Shear Performance and Sustainability Assessment of Reinforced Concrete Beams with Longitudinal Hollow Cores

This study investigates the shear performance of reinforced concrete beams containing longitudinal hollow cores, focusing on hollow-core diameter, shear span-to-effective depth ratio (a/d), and environmental benefits from reduced concrete consumption.

An experimental program was conducted on six reinforced concrete beam specimens subjected to four-point bending with two symmetrically applied concentrated loads until failure. Hollow-core diameter and a/d were varied. Measured shear capacities were compared with ACI 318 predictions. Material Production Energy (MPE) and CO₂ emissions were evaluated from the material quantities used in each specimen.

Increasing hollow-core diameter reduced beam stiffness and ultimate shear capacity, with reductions of up to 19.4% relative to the solid beam. Increasing a/d from 2.5 to 3.0 reduced ultimate shear capacity by approximately 10%. All specimens failed in a brittle diagonal shear mode. ACI 318 consistently underestimated measured shear capacities, providing conservative predictions. Reduced concrete quantities also decreased MPE and CO₂ emissions.

The results show that hollow-core diameter and a/d affect shear strength, cracking behavior, and stiffness. Longitudinal hollow cores can reduce material production impacts while maintaining acceptable shear performance within the investigated range.

Longitudinal hollow cores provide a viable approach for reducing concrete consumption and environmental impacts without disproportionate loss of shear capacity within the investigated geometric limits. Further studies with larger specimen sizes and repeated specimens are required to verify these findings.