Wind load is one of the factors that Megadoor uses to ensure that every overhead door is designed to meet each customer’s specific need. Wind pressure data provides Megadoor with wind load calculations that are required to meet minimum local environmental conditions in all applications. As a result, overhead doors supplied by Megadoor operate in high wind load areas where other doors would simply fail.
Wind load is defined in units of force per unit area [e.g. pounds per square foot (psf), kilonewtons per square meter (kN/m2)]. By stating the wind load in this way, each door can be built to a standard regardless of its size or the geographic area.
For designing purposes, the wind load is calculated using an equation for:
- Local wind pressure
- Exposure factor
- Wind gust factor
- Other
Of these, wind pressure is the most significant component.
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The National Building Code – 1995 and the Building Code for each province (e.g. Ontario – OBC 1997 Regulation 403/97, Amendments O. Reg 22/98 and 102/98) provide listings of wind pressure for various cities and areas. The values are given in Kilopascals (kPa) for three levels. For example, a Winnipeg, Manitoba listing of q 1/10 = 0.35 means that in one year out of ten years the average one-hour wind pressure would exceed 0.35 kPa. The other levels are 1/30 and 1/100. All calculations are based on long term recordings (i.e. 10 to 25 years).
A formula provides the wind pressure value by defining the relationship between wind speed and air density. For example, air (at zero degree C and standard atmospheric pressure) traveling at 25.2 meters per second creates a wind pressure of 0.41 kPa.
As shown, wind pressure defined in terms of wind speed is not valid.
The National Research Council of Canada and the Institute of Research in Construction
have written three detailed articles related to wind. You can read these articles by
clicking on the following links:
Wind on Buildings
Brief description of the cause and structure of wind and explains how its structure complicates the determination of a reasonable wind speed.
Wind Pressure on Buildings
Outlines conversion of wind speeds to wind pressures, interaction of wind and structures, wind pressure coefficients and variable affecting wind pressure distributions
Wind and Air Pressure on the Building Envelope
Deals with 3 mechanisms that influence the direction and magnitude of air pressures on a building envelope - stack effect, fan pressurization and wind
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