The use of post-tensioning permits the construction of economical, long-span bridges. In recent years, repair and maintenance of post-tensioned bridges have gained importance in light of a few instances of serious tendon degradation[i]. Guidance documents exist for early life stages of these structures: the AASHTO Load and Resistance Factor Design (LRFD) Bridge Design Specifications identify the minimum bridge design requirements, while the(2013) provides guidance on construction practices. Practices aimed to improve post-tensioned structures’ durability over the long-term are qualitatively discussed in a few guidance documents, such as fib’s Bulletin 33. However, very limited information is available to guide bridge owners on how to maintain existing structures, or, more specifically, to repair degraded post-tensioned bridges for example cast–in–place box girders, spliced girders, segmental bridges, adjacent box girders, pier caps, etc. While bridge owners approach issues requiring remediation on a case-by-case basis, identification of current practices and knowledge transfer across states could improve structure integrity and reduce maintenance and repair efforts.
The objective of this synthesis is to gather information on the practices used by bridge owners to repair and maintain post-tensioned bridges, both in service and during construction. The goal is to further facilitate knowledge transfer across state DOTs, aiding bridge owners in the identification, repair and maintenance practices that are working.
The report should include the following aspects (not an exhaustive list) about repair and maintenance of post- tensioned concrete bridges in-service and during construction:
· Identification of issues and specific cases where these are highlighted.
· Problematic and preferred design details, specifications, and construction practices (grouting, materials, post-tensioning practices, etc.)
· Repair methodologies for issues due to construction errors, corrosion, damage caused by over-height vehicle impacts, etc. Including repair and/or replacements of decks on top of post-tensioned bridges.
· Inspection and maintenance documentation (NDT specifically to post-tensioned bridges, special requirements and inspections).
Information will be gathered by literature review including domestic and international sources which identifies the most relevant examples, techniques and conditions under which consistent results are achieved. Surveys and/or interviews of the state DOTs and selected contractors, and a minimum of five case examples shall be included. Case examples should focus on corrective actions and should consider:
· Owner’s existing policies, specifications;
· Recent remediation actions and after-action feedback from the owner’s perspective;
· Guidance documents, as they exist.
American Association of State Highway and Transportation Officials (AASHTO). (2017).
AASHTO-LRFD Bridge Design Specifications. American Association of State Highway and Transportation Officials, Washington D.C
Corven Engineering, Inc. (2001). “Mid-Bay Bridge Post-tensioning Evaluation: Final Report.”
Federal Highway Administration (FHWA). (2013). “Post-tensioning Installation and Grouting Manual.” Federal Highway Administration, Washington D.C.
Federal Highway Administration ( FHWA) Project DTFH61-11-H-0027 Advancing Steel and Concrete Bridge Technology to Improve Infrastructure Performance, Task No. 11 Designing and Detailing Post Tensioned Bridges to Accommodate Non-Destructive Evaluation
Inspection Guidelines for Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods, NCHRP Report 848
Fuzier, J-P., Ganz, H-R., Matt, P. (2005). “Bulletin 33: Durability of post-tensioning tendons.” fédération internationale du béton (fib). Sprint-Digital-Druck, Stuttgart.
[i] (Corven Engineering 2001). Add more recent references for degradation of internal post-tensioned tendons.