2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Mrs. Zannatul Mawa Dalia, Concordia University
Dr. Ted Stathopoulos, Concordia University
Dr. Anjan Bhowmick, Concordia University
Mr. Hatem Alrawashdeh, Concordia University
Overhangs are commonly used in residential and industrial buildings for the convenience of residents and users. These overhangs can be found with different names such as building eaves, patio covers, canopies, awnings or porches. In most cases, practitioners and designers struggle to evaluate design wind loads for canopies because wind standards and codes of practice only rarely refer to provisions of wind-induced pressures for their design. However, canopies are very prone to wind due to the suction developing on their upper surface along with the pressure occurring on their lower surface (for most wind directions), which together may generate critical uplift forces causing lots of damage on these elements under strong winds.
The paper refers to the results of a study collecting all available literature research data originating from wind tunnel experiments simulating adequately the natural wind conditions. Comparisons of the results with a few computational evaluations, as well as the limited provisions of codes and standards show significant discrepancies that are discussed in detail. Some of these differences are due to the various configurations used in the previous studies, e.g. geometry, size and slope of overhangs, specific location on the wall(s), existence of openings, as well as roof shape (flat, gabled or curved / arched). This topic is very timely due to the new canopy pressure coefficient provisions included in the ASCE 7 (2016) version of the American standard and the upcoming 2020 edition of the National Building Code of Canada. The paper will discuss the origin of these provisions, the extent of their applicability, as well as the common errors designers may make by using, for instance, internal pressures from other sections of the code(s) or by neglecting the critical effects of wind direction given that some of these literature values are validated for a single wind direction.
Finally, a review of the current activities on this area, as part of our program on wind engineering and building aerodynamics at Concordia University will be presented.