Note: Descriptions are shown in the official language in which they were submitted.
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CEILING GRID SYSTEM
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of United States Provisional Application
Serial
No. 60/271,660, filed February 26, 2001, which is incorporated herein in its
entirety by
reference.
FIELD OF THE INVENTION
The present invention generally relates to a ceiling grid system and more
specifically to a system comprising a bracing attachment clip to aid in
providing
resistance to a wind up-lift force.
BACKGROUND
Ceilings typically can be comprised of a system of panels or formed from
drywall
sheeting. Preferably, ceilings exposed to the elements are designed to
withstand various
environmental conditions. The two most common environmental conditions are
rain and
wind. Ceilings comprise of drywall or formed finm panels having a moisture
sensitive
binder such as starch are the most sensitive to rain while ceilings formed
fibm corrosive
resistant metal panels are the least sensitive to moisture.
However, the opposite is true for wind resistance. Ceilings formed from sheets
of
drywall have considerable bridging and resistance strength as compared to
ceilings
formed from panels. Once a drywall sheet has been screwed into a ceiling grid,
the
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drywall sheet stabilizes the whole system and helps distribute the load. In a
ceiling
comprised of metal panels there is no such bridging and resistance strength.
Thus, metal panels are especially vulnerable to uplifting forces caused by
strong
winds such as in the case of hurricanes. Panels can break free of the
supporting grid
system and become flying projectiles capable of causing injury to persons or
property. In
response to such dangers many communities require that exterior ceiling
applications
meet an up-lift capability of Class 90.
The support grid of a paneled ceiling can be strengthened to help meet up-lift
restrictions and to prevent panels from becoming projectiles in a wind storm.
One
method used to strengthen the support grid includes the use of compression
posts attached
to both the building structure and the ceiling grid. The compression posts are
notched to
come down around the bulb of the grid and are typically nailed to the truss
system of the
roof. Unfortunately, the precision cut required to form a notch that can fit
around the
bulb part of the grid is very difficult to make and requires extreme care
since there is very
little tolerance in the cut.
While the use of compression posts is an egective mechanism for preventing up-
lift, the current method of installation is both expensive and time consuming.
Thus, what
is needed is a compression post method of attachment that is both quick and
inexpensive.
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SITJVIMA.RY
The present invention includes a ceiling system capable of meeting a wind up-
lift
capability of at least Class 90 or greater. Additionally, further embodiments
are provided
meeting wind up-lift requirements of at least Class 60 or greater and at least
Class 30 or
greater. The, ceiling system includes a grid formed from a plurality of
parallel-extending
main runners having a plurality of cross runners extending between the main
runners.
The grid can be suspended from and attached to a ceiling using a plurality of
compression
struts perpendicular to the ceiling. A bracing attachment clip is attached to
a runner and a
compression strut. The clip essentially comprises a first and second leg and a
mid-
portion. The first Ieg secures the clip to a runner and the second leg secures
the clip to an
adjoining compression strut. The mid-portion of the clip conforms to the bulb
portion of
the runner. The attached clip is designed to prevent the grid main runners
from rotating
away from the compression posts. The clip provides positive engagement of the
main
runner bulb and the compression post.
The system aids in the prevention of grid main runner rotation and vertical
lift
which takes place when the system is subjected to strong wind forces. The clip
can be
positioned about every 2 feet on the main beam to meet a 90 classification.
The spacing
may be an even fraction of about 12 feet since most runners are 12 feet in
length. The
clip may be positioned across the runner splice to strengthen the splice
against twisting.
A fiu-ther embodiment includes a support member for a ceiling grid having a
main
runner having a bulb portion. Typically, the main runner has the form of an
inverted "T".
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A clip having a mid-portion disposed between two legs is attached to the main
runner by
one of the legs. Additionally, the mid-portion is substantially shaped to
conform to the
bulb of the main runner.
