are scarce and sometimes controversial. In this study, predictions by the existing analytical models developed for externally bonded FRP shear reinforcements were evaluated and compared to experimental results available in the literature. The results of this investigation show that the models are not reliable for predicting the shear strengthening effect of externally bonded FRPs in a majority of cases. Results from full-scale testing and a comprehensive collection of data from the literature were used in the development and calibration of new design equations which give better predictions of the FRP contribution to shear resistance. This paper presents the results and final recommendations of this study.