Confinement Effect of Narrow Baseplates or Reaction Area on Anchor Breakout, Part 3

Details

• Creators:
  Suksawang, Nakin ; Nolan, Steven
• Corporate Creators:
  Florida Institute of Technology
• Corporate Contributors:
  Florida. Department of Transportation
• Subject/TRT Terms:
  • Bridge railings
  • Ground anchors
  • Bridge design
  • Failure
  • Crash investigation
  • Resistance tests
  • Strength of materials
  • Test procedures
  • Baseplates
  • Confinement Modification Factor
  More +
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Edition:
  Draft Final: May 2021 – Dec 2023
• Corporate Publisher:
  Florida. Department of Transportation
• Abstract:
  The AASHTO Committee on Bridges and Structures has approved the updated ACI CODE-318, 2019 edition (ACI CODE 318-19,) into the 10th edition of the AASHTO LRFD Bridge Design Specifications. This would allow the adoption of screw anchor designs that benefit from rapid, reliable, and simplified installation procedures. However, the ACI CODE approach has been shown to be too conservative in typical FDOT applications because it does not account for the confinement effect caused by the metal baseplate's compressive force in the concrete breakout cone. Furthermore, previous studies have shown that the predominant failure mode of screw anchor is a combined failure with a much higher breakout capacity than the concrete breakout failure limited by the ACI CODE. Therefore, this research provides an experimental investigation of the failure mechanism and appropriate confinement effect of screw anchors used in typical FDOT applications. Results indicated that the screw anchors’ breakout resistance consistently exceeded nominal strength predicted by ACI CODE and the required design loads. It is recommended that FDOT permit the use of screw anchors because it reduces installation cost and time because there is no additional adhesive cost or need to wait for adhesive to cure. It is also recommended that FDOT adopts a strength reduction factor of ϕ = 0.75 for both design purposes and when evaluating future test results for screw anchors instead of the ACI CODE ϕ = 0.65.
• Format:
  PDF
• Funding:
  BDV28-977-09 & BED28-977-02
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/89389/dot_89389_DS1.pdf
• File Type:
  [PDF - 28.61 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:ed6dca1a6a8a10c73bb3b1543519ef729c1e677647f5999d9001d2b25d0378acc56e9881edcd145e41424d94700556cbf682500ee929d33cdd841f98fcdb1286