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 (3) Floors above Grade. Above ground floors are typically concrete topping on
steel deck over structural steel or open web steel joists. The concrete may or may not be
composite with the system depending upon the design goal and considerations of economy.
(4) Other. There may be a requirement for catwalks, mezzanines, etc. fabricated
from steel bar gratings, diamond tread steel deck or more esoteric materials. These surfaces
should be designed according to the applicable codes for the loads and criteria determined by the
design professional.
Doors
Doors should meet the criteria defined elsewhere in this handbook. Design hangar doors in
accordance with components and cladding, Wind Pressure coefficients determined in accordance
with ASCE 7. Designers should consider the full operating range of the roof structure and wind
uplift to design door guide system.
Designers are cautioned to consider air leakage around hangar doors when determining internal
pressure coefficients for wind analysis. The commentary of ASCE 7 recommends against
assuming that hangar doors in the closed position are sufficiently air tight to consider the
building as "enclosed." However, if the "partially enclosed" condition is deemed appropriate,
the large volume reduction factor for the internal pressure coefficient mitigates the effect
substantially.
Horizontal Rolling Hangar Doors
Horizontal rolling hangar doors are typified by supporting their own gravity load and only
imparting lateral (wind, seismic) loads to the main structural system through a track system at the
door head. Furthermore, an extensive structure is required at grade to support the bottom door
tracks as well as some means to ensure that the bottom tracks remain clear of obstructions.
Depending upon the requirements of the end user, the entire clear span of the door may or may
not be available for use. If there is a requirement that the entire span be available, the designer
must make provision for door pockets at one or both ends of the hangar. The inclusion of door
pockets will typically require a tall, laterally unsupported structure, outside of the regular plan of
the building. Careful consideration of the resulting effects on the structural response to lateral
loads in required.
Vertical Lifting Fabric Hangar Doors
Vertical lifting fabric doors are lighter than rolling doors, but their entire weight must be carried
by the superstructure. Additionally, beyond a practical limit of about 15 m (49 ft) multiple door
leaves are required. A complicated swinging mullion with additional overhead equipment is
required for every vertical lift fabric door beyond the first. However, vertical lifting fabric doors
do not require door pockets to entirely clear the hangar opening nor do they require extensive
support at grade.
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