Shear and Bending Performances of Reinforced Concrete Beams with Different Sizes of Circular Openings

The present study pertains to the effects of transverse opening diameters and shear reinforcement ratios on the shear and flexural behavior of RC beams with two web openings across different spans, i.e., a single opening in each half-span. Within the scope of the study, a total of 12 RC beams with five different opening diameter-to-beam depth ratios (0, 0.20, 0.27, 0.33, 0.40, and 0.47) and two shear reinforcement ratios were tested to failure under four-point bending. The load capacities, ductilities, rigidities and energy dissipation capacities in the elastic and plastic ranges of beam behavior were compared. Furthermore, the load capacities of the beams were compared to the existing analytical shear strength formulations in the literature. The test results indicated that whether an RC beam with openings has adequate or inadequate amounts of shear reinforcement, the frame-type shear failure becomes much more pronounced with increasing opening diameter. The reductions in the load capacity and modulus of toughness with increasing opening diameter are more considerable in the presence of inadequate amounts of shear reinforcement, while the beam ductility is less affected in shear-deficient RC beams with openings as compared to the ones with adequate shear reinforcement.

Automated summary

The present study investigated the effects of transverse opening diameters and shear reinforcement ratios on the shear and flexural behavior of RC beams with two web openings of different spans. Twelve RC beams with various opening diameter-to-beam depth ratios and shear reinforcement ratios were tested until failure under four-point bending. The results showed that increasing opening diameter led to more pronounced frame-type shear failure, and the reductions in load capacity and modulus of toughness were more significant in the presence of inadequate shear reinforcement.