LRFD Calibration of Simple Soil-Structure Limit States Considering Method Bias and Design Parameter Variability
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 143, Issue 9
Abstract
A general closed-form solution for the reliability index (or probability of failure) of a simple linear limit-state design function with one load term and one resistance term is used to compute the resistance factor expressed in a load and resistance factor design (LRFD) format. The solution considers method bias, bias dependencies, and uncertainties in choice of nominal values of load and resistance determined as part of the project-specific design process. Uncertainty in the choice of nominal values for design is linked quantitatively to the concept of project level of understanding that has been recently adopted in Canadian design practice. All random variables are assumed to be lognormally distributed. Parametric analyses are carried out to show that ignoring possible correlations between random variables can lead to conservative (safe) values of resistance factor and in other cases to nonconservative (unsafe) values. Example LRFD calibrations are carried out using different load and resistance models for the pullout internal stability limit state of steel-reinforced soil walls together with matching bias data reported in the literature. The results demonstrate the practical influence of model type, method bias statistics including dependencies, and operational factor of safety on computed resistance factors.
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Acknowledgments
The work reported in this paper was supported by a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) awarded to the first author.
References
AASHTO. (2014). LRFD bridge design specifications, 7th Ed., Washington, DC.
Allen, T. M. (2005a). “Development of geotechnical resistance factors and downdrag load factors for LRFD foundation strength limit state design.”, National Highway Institute, Federal Highway Administration, Washington, DC.
Allen, T. M. (2005b). “Development of the WSDOT pile driving formula and its calibration for load and resistance factor design (LRFD).”, Washington Dept. of Transportation, Olympia, WA.
Allen, T. M. (2013). “AASHTO geotechnical design specification development in the USA.” Modern geotechnical design codes of practice–Implementation, application, and development, P. Arnold, G. Fenton, M. Hicks, T. Schweckendiek, and B. Simpson, eds., IOS Press, Amsterdam, Netherlands, 243–260.
Allen, T. M., and Bathurst, R. J. (2015). “An improved simplified method for prediction of loads in reinforced soil walls.” J. Geotech. Geoenviron. Eng., 04015049.
Allen, T. M., Bathurst, R. J., Holtz, R. D., Lee, W. F., and Walters, D. (2004). “New method for prediction of loads in steel reinforced soil walls.” J. Geotech. Geoenviron. Eng., 1109–1120.
Allen, T. M., Nowak, A. S., and Bathurst, R. J. (2005). “Calibration to determine load and resistance factors for geotechnical and structural design.”, Transportation Research Board, Washington, DC.
Bathurst, R. J. (2014). “LRFD calibration of simple limit state functions in geotechnical soil-structure design.” Reliability-based design in geotechnical engineering: Computations and applications, K. K. Phoon and J. Ching, eds., Spon Press, London, 339–354.
Bathurst, R. J., Allen, T. M., and Nowak, A. S. (2008). “Calibration concepts for load and resistance factor design (LRFD) of reinforced soil walls.” Can. Geotech. J., 45(10), 1377–1392.
Bathurst, R. J., Huang, B., and Allen, T. M. (2011a). “Load and resistance factor design (LRFD) calibration for steel grid reinforced soil walls.” Georisk, 5(3–4), 218–228.
Bathurst, R. J., Huang, B., and Allen, T. M. (2012). “LRFD calibration of the ultimate pullout limit state for geogrid reinforced soil retaining walls.” Int. J. Geomech., 399–413.
Bathurst, R. J., and Javankhoshdel, S. (2017). “Influence of model type, bias and input parameter variability on reliability analysis for simple limit states in soil-structure interaction problems.” Georisk, 11(1), 42–54.
Bathurst, R. J., and Miyata, Y. (2015). “Reliability-based analysis of combined installation damage and creep for the tensile rupture limit state of geogrid reinforcement in Japan.” Soils Found., 55(2), 437–446.
Bathurst, R. J., Miyata, Y., and Konami, T. (2011b). “Limit states design calibration for internal stability of multi-anchor walls.” Soils Found., 51(6), 1051–1064.
Becker, D. E. (1996a). “Eighteenth Canadian Geotechnical Colloquium: Limit states design for foundations. Part 1: An overview of the foundation design process.” Can. Geotech. J., 33(6), 956–983.
