Title: Design of High-Strength Concrete Columns for Strength and Ductility

Author(s): M. Saatcioglu

Publication: Symposium Paper

Volume: 213

Issue:

Appears on pages(s): 83-102

Keywords: column design; concrete columns; confinement; high-strength concrete (HSC); rectangular stress block; reinforced concrete

DOI: 10.14359/12747

Date: 5/22/2003

Abstract:
The use of high-strength concrete in construction industry has expanded in recent years for its superior strength and performance. However, many aspects of structural design for high-strength concrete columns remain to be developed. Of fundamental importance is the development of a rectangular stress block that is applicable to high-strength concrete. The current rectangular stress block parameters, intended for normal-strength concrete, are not suitable for use in high-strength concrete columns. A new rectangular stress block is presented in the paper for the computation of column strength under combined flexure and axial compression. Strength and ductility of concrete are inversely proportional. Therefore, high- strength concrete columns exhibit brittle characteristics, developing sudden and explosive failures under concentric compression. Therefore, the design of high-strength concrete columns becomes a challenge, especially for seismically active regions. While column ductility can be increased through confinement, the ACI 318-02 (1) confinement requirements are intended for normal-strength concrete columns and are not applicable to columns cast from high-strength concrete. A displacement based design procedure has been developed for the confinement of high-strength concrete columns. The procedure is presented in the paper with related design expressions. Summary of experimental findings on inelastic deformability of high-strength concrete columns is also presented with the effects of design parameters highlighted.