Capabilities of diagonally-cracked girders repaired with CFRP.

Details

• Creators:
  Higgins, Christopher ; Williams, Grahme ; Elkins, Lori
• Corporate Creators:
  Oregon. Department of Transportation
• Subject/TRT Terms:
  • Girder bridges
  • Concrete bridges
  • Reinforced concrete bridges
  • Polymer concrete
  • Crack and seat treatment
  • Transverse cracking
  • Cracking
  • Pavement cracking
  • Girders
  • Bridge decks Concrete bridges¿Cracking
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• Publication/ Report Number:
  FHWA-OR-RD-06-16
• Resource Type:
  Tech Report
• Geographical Coverage:
  Oregon
• Corporate Publisher:
  Oregon. Dept. of Transportation
• Abstract:
  The technique of using carbon fiber reinforced polymer (CFRP) for strengthening conventionally reinforced concrete ; (CRC) girders in flexure is well understood, but strengthening girders for shear is a newer application and less data are available. ; A literature review and survey were conducted to document the state of understanding and experience with respect to using CFRP ; for shear reinforcement of CRC girders. A laboratory investigation using full-size T- and inverted T-girder specimens with ; diagonal (shear) cracks was conducted to investigate the shear capacity improvement due to CFRP reinforcement and the effect of ; cyclic loading on CFRP shear strengthening. National and international code provisions for the design of CFRP in shear were ; used to compare the predicted shear capacity with the experimental results. An example application was included for using ; external CFRP strips to strengthen a bridge girder. ; Strengthening with carbon CFRP strips provided a significant increase in load capacity and stiffness compared to ; unrepaired beams, and the improved capacity was maintained even after being exposed to the equivalent of twenty years of ; traffic-induced fatigue. At high load levels prior to failure, progressive debonding of multiple strips provided a clear, visual ; warning of distress. ; The ACI 440 methodology provided a reasonably simple approach for shear capacity prediction of RC girders with ; externally bonded CFRP shear reinforcing for T-beams and is recommended for design. However, the ACI 440 method was ; unconservative where the CFRP strips terminate in the flexural tension zone. To provide a consistent level of reliability between ; T- and inverted T- conditions, the CFRP stress should be reduced by a factor of 2 for conditions when the CFRP strip is ; terminated in the flexural tension zone. ; Placement of at least one CFRP strip across the diagonal crack with an anchorage length of at least one-half the height of ; the web is critical. An equation for strip layout is presented. In addition, girder shear strength can be increased using a targeted ; repair approach, applying CFRP material only to key critical sections rather than over the entire member. Thus, better economy ; may be achieved by judiciously applying CFRP materials just to those sections that are understrength for shear.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/21866/dot_21866_DS1.pdf
• File Type:
  [PDF - 39.50 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:2dc420ed59015a4ed4ff293f3923202d7b3beffa8e451a2b19e76d75938188916fdc165ddef6d6b9e164de55a45509bbfb717c9f4b50aba56ea1a86dd509d3d4