Influence of Web Opening Size on Shear Behavior of GFRP-Reinforced High Strength Concrete Deep Beams

This paper explores shear behavior of high-strength concrete (HSC) deep beam reinforced with Glass Fiber Reinforced Polymer (GFRP) bars and with square web openings, as part of the development of construction materials that are environmentally-friendly. Three full-size beam samples were made and tested at four-point bending to determine the effect of varying opening size (75 × 75, 125 × 125 and 175 × 175 mm) on shear capacity, load-deflection behavior, strain distribution and failure modes. Digital Image Correlation (DIC) presented detailed information on strain development, crack shape and reinforcement performance. The findings showed that shear capacity and ductility reduced drastically with the increase in opening size. The beam that had the least opening (75 mm) had the highest load capacity (714.7 kN), the most ideal strain distribution and had the best ductility. Openings with larger sizes (125 and 175 mm) had lower load capacities, concentrated strain around openings, were under rapid crack formation and failed by brittle fractures. The results highlight the need to reduce the opening dimensions and introduce appropriate reinforcement description to ensure structural performance in GFRP-reinforced HSC deep beams. The work offers important insights that will be critical towards designing concrete beams that are sustainable, durable, and structurally efficient in environments that require concrete in construction.