Strength and Ductility of Confined Concrete
Publication: Journal of Structural Engineering
Volume 118, Issue 6
Abstract
An analytical model is proposed to construct a stress‐strain relationship for confined concrete. The model consists of a parabolic ascending branch, followed by a linear descending segment. It is based on calculation of lateral confinement pressure generated by circular and rectilinear reinforcement, and the resulting improvements in strength and ductility of confined concrete. A large volume of test data, including poorly confined and well‐confined concrete was evaluated to establish the parameters of the analytical model. Confined concrete strength and corresponding strain are expressed in terms of equivalent uniform confinement pressure provided by the reinforcement cage. The equivalent uniform pressure is obtained from average lateral pressure computed from sectional and material properties. Confinement by a combination of different types of lateral reinforcement is evaluated through superposition of individual confinement effects. The descending branch is constructed by defining the strain corresponding to 85% of the peak stress. This strain level is expressed in terms of confinement parameters. A constant residual strength is assumed beyond the descending branch, at 20% strength level. The model is compared against a large number of column tests. Circular, square, and rectangular columns, with spiral and rectilinear reinforcements, as well as welded wire fabric, are used for comparison. Comparisons include concentric and eccentric loadings, as well as slow and fast strain rates. The results indicate good agreement.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Abdulkadir, R., and Saatcioglu, M. (1991). “Tests of concrete columns reinforced with welded wire fabric.” Research Report No. 9104, Dept. of Civ. Engrg., Univ. of Ottawa, Ottawa, Canada.
2.
Balmer, G. G. (1949). “Shearing strength of concrete under high triaxial stress‐computation of Mohr's envelope as a curve.” Structural Research Lab. Report No. SP‐23, U.S. Bureau of Reclamation, Denver, Co.
3.
Building code requirements for reinforced concrete and commentary. American Concrete Inst., Detroit, Mich., 353.
4.
Hognestad, E. (1951). “A study of combined bending and axial load in reinforced concrete members.” Bulletin Series No. 399, Univ. of Illinois Engrg. Experimental Station, Urbana, III.
5.
Mander, J. B., and Priestley, M. J. N., Park, R. (1988). “Observed stress‐strain behavior of confined concrete.” J. Struct. Engrg., ASCE, 114(8), 1827–1849.
6.
Razvi, S. R., and Saatcioglu, M. (1989). “Confinement of reinforced concrete columns with welded wire fabric.” ACI Struct. J., 85(5), 615–623.
7.
Richart, F. E., Brandtzaeg, A., and Brown, R. L. (1928). “A study of the failure of concrete under combined compressive stresses.” Bulletin No. 185, Univ. of Illinois Engrg. Experimental Station, Urbana, III.
8.
Richart, F. E., Brandtzaeg, A., and Brown, R. L. (1929). “The failure of plain and spirally reinforced concrete in compression.” Bulletin No. 190, Univ. of Illinois Engrg. Experimental Station, Urbana, III.
9.
Saatcioglu, M., and Razvi, S. R. (1991). “Analytical model for confined concrete.” Research Report No. 9101, Dept. of Civ. Engrg., Univ. of Ottawa, Ottawa, Canada.
10.
Salamat, A., and Saatcioglu, M. (1991). “Tests of confined columns under eccentric loading.” Research Report No. 9103, Dept. of Civ. Engrg., Univ. of Ottawa, Ottawa, Canada.
11.
Sato, T., and Ibushi, K. (1988). “Effect of confinement on ductile behavior of reinforced concrete short columns.” Trans. of the Japan Concrete Inst., Japan Concrete Institute, 10(5), 337–344.
12.
Scott, B. D., Park, R., and Priestley, M. J. N. (1982). “Stress‐strain behavior of concrete confined by overlapping hoops at high and low strain rates.” ACI J., 79(1), 13–27.
13.
Sheikh, S. A. (1982). “A comparative study of confinement models.” ACI J., 79(4), 296–305.
14.
Sheikh, S. A., and Uzumeri, S. M. (1980). “Strength and ductility of tied concrete columns.” J. of Struct. Engrg., ASCE, 106(5), 1079–1102.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 118 • Issue 6 • June 1992
Pages: 1590 - 1607
Copyright
Copyright © 1992 ASCE.
History
Published online: Jun 1, 1992
Published in print: Jun 1992
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.