c.
Seismic Design Forces. Equations 10-1, 10-
on the response of the building. Equipment that is
not within the above limitations is outside the scope
2, and 10-3 prescribe seismic forces for equipment
of this manual, and must be designed using a more
that is supported by buildings or other structures.
rigorous method of analysis.
The amplification of the floor response motion in the
higher level of the structure is represented by the
factor (1+z/h), and the amplification of the design
(4)
Rigorous analysis.
No portion of this
chapter will be construed to prohibit a rigorous
force due to the dynamic response of the equipment
analysis of equipment and the supporting mechanism
and/or its supports is represented by the component
amplification factor, Ap.
by established principles of structural dynamics.
Equation 10-1 is a
Such
an
analysis
will
demonstrate
that
the
simplistic, but acceptable, determination of the
fundamental principle and underlying criterion of
seismic design force for equipment supports in
Paragraph 10-3a are satisfied. In no case will the
structures. More rigorous determinations include the
design result in capacities less than 80 percent of
use of floor response spectra together with the
those required by Paragraph 10-1b.
determination of the fundamental period of the
component and its attachment to the structure.
(5) Securing Equipment. Friction resulting
d.
Lighting Fixtures in Buildings. In addition
from gravity loads as a method of resisting seismic
forces is not acceptable and will not be allowed.
to the requirements of the preceding paragraphs,
Both vertical and horizontal accelerations are
lighting fixtures and supports will conform to the
possible during an earthquake.
Under vertical
following
seismic
requirements
in
structures
acceleration, the gravity force required to maintain
conforming to Seismic Design Criteria C, D, E, and
friction can be greatly diminished. This could result
F.
in a reduction or elimination of the friction force
available to resist horizontal seismic loads, as
(1) Materials and construction.
simultaneous vertical and horizontal accelerations
are possible.
Equipment will thus be secured by
(a) Fixture supports will employ materials
bolts, embedment, or other acceptable positive means
that are suitable for this purpose. Cast metal parts,
of resisting horizontal forces. Refer to Figures 10-12
other than those of malleable iron, and cast or rolled
and 10-13 for typical details.
threads, will be subject to special investigation to
ensure structural adequacy.
(6) Special requirements. Requirements for
lighting fixtures and supports, piping, stacks, bridge
(b)
Loop and hook or swivel hanger
cranes and monorails, and elevator systems are
assemblies for pendant fixtures will be fitted with a
covered in Paragraphs 10-3d through 10-3h.
restraining device to hold the stem in the support
position during earthquake motions.
Pendant-
supported fluorescent fixtures will also be provided
10 17
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