Optimizing openings through tall buildings to mitigate their crosswind response

Lhotka, Cory Stewart

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https://hdl.handle.net/2142/120342 Copy

Description

Title

Optimizing openings through tall buildings to mitigate their crosswind response

Author(s)

Lhotka, Cory Stewart

Issue Date

2023-03-17

Director of Research (if dissertation) or Advisor (if thesis)

Lombardo, Franklin

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Crosswind
• Vented Structures
• Separated-shear Layer
• Near-wake
• High-rise Structures
• Vortex Shedding
• Tall Buildings
• Dampers
• Architectural Form
• Wind Tunnel Testing
• High-frequency Force Balance

Language

eng

Abstract

High-rise structures are becoming taller and more slender due to developers attempting to maximize their project location's value. However, with increasing slenderness ratios comes increased crosswind response due the phenomenon of vortex shedding. Mitigating this response often requires stiffening the structure or using active systems such as damping devices. These systems come with increased costs and material usage, which goes against the economic and environmental focus of modern developers. However, the development of passive systems that utilize the wind to disrupt wind acting on the structure could reduce the crosswind response, costs, and environmental impact in an elegant manner. The crosswind response of the structure is primarily caused by the phenomenon of vortex shedding. The primary vortex shedding mitigation techniques are reducing the coherence of vortex shedding along a building's height, modifying separated shear layer structure, and stabilizing the near-wake region of a building. This study builds upon previous works by focusing on the importance of stabilizing the near wake region versus altering the separated shear layer. These methods are explored via differing vent configurations that passively direct the flow to the areas of interest. This study developed vent configurations to maximize usable floor space while minimizing a structure's crosswind response. In total, thirty-one vent configurations were tested at Skidmore, Owings & Merrill's boundary layer wind tunnel facility. Stabilizing the windward portion of the near shear layer was the most influential in reducing the crosswind response of a structure by reducing the peak power spectral density, the crosswind moment coefficient, and the full-scale overturning moment. A modified overturning moment was developed for the purpose of maximizing total building floor space while reducing full-scale overturning moment. Two vent configurations successfully resulted in similar or better moment-area optimization parameters than having an entirely open mechanical floor. The effectiveness of vent configurations with differing intended flow characteristics were studied with the intent of applying this knowledge to future vented structures.

Graduation Semester

2023-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/120342

Copyright and License Information

Copyright 2023 Cory Lhotka

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