Design of anchorage zones using strut-and-tie methods: Applications to retrofit of post-tensioned bent caps

Recent developments in the AASHTO Bridge Specifications have incorporated new methods for design of post-tensioned anchorage zones. This paper describes the application of new design methods for post-tensioned anchorage zones as applied to the retrofit of bent caps. The project is associated with the seismic upgrading of the I-280 double-deck viaduct (Southern Viaduct) in San Francisco. New design and construction methods were developed and implemented for this project. Design aspects presented include the configurations of several different types of anchorage zones. Conceptual approaches are reviewed for each. Construction aspects include a review of specific construction techniques implemented. Additionally, the role of the engineer-of- record vs. the fabricator is outlined along with resulting implications for both design and construction.