High-Strength Concrete Columns under Simulated Earthquake Loading

Abstract

The main objectives of this research were to evaluate performance of high-strength concrete (HSC) columns for ductility and strength and to critically examine ACI's Code requirements for confinement steel. Results from four HSC specimens with concrete strength of 72 MPa tested under simulated earthquake loading are presented and compared with similar specimens made of normal strength concrete (NSC). Each specimen consisted of a 305 x 305 x 1473 mm column and 508 x 762 x 813 mm stub that represented a discontinuity like a beam column joint or a footing. The variables studied are the concrete strength, steel configuration, axial load level, amount of lateral steel, and the presence of a heavy stub. As in the case of NSC, an increase in the amount of lateral steel, reduction in axial load, and increased effectiveness of the lateral support provided to longitudinal bars resulted in increases in energy absorption and dissipation capacity as well as ductility. For a specified column performance, the required amount of lateral steel appears to be proportional to the strength of concrete, in the 30-72 MPa strength range considered in this study.