Effectiveness factor of strut-and-tie model for concrete deep beams reinforced with FRP rebars

This paper focuses on the shear strength of a fiber reinforced polymer (FRP) reinforced concrete deep beam without any web reinforcement, and proposes a new effectiveness factor for concrete struts for its design using the strut-and-tie model. A total of fifteen deep beam specimens reinforced with steel, AFRP, and CFRP rebar were tested by considering the effective beam depth, shear-span-to-depth ratio, and reinforcement ratio as test variables. The general behavior of the test specimens was examined and the effects of the test parameters on the shear strengths of the test specimens were investigated. The derivation of the new effectiveness factor of concrete struts was based on the test results performed in this work and the well-known effect of concrete specimen geometry on effective compressive strength. The experimental data obtained from the test results of this study was compared with the suggested prediction and other available proposals. It showed that the proposed effectiveness factor is able to provide highly accurate predictions on the shear strength of FRP reinforced deep beams without any web reinforcement.