Strut-and-Tie-Model for Predicting the Shear Strength of Concrete Deep Beams Reinforced with FRP Bars

Abstract

This paper presents a strut-and-tie model for predicting the shear strength of concrete deep beams reinforced with FRP bars. The model was developed based on the diagonal compression strut and truss mechanisms. The diagonal strut mechanism considers the compression softening effect whereas the truss mechanism provides the shear strength contributed by the horizontal and vertical web reinforcement. The nominal shear strength is predicted as the summation of the strength provided by the two independent mechanisms. Based on a large database of 121 FRP reinforced concrete deep beams, four empirical parameters including two parameters for describing the softening effect and two parameters for web reinforcement were determined using nonlinear optimization. The ten-fold cross-validation was used to confirm the model accuracy and generalization. The prediction by the proposed model is then compared with those computed using the U.S. and Canadian concrete codes of practice and the models from recently researches. The comparison shows that the proposed model yields better precise and consistent prediction than the benchmark models with the average strength ratio of 1.01 and coefficient of variation of 19.82%.