Controlling the damage of concrete columns through compression yielding

For reinforced concrete (RC) members, the crushing of concrete governs the ultimate failure of a cross-section. As the ultimate strain of a particular grade concrete is a certain value, the curvature capacity of an RC section depends on the tensile strain of the member at concrete crushing. Similarly, the curvature ductility depends on the extent of tensile yielding of the steel reinforcement. In RC columns, the existence of the axial force reduces the strain at the tension side of the cross-section. Therefore, the deformation capacity and the ductility of an RC column is usually smaller than that of an RC beam. The ductility is critical for RC columns, particularly for seismic structures to survive a major earthquake. As a result, the development of technology that can control the damage and increase the ductility of RC columns is of major theoretical significance and practical importance for RC structures. A novel structural concept for controlling the damage and increasing the flexural ductility of RC beams through compression yielding (CY) instead of tension yielding has recently been developed by the authors. Preliminary theoretical studies and experimental investigations have demonstrated that the CY concept is highly effective in reducing the damage and increasing the ductility of RC beams. In principle, the CY concept should be equally applicable and effective for RC columns. This work aims at controlling the damage and increasing the deformability and ductility of RC columns through the application of the newly developed CY technology.