Title:
Transverse Steel Content in Spiral Concrete Columns
Subject to Eccentric Loading
Author(s):
Raed M. Samra, Nidal A. A. Deeb, and Usama R. Madi
Publication:
Structural Journal
Volume:
93
Issue:
4
Appears on pages(s):
412-419
Keywords:
columns (supports); confinement; curvature; ductility; eccen-tric
loading; reinforced concrete; spiral; transverse steel.
DOI:
10.14359/9700
Date:
7/1/1996
Abstract:
The ACI Code equation for the ratio of spiral reinforcement is modified to account for the level of eccentricity of applied loads. The available ductility of spirally confined reinforced concrete column sections, with a range of longitudinal and transverse steel ratios, strengths of steel and concrete, and also different ratios of eccentricity level-to-section diameter are studied. The method of analysis is based on a theoretical study using a unified stress-strain model for concrete subjected to uniaxial compressive loading and confined by transverse reinforcement proposed by Mander et al. The steel stress-strain model includes strain hardening. It is concluded that the current ACI Code requirements for transverse reinforcement are low at high eccentricity levels and high for axially loaded columns. Based on this theoretical study a modification is proposed of the ACI requirements that involves adding a term, a function of the eccentricity-to-column diameter ratio multiplied by the original ACI expression for spiral steel.