Performance-Based Design of Confining Reinforcement: Research and Seismic Design Provisions

In performance-based seismic design, evaluation of the deformation capacity of reinforced concrete columns is of paramount importance. The deformation capacity of a column can be expressed in several different ways: (1) curvature ductility, (2) displacement ductility, or (3) drift. Even though several performance-based confining reinforcement design procedures have been proposed, the relationship between different ductility factors is not clearly understood. The effect of concrete strength, longitudinal reinforcement ratio, volumetric ratio of confining reinforcement, shear span-to-depth ratio, and axial load level on the relationship between different ductility factors was studied. Finally, the confinement reinforcement design requirements of current design codes and recently proposed performance-based design methods were compared and critically examined.