Bridge Rating Using System Reliability Assessment. I: Assessment and Verification by Load Testing
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Volume 16, Issue 6
Abstract
Condition assessment and safety verification of existing bridges and decisions as to whether a bridge requires posting currently are addressed through analysis, load testing, or a combination of these methods. The rating process is described in AASHTO’s Manual for Bridge Evaluation, which permits ratings to be determined by allowable stress, load factor, or load and resistance factor methods, the latter of which is keyed to AASHTO LRFD Bridge Design Specifications. These three rating methods may lead to differently rated capacities and posting limits for the same bridge, a situation that has serious implications with regard to public safety and the economic well-being of communities that may be affected by bridge postings or closures. This paper is the first of two papers that summarize a research program to develop improvements to the current bridge rating process using structural reliability methods. This paper appraises current bridge rating methods and summarizes a coordinated program of analysis and load testing of several bridges to support recommended improvements to the bridge rating process. The second paper presents the reliability basis for the recommended load rating and recommends specific improvements to current bridge rating methods in a format that is consistent with the load and resistance factor rating (LRFR) option in the Manual for Bridge Evaluation.
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Acknowledgments
The research described in this paper was supported by the Georgia DOT, under an award entitled, “Condition Assessment of Existing Bridge Structures.” The writers extend their gratitude to the representatives of the 41 state departments of transportation, who shared information regarding current bridge inspection and condition assessment practices in an early stage of this research program and provided valuable assistance to the research team as they established perspectives on the ASR-, LFR- and LRFR-rating methods. However, the views are solely those of the writers, and may not represent the positions of the sponsoring organization or other state DOT.
References
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Wang, N., Ellingwood, B. R., and Zureick, A.-H. (2011). “Bridge rating using system reliability assessment. II: Improvements to bridge rating practices.” J. Bridge Eng., 16(6), 863–871.
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Information
Published In
Journal of Bridge Engineering
Volume 16 • Issue 6 • November 2011
Pages: 854 - 862
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Mar 19, 2010
Accepted: Aug 2, 2010
Published online: Oct 14, 2011
Published in print: Nov 1, 2011
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