A research study on shear behavior of GFRP reinforced deep beams

In this study, shear behavior of (Glass fiber reinforced polymer, GFRP) reinforced concrete deep beams was investigated experimentally and numerically. In the experimental study, 12 deep beam specimens with the same length and cross-section properties were tested under the effect of four-point loading. The effects of shear span/depth ratio (a/d), reinforcement ratio and concrete steel fiber ratio on shear behavior of GFRP reinforced deep beams were investigated. In the tests, arch behavior was effective in all beams and the ultimate load capacity was achieved by shear failure. It has been observed that a/d ratio, reinforcement ratio and concrete steel fiber ratio are considerable effective in the shear behavior of deep beams. In numerical study, strut-and-tie model is discussed. The parameters affecting the strut efficiency factor (βs), which effective in the estimation of the deep beam ultimate shear strength, were examined and because of the analyses linear and nonlinear models were proposed for ACI 318-19 and CSA S806. As a result of the analyses, it was determined that the investigated parameters have a significant effect on the shear behavior of FRP reinforced deep beams. When the experimental results in the literature are compared with the numerical results, the deep beam ultimate load capacities are overestimate with the ACI 318-19 model, while it is underestimated and on the safe side with the CSA S806 model. The βs models proposed within the scope of the study showed a very successful performance in estimating the deep beam ultimate load capacities.