Methods To Ensure Appropriate Installation And Prevent Loosening Of Anchor Nuts On Ancillary Highway Structures

About the project:

In recent years, the Virginia Department of Transportation and other highway agencies have experienced recurring problems of anchor bolt nuts discovered to be loose on ancillary highway structures. The cause of loosening is unknown and the structures vary widely in type, age, size, and material. This study will investigate the causes of loose nuts on anchor bolts and isolate parameters that may contribute to this behavior. Parameters to be investigated include the anchor rod diameter, nut and anchor configuration details, thread fabrication method, thread tolerance, and material type(s). In addition, methods to appropriately tighten and evaluate the in-situ pretension of anchor nuts will be investigated. The required tension for anchor rods connected to aluminum structures, which are currently not addressed in any specifications, will be evaluated and reported. The research will provide guidance on how to prevent the loosening of anchor nuts.

Project Team

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