Historically, the AASHTO Standard Specifications for Highway Bridges did not provide adequate guidance for designing reinforcement for tendon anchorage zones of post-tensioned concrete girders and slabs. Designs had the potential for excessive cracking or congested reinforcing details. Additionally, the wide variation of design practices in use suggested the need for research in this area.
The objective of this research was to develop design procedures for end and intermediate anchorage zones for post-tensioned concrete girders and slabs. The project tasks included a review of relevant research findings and practice, the conduct of laboratory tests and analytical studies, and the development of analysis and proportioning criteria for anchorage applications. Recommended specification provisions were prepared.
Research on the project was completed in 1992. The research results were published in NCHRP Report 356. The recommended specifications represent a comprehensive revision to the existing AASHTO provisions. Detailed procedures are included for predicting first cracking load and ultimate load in post-tensioned concrete girder anchorage zones, and the overall recommendations are based on a limit state approach. A load factor for the maximum post-tensioning load is proposed, as well as a strength-reduction factor for anchorage zone calculations. In addition to these and other design (Division I) provisions, recommendations for construction (Division II) also are presented, including a section on a special anchorage-device acceptance test that replaces Sections 10.3.1.4.3 through 10.3.1.4.5 of the 15th Edition of the AASHTO Standard Specifications for Highway Bridges. The recommended specifications provide for efficient and conservative design, and they were adopted by the AASHTO Highway Subcommittee on B
ridges and Structures in 1993.