Specifications - - -- / 5 �� (1,14-4--- E7.` y Yom( 4- - 3
.„0 . ' a. Connections and panel joints shall allow for The seismic force, F shall be transmitted through
- / . . the story drift.caused by relative seismic dis- the ceiling attachments to the building structural
" i �, placements (D determined in Section 9.6.1.4, elements or the ceiling - structure bound.
"1' • or 1/2 in. " �'
( 13 mm , whichever is g reatest. Design of anchorage and connections shall be in
b. Connections to permit movement in the plane accordance with these provisions. •
of the panel for story drift shall be sliding
connections using slotted or oversize holes, 9.6.2.6.2 Industry Standard Construction. Unless
connections that permit movement by bending designed in accordance with Section 9.6.2.6.3, sus -
of steel, or other connections that provide pended ceilings shall be designed and constructed in
equivalent sliding or ductile capacity. accordance with this Section.
c. The connecting member itself shall have suffi-
cient ductility and rotation capacity to preclude 9.6.2.6.2.1 Seismic Design
fracture of the concrete or brittle failures at or Category C. Sus-
pended ceilings in Seismic Design Category C
near welds. shall be designed and installed in accordance with
d. All fasteners in the connecting system such the CISCA recommendations for seismic Zones 0-
as bolts, inserts, welds, and dowels and the 2, (Ref. 9.6 -16), except that seismic forces shall
body of the connectors shall be designed for be determined in accordance with Sections 9.6.1.3
the force (F p ) determined by Eq. 9.6.1.3 -2 with and 9.6.2.6.1.
values of R and a taken from Table 9.6.2.2 Sprinklee.heads and other penetrations in Seis-
applied at the center of mass of the panel. mic Design Category C shall have a minimum of
e. Anchorage using flat straps embedded in- con-
1/4 in. (6 mm) clearance on all sides.
crete or: masonry shall be attached to or hooked
around reinforcing steel or otherwise terminated 9.6.2.6.2.2 Seismic Design Categories D, E, and
so as to effectively transfer forces to the rein- F. Suspended ceilings in Seismic Design Cate -
forcing steel or to assure that pullout of anchor- gories D, E, and•F shall be designed and installed
I age is not the - initial failure mechanism. in accordance with the CISCA recommendations
,41 for seismic Zones 3 -4 (Ref. 9.6-1) and the addi-
9.6.2.4.2 Glass. Glass in glazed curtain walls and ti0 °al Ce9uirements listed in this subsection.
storefronts shall be designed and installed in•accor-
dance with Section 9.6.2.10. a. A heavy duty T -bar grid system shall
• be used.
9.6.2.5 Out -of -Plane Bending. Transverse or out -of- b The width of the perimeter supporting
plane bending or deformation of a component or closure angle shall be not less than 2:0 in.
system that is subjected to forces as determined in (50 mm). In each orthogonal horizontal
Section 9.6.2.2 shall not exceed the deflection capability direction, one end of the ceiling grid shall
be attached to the closure angle. The other
of the component or system.
end in each horizontal direction shall have
9.6.2.6 Suspended Ceilings. Suspended ceilings shall a 3/4 in: (19 tnm) clearance from the wall
requirements and shall angle. rest upon and be free to slide on a
be designed to meet the seismic • force re
q closure angle.
of Section 9.6.2.6.1. In addition, suspended ceilings
shall meet the requirements of either industry standard c. For ceiling areas exceeding 1000 ft'
construction as modified in Section 9.6.2.6.2 or integral (92.9 m horizontal restraint of the ceil-
construction as specified in Section 9.6.2.6.3. ing to the structural system shall be pro-
vided. The tributary areas of the horizontal
r
restraints shall be approximately equal.
9.6.2.6.1 Seismic Forces. Suspended ceilings shall
be designed to meet the force requirements of Exception: Rigid braces are permitted to
Section 9.6.1.3. be used instead of diagonal splay wires.
