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Wind and Structures
  Volume 14, Number 5, September 2011 , pages 383-411
DOI: https://doi.org/10.12989/was.2011.14.5.383
 


Generalized load cycles for dynamic wind uplift evaluation of rigid membrane roofing systems
Baskaran, A., Murty,B. and Tanaka, H.

 
Abstract
    Roof is an integral part of building envelope. It protects occupants from environmental forces such as wind, rain, snow and others. Among those environmental forces, wind is a major factor that can cause structural roof damages. Roof due to wind actions can exhibit either flexible or rigid system responses. At present, a dynamic test procedure available is CSA A123.21-04 for the wind uplift resistance evaluation of flexible membrane-roofing systems and there is no dynamic test procedure available in North America for wind uplift resistance evaluation of rigid membrane-roofing system. In order to incorporate rigid membrane-roofing systems into the CSA A123.21-04 testing procedure, this paper presents the development of a load cycle. For this process, the present study compared the wind performance of rigid systems with the flexible systems. Analysis of the pressure time histories data using probability distribution function and power spectral density verified that these two roofs types exhibit different system responses under wind forces. Rain flow counting method was applied on the wind tunnel time histories data. Calculated wind load cycles were compared with the existing load cycle of CSA A123.21-04. With the input from the roof manufacturers and roofing associations, the developed load cycles had been generalized and extended to evaluate the ultimate wind uplift resistance capacity of rigid roofs. This new knowledge is integrated into the new edition of CSA A123.21-10 so that the standard can be used to evaluate wind uplift resistance capacity of membrane roofing systems.
 
Key Words
    wind uplift; rigid roof; flexible roof; dynamic procedure; wind tunnel; design pressure; certification.
 
Address
Baskaran, A.: National Research Council of Canada, 1200 Montreal Rd., Ottawa, Canada, K1A 0R6
Murty,B. and Tanaka, H.: Department of Civil Engineering, University of Ottawa, Ottawa, Canada, K1N 6N5
 

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