Shear capacity and behavior of high-strength concrete beams with openings

Abstract

Transverse openings alter the structural behavior and undermine the integrity of concrete beams, resulting in stiffness degradation, shear strength reduction, stress concentration, premature cracking, and force-flow disturbances. Consequently, they require special attention during the design and construction of concrete beams with openings. Owing to the abrupt change in the beam's cross-sectional area, the strain distribution in the region around an opening is disturbed and nonlinear, making conventional bending and shear theories irrelevant. Few studies have investigated the impact of openings on concrete beams, especially that of openings on high-strength concrete (HSC) beams. Therefore, in this study, we perform tests on 12 reinforced concrete beam specimens to investigate the influence of depth, length, and location of openings on the ultimate shear strength of HSC beams with openings. The results revealed that the opening depth and length of HSC beams are negatively and almost linearly correlated to the ultimate shear strength; furthermore, based on their size and location, the shear capacity reduces by 2–53%. Similarly, the opening location along the shear span had a substantial impact on the capacity and behavior of the beam. Subsequently, finite element models of the tested beams were developed in ABAQUS software package and validated in compliance with the experimental results. The simulations exhibited good performance in predicting the ultimate strength, load–deflection relationship, and crack propagation in the beams. Accordingly, the developed models can be utilized to conduct further parametric studies and develop strut-and-tie models.