Live Load Rating of Short Span Highway Bridges as Controlled by the Exterior Girder

Report No: 78-R13

Published in 1977

About the report:

The 1973 AASHTO Standard Specifications for Highway Bridge introduced the requirement that “In no case shall an exterior stringer have less carrying capacity than an interior stringer.” This statement resulted from the concern that many original exterior stringers became interior stringers when bridges were widened. Since current specifications are used when rating live load capacity of existing bridges, this newly introduced requirement has in some cases resulted in an unnecessary reduction in live load ratings. This study examines a number of cases in which exterior stringers are lighter than the interior ones and illustrates the effects of the new provision. The report concludes with a recommendation from an exemption provision from this requirement in the appropriate article of the Manual for Inspection Maintenance of bridges, 1974, 2nd ed., AASHTO.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.


  • H. L. Kinnier, Furman W. Barton, Ph.D.

Last updated: January 27, 2024

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