01-06M
C. Unless otherwise shown by SMACNA or NUSIG, provide required details
and structural calculations to completely address seismic bracing
requirements. See paragraph 13.4 "CALCULATIONS".
D. SMACNA does not cover all conditions such as, providing bracing
details for seismic restraints of equipment or details of flexible
joints when crossing seismic or expansion joints, or bracing of in-
line equipment, etc.
E. Coordinate earthquake-resistive design with the project Professional
Structural Engineer for appropriateness and soundness.
F. Both, SMACNA and NUSIG list conditions under which seismic bracing
may be omitted. However, a design professional may revoke these
omissions on an individual project basis.
13.2 CONFORMANCE WITH SMACNA:
A. Requires a design professional to develop a Seismic Hazard Level
(SHL) for a specific project for use of its manual. The SHL is
derived from a combination of factors such as applicable building
codes, seismic zones, and importance factors into a single system for
determining appropriate bracing or restraints. A building with an SHL
of "A" requires the strongest restraints, whereas, a building with
SHL of "C" requires the least restraints. The design professional is
responsible for specifying the SHL of "C" requires the least
restraints. The design professional is responsible for specifying the
SHL, not the contractor.
B. Bracing in SHL "A" is designed to resist 48% of the weight of the
pipes. Bracing in SHL "B" is designed to resist 30%, and in the
bracing in SHL "C" is designed to resist 15% of the weight of the
ducts or pipes. In addition to the horizontal seismic force, a
vertical seismic force equal to one-third of the horizontal force is
included in the analysis.
C. Current building codes require most structures and their components
to be designed for a horizontal seismic force that is a given percent
of the supported weight. Each code has its own method for determining
the percent. The formulas are in the form:
Fp - Cs x Wp
Where Wp is the weight of the ducts or pipes, Fp is the seismic
force, and Cs is a seismic coefficient which represents a combination
of factors that varies with the building code. Use more severe of the
Local Code and the Uniform Building Code (UBC) to determine seismic
force, Fp.
D. The percent horizontal seismic factor is:
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