Beam Strength Enhancement at Design Ductility Factor Demands
Publication: Journal of Structural Engineering
Volume 116, Issue 12
Abstract
A refined bending‐analysis model is presented that accurately predicts available experimental results. By means of this model, the relations of the ultimate‐to‐yielding moment ratio versus the longitudinal reinforcement ratio are deduced for a beam that is rectangular in cross section with two reinforcement layers. Two values of the curvature‐ductility factor were assumed to be boundary values of the demand during a severe earthquake. From each of the two values a moment value is then derived, which is considered ultimate. The results show that the strength enhancement due to strain‐hardening of the reinforcing steel can vary over a wide range of values (12‐65%) depending on the longitudinal (in tension and compression) and transverse reinforcement ratios. Hence the ACI Committee 352 recommendation of a constant (40%) increase in the sum of beam's nominal moment strength at beam‐column joints is found to be inadequate. To provide an approximate evaluation of the strength enhancement, thus avoiding the iterative analytical solution, a simple numerical model that gives reasonable agreement with the more exact values is proposed.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
“Building code requirements for reinforced concrete.” (1983). ACI‐318, 83, American Concrete Institute (ACI), Detroit, Mich.
2.
Burns, N. H., and Siess, C. P. (1962). “Load‐deformation characteristics of beam‐column connections in reinforced concrete.” Civil Engineering Studies, Structural Research Series No. 234, Univ. of Illinois, Urbana, Ill.
3.
Cook, R. D. (1981). Concepts and applications of finite element analysis. John Wiley and Sons, New York, N.Y.
4.
Papia, M., and Russo, G. (1989). “Compressive concrete strain at buckling of longitudinal reinforcement.” J. Struct. Engrg., ASCE, 115(2), 382–397.
5.
Park, R., and Paulay, T. (1975). Reinforced concrete structures. John Wiley and Sons, New York, N.Y.
6.
Park, R., Priestley, M. J. N., and Gill, W. D. (1982). “Ductility of square confined concrete columns.” J. Struct. Div., ASCE, 108(4), 929–950.
7.
Park, R., and Ruitong, D. (1988). “Ductility of doubly reinforced concrete beam section.” ACI Struct. J., 85(2), 217–225.
8.
“Recommendations for design of beam‐column joints in monolithic reinforced concrete structures. ACI 352 R‐85,” ACI J., 82(3), 266–283.
9.
Russo, G., Zingone, G., and Romano, F. (1990). “Analytical solution for bond slip of reinforcing bars in R.C. joints.” J. Struct. Engrg., ASCE, 116(2), 336–355.
10.
Scott, B. D., Park, R., and Priestley, M. J. N. (1982). “Stress‐strain behavior of concrete confined by overlapping hoops at low and high strain rates.” ACI J., 79(1), 13–27.
11.
Wang, P. T., Shah, S. P., and Naaman, A. E. (1978). “High‐strength concrete in ultimate strength design.” J. Struct. Div., ASCE, 104(11), 1761–1773.
Information & Authors
Information
Published In
Copyright
Copyright © 1990 ASCE.
History
Published online: Dec 1, 1990
Published in print: Dec 1990
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.