Confinement reinforcement design considerations for ductile HSC columns

This paper presents results from a continuing research program that aims to study confinement of concrete by lateral reinforcement. The current work deals with the experimental behavior of high-strength concrete (HSC) and ultrahigh-strength concrete (UHSC) column behavior. Realistically sized columns (305 X 305 X 1,473 mm) with heavy stubs (508 X 762 X 813 mm) were tested under moderate to high axial load levels and reversed cyclic displacement excursions. The behavior of UHSC and HSC columns were examined and compared to normal strength concrete column behavior. The variables studied in this research program are the concrete strength, axial load level, steel configuration, amount of lateral steel, and the presence of a heavy stub. A performance-based design procedure for the design of confinement reinforcement in HSC and UHSC columns is presented and compared with current American Construction Institute (United States) and New Zealand Standards (New Zealand) codes.