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Wind and Structures
  Volume 34, Number 2, February 2022 (Special Issue) pages 512-230
DOI: https://doi.org/10.12989/was.2022.34.2.512
 


The effect of different tornado wind fields on the response of transmission line structures
Nima Ezami, Ashraf El Damatty, Ahmed Hamada and Mohamed Hamada

 
Abstract
    Majority of transmission line system failures at many locations worldwide have been caused by severe localized wind events in the form of tornadoes and downbursts. This study evaluates the structural response of two different transmission line systems under equivalent F2 tornadoes obtained from real incidents. Two multi-span self-supported transmission line systems are considered in the study. Nonlinear three-dimensional finite element models are developed for both systems. The finite element models simulate six spans and five towers. Computational Fluid Dynamics (CFD) simulations are used to develop the tornado wind fields. Using a proper scaling method for geometry and velocity, full-scale tornado flow fields for the Stockton, KS, 2005 and Goshen County WY, 2009 are developed and considered together with a previously developed tornado wind field. The tornado wind profiles are obtained in terms of tangential, radial, and axial velocities. The simulated tornadoes are then normalized to the maximum velocity value for F2 tornadoes in order to compare the effect of different tornadoes having an equal magnitude. The tornado wind fields are incorporated into a three-dimensional finite element model. By varying the location of the tornado relative to the transmission line systems, base shears of the tower of interest and peak internal forces in the tower members are evaluated. Sensitivity analysis is conducted to assess the variation of the structural behaviour of the studied transmission lines associated with the location of the tornado relative to the tower of interest. The tornado-induced forces in both lines due to the three different normalized tornadoes are compared with corresponding values evaluated using the simplified load case method recently incorporated in the ASCE-74 (2020) guidelines, which was previously developed based on the research conducted at Western University.
 
Key Words
    computational fluid dynamics; finite element; tornado; transmission line system; wind
 
Address
Nima Ezami:Department of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada

Ashraf El Damatty:Department of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada

Ahmed Hamada:Department of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada

Mohamed Hamada:Department of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada
 

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