Title: Experimental Tests on Eccentrically Loaded High Strength Concrete Columns

Author(s): Stephen J. Foster and Mario M. Attard

Publication: Structural Journal

Volume: 94

Issue: 3

Appears on pages(s): 295-303

Keywords: column; ductility; eccentric loading; high-strength concrete; strength;

DOI: 10.14359/481

Date: 5/1/1997

Abstract:
Reported in this paper are the test results for 68 eccentrically loaded conventional and highstrength concrete columns. The columns were 150x150 mm (5.91 x 5.91 in.) at the midsection and haunched at the ends to apply the eccentric loading and prevent boundary effects. Concrete strengths used were 40, 55, 75, and 90 M.B.A. (5800, 8000, 10,900, and 13,100 psi) with load eccentricities of 8, 20, and 50 mm (0.32, 0.79, and 1.97 in.). The columns had either 2 or 4 percent longitudinal reinforcement and tie spacings of 30, 60, or 120 mm (1.81, 2.36, or 4.72 in.). The ultimate strength of the columns is compared to the strength predictions based on the ACI 31889 rectangular stress block parameters. The predictions compare reasonably well, although lower strengths than predicted occurred for some highstrength concrete specimens. Ductilities are calculated based on the area under the load versus average strain plus curvature times eccentricity relationship. This measure showed a weak correlation with the confinement parameter adopted. Strains in the tie reinforcement were measured at the side face for some of the medium and highstrength concrete columns. The measured strains were not at yield when the peak load was reached.