U.S. patent number 3,640,042 [Application Number 04/840,910] was granted by the patent office on 1972-02-08 for access-providing direct suspended ceiling structure with removable locked-in tile sections.
Invention is credited to Bruce W. Kidney.
United States Patent |
3,640,042 |
Kidney |
February 8, 1972 |
ACCESS-PROVIDING DIRECT SUSPENDED CEILING STRUCTURE WITH REMOVABLE
LOCKED-IN TILE SECTIONS
Abstract
An access-providing, rigid, properly aligned, suspended ceiling
structure for acoustic tiles and the like is described, having
removable locked-in tile sections and hidden support structure. The
structure employs selectively shaped horizontal parallel beams
which have flanges to fit within tile kerfs to provide a
tile-supporting structure, which is hidden from view of persons in
the room below. Spacer bars extend across between the beams and
rigidly anchor them in place. Enlarged ceiling sections are
removable by the employment of crossbars sized to fit in tile kerfs
between beams with the ends of the crossbars being provided with
selectively sized cutouts to permit free longitudinal, unobstructed
movement of slidable splines located on the beam flanges. The
slidable splines have lengths smaller than tile dimensions
supported by the beam flanges and are movable within tile kerfs for
ceiling section removal. The horizontal parallel beams are shaped
to provide a high load-carrying capability, with their shaping
advantageously employed to enhance removability of individual
tiles.
Inventors: |
Kidney; Bruce W. (Brooklyn,
NY) |
Family
ID: |
25283553 |
Appl.
No.: |
04/840,910 |
Filed: |
July 11, 1969 |
Current U.S.
Class: |
52/506.09;
52/127.5; 52/779 |
Current CPC
Class: |
E04B
9/247 (20130101) |
Current International
Class: |
E04B
9/24 (20060101); E04B 9/22 (20060101); E04b
005/54 () |
Field of
Search: |
;52/144,127,145,496,484,488,495,467,669,668,664,667
;287/189.36C |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Murtagh; John E.
Claims
What is claimed is:
1. In a suspended ceiling assembly formed of selectively removable
tiles, each having peripherally located kerfs and having
horizontally mounted parallel spaced longitudinal supporting beams,
each beam having a longitudinal web and a horizontally disposed
longitudinal tile-supporting flange extending generally
transversely from one side of the lower edge of the web and sized
to fit within tile kerfs to support a plurality of tiles,
supporting splines slidably mounted on the tile-supporting flange
for sliding movement therealong and within tile kerfs, each of said
splines having a tile-supporting member extending generally
transversely from the web on the other side thereof and with the
member located generally coplanar with the supporting flange for
sliding within tile kerfs, said splines having lengths smaller than
the tile dimensions supported by the supporting flange for tile
removal upon the longitudinal movement of a spline along the
supporting flange, the improvement comprising crossbars mounted
generally transversely to and between webs of adjacent supporting
beams, said crossbars being sized and shaped to fit between
adjacent supporting beam webs to assure unobstructed longitudinal
movement of splines, with each of said crossbars further having a
cross-tile-supporting flange located in general coplanar
relationship with the supporting beam flange and extending
generally transversely from a side of the lower edge of the
crossbar to fit within tile kerfs, said crossbars being removable
along with tiles upon selective longitudinal movement of splines
along flanges of the supporting beams, the cross flanges of the
crossbars being sized to terminate with selective clearance from
the webs of the longitudinal supporting beams to permit free
longitudinal movement of the splines with the webs of the crossbars
having an effective length sufficient to maintain clearance of
cross flanges from the longitudinally moving splines.
2. The assembly as claimed in claim 1, wherein the cross flanges of
the crossbars are provided with vertical protrusions sized to
locate said cross flange in tile kerfs with reduced vertical play
between tiles and crossbars and maintain the tile portions between
supporting bars in horizontal alignment.
3. The assembly as claimed in claim 2, wherein the vertical
protrusions are discreet portions with limited longitudinal
dimensions, said crossbar flanges providing tile support between
supporting beams.
