Investigation on the effects of the wind vertical angle of attack and the wind speed profile on low-rise building pressures and its implications for wind loading by severe convective storms

Zaldivar De Alba, Antonio

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https://hdl.handle.net/2142/115813 Copy

Description

Title

Investigation on the effects of the wind vertical angle of attack and the wind speed profile on low-rise building pressures and its implications for wind loading by severe convective storms

Author(s)

Zaldivar De Alba, Antonio

Issue Date

2022-04-20

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

Lombardo, Franklin T.

Doctoral Committee Chair(s)

Lombardo, Franklin T.

Committee Member(s)

• Fahnestock, Larry A.
• Trapp, Robert J.
• Mason, Matthew S.

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• wind loading
• severe convective storms
• vertical angle of attack
• wind speed profile
• low-rise buildings

Abstract

Severe convective storms generate extreme wind events such as downbursts and tornadoes. These winds generated by severe convective storms (WGSCS) cause tremendous damage in the United States and worldwide. Wind characteristics and induced loading during WGSCS are scarce due to their short temporal and spatial scales, hindering our understanding of how WGSCS load structures. For this reason, a novel instrument, called mSWERF3, short for mobile Smart Wind Engineering Research Laboratory cube, was developed and validated. The validation shows that mSWERF3 can obtain meaningful wind-induced loading for low-rise buildings. Moreover, the mobile capabilities of mSWERF3 allowed the collection of novel wind-induced loading from WGSCS events. The few available full-scale records of WGSCS display different characteristics to those observed in Atmospheric Boundary Layer (ABL) winds. Characteristics of ABL winds are used as the basis of structural design for wind loading. These differing characteristics of WGSCS may cause distinct loading effects that, in turn, are reflected in the observed damage. Two major characteristics have been identified for this work that have significant potential to influence loading. The first is the vertical angle of attack, which correlates to high overall wind speed values during WGSCS, but not during ABL winds. The second is the wind speed profile, where the highest wind speeds are closer to the ground than ABL winds. The effects of the vertical angle of attack and the wind speed profile on loading are considered by constructing a set of loading models. The loading models were built using wind and wind-induced loading data collected during ABL winds using mSWERF3 and available data from archived experiments. Despite the mentioned differences between ABL winds and WGSCS, the current research shows that it is possible to extract characteristics of the vertical angle of attack and wind speed profiles during ABL winds by using a shorter averaging time to analyze their effect on loading. The new loading models were shown to predict loads during ABL winds with no significant difference from previous models. However, the new models allow estimating the effects of the vertical angle of attack and the wind speed profile in loading and show a significant difference during WGSCS events. It is found that a high value of vertical angle of attack tends to increase loading in the roof. Moreover, unique wind speed profiles such as those found in WGSCS with higher wind speed closer to the ground increase loading in the roof and shift the maximum pressure position in the windward wall. Several records from WGSCS are evaluated using the loading models created. The WGSCS records are from downbursts, thunderstorms, dust devils, and a tornado. The peak pressures from the WGSCS records obtained with the models considering and not considering the characteristics are compared. In general, an increase in loading is seen during WGSCS when considering the effects of the vertical angle of attack and the wind speed profile. For the vertical angle of attack, records from vortex flow, such as tornadoes and dust devils, showed the most increase in loading. For the wind speed profile, records from downburst events showed the most increase in loading. It is shown that the vertical angle of attack and the wind speed profile have a distinct influence on the loading of low-rise buildings and that they need to be considered in structural design.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Antonio Zaldivar de Alba

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