SEISMIC EVALUATION OF RC COLUMNS CONSIDERING EQUIVALENCY OF

In this paper, a simple approach for circular column design is proposed. As the current flexural and shear design methods of the RC members are mainly based upon the rectangular cross-sectional shape, the circular shaped members might be simply converted to equivalent square shape based upon equal amount of concrete and reinforcement. The experimentally verified 3D FEM called COM3D is used to investigate the seismic performance of the circular shape and its equivalent square. RC columns with both cross-sectional shapes under varied axial load and web reinforcement are laterally pushed-over to fail in different modes. The analytical results show a good agreement in seismic performance of both. As per the analytical results, the proposed approach is found satisfactory. The governing value of ductility index to ensure ductile flexural failure rather than brittle shear mode (JSCE specifications) is more than 1.0. The analytical results show that the RC members with ductility index ranging between 0.7 to 1.0 shows minimum ductile performance to survive against total collapse as they fail in flexural-shear mode. This is attributed to the longitudinal bars as part of shear reinforcement