Comparative assessment of existing shear models for RC beams using experiments and FE analysis

Abstract Shear failure in reinforced concrete (RC) beams can be sudden and brittle, necessitating an accurate prediction of shear strength. This study investigates parameters influencing the shear strength of RC beams and develops an improved analytical model through experimentation and finite element analysis. Two RC beams were tested under three-point bending to examine the effect of stirrup spacing. A validated 3D nonlinear finite element model was used to further analyze six beams with different stirrup configurations. The results showed that the shear span-to-depth ratio, longitudinal steel ratio, concrete strength, and crucially, the web reinforcement ratio significantly affect shear strength. While existing code equations like ACI and ECP neglect some of these parameters, an enhanced empirical equation was formulated based on test data and an extensive literature review. The new shear model incorporates shear span-to-depth ratio, longitudinal reinforcement, concrete strength, and web reinforcement amount, unlike ACI and ECP codes. Compared to Zsutty’s equation, it additionally accounts for web reinforcement. The proposed model was validated against 78 beam test results from the literature, showing good accuracy (average $${\text{V}}_{\text{pre}}/{\text{V}}_{\text{exp}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mtext>V</mml:mtext> <mml:mtext>pre</mml:mtext> </mml:msub> <mml:mo>/</mml:mo> <mml:msub> <mml:mtext>V</mml:mtext> <mml:mtext>exp</mml:mtext> </mml:msub> </mml:mrow> </mml:math> of 1.00) and low deviation, outperforming ACI, ECP, and Zsutty equations. This study thus develops and validates an improved shear strength model for RC beams by considering multiple influential parameters neglected in codes. The model can be used for the safer and more economical design of RC beams susceptible to shear failure.