Effect of New Prestress Loss Estimates on Pretensioned Concrete Bridge Girder Design

In 2008, Texas Department of Transportation (TxDOT) initiated Project 0-6374 to investigate prestress losses in pretensioned concrete girders. The prestress loss estimates in the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications had been recalibrated in 2005 to be more accurate for “high-strength [conventional] concrete.” Greater accuracy implies less conservatism, the result of which may be flexural cracking of beams under service loads. Project 0-6374 was therefore funded to provide an experimental evaluation and an engineering recommendation of whether implementation of the new prestress loss estimates (currently outlined in AASHTO LRFD 2012) is appropriate for TxDOT. The primary objectives were: (1) to assess the conservatism and accuracy of the current prestress loss provisions; (2) to identify the benefits and weaknesses of using the AASHTO LRFD 2004 and 2012 prestress loss provisions; and (3) to make recommendations to simplify the prestress loss provisions of AASHTO LRFD 2012. These objectives were accomplished through: (1) the fabrication, conditioning, and testing of 30 field-representative girders; (2) the assembly and analysis of a prestress loss database; and (3) a parametric study of the design implications of the various prestress loss provisions. The database evaluation, coupled with the experimental results, revealed that use of the AASHTO LRFD 2012 prestress loss provisions resulted in underestimation of the prestress loss in nearly half of all cases. With this in mind, new prestress loss provisions were developed through simplification and recalibration of the method outlined in AASHTO LRFD 2012. The TxDOT Project 0-6374 prestress loss provisions were found to be simpler, more conservative, and more precise than the current methods outlined within the AASHTO LRFD Bridge Design Specifications.

• Record URL:
  http://library.ctr.utexas.edu/ctr-publications/0-6374-2.pdf
• 
• Summary URL:
  https://library.ctr.utexas.edu/Presto/catalogid=31820
• Supplemental Notes:
  • October 2012, Rev. June 2013, Published August 2013. Project Title: Effects of New Prestress Loss Predictions on TxDOT Bridges.
• Corporate Authors:

  University of Texas, Austin

  Center for Transportation Research, 1616 Guadalupe Street
  Austin, TX  United States  78701-1255

  Texas Department of Transportation

  Research and Technology Implementation Office, P.O. Box 5080
  Austin, TX  United States  78763-5080

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Garber, David
  • Gallardo, Jose
  • Deschenes, Dean
  • Dunkman, David
  • Bayrak, Oguzhan
• Publication Date: 2013-8

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Technical Report
• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 300p

Subject/Index Terms

• TRT Terms: Bridge design; Field tests; Girders; High strength concrete; Load and resistance factor design; Prestressed concrete bridges; Prestressing
• Identifier Terms: AASHTO LRFD Bridge Design Specifications
• Geographic Terms: Texas
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 01491300
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-12/0-6374-2, 0-6374-2
• Contract Numbers: 0-6374
• Files: TRIS, ATRI, USDOT, STATEDOT
• Created Date: Sep 3 2013 12:24PM