BACKGROUND: Bonded Fiber-Reinforced Polymer (FRP) systems have proven to be an economical means for the repair and strengthening of concrete bridge elements in many projects. The first edition of the AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements, published in 2012, provides design tools for bridge elements subjected to flexure, shear and torsion, and combined axial force and flexure. However, many projects have been constructed and changes in the state of practice have occurred since the publication of these guide specifications. Also, during this period, substantial research on the different aspects of bonded FRP system applications has been performed. In addition, the current guide specifications are limited in scope (e.g., do not explicitly cover flanged sections, prestressed concrete elements, and FRP anchoring design). Because of these changes and limitations, there is a need for updating the guide specifications to recognize these issues and provide updated information and guidance on all aspects bonded FRP systems for repair and strengthening, including topics such as FRP near surface mounted applications, anchorage detailing, material specifications, and test requirements. Such guide specifications will help highway agencies address relevant issues and improve the use of FRP systems for repair and strengthening applications.
OBJECTIVE: The objective of this research is to update the 2012 AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements.
Accomplishment of this objective will require at least the following tasks.
Phase I: (1) Review the 2012 AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements, related domestic and foreign literature and research findings, and other information relevant to the design of bonded FRP systems for repair and strengthening of concrete bridge elements (e.g., design guidelines; specifications; criteria for analysis and design; repair methods, materials, and techniques), including guidance documents (e.g., ACI, AWWA, CSA, and fib) and the AASHTO LRFD Bridge Design Specifications. This information may be obtained from published and unpublished sources and contacts with practitioners. (2)Based on the information gathered in Task 1, propose an updated research plan to be executed in Phase II. The plan must identify those items pertaining to the design of bonded FRP for repair and strengthening of concrete bridge elements that will be revised, added, or removed to support the production of a new edition of the AASHTO guide specifications and provide details of the proposed analysis and design examples. It is expected that the plan will incorporate work items to (a) Describe the rationale for the proposed equations and guidelines through comparisons with those developed in other research or included in other design guidelines, (b) Provide a section on anchorage of FRP, development length, capacity, detailing, etc., (c) Provide guidance on surface preparation and requirements, (d) Provide additional material specifications, (e) Propose both material strength and modulus adjustment factors for various environmental exposure conditions, and testing requirements for wet-layup FRP systems, (f) Develop a section on near-surface mounted applications (including groove geometry, development length, and field proof testing), and (g) Address other items as deemed necessary. (3) Prepare and submit an interim report that documents the research performed in Task 1 and the updated research plan developed in Task 2 for NCHRP review and approval. Work on Phase II will not begin until the interim report and the proposed research plan are approved by the NCHRP.
Phase II: (4) Execute the plan approved in Task 3. Based on the results of this work, propose changes to the current AASHTO guide specifications (in the form of revisions, additions, or deletions). (5) Using the proposed changes to the AASHTO guide specifications, prepare detailed analysis and design examples for strengthening of reinforced and prestressed concrete rectangular and flanged bridge elements subjected to flexure, shear and torsion, and both rectangular and circular bridge elements subjected to combined axial force and flexure. (6) Prepare a draft final deliverable that documents the entire research effort, and submit for NCHRP review. The proposed updates of the AASHTO guide specifications shall be prepared as a stand-alone document appropriate for review by the AASHTO Committee on Bridges and Structures and publication by AASHTO as the second edition of AASHTO Guide Specifications for Design of Bonded FRP Systems for Repair and Strengthening of Concrete Bridge Elements. The analysis and design examples shall be included as an appendix to the deliverable. (7) Task 7. Prepare a revised final deliverable that addresses the comments on the draft deliverable together with a point-by-point response to comments.
STATUS: Research in progress.