Thesis Format
Monograph
Degree
Doctor of Philosophy
Program
Civil and Environmental Engineering
Supervisor
Kopp, Gregory A.
Abstract
This thesis presents an analysis and simulation framework for evaluating tornado-induced wind loads on low-rise buildings. The research addresses a gap in understanding the interactions between tornado wind fields and building structures, which are not fully captured by existing design codes. This methodology enables the simulation of aerodynamic, static, and internal pressure loads, offering a framework for assessing a wide spectrum of tornado-induced wind loads. By varying key parameters, like tornado intensity, core radius, and building position relative to the tornado path, the study captures the variability in load distributions, highlighting the role of aerodynamic loads in horizontal directions which account for 80% - 90% of the total horizontal loads. In addition, the research investigates the effects of tornado translation speed on load distribution, finding that slower-moving tornadoes generally result in higher loads, particularly for stronger tornadoes (EF3 and above). The position of the worst load cases shifts with increasing tornado intensity, often occurring near the radius of maximum winds, where aerodynamic pressure effects are most pronounced. The study also reveals that building orientation and opening configurations significantly influence the distribution and magnitude of loads, with buildings aligned perpendicular to the tornado path experiencing the highest forces. Validation against experimental data confirms the framework’s acceptable accuracy in predicting worst-case scenarios. Key findings reveal that while aerodynamic loads dominate for large tornadoes, static pressure effects are critical for smaller tornadoes, especially with the building within the vortex core. These findings have implications in the tornado rating process, which depends on wind speed estimates.
Summary for Lay Audience
Tornadoes are powerful and unpredictable natural disasters that can cause significant damage to buildings and other infrastructure. This thesis focuses on understanding and simulating the forces that tornadoes exert on low-rise buildings, like homes. Traditional building codes and design standards, such as those for straight-line winds, often do not account for the unique and intense forces generated by tornadoes. This research aims to fill that gap by developing and validating a simulation method to estimate tornado-induced wind loads accurately. The study employs computer simulations to model the behavior of tornado winds and their impact on buildings. It uses a combination of a tornado wind field model and an aerodynamic model, enhanced by systematic simulations, to account for the variability in tornado characteristics and building configurations. These simulations consider different factors, such as wind speed, tornado size, and building position relative to the tornado's path, to simulate the maximum loads a building might experience during a tornado passage. Key findings from the research include the contribution of aerodynamic loads (wind forces) in horizontal directions, making up 80% and 90% of the total horizontal load on average. The study also highlights how the position and orientation of a building can significantly influence the loads it experiences, with buildings closer to the tornado center facing higher static pressures and those at the edge of maximum winds facing maximum aerodynamic forces. Validation against experimental data confirms the accuracy of the proposed models, showing implications to the tornado rating process which is based in estimated wind speeds. In summary, this research provides a comprehensive framework for predicting tornado-induced wind loads.
Recommended Citation
Hernandez Cruz, Osmany, "Simulation and Analysis of Tornado-Induced Loads on Low-rise Buildings" (2024). Electronic Thesis and Dissertation Repository. 10503.
https://ir.lib.uwo.ca/etd/10503