American Society of Civil Engineers


Bridge Rating Using System Reliability Assessment. I: Assessment and Verification by Load Testing


by Naiyu Wang, M.ASCE, (Senior Structural Engineer, Simpson, Gumpertz, and Heger, Inc., 41 Seyon St., Waltham, MA 02453; formerly, Graduate Research Assistant, School of Civil and Environmental Engineering, Georgia Institute of Technology.), Curtis O’Malley, A.M.ASCE, (Graduate Research Assistant, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332.), Bruce R. Ellingwood, (corresponding author), M.ASCE, (Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Dr., Atlanta, GA 30332-0355. E-mail: ellingwood@gatech.edu), and Abdul-Hamid Zureick, M.ASCE, (Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive, Atlanta, GA 30332-0355.)

Journal of Bridge Engineering, Vol. 16, No. 6, November/December 2011, pp. 854-862, (doi:  http://dx.doi.org/10.1061/(ASCE)BE.1943-5592.0000172)

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Document type: Journal Paper
Special Issue: AASHTO-LRFD Bridge Design and Guide Specifications: Recent, Ongoing, and Future Refinements
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.


ASCE Subject Headings:
Concrete bridges
Reinforced concrete
Prestressed concrete
Load factors
Reliability
Steel
Ratings

Author Keywords:
Bridges (rating)
Concrete (reinforced)
Concrete (prestressed)
Condition assessment
Loads (forces)
Reliability
Steel
Structural engineering