Evaluating FRP Repair Method for Cracked Prestressed Concrete Bridge Members Subjected to Repeated Loadings (Phase 1)

This report presents the details of a research study on the use of carbon fiber reinforced polymer (CFRP) sheets to repair and strengthen prestressed concrete bridge girders in flexure and shear. Five specimens that were removed from an overloaded bridge (Bridge #56) in Graham County, Kansas were tested. Three of the beams were statically tested to failure to determine their flexural capacity with and without strengthening. It was found that longitudinal CFRP sheets significantly increased the ultimate flexural capacity of the specimens. The other two specimens were tested in fatigue. High stress ranges in the prestressing strands caused the early failure of both specimens. Failure of Specimen 4 occurred by rupture of strands at the location of the mid-span push down device. A special strengthening scheme was applied to Specimen 5 to reduce any tensile stress concentration expected to develop at the push down device detail of the harped strands. This scheme successfully protected the push down device area causing failure to shift outside the mid span region, where higher strand stress range existed. Corrosion may have also contributed to the premature failure. Shear capacity was also examined on the two ends of each of the failed specimens. Two cases were evaluated in shear. The first one had the applied load such that shear cracks would form within the transfer length of the prestressing strands (allowing a bond-slip failure within that region). The second case had the applied load outside the transfer length of the prestressing strand (preventing bond-slip failure). The test results showed that transverse CFRP sheets increased the shear capacity of the specimens tested, but did not prevent bond-slip failures when diagonal cracks propagated into the transfer zone.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 117p

Subject/Index Terms

Filing Info

  • Accession Number: 01001254
  • Record Type: Publication
  • Report/Paper Numbers: K-TRAN: KSU-01-2
  • Contract Numbers: C1245
  • Files: NTL, TRIS, STATEDOT
  • Created Date: Jun 20 2005 3:14PM