Wind and Structures

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Updates to the wind tunnel method for determining design loads in ASCE 49-21

  • Gregory A. Kopp (Boundary Layer Wind Tunnel Laboratory, Faculty of Engineering, Western University)
  • Received : 2022.12.13
  • Accepted : 2023.07.05
  • Published : 2023.08.25
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Abstract

The paper reviews and discusses the substantive changes to the ASCE 49-21 Standard, Wind Tunnel Testing for Buildings and Other Structures. The most significant changes are the requirements for wind field simulations that utilize (i) partial turbulence simulations, (ii) partial model simulations for the flow around building Appurtenances, along with requirements for determining wind loads on products that are used at multiple sites in various configurations. These modifications tend to have the effect of easing the precise scaling requirements for flow simulations because it is not generally possible to construct accurate models for small elements placed, for example, on large buildings at the scales typically available in boundary layer wind tunnels. Additional discussion is provided on changes to the Standard with respect to measurement accuracy and data acquisition parameters, such as duration of tests, which are also related to scaling requirements. Finally, research needs with respect to aerodynamic mechanisms are proposed, with the goal of improving the understanding of the role of turbulence on separated-reattaching flows on building surfaces in order to continue to improve the wind tunnel method for determining design wind loads.

Keywords

Acknowledgement

While the author has summarized some of the rationale used by the committee in the development of ASCE 49-21 (2021), the opinions and analysis expressed herein are those of the author. The actual ASCE 49 document provides the official consensus of the committee. The author is grateful to the entire committee for many interesting and fruitful discussions on the topics examined herein, but particularly with Drs. D. Banks, G. Bitsuamlak, P. Irwin, C. Letchford, M. Morrison, J. Wang, and Mr. T. Geleta. The author is also grateful for the financial support provided by ImpactWX.

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