Influence of Solid Area Distribution on the Drag of a Two-Dimensional Lattice Frame
Publication: Journal of Engineering Mechanics
Volume 140, Issue 3
Abstract
Many wind design codes provide recommended values of the drag coefficient for generic lattice frame geometries based on the solidity ratio. The solidity ratio of a lattice structure often varies along its length or height, resulting in a piecewise treatment in design. By definition, the solidity ratio is only dependent on the amount of solid area to the total enclosed area of a frame, and therefore does not account for member spacing or the number of members within the framework; this has implications for some nonuniform sections used in lattice tower design. Drag coefficients for many geometric configurations were measured in a wind tunnel with the focus placed on configurations having an identical solidity ratio but different member spacing ratios. It was observed that the drag coefficient varied with the member spacing ratio as well as with the number of members in the frame. The results suggest that the solidity ratio alone may not be sufficient for describing the drag coefficient of a lattice frame having a nonuniform solid area distribution. Recommendations are made for future research in this area, which may lead to better estimate of the drag coefficient for nonuniform lattice sections.
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Acknowledgments
The author acknowledges the financial support of the National Sciences and Engineering Research Council (NSERC) of Canada. Many useful discussions with T. C. E. Ho and G. A. Kopp are also greatly appreciated. The author is grateful for the constructive comments provided by the three reviewers, which led to improvements in the paper.
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Information & Authors
Information
Published In
Journal of Engineering Mechanics
Volume 140 • Issue 3 • March 2014
Pages: 644 - 649
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Nov 25, 2012
Accepted: Jun 5, 2013
Published online: Jun 7, 2013
Published in print: Mar 1, 2014
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