THE CONCRETE BRIDGE MAGAZINE

FALL 2017

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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CONCRETE BRIDGE TECHNOLOGY U-Girder Standards Upgraded for External Post-Tensioning Tendons New Go By sheets/concept drawings for curved, precast concrete spliced U-girders using bonded and unbonded post-tensioning for the next generation of structures by Sam Fallaha, Florida Department of Transportation, and William N. Nickas, Precast/Prestressed Concrete Institute Recent changes to Florida Department of Transportation's (FDOT's) post-tensioning policy that requires replaceable tendons have led to revisions of standard practices for posttensioning bridge structures. With the growing popularity of curved, precast concrete spliced U-girders, engineers saw a need to update and upgrade the existing Precast/Prestressed Concrete Institute (PCI) Zone 6 U-girder designs to meet the new requirements. The result was a new set of concept drawings for spliced U-girders that use replaceable external tendons. FDOT has taken a new look at the system that started in Colorado and was promulgated to the East coast by PCI. The latest concepts, which were approved by the Federal Highway Administration in July, were announced in FDOT Structures Design Bulletin 17-08, which can be found at www.fdot.gov/ design/bulletins/SDB17-08.pdf. In an earlier memorandum, FDOT Structures Design Bulletin 15-01, FDOT instituted a policy that profiled tendons must be replaceable, so these tendons must be filled with flexible filler; however, flat tendons can still be filled with cementitious grout. The revised PCI Zone 6 U-girder concept plans were developed as a joint effort between PCI and the Florida Prestressed Concrete Association (FPCA), the local PCI Chapter, to create standardized dimensions for curved, precast concrete spliced U-girders that allow access and replacement of external tendons during the service life of the structure. FPCA supported a team of consultants experienced with the system who developed the new concepts; their findings were presented to FDOT in 2016 for review. (For a list of those participating in the study, see the sidebar.) In addition to meeting FDOT's requirements for replaceable tendons, the new concept drawings (listed below) were also intended to establish a set of standardized sections that could (cont. next page) Study Participants The team participating in the FPCA-PCI study on wax-filled tendons for curved, spliced U-girders comprised: Bob Anderson, AECOM (formerly URS), Tampa, Fla. Roger Becker, PCI, Chicago, Ill. John Corven, Corven Engineering, Tallahassee, Fla. John Crigler, VStructural LLC, Baltimore, Md. Kent Fuller, Dura-Stress Inc., Leesburg, Fla. Trevor Kilpatrick, AECOM (formerly URS), Tampa, Fla. Mason H. Lampton, Standard Concrete Products, Columbus, Ga. Tom Newton, Gate Precast, Jacksonville, Fla. William N. Nickas, PCI, Chicago, Ill. Richard Potts, Standard Concrete Products, Savannah, Ga. Dr. Audi Sriboonlue, Dura-Stress Inc., Leesburg, Fla.

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