UFC 4-211-01N
25 October 2004
maximum wind velocity for the geographic area; design as an
"enclosed structure."
Hangars are prone to large eccentricities between centers of wind
pressure and centers of rigidity (especially cantilevered hangars). Even
unfactored loads resulting from this eccentricity may be significant. The designer
should consider this eccentricity and to locate the center of rigidity as near to the
center of applied force as practical by careful arrangement of the lateral load
resisting elements.
4-4.3
Seismic Loads. Design seismic with importance factor of 1.
Seismic design criteria may impose significant constraints upon the structural
frame, not only in the loads applied but also in the fundamental choice of framing
system. For instance, an STMF system (per AISC) is limited to a span of 20 m
(65 ft). A combination of site condition, design approach and structural layout will
determine the AISC criteria.
A poor selection of framing, arrangement of bracing or large
asymmetries may result in expensive connection fabrication and testing
requirements or outright prohibition of the fundamental design. The facility
designers should investigate the seismic issues early in the design phase and
plan the building's geometry and structure accordingly.
Hangars are prone to large eccentricities between centers of mass
and centers of rigidity (especially cantilevered hangars). Regardless of the
structural system, the unfactored loads from this eccentricity may be significant.
For general information about structural loads, see UFC 1-200-01. For detailed
information, see TI 809-04, Seismic Design for Buildings; FEMA 368, NEHRP
Recommended Provisions for Seismic Regulations for New Buildings and Other
Structures, Part 1 Provisions; FEMA 369, NEHRP Recommended Provisions
for Seismic Regulations for New Buildings and Other Structures, Part 2
Commentary; and AISC Pub S341, Seismic Provisions for Structural Steel
Buildings.
4-4.3.1
use one of the following force-resisting systems, as referenced in AISC Pub
S341:
(EBF) Eccentrically Braced Frames (Part 1, Sec 15)
(SCBF) Special Concentrically Braced Frames (Part 1, Sec 13)
(OCBF) Ordinary Concentrically Braced Frames (Part 1, Sec 14)
(STMF) Special Truss Moment Frame (Part 1, Sec 12)
(IMF) Intermediate Moment Frame (Part 1, Sec 10)
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