Behavior of a Novel Circular HSC Column with Double High Strength Spirals

Abstract

During the last decades, great progress has been made in the research and application of high strength concrete (HSC). Due to its high strength, low dilation and brittle nature, substantial more transverse reinforcement is needed for HSC columns to obtain ductile behavior, especially for columns with large axial load ratio and/or located in seismic zones. In this paper, a novel HSC concrete column with double high-strength stirrups is proposed, which features two concentric transverse stirrups. The concrete in the cross section are divided into three parts under different confinement level, namely unconfined concrete, singly and doubly confined concrete. This structural form possesses many advantages over traditional HSC with single stirrup and steel-concrete composite columns, including enhanced strength and ductility, easy to construction and easy to connection with RC beams. Three demonstrative circular HSC columns with double spirals were prepared and tested under concentric axial compression. A current stress-strain model for steel confined HSC was modified and found suitable to predict the behavior of present HSC column with double spirals. A parametric study was then conducted to investigate the influence of several key parameters on load-strain response of HSC column with double spirals, including concrete strength, transverse reinforcement ratio, yield strength of transverse reinforcement and center to center diameter of inner spiral.