Design Procedures of Retrofitted Bridge Rail

A number of bridges can be identified within Nebraska that require a retrofitted bridge rail. Currently bridge retrofits are performed on most resurfacing, restoration, and rehabilitation (3R) projects to meet the objectives of extending the surface life and enhancing safety. When bridge rail requiring retrofit is identified, a block type rail is directly tied into the existing bridge deck with the use of bonded (adhesive or epoxy) anchorage. The performance of retrofitted bridge rail to resist the design loads (typically TL-4) relies on the connection of the group of bonded anchorage at the bridge rail's baseplate to the bridge deck slab. Bonded anchorage is specified in the current retrofit rail policy as #3 bars (#10M) with a yield strength of 60 ksi (414 MPa) at 12 inches (30.5 cm) on center with a minimum embedment depth of 4.75 inches (12.1 cm). This embedment depth is the minimum value specified for applications on thin or tapered bridge deck thicknesses of 6.5 inches (16.5 cm), which provides adequate concrete cover to the anchorage and existing reinforcing steel. Furthermore, this value of embedment depth is based on conservative design equations and sought to produce the desired ductile failure mode of steel rupture, rather than brittle failure modes of concrete breakout or adhesive bond failure. However due to the uncertainty of the implemented design equations, it is proposed to experimentally verify the anchor capacity and behavior for a minimum embedment depth of 4.75 inch (12.1 cm). This research will produce an understanding of the capacities of bridge rail retrofit installation with implementation in future specifications, such as a special provision and an updated rail policy. The use of shallow embedded anchors will provide for a low-cost and time-effective installation for bridge rail retrofit to extend the service life and enhance safety of countless bridge structures in Nebraska. Furthermore, the developed methods can minimize the direct costs associated with construction and indirect costs associated with downtown due to traffic closures and detours.

    Language

    • English

    Project

    • Status: Active
    • Funding: $38968.00
    • Contract Numbers:

      SPR-P1(15) M028

    • Sponsor Organizations:

      Federal Highway Administration

      1200 New Jersey Avenue, SE
      Washington, DC  United States  20590

      Nebraska Department of Roads

      P.O. Box 94759
      Highway Building
      Lincoln, NE  United States  68509-4759
    • Performing Organizations:

      University of Nebraska, Lincoln

      Lincoln, NE  United States 
    • Principal Investigators:

      Wood, Richard

    • Start Date: 20140701
    • Expected Completion Date: 0
    • Actual Completion Date: 20151231
    • Source Data: RiP Project 36241

    Subject/Index Terms

    Filing Info

    • Accession Number: 01560304
    • Record Type: Research project
    • Source Agency: Nebraska Department of Roads
    • Contract Numbers: SPR-P1(15) M028
    • Files: RiP, STATEDOT
    • Created Date: Apr 11 2015 1:00AM