Alternative Support Systems for Cantilever - National Transportation ...

1. Report No.
BDK75 977-04
4. Title and Subtitle
2. Government Accession No.
Alternative Support Systems for Cantilever Signal/Sign
Structures
7. Author(s)
R. A. Cook and K. L. Jenner
9. Performing Organization Name and Address
University of Florida
Department of Civil and Coastal Engineering
345 Weil Hall / P.O. Box 116580
Gainesville, FL 32611-6580
12. Sponsoring Agency Name and Address
Florida Department of Transportation
Research Management Center
605 Suwannee Street, MS 30
Tallahassee, FL 32301-8064
15. Supplementary Notes
iv
Technical Report Documentation Page
3. Recipient's Catalog No.
5. Report Date
August 2010
6. Performing Organization Code
8. Performing Organization Report No.
00072913
10. Work Unit No. (TRAIS)
11. Contract or Grant No.
BDK75 977-04
13. Type of Report and Period Covered
Final Report
April 2008-Aug 2010
14. Sponsoring Agency Code
16. Abstract
During the 2004 hurricane season, several anchor embedment failures of the support structures of
cantilever signal/sign structures occurred. A previous research program determined the cause of these
failures was by concrete breakout due to shear on the anchors directed parallel to the edge of the
foundation. The purpose of the current research program was to take the knowledge obtained on the
previous research program and identify a suitable alternative support structure without the use of anchor
bolts. After a literature review and experimental testing, it was determined that an embedded pipe with
welded plates was a suitable alternative support structure. The torsion could be adequately transferred to
the support structure concrete through the vertical torsional plates and the flexure could be adequately
transferred to the concrete through the welded annular plate on the bottom of the pipe. Furthermore, it
was determined that the alternative selected was not only a viable alternative to the anchor bolt system,
but it had greater strength for a given foundation size than the anchor bolt system.
The test specimens were designed to fail by concrete breakout originating from the torsional and
flexural plates and to preclude other failure modes. The results of the testing indicated that the concrete
breakout was the failure mode for the embedded pipe and plate configuration and that the concrete
breakout strength could be accurately predicted using modified equations for concrete breakout from
American Concrete Institute (ACI) 318-08 Appendix D. The results of these tests led to the
development of guidelines for the design of the embedded pipe and plate configuration.
Recommendations for future testing include an alternative base connection that precludes the use of
annular plates.
17. Key Word
Anchorage, cantilever sign structures, torsion,
anchors, wind loads
19. Security Classif. (of this report)
Unclassified
20. Security Classif. (of this page)
Unclassified
18. Distribution Statement
No restrictions
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
21. No. of Pages
212
22. Price