Title: Torsion tests on spun-cast prestressed concrete poles
Date: Spring, 2012
Volume: 57
Issue: 2
Page number: 120-141
Author(s): Michael Kuebler, Maria Anna Polak
https://doi.org/10.15554/pcij.03012012.120.141
Click here to access the full journal article
Abstract
This paper focuses on the effect of the transverse reinforcement - its amount, spacing, and direction - on torsional strength in an effort to simplify the governing codes and provide general information on the behavior of spun-cast prestressed concrete poles under pure torsion. The rationale behind the typical code values for spacing and direction of the transverse reinforcement is not apparent. A total of 14 specimens were produced as part of a testing program. The testing program consisted of two groups of seven specimens with two different tip diameters: 6.5 in. (165 mm) and 8.3 in. (210 mm). Within each group the spacing and direction of the wound helical transverse reinforcement was varied. Each specimen was clamped at the butt end, and a counterclockwise torque load was applied at 2 ft (0.6 m) from the tip end. Applied torque and rotation of the tip were recorded using an inline load cell and electronic clinometers. The test concluded when the rotation reached approximately 13° to 15° or failure occurred. Experimental cracking torque values were compared with code-calculated theoretical values using current codes. Precracking and postcracking torque-twist responses were analyzed with elastic torsion and torsional compression field theory models. It was concluded that the primary function of the transverse reinforcement is to minimize the longitudinal precracking due to prestressing transfer forces. The prestressed concrete pole failure mode in torsion is brittle and sudden, and the transverse reinforcement provides no postcracking ductility.
References
1. Technical Committee on Concrete Poles. 2007. Concrete Poles. CSA A14-07. Mississauga, ON, Canada: Canadian Standards Association International.
2. Fouad, F. H., N. L. Scott, E. Calvert, and M. Donovan. 1994. Performance of Spun Prestressed Concrete Poles during Hurricane Andrew. PCI Journal, V. 39, No. 2 (March–April): pp. 102–110.
3. Chahrour, A. H., and K. A. Soudki. 2006. Structural Retrofitting of Deteriorated Concrete Lighting Poles Using FRP Sheets in Wet Layup-Field Application. ASCE Journal of Composites for Construction, V. 10, No. 3 (May–June): pp 234–243.
4. Rosson, B. T., J. R. Rohde, and R. Klovsky. 1996. Behavior and Design of Static Cast Prestressed Concrete Distribution Poles. PCI Journal, V. 41, No. 5 (September– October): pp. 94–107.
5. Terrasi, G. P., and J. M. Lees. 2003. CFRP Prestressed Concrete Lighting Columns. In Field Applications of FRP Reinforcement: Case Studies, SP 215, pp. 55–74. Farmington Hills, MI: American Concrete Institute (ACI).
6. Ghosh, R. S., and G. A. Senkiw. 1978. Load Testing of Prestressed Concrete Transmission Pole and Its Concrete Footing. Canadian Journal of Civil Engineering, V. 5 No. 2 (June): pp. 274–281.
7. Dilger, W. H., and A. Ghali. 1986. Response of Spun Cast Concrete Poles to Vehicle Impact. PCI Journal, V. 31, No. 1 (January–February): pp. 62–82.
8. Fouad, F. H., D. Sherman, and R. J. Werner. 1992. Spun Prestressed Concrete Poles-Past, Present, and Future. Concrete International, V. 14, No. 11 (November): pp. 25–29.
9. Subcommittee C27.20. 2006. Standard Specification for Spun Cast Prestressed Concrete Poles. ASTM C 1089-06. West Conshohocken, PA: ASTM International.
10. ASCE Task Force/PCI Committee on Concrete Poles and PCI Committee on Prestressed Concrete Poles. 1997. ASCE-PCI Committee Report: Guide for the Design of Prestressed Concrete Poles. PCI Journal, V. 42, No. 6 (November–December): pp. 93–134.
11. Technical Committee on Reinforced Concrete Design. 2004. Design of Concrete Structures. CSA A23.3-04. Mississauga, ON, Canada: Canadian Standards Association International.
12. ACI Committee 318. 2008. Building Code Requirements for Structural Concrete (ACI 318-08) and Commentary (ACI 318R-08). Farmington Hills, MI: ACI.
13. Subcommittee B/525. 2004. Eurocode 2: Design of Concrete Structures, Part 1-1: General Rules and Rules for Buildings. BS EN 1992-1-1:2004: London, England: British Standards Institution.
14. Kuebler, M. 2008. Torsion in Helically Reinforced Prestressed Concrete Poles. Master’s thesis. Waterloo, ON, Canada: University of Waterloo.
15. MagGregor, J. G., and M. G. Ghoneim. 1995. Design for Torsion. ACI Journal, V. 92, No. 2 (March–April): pp. 211–218.
16. Hsu, T. T. C. 1984. Torsion of Reinforced Concrete. New York, NY: Van Nostrand Reinhold Inc.
17. Highways Subcommittee on Bridges and Structures. 2009. Standard Specification for Structural Supports for Highway Signs, Luminaries and Traffic Signals. AASHTO LTS-5-M. Washington, DC: American Association of State Highway and Transportation Officials.
18. Technischen Komitee CEN/TC 229. 2004. Betonfertigteile- Maste [Precast Concrete Products-Masts and Poles]. DIN EN 12843:2004. Berlin, Germany: Deutsche Institut für Normung eV.
19. Technischen Komitee CEN/TC 50. 2006. Lichtmaste- Teil 4: Anforderungen an Lichtmaste aus Stahl- und Spannbeton [Lighting Columns-Part 4: Requirements for Reinforced and Prestressed Concrete Lighting Columns]. DIN EN 40-4:2005. Berlin, Germany: Deutsche Institut für Normung eV.
20. Beer, F. P., and E. R. Johnston. 1992. Mechanics of Materials. 2nd ed. SI units. New York, NY: McGraw Hill Book Co.
21. Collins, M. P., and D. Mitchell. 1987. Prestressed Concrete Basics. Ottawa, ON, Canada: Canadian Prestressed Concrete Institute.
22. Mitchell, D., and M. P. Collins. 1974. Diagonal Compression Field Theory: A Rational Model for Structural Concrete in Pure Torsion. ACI Journal, V. 71, No. 8 (August): pp. 396–408.