Title:
Condition assessment of existing bridge structures
Condition assessment of existing bridge structures
Author(s)
Ellingwood, Bruce R.
Zureick, Abdul-Hamid
Wang, Naiyu
O’Malley, Curtis
Zureick, Abdul-Hamid
Wang, Naiyu
O’Malley, Curtis
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Editor(s)
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Abstract
Condition assessment and safety verification of existing bridges and decisions as to whether
posting is required currently are addressed through analysis, load testing, or a combination of
these methods. Structural analysis-based rating is by far the most common method for rating
existing bridges. Load testing may be indicated when the analysis produces an unsatisfactory
result or cannot be completed due to a lack of design documentation, information, or the presence
of deterioration. The current rating process is described in the American Association of State
Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), First
Edition (2008). This recently published Manual permits ratings to be determined through either
allowable stress (ASR) or load factor (LFR) methods (Section 6B), or the load and resistance
factor (LRFR) method (Section 6A). The LRFR method is keyed to the AASHTO LRFD Bridge
Design Specifications, Fourth Edition (2007) which has been required for the design of new
bridges since October, 2007. The State of Georgia currently utilizes the LFR method, which was
permitted under the Manual for Condition Evaluation of Bridges, Second Edition. These three
rating methods which continue to be commonly used – ASR, LRF, LRFR - may lead to different
rated capacities and posted 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. To address this issue, the Georgia Institute of Technology has conducted a research program, sponsored by the Georgia Department of Transportation, to develop improvements to the process by which the condition of existing bridge structures in the State of Georgia is assessed. The
product of this research program is the Recommended Guidelines for Condition Assessment and
Evaluation of Existing Bridges in Georgia. These guidelines address condition assessment and
capacity evaluation by analysis, load test, or a combination of the two methods, depending on the
circumstances and preferences of the GDOT. Part I of this report summarizes the technical
approach taken to develop the Recommended Guidelines. Part II presents the Recommended
Guidelines. An Appendix to Part II illustrates their use in typical rating situations.
Sponsor
Georgia. Department of Transportation
Date Issued
2009-08-01
Extent
Resource Type
Text
Resource Subtype
Technical Report