UFC 4-211-01N
25 October 2004
Including change 1, 1 October 2006
4-5.8
Roof Systems. Roof systems are typically metal deck on a
combination of open web steel joist and structural steel substructure.
Historically, it has been difficult to maintain the necessary level of quality control
required to weld decks at sidelaps and at supports. The designer is cautioned to
avoid specifying welding for roof decks unless necessary. Mechanical fasteners
are the desired option. Additionally, there may be significant economy in erection
by allowing pneumatic and powder actuated fastening systems. If welding is
required, the designer should specify additional quality control procedures to
ensure that welds are done properly and do not deteriorate over time.
4-5.8.1
Diaphragms. Given the difficulty in providing lateral load
resistance for the large open spans associated with hangar bay structures, it
often appears desirable to incorporate the roof deck into the lateral load system
as a flexible diaphragm. However, these same large spans involved in hangar
structures often require large deflections in the frame before the deck produces
the desired resisting forces. Designers should therefore avoid relying on a steel
deck as a diaphragm in the hangar bay and provide a dedicated secondary
horizontal lateral load system unless careful analysis is conducted on the deck's
stiffness and load response. The deck may, however, be assumed to provide
local support to elements, such as top chord/flange support to joists/beams.
The designer should consider whether it is permissible to support
suspended loads directly from the underside of the steel deck. (See UFC 1-200-
01 for more information on loads.) The contract drawings should clearly indicate
when this is allowed and the means by which the connection is to be
accomplished.
4-5.9
Wall Systems. Walls and partitions of the hangar bay should be
non-load bearing. The walls of the O1/O2 portion of the facility may be designed
as load bearing if structurally isolated from the hangar structure. This is
particularly useful as load bearing wall structures are typically more rigid than the
steel frame of the hangar bay. The O1/O2 structure may or may not be built as
an integral part of the hangar structure. In either case, the weight of the O1 and
O2 structure may be used to help provide stability in those cases where
additional dead load is desirable.
4-5.9.1
Exterior Walls. Side walls of the OH space should be insulated
hollow concrete masonry units (CMU) sized in accordance with American Society
for Testing and Materials (ASTM) C 90, Loadbearing Concrete Masonry Units or
reinforced concrete (RC) walls to a height of 3 meters (10 feet) above the hangar
deck. Above this height, use preformed (corrugated), protected-metal panels or
similar materials. Alternatively, an interior wainscot wall of CMU or RC may
protect an exterior wall of architectural fascia that extends to the ground
elevation.
54
Previous Page
