Develop/Refine Design Provisions for Headed and Hooked Reinforcement

The usefulness of reinforced concrete is dependent on sufficient anchorage between concrete and reinforcing steel. Sufficient anchorage occurs when reinforcing steel is embedded into the concrete a distance referred to as the development length. When this length of embedment is achieved the reinforcing steel is expected to reach or exceed stresses beyond yield. Geometric constraints within structural members may prevent straight lengths of reinforcement from developing their yield strength, such as straight bars being terminated within a beam-column joint. In these cases, the addition of a hook or headed bar attachment provides a more efficient anchorage mechanism compared to straight bars. Both hooked and headed bars have shorter development lengths than straight bars. However, the current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications (9th edition) has not developed standard details for headed reinforcement in bridge structures. In addition, current AASHTO LRFD design provisions for hooked bars are adapted from the American Concrete Institute (ACI) 318-14 Building Code Requirements for Structural Concrete. Considerable revisions to the current ACI 318-19 specification for the design of hooked reinforcement, which require increased lengths (50 to 70 percent longer) relative to previous code cycles, necessitates Texas Department of Transportation (TxDOT) to revisit its current design practice for hooked reinforcement. This research seeks to provide TxDOT with clear and concise design guidance for engineers to use both hooked and headed bar attachments in TxDOT bridge structures. The research teams will accomplish this through large-scale experimental testing of specimens with hooked and headed bars representative of TxDOT bridge structures and current design practice.


  • English


  • Status: Active
  • Funding: $999401
  • Contract Numbers:


  • Sponsor Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Managing Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Project Managers:

    Schwerdt, Tom

  • Performing Organizations:

    Texas A&M Transportation Institute

    Texas A&M University System
    3135 TAMU
    College Station, TX  United States  77843-3135

    University of Texas at San Antonio

    One UTSA Circle
    San Antonio, TX  United States  78249
  • Principal Investigators:

    Skillen, Kinsey

  • Start Date: 20220901
  • Expected Completion Date: 20260228
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01863349
  • Record Type: Research project
  • Source Agency: Texas Department of Transportation
  • Contract Numbers: 0-7155
  • Files: RIP, STATEDOT
  • Created Date: Nov 3 2022 4:48PM