Becker, D. E. (1996b). “Eighteenth Canadian Geotechnical Colloquium: Limit states design for foundations. Part II: Development for the national building code of Canada.” Can. Geotech. J., 33(6), 984–1007.
CSA (Canadian Standards Association). (2014). “Canadian highway bridge design code.” CAN/CSA-S6-14, Mississauga, ON, Canada.
Fenton, G. A., Naghibi, F., Dundas, D., Bathurst, R. J., and Griffiths, D. V. (2016). “Reliability-based geotechnical design in the 2014 Canadian highway bridge design code.” Can. Geotech. J., 53(2), 236–251.
FHWA (Federal Highway Administration). (2009). “Design and construction of mechanically stabilized earth walls and reinforced soil slopes: Vols. 1 and 2.” FHWA-NHI-10-024, U.S. Dept. of Transportation, Washington, DC.
Goble, G. (1999). “Geotechnical related development and implementation of load and resistance factor design (LRFD) methods.” National Cooperative Highway Research Program, Transportation Research Board, Washington, DC.
Harr, M. E. (1987). Reliability-based design in civil engineering, McGraw-Hill, New York.
Huang, B., Bathurst, R. J., and Allen, T. M. (2012). “Load and resistance factor design (LRFD) calibration for steel strip reinforced soil walls.” J. Geotech. Geoenviron. Eng., 922–933.
Lazarte, C. A., Robinson, H., Gómez, J. E., Baxter, A., Cadden, A., and Berg, R. (2015). “Geotechnical engineering circular No. 7 soil nail walls—Reference manual.”, Federal Highway Administration (FHWA), U.S. Dept. of Transportation, Washington, DC.
Lin, P., Bathurst, R. J., Javankhoshdel, S., and Liu, J. (2017a). “Statistical analysis of the effective stress method and modifications for prediction of ultimate bond strength of soil nails.” Acta Geotechnica, 12(1), 171–182.
Lin, P., Bathurst, R. J., and Liu, J. (2017b). “Statistical evaluation of the FHWA simplified method and modifications for predicting soil nail loads.” J. Geotech. Geoenviron. Eng., 04016107.
Miyata, Y., and Bathurst, R. J. (2012a). “Analysis and calibration of default steel strip pullout models used in Japan.” Soils Found., 52(3), 481–497.
Miyata, Y., and Bathurst, R. J. (2012b). “Measured and predicted loads in steel strip reinforced c-ϕ soil walls in Japan.” Soils Found., 52(1), 1–17.
Miyata, Y., and Bathurst, R. J. (2012c). “Reliability analysis of soil-geogrid pullout models in Japan.” Soils Found., 52(4), 620–633.
Nowak, A. S. (1999). “Calibration of LRFD bridge design code.”, National Cooperative Highway Research Program, Transportation Research Board, Washington, DC.
Nowak, A. S., and Collins, K. R. (2000). Reliability of structures, McGraw-Hill, New York.
Paikowsky, S. (2004). “Load and resistance factor design (LRFD) for deep foundations.”, National Cooperative Highway Research Program, Transportation Research Board, Washington, DC.
Phoon, K. K. (2008). Reliability-based design in geotechnical engineering: Computations and applications, Taylor & Francis, New York.
Public Works Research Center. (2003). Design method, construction manual and specifications for steel strip reinforced retaining walls, 3rd Ed., Tsukuba, Ibaraki, Japan (in Japanese).
Reddy, S. C., and Stuedlein, A. W. (2013). “Accuracy and reliability-based region-specific recalibration of dynamic pile formulas.” Georisk, 7(3), 163–183.
Withiam, J. L., et al. (1998). “Load and resistance factor design (LRFD) for highway bridge substructures.”, Federal Highway Administration, Washington, DC.
Yu, Y., and Bathurst, R. J. (2015). “Analysis of soil-steel bar mat pullout models using a statistical approach.” J. Geotech. Geoenviron. Eng., 04015006.
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©2017 American Society of Civil Engineers.
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Received: Sep 3, 2016
Accepted: Feb 23, 2017
Published online: May 30, 2017
Published in print: Sep 1, 2017
Discussion open until: Oct 30, 2017
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