Shear Behavior of Large Reinforced Concrete Beams without Web Reinforcement

This study presents an investigation on the influence of beam depth and longitudinal reinforcement ratio on shear strength. Seven reinforced concrete beams without web reinforcement with depth varying from 500 mm to 1200 mm were tested. Maximum shear crack width, crack spacing and inclinations of shear cracks were measured and shear mechanism of concrete was discussed. In addition, other shear test data found in the literature were used to supplement the experimental data. Based on test results, the shear design methods in the GB50010 code and the ACI 318 code were examined. It was found that the size effect factor in the GB50010 shear design equations was unable to represent the reduction of shear strength for large beams due to the size effect, and that both the GB50010 method and the ACI 318 method are dangerously unconservative when applied to large beams or to beams with low longitudinal reinforcement ratio. The CSA 2004 code method developed based on the Modified Compression Field Theory was also used to analysis the test data and satisfactory results were achieved.