Axial-Shear-Flexure Interactive Behavior of Concrete Member with Low-Bond Reinforcements and Shear Failure

To study the axial-shear-flexure-interactive (ASFI) behavior of reinforced concrete (RC) members with low-bond reinforcement, twenty-three high-strength fly ash concrete with low-bond high-strength SBPDN 1275/1420 rebars were fabricated to test. The experimental results indicate that the degradation of shear strength carried by concrete controlled the overall shear strength behavior of test beams. Shear failure typically occurred along a diagonal shear cracking plane. To develop a calculation method for predicting the ASFI behavior of RC member, a model was proposed to estimate the neutral axial depth of cross-section, which simplified the estimation of the lateral force behavior without numerous mathematical iterations. The calculation method took into account flexural deformation, deformation due to steel-bond slip, and shear deformation based on the modified compression-field theory. An analytical model was derived to calculate the nominal shear strength using the shear-friction mechanism and Mohr – Coulomb failure criterion. The degraded drift ratio and stiffness of the shear strength were determined through regression analysis of the test data. Finally, the proposed calculation program for the ASFI behavior and shear strength capacity model were used to predict the lateral behaviors of RC members with different structural parameters. The comparison results indicated that the ASFI calculation program successfully predicted the lateral behavior with good accuracy. Additionally, the proposed shear strength capacity model was able to determine the failure mode of RC members.