Title: Steel-Confined Circular Columns under Simulated Seismic Loads
Author(s): James Liu, Shamim Sheikh, and Zahra Kharal
Publication: Structural Journal
Appears on pages(s): 189-200
Keywords: circular columns; confined concrete; ductility; enhancement; flexural strength; seismic test; steel confinement
Test results are presented for eight large-scale reinforced concrete circular columns that were laterally confined by a different amount of steel spirals and tested under simulated seismic loads. Behavior of these specimens was evaluated against the requirements in different concrete design codes for the transverse reinforcement in frame columns. Test results showed that seismic resistance of columns could be significantly improved by an increase of lateral confinement and the decrease of axial load level. However, while curvature ductility and energy dissipation capacity of a section increase with the increase of confinement, the displacement ductility of the member does not increase beyond a limit. The flexural strength of columns under high axial load is enhanced significantly, especially under high axial loads, due to the confinement, which is neglected currently by most design codes. A procedure to evaluate the strength enhancement owing to lateral steel confinement is proposed.