Unified Bending Strength Design of Concrete Members: AASHTO LRFD Code
Publication: Journal of Structural Engineering
Volume 121, Issue 6
Abstract
This paper summarizes the procedure for the computation of nominal bending resistance of reinforced, prestressed, and partially prestressed concrete members according to the 1994 “AASHTO LRFD Specifications for Highway Bridge Design.” The cases of rectangular or flanged sections, underreinforced or overreinforced, with a combination of reinforcing bars and prestressing tendons, whether bonded or unbonded, are covered. Provisions on limiting the flexural reinforcement adopted in the new specifications are summarized. They address minimum and maximum levels of reinforcement in flexural members, the percent of moment redistribution in continuous bending members, and the prediction of stress at ultimate in bonded and unbonded tendons. The provisions are nondimensional and can be applied to any code. Logical flowcharts showing the various computational steps are provided, and examples illustrating the procedure are developed.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
“AASHTO LRFD specifications for highway bridge design, 1994; American Association of State Highway and Transportation Officials, Washington, D.C.; and NCHRP project 12-33.” (1993). Development of Comprehensive Bridge Specifications and Commentary, Modjeski and Masters, Pittsburgh, Pa.
2.
“Building code requirements for reinforced concrete.” (1989). ACI Committee 318, Am. Concrete Inst., Detroit, Mich.
3.
Alkhairi, F. M., and Naaman, A. E.(1993). “Analysis of beams prestressed with unbonded internal or external tendons.”J. Struct. Engrg., ASCE, 119(9), 2680–2700.
4.
Bondy, K. B.(1992). “Variable prestress force in unbonded post-tensioned concrete members.”Concrete Int., 14(1), 27–33.
5.
Burns, N., Helwig, T., and Tsujimoto, T.(1991). “Effective prestress force in continuous post-tensioned beams with unbonded tendons.”ACI Struct. J., 88(1), 84–90.
6.
Harajli, M., and Naaman, A. E.(1985). “An evaluation of the ultimate steel stress in partially prestressed flexural members.”PCI J., 30(5), 54–81.
7.
Loov, R. E.(1988). “A general equation for the steel stress for bonded prestressed tendons.”PCI J., 33(6), 108–137.
8.
Mojtahedi, S., and Gamble, W. L.(1978). “Ultimate steel stresses in unbonded prestressed concrete.”J. Struct. Engrg., ASCE, 104(7), 1159–1165.
9.
Naaman, A. E.(1985). “Partially prestressed concrete: review and recommendations.”PCI J., 30(6), 30–71.
10.
Naaman, A. E., and Alkhairi, F. M.(1991a). “Stress at ultimate in unbonded prestressing tendons. Part I: Evaluation of the state-of-the-art.”ACI Struct. J., 88(5), 641–651.
11.
Naaman, A. E., and Alkhairi, F. M.(1991b). “Stress at ultimate in unbonded prestressing tendons. Part II: Proposed methodology.”ACI Struct. J., 88(6), 683–692.
12.
Naaman, A. E.(1992). “Unified design recommendations for reinforced prestressed and partially prestressed concrete bending and compression members.”ACI Struct. J., 89(2), 200–210.
13.
Naaman, A. E. (1992). “Closure to discussion of `Unified design recommendations for reinforced, prestressed, and partially prestressed concrete bending and compression members,”' ACI Struct. J., 89(5), 594–601.
14.
Naaman, A. E., and Hamza, A. M.(1993). “Prestress losses in partially prestressed high strength concrete beams.”PCI J., 38(3), 98–114.
15.
Naaman, A. E. (1994). “The new AASHTO recommendations on reinforcement for reinforced prestressed, and partially prestressed concrete.”Proc., FIP World Congr., Vol. 2, Struc. Engrs. Trading Organization Ltd., London, England, 952–957.
16.
Naaman, A. E. (1994). “Unified code provisions for concrete bridges.”Proc., ASCE Struct. Congr. XII, N. C. Baker and B. J. Goodno, eds., ASCE, New York, N.Y.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 121 • Issue 6 • June 1995
Pages: 964 - 970
Copyright
Copyright © 1995 American Society of Civil Engineers.
History
Published online: Jun 1, 1995
Published in print: Jun 1995
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.