Seismic performance of concrete columns with innovative seven- and eleven-spiral reinforcement

This research proposes innovative seven- and 11-spiral transverse reinforcement to replace two- and six-spiral reinforcement, respectively, to decrease spiral size to address the issue of spiral fabrication in large columns. Moreover, this research proposes using large reinforcing bars or H-shaped steel as longitudinal reinforcement to reduce the potential of reinforcing bar cage failure. The objectives of this research were to investigate the seismic performance of seven- and 11-spiral columns and the effect of using large reinforcing bars and H-shape steel as longitudinal reinforcement. Cyclic tests of columns showed that seven- and 11-spiral columns, even with less amounts of transverse reinforcement, exhibited higher ductility capacities than tied columns. The use of H-shaped steel as longitudinal reinforcement increased ductility and energy dissipation of the column. Among ACI 318, Caltrans BDS, and Caltrans SDC methods to estimate probable moment strength, only the Caltrans SDC method produced conservative results for all columns examined.