DOI QR코드

DOI QR Code

Behaviour and design of guyed pre-stressed concrete poles under downbursts

  • Ibrahim, Ahmed M. (Department of Civil and Environmental Engineering. Western University) ;
  • El Damatty, Ashraf A. (Department of Civil and Environmental Engineering. Western University)
  • 투고 : 2018.04.26
  • 심사 : 2019.09.07
  • 발행 : 2019.11.25

초록

Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors' knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator's stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.

키워드

참고문헌

  1. Aboshosha, H. and El Damatty, A.A. (2014), "Effective technique for the reactions of transmission line conductors under high intensity winds", Wind Struct., 18(3), 235-252. http://dx.doi.org/10.12989/was.2014.18.3.235.
  2. American Society of Civil Engineers (ASCE), (2010) "Guidelines for electrical transmission line structural loading", ASCE manuals and reports on engineering practice, No. 74, New York, NY, USA.
  3. American Society of Civil Engineers (ASCE), (1997) "Design of guyed electrical transmission structures", ASCE Manuals and Reports on Engineering Practice, vol. 91, New York, NY, USA.
  4. American Society of Civil Engineers (ASCE), (2012) "Prestressed Concrete Transmission Pole Structures", ASCE manuals and reports on engineering practice, No. 123, Reston, VA, USA.
  5. Australian Standard/New Zealand Standard (AS/NZS) 7000, (2010) "Overhead line design detailed procedures", Standards Australia Limited/Standards New Zealand, North Sydney, Australia.
  6. Australian Wind Alliance, (2016): http://www.windalliance.org.au/
  7. Choi, E.C.C. (2004), "Field measurement and experimental study of wind speed profile during thunderstorms", J. Wind Eng. Ind. Aerod., 92(3-4), 275-290. https://doi.org/10.1016/j.jweia.2003.12.001.
  8. Darwish, M., El Damatty A.A. and Hangan, H. (2010), "Dynamic characteristics of transmission line conductors and behaviour under turbulent downburst loading", Wind Struct., 13(4), 327-346. http://dx.doi.org/10.12989/was.2010.13.4.327.
  9. Darwish, M. and El Damatty, A.A. (2011), "Behavior of selfsupported transmission line towers under stationary downburst loading", Wind Struct., 14(5), 481-4. https://doi.org/10.12989/was.2011.14.5.481
  10. Elawady, A. and El Damatty A.A. (2016), "Longitudinal force on transmission towers due to nonsymmetric downburst conductor loads", Eng. Struct., 127, 206-226. https://doi.org/10.1016/j.engstruct.2016.08.030.
  11. El Damatty, A.A. and Elawady, A. (2018), "Critical load cases for lattice transmission line structures subjected to downbursts: Economic implications for design of transmission lines", Eng. Struct., 159, 213-226. https://doi.org/10.1016/j.engstruct.2017.12.043.
  12. Fujita, T. (1985), "The downburst: microburst and macroburst", SMRP Research Paper 210, University of Chicago, USA.
  13. Fujita, T. (1990), "Downbursts: meteorological features and wind field characteristics", J. Wind Eng. Ind. Aerod., 36, 75-86. https://doi.org/10.1016/0167-6105(90)90294-M.
  14. Gast, K.D. and Schroeder, J.L. (2003), "Supercell rear-flank downdraft as sampled in the 2002 thunderstorm outflow experiment", Proceedings of the 11th International Conference on Wind Engineering. ICWEIA, 2233-2240.
  15. Gere, J.M. and Carter, W.O. (1962), "Critical buckling loads for tapered columns", J. Struct. Div- ASCE, 88(1), 1-12. https://doi.org/10.1061/JSDEAG.0000737
  16. Hangan, H., Roberts, D., Xu, Z. and Kim, J. (2003), "Downburst simulation. Experimental and numerical challenges", Proceedings of the 11th International Conference on Wind Engineering, Lubbock, TX, USA.
  17. Holmes, J., Hangan, H., Schroeder, J., Letchford, C. and Orwig, K. (2008), "A forensic study of the Lubbock-Reese downdraft of 2002", Wind Struct., 11(2), 137-152. http://dx.doi.org/10.12989/was.2008.11.2.137.
  18. Ibrahim, A.M. and El Damatty, A.A., (2014), "Behaviour of Prestressed Concrete Poles under Downburst Loading", Proceeding of ASCE conference, Hamilton, ON, Canada.
  19. Ibrahim, A.M., El Damatty, A.A. and Elansary A.M. (2017), "Finite element modelling of pre-stressed concrete poles under downbursts and tornadoes", Eng. Struct., 153, 370-382. https://doi.org/10.1016/j.engstruct.2017.10.047.
  20. Ladubec, C., El Damatty, A.A. and El Ansary, A. (2012), "Effect of geometric nonlinear behaviour of a guyed transmission tower under downburst loading", Proceedings of the International Conference on Vibration, Structural Engineering and Measurement, Shanghai, China, Trans. Tech. Publications, 1240-1249.
  21. Li, C.Q. (2000), "A stochastic model of severe thunderstorms for transmission line design", Probablist. Eng. Mech., 15(4), 359-364. https://doi.org/10.1016/S0266-8920(99)00037-5.
  22. McCarthy, P. and Melsness, M. (1996), "Severe weather elements associated with September 5, 1996 hydro tower failures near Grosse".
  23. Shehata, A., El Damatty, A.A. and Savory, E. (2005), "Finite element modeling of transmission line under downburst wind loading", Finite Elem. Anal. Des., 42(1), 71-89. https://doi.org/10.1016/j.finel.2005.05.005.
  24. Shehata, A. and El Damatty, A.A. (2007), "Behaviour of guyed transmission line structures under downburst wind loading", Wind Struct., 10(3), 249-268 http://dx.doi.org/10.12989/was.2007.10.3.249.
  25. Wang, X., Lou, W., Li, H. and Chen, Y. (2009), "Wind-induced dynamic response of high-rise transmission tower under downburst wind load", J. Zhejiang Univ., 43(8), 1520-1525.
  26. Wolfson, M., DiStefano, J. and Fujita, T. (1985), "Low-altitude wind shear characteristics in the Memphis, TN area", Proceedings of the 14th conference on severe local storms, American Meteorological Society, Indianapolis, IN, USA., 322-7.
  27. Yang, F. and Zhang, H. (2016), "Two case studies on structural analysis of transmission towers under downburst", Wind Struct., 22(6), 685-701. http://dx.doi.org/10.12989/was.2016.22.6.685.
  28. Zhang, Y., (2006), "Status quo of wind hazard prevention for transmission lines and countermeasures", East China Electric Power, 34(3), 28-31. https://doi.org/10.3969/j.issn.1001-9529.2006.03.008