An additional embodiment includes a clip for attaching a main runner to a
compression strut. The clip includes at least two ends which connect a
compression strut
and a main runner. The clip also has a mid-section that fits partially around
the bulb
portion of the main runner.
DESCRIPTION OF THE DRAWINGS
In the drawings:
Figure 1 a is a schematic view of the clip attached to the main beam;
Figure 1b is a schematic view of the.back of the clip attached to the main
beam
and compression strut;
Figure 1c is a schematic view of the clip attached to the main beam and the
compression strut attached to a truss;
Figure 2 illustrates various views of the clip; and
Figure 3 illustrates the grid structure, clip and strut.
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DETAILED DESCRIPTION
The present invention provides far a ceiling system comprising a grid formed
from a plurality of parallel-extending main runners having a plurality of
cross runners
extending between the main runners. A plurality of compression struts are
attached to the
grid and a clip is secured to the main runner and the compression strut.
The clip aids in providing a wind up-lift capability up to Class 90 for the
ceiling
system. The clip may be made of most any material that is resilient enough to
provide
the stability required for the desired up-lift capability. The clip maybe
comprised of a
metallic composition and typically steel. The clip is fastened to the
compression post and
main runner typically by screws. Of course other fastening means may also be
used such
as rivets.
The clip 2 can be placed across a runner splice. When the clip 2 is placed
across
the splice the clip 2 provides added strength. One configuration of the clip 2
includes
half of the clip leg attached to one runner and the other half attaches to a
second runner.
The clips may also be placed at various desired intervals depending upon the
up-lift
strength desired and the strength or gauge of runners. For example, the clip 2
can be
positioned about every 2 feet on the main beam to meet a 90 classification.
The spacing
may be an even fi~action of about 12 feet, since most runners are 12 feet in
length. Of
course, lower classifications, such as 60, can be met with wider spacings.
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In greater detail, the clip 2 may be made of 18 gauge hot dipped galvanized
steel
with a zinc coating level of G60. The clip 2 can be formed from stamped steel
blank and
drilled to add pilot holes. The pilot holes maintain the screw placement
accuracy and the
integrity of attachment to the grid The clip 2 physically wraps around the
bulb 14 of the
grid and after securing the clip to the main runner with screws, becomes an
integral part
of the grid system.
The panels are typically installed as downward access panels. The panels may
also be installed as upward access, but for ease of use and clearance, the
downward
access panels are typically employed. The panels may be comprised of most any
material
suitable for the environment in which the ceiling is to be installed. An
example panel is
typically comprised of metal or alloy. Such panels provide both strength and
durability.
The panels may also have an edge configuration to prevent the panel from being
dislodged by an up-lift draft. In greater detail, the panels are attached to
the grid such
that they are held in place and are not easily dislodged from the facing side
of the ceiling
or upward side. The panels are downwardly accessible, wherein the panels may
be
removed from the grid on the plellum side or the backing side of the panel.
Examples of
locking mechanisms that may be used to secure the panels in place are further
illustrated
in U.S. Patent Nos. 5,417,025 and 5,355,646, all of which are incorporated
herein in their
entirety by reference.
Turning to the figures, in Figures la-c the clip 2 is illustrated attached to
the main
beam 10 by two sets of self drill screws. It is to be understood that the clip
may be
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attached to the main beam 10 and compression strut 12 by any means, such as
rivets,
adhesives, bolts, or other mechanical or chemical fastening devices. The mid-
section 8 of
the clip 2 fits over the bulb 14 portion of the main beam 10 to hold the main
beam 10
securely in place against the compression strut 12.
Figure 2 illustrates an embodiment of the clip 2. The clip 2 has a first end 6
and a
second end 4. The ends may have at least one hole for fastening the clip 2 to
both the
main beam and the compression strut via the respective ends. The mid-section 8
has a
ridge or indentation that approximates the bulb portion 14 of the main beam
10. Thus,
the bulb portion 14 of the main beam 10 may fit within the mid-section 8 of
the clip.
