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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.


Fatigue Assessment for the Failed Bridge Deck Closure Pour at Mile Marker 43 on I-81
Elias Rivera, Ebrahim K. Abbas, William J. Wright, Ph.D., P.E., Richard E. Weyers, Ph.D., P.E., C.L. Roberts-Wollmann, Ph.D., P.E.
Year: 2014
VTRC No.: 14-R12

Fatigue of reinforcing steel in concrete bridge decks has not been identified as a common failure mode. Generally, the stress range occurring in reinforcing steel is below the fatigue threshold and infinite fatigue life can be expected. Closure pour  joints, however, may be vulnerable to fatigue if some specific design details are present. This research shows that fatigue was a likely contributor to the I-81 closure pour failure. It is much less likely that corrosion directly caused a strength failure but it is very likely that corrosion accelerated the onset of fatigue.

The joints in the I-81 deck had vertical joint faces that did not provide any means for shear transfer across the joint. The joints were located under a wheel load path and were located away from beams or other means of deck support. This created atypical conditions where shear forces across the joint due to wheel loads were carried only by the reinforcing steel. The stress range in the reinforcing steel is greatly magnified under this scenario thereby making fatigue a possibility.

New closure pour joints can easily be designed to prevent fatigue by providing structural support for both sides of the joint. Existing joints, however, need to be evaluated to determine if fatigue vulnerability exists. Lacking knowledge of the joint internal details, a simple differential deflection test can be performed to detect fatigue vulnerability. If the two sides of the joint are deflecting vertically relative to each other under wheel loads, than fatigue can be considered a possibility. No deflection indicates that fatigue is unlikely.