A framework to compare wind loads on low-rise buildings in tornadoes and atmospheric boundary layers

Kopp, Gregory A.; Wu, Chieh-Hsun

doi:10.1016/j.jweia.2020.104269

Cited by 23 publications

(5 citation statements)

References 32 publications

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“…This research includes several assumptions for applying tornado loads using the same approach as laid out in ASCE 7-22. The static pressure drop in tornadoes and aerodynamic effects are relatively small in larger tornadoes for small buildings (Kopp and Wu, 2020). However, the wind profile effects are significant with maximum wind speeds occurring very close to the ground (Wurman and Kosiba, 2018).…”

Section: Loadsmentioning

confidence: 99%

Design of stick-framed wood roofs under tornado wind loads

Bain

Kopp

Ansary

2022

Front. Built Environ.

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Light-frame wood construction comprises nearly 90% of the housing industry in Canada and the United States. The roofs of these houses can be constructed either entirely on site or using prefabricated trusses. Assembling the roof structure on site, otherwise known as stick-framing, is a framing technique with current code guidelines that are based on past practice and limited consideration of wind loads. This makes these roof structures susceptible to failure in high-speed wind events, such as tornadoes. This research proposes improved stick-framing guidelines that would work for EF-2 tornadoes. Using non-linear finite element analysis, a stick-framed roof was designed following the guidelines in the National Building Code of Canada. Non-linear links were used to model all of the connections between the members in the roof structure, with frame elements used to represent the members. Increasing wind loads were applied to the structure and the first elements of the roof that failed were improved using an iterative performance-based design approach until the performance target of resistance to EF-2 tornadoes was achieved. The failure of the roof-to-wall-connections and the lack of members used in the framing were the two main issues highlighted and addressed. Damage survey photos were used to compare failures observed in the model with failures after real tornado events, which demonstrate many similar failure modes. The research recommends the requirements to ensure stick-framed roofs can withstand EF-2 tornadoes. Most notable is an improved gable end frame, which gives the structure more roof-to-wall connections, as well as a more structurally sound frame where the loads are the highest. Other additions include struts, hurricane ties at all roof-to-wall connection locations and increased number of nails in various connections throughout the repeating inner frames. Minimum member sizes and qualities for each type of member used in the roof structure are also recommended.

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Section: Loadsmentioning

confidence: 99%

Design of stick-framed wood roofs under tornado wind loads

Bain

Kopp

Ansary

2022

Front. Built Environ.

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“…Another work on the topic of wind pressure on low-rise buildings is the example of G. Kopp, Chieh-Hsun Wu (2020) [14]. They compared wind loads during tornadoes and atmospheric boundary layers and tested the hypothesis about the possibility of separating aerodynamic and static pressure.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Pressure Distribution on a Single-Family Building Caused by Standard and Heavy Winds Based on a Numerical Approach

Lamparski,

Dutkiewicz

2024

Applied Sciences

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The aim of this research is to analyze the pressure distribution caused by wind pressure on the structure of a single-family house. The research object is a model reflecting a real structure, which was damaged in 2018 because of heavy winds. The main idea is to create numerical models using various complex structural analysis software and compare the results. The obtained results will be compared with each other to analyze the impact of various factors, hereinafter referred to as boundary conditions, on the pressure values in characteristic places of the facility. The values closest to the normal distribution will be compared to the actual damage to the house structure. The essence of the research will be the identification of phenomena occurring during the action of heavy winds in global conditions (European and American), considering modifications and different ways of creating seemingly similar numerical models and the way they work. Everything will be compared with each other to find the most optimal design method in the given programs and to obtain wind pressure results that are closest to the real ones.

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“…Wang et al (2018) found that the aerodynamic loads on a cubic building caused by tornado-like vortices resembles to those from boundary layer wind when the building is situated within the tornado core radius. Recently, Kopp and Wu (2020) presented a framework comparing the wind load on low-rise buildings in tornado-like wind field and in straight-line boundary layer wind. It was found that the swirling vortex flow created a lower pressure zone on the leeward walls of the building as well as altering the surface pressure distribution on the walls, resulting in a different vortex structure behind the building compared to the measurements from the boundary layer wind field.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Effects of Tornado Translation on Wind Loading Using a Potential Flow Model

Huo

Wang

Haan

et al. 2022

Front. Built Environ.

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This paper investigates the effects of tornado translation on pressure and overall force experienced by an airfoil subjected to tornado loading and presents a framework to reproduce the flow conditions and effects of a moving tornado. A thin symmetrical airfoil was used to explore the effects of tornado translation on a body. A panel method was used to compute the flow around an airfoil and an idealised tornado is represented using a moving vortex via unsteady potential flow. Analysis showed that the maximum overall pressure at a point was found to increase by up to 20% when the normalised translating velocity was 10% of the tangential velocity, but increases up to 60% when the normalised translating velocity is 30% of the tangential velocity. Investigation on the impact of varying airfoil thickness (Case 2) revealed that the location of the tornado has significant effect on the overall lift force. However, the overall lift force appeared to be largely insensitive to the tornado translation velocity due gross changes in pressure on either side of the airfoil cancelling each other out. Further comparison with varying airfoil sizes and distance to tornado translating path (Case 3) showed that the relative inflow and outflow angle is the primary factor affecting the lift on the airfoil. Additionally, the maximum forces on a body subjected to a moving tornado can be predicted using uniform flow providing that the appropriate range of inflow angles are known. Based on the analysis on the database of National Oceanic and Atmospheric Administration (NOAA), the normalised translation speed of the recorded tornadoes across the EF scales, appears to vary from 0.25 to 0.37, with an average of 0.32 (∼18.8 m/s). Finally, the framework using uniform flow to reproduce the flow conditions which are comparable to those generated by a translating vortex simulator is proposed and discussed in detail.

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A framework to compare wind loads on low-rise buildings in tornadoes and atmospheric boundary layers

Cited by 23 publications

References 32 publications

Design of stick-framed wood roofs under tornado wind loads

Design of stick-framed wood roofs under tornado wind loads

Analysis of Pressure Distribution on a Single-Family Building Caused by Standard and Heavy Winds Based on a Numerical Approach

A Study of the Effects of Tornado Translation on Wind Loading Using a Potential Flow Model

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