Figure 3 illustrates an embodiment of the ceiling system comprising the clip
2,
main beam 10, compression strut 12 and the cross beams forming a grid wherein
a panel,
not illustrated, may rest within the grid opening.
The following example is intended to illustrate the invention and it is
thought
variations will occur to those skilled in the art. Accordingly, it is intended
that the scope
of the invention should be limited only by the appended claims.
Example
Described below are the test procedures and the results for an up-lift
resistant
ceiling assembly according to the present invention.
A test specimen was prepared measuring 10-foot square, and was tested in
accordance with Underwriters Laboratories, Inc. UL 580 Standard for Safety,
Tests for
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Uplift Resistance of Roof Assemblies. This test simulates the effects of wind
gusts by use
of oscillating exterior pressure and constant interior pressures. The IJL 580
standard
provides a rating system to evaluate the comparative wind resistance of roof
assemblies.
Chart 1 illustrates the UL 580 load table test pressures.
The ceiling system was installed into the 10-foot square opening created by
the
test frame and nominal 4" by 4" diameter lumber. Ceiling tile system fasteners
included
wafer-head streaker screws secured to the perimeter angle and studs, Hex-head
self
drilling #8 x'/4" long secure the stud hanger to main runners and cross t's.
The peripheral support test apparatus frame was fabricated from C15 by 33.9
steel
channels having a dimension of 10'0" wide by 10'0" long by 1'3" deep. Two
chambers
were welded together forming a 30" deep chamber to provide simulated roof
trusses.
Nominal 4" x 4" wood members were installed to the base of the steel channel
frame.
The test results essentially indicated no visible damage for all the classes
tested.
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CHART #1
UL 580 Load Table Test Pressures
Negative _Positive
Pressure Pressure
Time Pounds Pounds
Duration, Per Inches (mm)Per Inches
est Phase Minutes Square of Water Square (mm)
Foot Foot of Water
psf (kPA) psf (kPa)
Class 30
(not an
obtainable
Dade County
rating)
1 5 16.2 (0.79)3.1 (79) 0.0 (0.00)0.0 (0)
2 S 16.2 (0.79)3.1 (79) 13.8 (0.66}2.7 (69)
3 60 8.1-27.7 1.5-5.3 13.8 (0.66)2.7 (69)
(0.39-1.33)(38-I35}
4 ~ 5 24.2 (l 4.7 (I 19) 0.0 (0.00)0.0 (0)
.I6)
5 24.2 (1.16)4.7 (119) 20.8 (1.00)4.0 (102)
Class 60
(not an
obtainable
Dale County
rating)
1 5 32.3 (1.55)6.2 (157) 0.0 (0.00)0.0 (0)
2 5 32.3 (1.556.2 (157) 27.7 (1.33)5.3 (135)
3 60 16.2-55.4 3.1-10.7 27.7 (1.33)5.3 (135)
(0.79-2.66)(79-272)
4 5 40.4 ( 7.8 ( 198) 0.0 (0.00)0.0 (0)
1.94)
5 5 40.4 (1.94)7.8 (198) 34.6 (1.66}6.7 (1.70)
Class 90
(maximum
combined
up-lift
pressure
of 105
psf)
1 5 48.5 (2.33)9.3 (236) 0.0 (0.00)0.0 (0)
2 5 48.5 (2.33}9.3 (236) 41.5 (1.99)8.0 (203)
3 60 24.2-48.5 4.7-9.3 4I.5 (I.99)8.0 (203)
(1.16-2.33)(I I9-236)
4 5 56.5 (2.71)10.9 (277) 0.0 (0.00)0.0 (0)
,
5 5 56.5 (2.71)10.9 (277) 48.5 (2.33}9.3 (236)
It will be understood by those skilled in the art that while the present
invention
has been disclosed above with reference to preferred embodiments, various
modifications, changes and additions can be made to the foregoing invention,
without
departing from the spirit and scope thereof.
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