Numerical study on shear failure and the corresponding size effect of interior RC beam-column joints

Abstract

The shear failure of the core zone of reinforced concrete (RC) beam-column joint has brittle characteristics, so the size effect of shear strength can be caused. Based on the existing experimental research results, the numerical test method is used to analyze the structural size, axial compression ratio, and stirrup ratio on the effect of failure mechanism and failure mode of the RC beam-column joint, and reveal their influence on the size effect of shear strength. The maximum cross-sectional dimension of the joint is 900 mm × 900 mm. The results show that: (1) under the monotonic loading, the beam-column nodes exhibit brittle shear failure in the core region, and the nominal shear strength has a significant size effect; (2) the increase in the axial compression ratio can enhance the shear capacity of the middle joint and also strengthen the size effect of shear strength; (3) an increase in the stirrup ratio can increase the shear capacity of the joint, but it can also weaken the size effect of the shear strength. Lastly, the classical size effect law proposed by Bažant can reflect the size effect of shear failure of the middle node, but it cannot describe the quantitative influence of the axial compression ratio and stirrup ratio.