The weight of the ceiling, W shall include the Braces and attachments to the structural
ceiling grid and panels; light fixtures if attached to, system above shall be adequate to limit
clipped to, or laterally supported by the ceiling grid; relative lateral deflections at point of
and other components which are laterally supported attachment of ceiling grid to less than
s :. . by the ceiling. W shall be taken as not less than 1/4 in. (6 mm) for the loads prescribed in •
4 lbs/ft (19 N/m ). Section 9.6.1 3
Minimum Design Loads for Buildings and Other Structures
1 . "
• 1 - - /
i . 4 L i y ,, r ev t c 7 rv> o1 G' ,
L c-c) i
g exc eeding 2
( ' d. For, _ceilin
- 2500 ft from the top surface of tbe. -acce floor to the
(232 2 , 'a seismic separation joint . . •oring_structure -----`
full eight partition that • .. - e ceil- Overturning, effects of equipment fastened to the
ing not exceeding 2500 ft access floor panels also shall be considered. The
shall be provided unless structural analyses ability of "slip on" heads for pedestals shall be
are performed of the ceiling bracing sys- evaluated for suitability to transfer overturning effects
tern for the prescribed seismic forces which of equipment.
. demonstrate ceiling system penetrations and When checking individual pedestals for overturn-
closure angles provide sufficient clearance ing effects, the maximum concurrent axial load shall
to accommodate the additional movement. not exceed the portion of W assigned to the pedestal
Each area shall be provided with closure under consideration.
angles in accordance with Item b and hor-
izontal restraints or bracing in accordance 9.6.2.7.2 Special Access Floors. Access floors shall
with Item c. be considered to be "special access floors" if they are
e. Except where rigid braces are used to limit designed to comply with the following considerations:
lateral deflections, sprinkler heads and other
penetrations shall have a 2 in. (50 mm) over- 1. Connections transmitting seismic loads con -
size ring, sleeve, or adapter through the ceil- sist of mechanical fasteners, concrete anchors,
ing tile to allow for free movement of at least welding, or bearing. Design load capacities
1 in. (25 mm) in all horizontal directions. comply with recognized design codes and/or
Alternatively, a swing that can accom- certified test results.
modate 1 in. (25 mm) of ceiling movement . 2. Seismic loads are not transmitted by fric-
in all horizontal directions are permitted tion, produced solely by the effects of gray-
• to be . provided at the top of the sprinkler ity, powder- actuated fasteners (shot pins),
•
head extension. . or adhesives.
t f. Changes in ceiling plan elevation shall be 3. The design analysis of the bracing system
provided with positive bracing. includes the destabilizing effects of individual '
g. Cable trays and electrical conduits shall be members buckling in compression.
4,2:-.74.-i supported independently of the ceiling. 4. Bracing and pedestals are of structural or
h. Suspended ceilings shall be subject to the mechanical shape produced .to ASTM specifi-
special inspection requirements of Section A. cations that specify minimum mechanical prop-
9.3.3.9 of this.Standard. erties. Electrical tubing shall not be used.
5. Floor stringers that are designed to carry axial
9.6.2.6.3 Integral Ceiling/Sprinkler Construction. seismic loads and that are mechanically fas-
As an alternative to providing large clearances around tened to the supporting pedestals are used.
sprinkler system penetrations through ceiling systems,
the sprinkler system and ceiling grid are permitted to 9.6.2.8 Partitions. •
be designed and tied together as an integral unit. Such
a design shall consider the mass and flexibility of all 9.6.2.8.1 General. Partitions that are tied to the
elements involved, including: ceiling system, sprin- ceiling and all partitions greater than 6 ft (1.8 m)
kler system, light fixtures, and mechanical (HVAC) in height shall be laterally braced to the building
appurtenances. The design shall be performed by a structure. Such bracing shall be independent of any •
registered design professional. ceiling splay bracing. Bracing shall be spaced to
limit horizontal deflection at the partition head to
9.6.2.7 Access Floors. be compatible with ceiling deflection requirements as
determined in Section 9.6.2.6 for suspended ceilings
9.6.2.7.1 General. Access floors shall be designed to and Section 9.6.2.2 for other systems.
meet the force provisions of Section 9.6.1.3 and the
additional provisions of this Section. The weight of 9.6.2.8.2 Glass. Glass in glazed partitions shall
the access floor, W shall include the weight of the be designed and installed in accordance with
floor system, 100% of the weight of all equipment Section 9.6.2.10.
fastened to the floor, and 25% of the weight of
• , all equipment supported by, but not fastened to the 9.6.2.9 Steel Storage Racks. Steel storage racks sup -
L '✓ floor. The seismic force, F shall be transmitted ported at the base of the structure shall be designed
164