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Overhead Rolling door deflections



Upon analyzing the calculations for deflection, slat stresses and mounting conditions,

I have concluded that a reasonable specification for deflection of roll up doors would be L/20 for doors greater

than 20 feet wide and L/25 for doors less than 20 feet wide. In designing roll up doors they are generally

allowed to deflect so that the slat bending stress does not exceed 80%-90% of the yield stress of slat material.

If the deflection is very restrictive such, as L/120, the reaction forces at the guides would become prohibitive

and destructive to the support structure.

A further consideraion is the support structure for the door. If the support structure is to be concrete block or

concrete, reinforcing rods are required. The solution is generally steel columns or mullions. As an example for

a 24 ft wide door the horizontal reaction forces are 1420 lb/ft of door height and vertcal forces to the wall are

245 lb/ft of door height. The above door deflects approximately 12.8 inches.


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