Alternative Approaches to Predict Shear Strength of Slender RC Beams Strengthened with Externally Bonded Fiber-Reinforced Polymer Laminates

Abstract

The method provided in ACI 440.2R for predicting the shear strength of reinforced concrete (RC) beams strengthened with externally bonded reinforcement (EBR) gives conservative estimates of shear capacity due to its inability to capture the variation of β and θ. This paper presents three iterative approaches as well as a noniterative approach to predict the shear capacity of RC beams strengthened with EBR with greater accuracy and improved appropriate safety. The first iterative approach is based on the combination of a slightly revised version of the modified compression field theory and another model proposed in the literature. The second iterative approach is based on the combination of the simplified modified compression field theory and the aforementioned proposed model, and the third iterative approach is based on the combination of a revised version of AASHTO’s model with the aforementioned proposed approach. The noniterative approach is developed using Monte Carlo analyses using the first iterative model as the target function and includes two simple closed-form equations to capture the variation in β and θ. All proposed approaches are compared with the ACI 440.2R method in terms of accuracy and appropriate safety. A global sensitivity analysis is performed to assess the influence of various parameters on the shear capacity of RC beams strengthened with EBR using various approaches. A database of 172 RC beams strengthened with EBR is compiled to appraise the predictive capability of the proposed models and to demonstrate the improvement that they offer regarding accuracy and appropriate safety.