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Comprehensive study of wind loads on parapets

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Comprehensive study of wind loads on parapets

Bedair, Rania (2009) Comprehensive study of wind loads on parapets. PhD thesis, Concordia University.

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Abstract

The current thesis aims at defining and evaluating the local (components and cladding) wind loads on parapets. For the first time, it was attempted to measure such loads in full-scale, in order to address the issues encountered in previous wind tunnel studies. Field testing was carried out using the full-scale experimental building (3.97 m long, 3.22 m wide and 3.1 m high) of Concordia University (located near the soccer field at the Loyola Campus). In order to define individual surface pressures as well as their combined effect from both parapet surfaces, simultaneous peak and mean wind-induced pressures were measured on both exterior and interior surfaces of a uniform perimeter parapet with a height of 0.5 m. Roof edge and comer pressures were also recorded. In addition, a complete wind flow simulation was performed in the Boundary Layer Wind Tunnel (BLWT) of Concordia University using a 1/50 scale model of the experimental building with two different parapet heights, equivalent to 0.5 and 1 m. The choice of geometric scale based on correctly modeling the turbulence intensity at the roof height. The wind tunnel results were compared with the field data for validation purposes. In general, the comparison shows good agreement, although some discrepancies were identified for critical wind directions. In the past, it was difficult to directly model and record the parapet surface pressures, due to modeling limitations. Therefore, wind loads on parapets were mainly estimated from pressures measured on the wall and the roof of the building in the vicinity of a parapet. The current results demonstrate, in general, that the design method provided in the ASCE 7-05 overestimates the total load on the parapet. In addition, design recommendations are provided and can be considered by the standards. Numerical simulation of the wind flow over the test building model with the parapet was also performed by using the CFD code Fluent 6.1.22. The steady-state RANS equations were solved with two modified k -[varepsilon] turbulence models, namely the RNG k -[varepsilon] model and the RLZ k -[varepsilon] model. Considering the current state-of-the-art, peak pressures are not predicted reliably by computational approaches. Therefore, in the present study only mean wind-induced pressures on the roof and on parapet surfaces were computed. The computational results show that parapets act to reduce high negative pressures on the leading edge and to make the distribution of mean pressures on the roof more uniform. The simulated pressures are generally in good agreement with the corresponding wind tunnel data

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Building, Civil and Environmental Engineering
Item Type:Thesis (PhD)
Authors:Bedair, Rania
Pagination:xx, 185 leaves : ill. ; 29 cm.
Institution:Concordia University
Degree Name:Ph. D.
Program:Building, Civil and Environmental Engineering
Date:2009
Thesis Supervisor(s):Stathopoulos, T
ID Code:976384
Deposited By: Concordia University Library
Deposited On:22 Jan 2013 16:24
Last Modified:18 Jan 2018 17:42
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