Shear Behavior of Reinforced Concrete Columns with High-Strength Steel and Concrete

Eight shear-critical, large-scale, high-strength reinforced concrete columns under low axial load were tested. The specified concrete compressive strengths were 70 and 100 MPa (10,000 and 14,500 psi). The specified yield strengths were 685 and 785 MPa (100,000 and 114,000 psi) for the longitudinal and transverse reinforcement, respectively. Test results show that all the columns exhibited shear failure before longitudinal reinforcement yielding. The transverse reinforcement did not yield at the peak applied load for all the columns. In total, test data for 43 high-strength columns from this study and literature were collected. A comparison to the ACI 318 shear-strength equations show that the ACI simplified shear-strength equation provided conservative estimation for all the columns. However, the ACI detailed shear-strength equation yielded unconservative prediction for 19 columns. This study proposes modifications to the ACI detailed shear-strength equation to address this issue.