Framed openings include any opening in the building larger than a walk door, whether or not it is covered by a door. In fact, openings larger than a walk door are required to have a framed opening. Framed openings are not required nor considered for windows, vents, and the aforementioned walk doors unless the building is in a high-wind area.
Types of Framed Openings
Framed openings provide an added layer of support and security to your building as well as allow you to customize openings for your needs. Examples of framed openings include:
- Personnel doors
- Overhead doors
- Roll-up doors
- Bottom rolling hangar doors
- Sliding doors
- Single and continuous band wall-lites
These openings can be enhanced by wind-locks if you are in a region with high winds. Positioning the building so openings are away from prevailing winds also helps keep the opening from damage.
Motors, hydraulic lifts, and other equipment can be added to a framed opening to assist in lifting doors and louvers. Hangars, garages, and other buildings that require moving large pieces of equipment, vehicles, and/or supplies are some of the most obvious candidates for framed openings. But did you know you can also get framed openings for sky-lights and ventilation openings?
Structure of a Framed Opening
A moderately sized framed opening is built of extended jambs created from cold formed channels which continue on to the next horizontal girt or eave strut. The top header is created the same way.
However, for large industrial overhead doors the slats subjected to wind loading are too shallow and flexible for the span between the jambs. The doors act as membranes in high wind loads, deforming them and possibly forcing the door out of the guides.
Larger doors require wind locks to positively attach the door slats to the guides to keep them from being blown out. The jambs, in turn, must be designed for overstress situations like deflections and rotational forces.
Framed openings for large doors must also support the weight of the doors when raised as well as the surrounding siding and other wall materials. Different types of doors bestow different forces and may not be centered. Eave struts or other horizontal members spanning the columns will also be impacted by reactions from these types of doors.
Some framed opening designs include the use of tubular framing structures which resist torsion as well as horizontal loading from any directions. Other designs are created from build-up plates, wide-flange, and channel sections.
Things to Consider
When you design your steel building keep in mind the needs around the various openings. Structural enhancement for larger doors will extend the life of your building by mitigating damage from wind loading and other forces while supplying extra strength to the building’s structure.