Empirical Deck for Phased Construction and Widening

Compressive membrane action behavior in bridge decks has been known for many years. Some countries, such as Canada, have adopted the empirical deck design method in the Canadian Highway Bridge Design Code after extensive studies and research. In the United States, the American Association of State Highway and Transportation Officials (AASHTO) LRFD Bridge Design Specifications has provisions that allow the use of the empirical deck design method; however, state departments of transportation (DOTs) often require that reinforced concrete decks be designed using the traditional method and disallow the use of the empirical method. This is due in part to the fact that some of the current conditions (e.g., it is imperative to have a sufficient overhang length) are impossible to satisfy in phased construction and future widening scenarios. Compressive membrane action, although more complex to analyze, is a more realistic design approach than the traditional method that assumes a pure bending behavior. The behavior and failure modes of reinforced concrete bridge decks clearly exhibit membrane action, assuming lateral restraint is sufficient among other conditions. Although both methods are conservative, studies have shown that assuming a flexural behavior in reinforced concrete bridge deck design leads to a larger increase in the reserve strength compared to the empirical deck design method. To investigate the performance of concrete bridge decks designed with the empirical design method, extensive experimental testing of a full-size specimen was conducted. The fabricated deck specimen mimicked a widening scenario, was 47 feet in length and 18.5 feet in width, and was supported on two prestressed concrete beams with a 14-foot spacing and a 2-ft overhang beyond the edge of one of the two beams. The two 36-inch-deep Florida I-Beams (FIB-36) were used to support the 8-inch concrete deck reinforced with two layers of No.5 rebar at 12-inch spacing in both directions. Nine service and failure tests were conducted at different locations along the bridge deck. Not only will the empirical deck approach decrease the required amount of deck reinforcement compared to the traditional method, it will also provide ease in design and constructability, which may decrease those associated costs even further. The test specimen used in this study provided desirable results in strength and serviceability (a concern for most agencies). The outcome of this research study provides information to the FDOT officials regarding the feasibility of using the empirical method in design of bridge decks under conditions not currently covered by AASHTO LRFD provisions.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 293p

Subject/Index Terms

Filing Info

  • Accession Number: 01638633
  • Record Type: Publication
  • Contract Numbers: BDV34-977-01
  • Files: NTL, TRIS, ATRI, STATEDOT
  • Created Date: Jun 8 2017 2:34PM