Wind load is an essential part of the building design process. It’s calculated based on parameters like wind speed, building height, and exposure category to help structures withstand strong winds without collapsing or failing. Wind load is particularly important in openings and the construction of commercial rolling steel and sectional doors.
Wind pressure can cause commercial overhead doors to bow inward or outward, potentially dislodging the curtain from its guides. Wind load-rated doors are specifically designed to resist this pressure, ensuring the door remains securely in place.
Ross Baran, Architect Design Support (ADS) representative, explains more about the effects of wind load on a rolling door’s jamb and curtain.
Question: What are the different types of loads that are imposed on the jambs?
Answer: Loads can be separated into two different categories, live load and dead load.
Live load accounts for wind pressures. The wind will exert positive pressure on a rolling door’s curtain. This force is then transferred from the curtain to the guide assembly through the end lock or wind locks.
Dead load is the hanging weight of the door itself, which exerts force on the jambs. This is sometimes referred to as the static load.
Question: How do rolling doors react to wind pressure?
Answer: Rolling doors experience wind load differently than rigid structures, like beams. The calculation method for wind load on a rolling door is closer to one used for a cable under a uniformly distributed load. The curtain of a rolling door is designed to gradually deflect during wind load. When faced with high winds, the end lock or wind lock will engage the wind bar, securing the door.
As illustrated in Fig. 7, the solid line represents the deflection of the door curtain under wind load from elastic bending and slip. The dashed line shows the change in deflection of the door curtain due to elastic elongation caused by the catenary action (slat tension) of the wind load engaged ends (note: both lines are exaggerated for illustrative purposes). The tension, elongation, and change in deflection can be calculated using equations for designing a single cable under a uniformly distributed load. Once the loads from the curtain are calculated, these loads are taken back to the wall.
The end lock or wind lock assembly prevents the curtain from slipping out of the guide assembly. Critical wall fasteners span from the bottom of the guides to the top of the door coil. These fasteners are designed to support the rolling door in its installed position and withstand the wind load PSF rating that the door is designed to.
Question: How much wind load can a rolling door withstand?
Answer: Clopay® Corporation offers a wide variety of products that can be designed to withstand the PSF rating specific to your project’s needs. Wind load construction may consist of wind locks, specialized guide angle assemblies, and full-height wind lock bars. Specialized doors are available to meet additional operational wind load requirements, and ICC and FEMA compliance.
Our ADS team can help you specify or draft doors with design PSF wind load requirements, provide static wind load illustrations and drawings, and offers a summary of forces and loads drawings.
Ross Baran, Architect Design Support
With six years of industry experience, Ross works with his team to support architects in the design phase. Ross and the ADS team craft project-tailored CAD drawings and specifications and provide one-on-one design support.
