Design of confinement reinforcement for encased composite columns

Abstract

Confinement reinforcement for concrete columns is designed to ensure that the columns can withstand high lateral deformations during strong earthquakes. An accurate determination of the required confinement reinforcement is vital for achieving an efficient design, especially for encased composite columns in which reinforcement congestion can be a potential problem. This paper uses the confinement requirements among three selected specifications as the basis for developing confinement equations for encased composite columns. The specification selected herein are the ACI 318, AISC Seismic Specification, and Taiwan encased composite building code. In this study, new confinement reinforcement design equations are developed and validated against experimental results. The developed confinement provision, providing a means to quantify the confinement effect of I-shaped structural steel members, significantly reduces the required confinement reinforcement for encased composite columns, and consequently alleviates the reinforcement congestion problem.