Shear Resistance of High Strength Concrete I-Beams with Large Shear Reinforcement Ratios

Experiments were performed to examine the shear resistance of heavily reinforced I-beams. Six I-beams with identical cross sections were constructed using high strength self-consolidating concrete, and were tested under monotonic anti-symmetric loading. All specimens had almost the same amount of longitudinal reinforcement, which provided sufficient flexural capacities. There were two variables: shear span and shear reinforcement ratio. Test results showed that ACI code was too conservative in predicting the shear strengths of heavily shear reinforced I-beams, and the shear strength limit for deep beams should be increased to account for the benefit of high strength concrete. However, doubling the amount of stirrups did not improve the ultimate shear resistance much. The three beams that contained around 2.45 % stirrups showed over-reinforced shear failures. Longitudinal flange cracking occurred to every specimen due to lack of cross tie reinforcement in the flanges, and it was believed to have reduced the ultimate shear strength