Title:
Strength Reduction Factor for Circular Reinforced Concrete Columns
Author(s):
Tomasz A. Lutomirski, Andrzej S. Nowak, and Marta Lutomirska
Publication:
Structural Journal
Volume:
119
Issue:
4
Appears on pages(s):
303-310
Keywords:
calibration; circular columns; reinforced concrete; reliability model; resistance factor; strength reduction factor
DOI:
10.14359/51734653
Date:
7/1/2022
Abstract:
A reliability-based calibration for new strength reduction factors for eccentrically loaded short circular reinforced concrete columns is presented. The statistical parameters of resistance used in the calibration procedure are based on a developed procedure for the determination of the capacity of columns and Monte Carlo simulations for representative design cases. The reliability indexes
were calculated for predetermined resistance factors considering various dead load to live load ratios and all possible failure modes represented by the steel strain. Then, they were compared to the target reliability index, which was assumed as βT = 4.0. The determined strength reduction factors correspond to load and load-combination factors specified by ASCE 7-16 and adopted by ACI 318-19. They are compatible with the existing provisions for resistance factors for rectangular columns.
Related References:
1. Ellingwood, B.; Galambos, T. V.; MacGregor, J. G.; and Cornell, C. A., “Development of a Probability Based Load Criterion for American National Standard A58: Building Code Requirements for Minimum Design Loads in Buildings and Other Structures,” NBS Special Publication 577, National Bureau of Standards, Washington, DC, 1980, 222 pp.
2. Galambos, T. V., and Ravindra, M. K., “Load and Resistance Factor Design,” Journal of the Structural Division, ASCE, ST9, Proc. Paper 14008, Sept. 1978, pp. 1335-1335 .
3. Nowak, A. S., and Collins, K. R., Reliability of Structures, CRC Press, Boca Raton, FL, 2013, 407 pp.
4. Iatsko, O., and Nowak, A. S., “Load and Resistance Factors for Concrete Bridges and Buildings,” Dennis Mertz Symposium on Design and Evaluation of Concrete Bridges, SP-340, A. S. Nowak and H. Nassif, eds., American Concrete Institute, Farmington Hills, MI, 2020, pp. 19-31.
5. Szerszen, M. M.; Szwed, A.; and Nowak, A. S., “Reliability Analysis for Eccentrically Loaded Columns,” ACI Structural Journal, V. 102, No. 5, Sept.-Oct. 2005, pp. 676-688.
6. ACI Committee 318, “Building Code Requirements for Structural Concrete (ACI 318-19) and Commentary (ACI 318R-19),” American Concrete Institute, Farmington Hills, MI, 2019, 624 pp.
7. Nowak, A. S.; Szerszen, M. M.; Szeliga, E. K.; Szwed, A.; and Podhorecki, P. J., “Reliability-Based Calibration for Structural Concrete, Phase 3,” SN2849, Portland Cement Association, Skokie, IL, 2008, 110 pp.
8. Nowak, A. S.; Rakoczy, A. M.; and Szeliga, E. K., “Revised Statistical Resistance Models for R/C Structural Components,” Andy Scanlon Symposium on Serviceability and Safety of Concrete Structures: From Research to Practice, SP-284, P. H. Bischoff and E. Musselman, eds., American Concrete Institute, Farmington Hills, MI, 2011, 16 pp.
9. Wight, J. K., and MacGregor, J. G., Reinforced Concrete: Mechanics and Design, fifth edition, Pearson Prentice Hall, Hoboken, NJ, 2008, 1126 pp.
10. Mirza, S. A., and MacGregor, J. G., “Variability of Mechanical Properties of Reinforcing Bars,” Journal of the Structural Division, ASCE, V. 105, No. 5, May 1979, pp. 921-937. doi: 10.1061/JSDEAG.0005146
11. Lutomirski, T. A., “Reliability Models for Circular Concrete Columns,” doctoral dissertation, University of Nebraska–Lincoln, Lincoln, NE, 2009.
12. Lutomirski, T. A., and Lutomirska, M., “Variability of Statistical Parameters of Resistance for Reinforced Concrete Columns with Circular Cross-Section,” Archives of Civil Engineering, V. LXVII, No. 2, 2021, pp. 165-180.
13. Cornell, C. A., “Bounds on the Reliability of Structural Systems,” Journal of the Structural Division, V. 93, No. 1, Feb. 1967, pp. 171-200. doi: 10.1061/JSDEAG.0001577