Reliability and Model Accuracy for High-Strength Concrete Column Design
Publication: Journal of Structural Engineering
Volume 125, Issue 3
Abstract
Ultimate strength limit state provisions of the LRFD code ACI 318-95 are based largely on code-calibration considerations. Calibration exercises to date have been restricted to normal-strength concretes (NSC). The present paper calculates structural reliabilities of NSC and high-strength concrete (HSC) short columns sized to existing and proposed concrete rectangular stress block design models. Model errors for existing and proposed design models are presented also. It was found that the reliabilities of NSC and HSC short columns designed to ACI 318-95 are relatively consistent, and that the rectangular stress block design model proposed by the writers is the most accurate design model. Compared with all proposed design models, the reliabilities of NSC and HSC short columns designed to the writers' design model are the most consistent, though at a reliability slightly higher than that currently obtained for NSC columns designed to ACI 318-95. A strength reduction factor increase to 0.8 is proposed for the writer's design model so that existing safety indices would be met. The alternative is to use the existing ACI 318 rectangular stress block (which is a poorer predictor model) with the current strength reduction factor of 0.7. Both give consistent safety indices. The results can be subject to a number of interpretations, particularly since they relate to potential change to an existing code and the various implications that this may have. As such, issues relating to code development are discussed.
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References
1.
Attard, M. M., and Foster, M. M. ( 1995). “Ductility of high strength concrete columns.” UNICIV Rep. No. R-344, University of New South Wales, Sydney, Australia.
2.
Attard, M. M., and Stewart, M. G. ( 1998). “A two parameter stress block for high strength concrete.” ACI Struct. J., 95(3), 305–317.
3.
Bartlett, F. M., and MacGregor, J. M. ( 1995). “In-place strength of high performance concretes.” Fall Convention of ACI, American Concrete Institute, Detroit.
4.
Bartlett, F. M., and MacGregor, J. M. ( 1996). “Statistical analysis of the compressive strength of concrete in structures.” ACI Mat. J., 93(March-April), 158–168.
5.
Basappa, R. H., and Rangan, B. V. ( 1996). “Failure load of high strength concrete (HSC) columns under eccentric compression.” Australian Civ. Engrg. Trans., CE39(1), 19–29.
6.
Bridge, R. Q., and Pham, L. ( 1984). “Reliability analysis of short beam-columns in steel.” 9th Australian Conf. on Mech. of Struct. and Mat., 289–294.
7.
“Building code requirements for structural concrete.” (1995). ACI 318-95, American Concrete Institute, Detroit.
8.
“Concrete structures.” (1994). AS 3600, Standards Association of Australia, Sydney, Australia.
9.
“Design of concrete structure.” (1995). NZS 3101, Standards New Zealand, Wellington, New Zealand.
10.
“Design of concrete structures in buildings.” (1994). CAN 3-A23.3-M94, Canadian Standards Association, Rexdale, Ont., Canada.
11.
Diniz, S. M. C., and Frangopol, D. M. (1997a). “Reliability bases for high-strength concrete columns.”J. Struct. Engrg., ASCE, 123(10), 1375–1381.
12.
Diniz, S. M. C., and Frangopol, D. M. (1997b). “Strength and ductility simulation of high-strength concrete columns.”J. Struct. Engrg., ASCE, 123(10), 1365–1374.
13.
Ellingwood, B., Galambos, T. V., MacGregor, J. G., and Cornell, C. A. ( 1980). “Development of a probability based load criterion for American National Standard A58.” Nat. Bureau of Standards Spec. Publ. 577, U.S. Government Printing Office, Washington, D.C.
14.
Foster, S. F., and Attard, M. M. ( 1997). “Experimental tests on eccentrically loaded high strength concrete columns.” ACI Struct. J., 94(3), 295–303.
15.
Galambos, T., Ellingwood, B., MacGregor, J., and Cornell, A. (1982). “Probability based load criteria: Assessment of current design practice.”J. Struct. Div., ASCE, 108(5), 959–977.
16.
Hognestad, E. ( 1951). “A study of combined bending and axial load in reinforced concrete members.” Bull. Ser. No. 399, University of Illinois Engineering Experiment Station.
17.
Ibrahim, H. H. H., and MacGregor, J. G. ( 1997). “Modification of the ACI rectangular stress block for high strength concrete columns.” ACI Struct. J., 94(1), 40–48.
18.
Israel, M., Ellingwood, B., and Corotis, R. (1987). “Reliability-based code formulations for reinforced concrete buildings.”J. Struct. Div., ASCE, 113(10), 2235–2252.
19.
MacGregor, J. G. ( 1988). Reinforced concrete: Mechanics and design . Prentice-Hall, Englewood Cliffs, N.J.
20.
MacGregor, J. G., Breen, J. E., and Pfrang, E. O. ( 1970). “Design of slender concrete columns.” J. Am. Concrete Inst., 67(1), 6–28.
21.
Melchers, R. E. ( 1987). Structural reliability: Analysis and prediction. Ellis Horwood, Chichester, U.K.
22.
Mendis, P. A., and Pendyala, R. S. ( 1997). “Structural design with high-strength high-performance concrete—beams and columns.” Concrete in Australia, 23(2), 26–28.
23.
Mirza, S. A. ( 1996). “Reliability-based design of reinforced concrete columns.” Struct. Safety, 18(2/3), 179–194.
24.
Mirza, S. A., and MacGregor, J. G. (1979a). “Variability of mechanical properties of reinforcing bars.”J. Struct. Div., ASCE, 105(5), 921–937.
25.
Mirza, S. A., and MacGregor, J. G. (1979a). “Variations in dimensions of reinforced concrete members.”J. Struct. Div., ASCE, 105(4), 751– 766.
26.
Mirza, S. A., and MacGregor, J. G. ( 1982). “Probabilistic study of strength of reinforced concrete members.” Can. J. Civ. Engrg., Ottawa, 9, 431–448.
27.
Ngab, A. S., Floyd, O. S., and Nilson, A. R. ( 1981). “Microcracking and time-dependent strains in high strength concrete.” ACI J., July-August, 262–268.
28.
Pham, L. ( 1985). “Load combinations and probabilistic load models for limit states codes.” Civ. Engrg. Trans., CE27(1), 62–67.
29.
“Proposition d'Annexe BHP du Reglement Bael BAEL.” (1995). Final Rep., AFREM-95, Connaissance et Utilisation des BHP, LCPC, Paris.
30.
Smadi, M. M., Floyd, O. S., and Nilson, A. R. ( 1985). “High-, medium-, and low-strength concretes subject to sustained overloads—strains, strengths, and failure mechanisms.” ACI J., September-October, 657– 664.
31.
Stewart, M. G., and Attard, M. M. ( 1998). “Structural reliability and model errors for high strength concrete column design.” Res. Rep. No. 159.01.1998, Dept. of Civ., Surv., and Envir. Engrg., Univ. of Newcastle, Newcastle, Australia.
32.
Stewart, M. G., and Melchers, R. E. ( 1997). Probabilistic risk assessment for engineering systems. Chapman & Hall, London.
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Received: Mar 31, 1998
Published online: Mar 1, 1999
Published in print: Mar 1999
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