Investigation of Exterior Girder Rotation and the Effect of Skew during Deck Placement

Project status

In progress

Start date: 07/01/16
End date: 08/31/18


Principal investigators:

Co-principal investigator:

About the research

With many of the nation’s bridges approaching (or having already exceeded) their original design life, bridge replacement options, techniques, and technologies continue to need to advance to meet the challenges faced by the bridge engineering community. Recent statistics reveal there are approximately 600,000 bridges on the highway system and that approximately 25 percent of them, by deck area, are considered either structurally deficient or functionally obsolete. Although the situation has improved some in recent years, a significant problem still exists given the number of bridges needing regular replacement.

It is vitally important that, when constructed (or when only decks are replaced), the utmost highest construction practices are followed such that the final product has a high likelihood of achieving the target design life. It has been observed that current construction practices associated with constructing bridge decks sometimes result in excessive out-of-plane and torsional loads on exterior girders. Structurally, this can result in decks that are too thin or girders with excessive (and unintended) internal stresses. Functionally, this can result in bridges that are difficult to maintain or that have rideability issues.

The objective of this work is to develop both design guidance and construction procedure recommendations aimed at reducing girder rotations (exterior girders primarily). In addition, a research objective is to determine a skew threshold for which the finishing machine should be oriented parallel to the skew as opposed to the more common orientation perpendicular to the bridge centerline.



  • Iowa Department of Transportation
  • Iowa Highway Research Board