Skip to main content
SpringerLink
Log in

Assessment of Reliability Levels and Adjustment of Load-resistance Factors Using Optimization for Gravitational Loads-governed Limit States of the AASHTO LRFD Bridge Design Specifications

  • Structural Engineering
  • Published:
KSCE Journal of Civil Engineering Aims and scope

Abstract

This paper presents the reliability levels provided by the load-resistance factors of the AASHTO LRFD Bridge Design Specifications for the Strength Limit State-I and -IV, and an optimization scheme for adjusting the load-resistance factors of the specifications. It is shown that the load-resistance factors of the specifications result in lower reliability indices than the target reliability index and widely varying reliability indices with the load composition for reinforced concrete, steel and pre-stressed concrete members. An optimization scheme is proposed to obtain a new set of the load-resistance factors that yield more uniform reliability levels and better approximation to the target reliability index in a wide range of load compositions. The objective function of the proposed optimization scheme is defined as the L2-norm of the error between the target and calculated reliability indices by load-resistance factors over a given interval of load composition. The results of the optimization show that the dead load factor for structural components should be increased by 0.1 for the Strength Limit State-I, and that the vehicular live load should be included in the Strength Limit State-IV. The use of exact figures up to the second decimal point is recommended for the resistance factors. A unified limit state for gravitational loads is proposed to replace the two limit states with a single limit state.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • AASHTO (American Association of State Highway and Transportation Officials). (2014). AASHTO LRFD Bridge Design Specifications, Washington, DC.

  • CEN (European Committee for Standardization). (2002). Eurocode 0: Basis of Structural Design EN 1990.

  • Ellingwood, B. R., Galambos, T. V., MacGregor, J. G., and Cornell, C. A. (1980). Development of a Probability Based Load Criterion for American National Standard A58, Washington, DC: National Bureau of Standards.

    Book  Google Scholar 

  • Ellingwood, B., MacGregor, J. G., Galambos, T. V., and Cornell, C. A. (1982). “Probability based load criteria: Load factors and load combinations.” J. Struct. Div., ASCE, Vol. 108, No. 5, pp. 978–997.

    Google Scholar 

  • Gayton, N., Mohamed, A., Sørensen, J. D., Pendola, M., and Lemaire, M. (2004). “Calibration methods for reliability-based design codes.” Sturct. Safety, Vol. 26, pp, 91–121, DOI: 10.1016/S0167-4730(03)00024-9.

    Article  Google Scholar 

  • Haldar, A. and Mahadevan, S. (2000). Probability, Reliability and Statistical Methods in Engineering Design, John Wiley & Sons, Inc., New York, pp. 181–224.

    Google Scholar 

  • ISO (International Organization for Standardization). (1998). International Standard ISO 2394: General principles on reliability for structures, Switzerland.

  • Kohler, J. and Fink, G. (2012). “Reliability based code calibration of typical Eurocode 5 design equations.” World Conf. Timber Eng., 4, 99–103.

    Google Scholar 

  • MacGregor, J. G., Kennedy, D. J. L., Bertlett, F. M., Chernenko, D., Maes., M. A., and Dunaszegi, L. (1997). “Design criteria and load and resistance factors for the confederation bridge.” Can. J. Civ. Eng., Vol. 24, pp. 882–897, DOI: 10.1139/cjce-24-6-882.

    Google Scholar 

  • Nowak, A. S. (1995). “Calibration of LRFD bridge code.” J. Struct. Div., ASCE, Vol. 121, No. 8, pp. 1245–1251, DOI: 10.1061/(ASCE)0733-9445(1995)121:8(1245).

    Article  Google Scholar 

  • Nowak, A. S. and Lind, N. C. (1979). “Practical bridge code calibration.” J. Struct. Div., ASCE, Vol. 105, No. 12, pp. 2497–2510.

    Google Scholar 

  • Nowak, A. S. (1999). “Calibration of LRFD bridge design code.” NCHRP Report 368, Transportation Research Board, Washington, D.C.

    Google Scholar 

  • Rackwitz, R. and Fiessler, B. (1978). “Structural reliability under combined random load sequences.” Comput. Struct., Vol. 9, No. 5, pp. 489–494.

    Article  MATH  Google Scholar 

  • Siu, W. C., Parimi, S., and Lind, N. C. (1975). “Practical approach to code calibration.” J. Struct. Div., ASCE, Vol. 101, No. 7, pp. 1469–1480.

    Google Scholar 

  • Sørensen, J. D., Kroon, I. B., and Faber, M. H. (1994). “Optimal reliabilitybased code calibration.” Struct. Safety, Vol. 15, pp. 197–208, DOI: 10.1016/0167-4730(94)90040-X.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Dept. of Civil and Environmental Engineering, Seoul National University, Seoul, 08826, Korea

    Hae Sung Lee, Changhoon Bae & Ji Hyeon Kim

Authors
  1. Hae Sung Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Changhoon Bae
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Ji Hyeon Kim
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Hae Sung Lee.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Lee, H.S., Bae, C. & Kim, J.H. Assessment of Reliability Levels and Adjustment of Load-resistance Factors Using Optimization for Gravitational Loads-governed Limit States of the AASHTO LRFD Bridge Design Specifications. KSCE J Civ Eng 22, 3462–3472 (2018). https://doi.org/10.1007/s12205-017-0500-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12205-017-0500-6

Keywords

Search

Navigation