4. An acoustic ceiling assembly formed of selectively removable
acoustic tile sections with tiles having peripherally located kerfs
comprising horizontally mounted parallel longitudinal supporting
beams, each beam having a longitudinal web and a horizontally
disposed longitudinal tile-supporting flange extending generally
transversely from one side of the lower edge of the web and sized
to fit within tile kerfs to support a plurality of tiles,
supporting splines slidably mounted on the tile-supporting flange
for sliding movement therealong and within tile kerfs, each of said
splines having a tile-supporting member extending generally
transversely from the web on the other side thereof and with the
member located generally coplanar with the supporting flange for
sliding within tile kerfs, said splines having lengths smaller than
the tile dimensions supported by the supporting flange for tile
removal upon the longitudinal movement of a spline along the
supporting flange, crossbars each mounted generally transversely
between webs of adjacent supporting beams, said crossbars having
longitudinal webs of a length to fit between adjacent supporting
beam webs and selectively shaped to assure unobstructed
longitudinal movement of splines, with each of said crossbars
further having a crossbar-supporting flange located in general
coplanar relationship with the supporting beam flange and extending
generally transversely from a side of the lower edge of the web of
the crossbar to fit within tile kerfs, said crossbar flanges
providing tile support between supporting beams, said tile support
commencing at a point spaced from the beams by a distance
sufficient to permit unobstructed movement of splines, said
crossbars being removable along with tiles therebetween upon
selective longitudinal movement of splines along flanges of the
supporting beams.
5. The assembly as claimed in claim 4 and further including spacer
bars mounted between adjacent supporting beams to maintain said
crossbars in effectively close supporting relationship with splines
and supporting beam flanges.
6. The assembly as claimed in claim 5 wherein the spacer bars are
provided at the ends thereof with bendable tabs sized to engage the
supporting beams.
7. The assembly as claimed in claim 5 wherein the upper portions of
the webs of supporting beams are selectively enlarged to form a
grippable edge, and wherein the spacer bars are provided at ends
thereof with a slot sized to snugly engage the grippable edge.
8. The assembly as claimed in claim 7 wherein the spacer bars are
provided with laterally bendable tabs located to enlarge the slots
for insertion of the beam-grippable edge therein, and to capture
the beam within the slot upon a substantially coplanar bending of a
tab.
9. The assembly as claimed in claim 8 wherein the grippable beam
edge is rectangularly shaped and the slot is rectangular with the
tab sized to snugly engage a portion of the beam web upon a
coplanar bending of the tab.
10. The assembly as claimed in claim 4 wherein each of the webs of
the supporting beams are provided with a longitudinally extending
transverse lateral protrusion generally located opposite tiles for
slight displacement thereof to enhance accessibility to
splines.
11. The assembly as claimed in claim 10 wherein said lateral
protrusion is formed of a longitudinally extending substantially
rectangular deformation in the supporting member web.
12. The assembly as claimed in claim 10 wherein the supporting beam
is further provided with an upper enlargement sized to define with
the web and the lateral enlargement an open channel, and beam
splices sized to snugly fit within the channel for beam
support.
13. The assembly as claimed in claim 4 and wherein the beams at the
upper web end thereof are provided with an enlarged grippable edge
and beam clips having slots sized to capture the grippable beam
edge, said clips having laterally bendable tabs located to enlarge
the clip slots for grippable edge insertion with said edge being
captured in the slot upon generally planar closure of the laterally
bendable tab.
14. The assembly as claimed in claim 13 wherein the upper end of
the clip includes a transversely extending flange having a bendable
lip end for clip mounting.
15. An acoustic ceiling assembly formed of selectively removable
acoustic tiles having peripherally located kerfs comprising
horizontally mounted parallel-spaced longitudinal supporting beams,
each beam having a longitudinal tile-supporting flange extending
generally transversely from one side of the lower edge of a web and
sized to fit within tile kerfs to support a plurality of tiles on
said one side, supporting splines slidably mounted on the
tile-supporting flange for sliding movement therealong and within
tile kerfs, each of said splines having a tile-supporting member
extending generally transversely from the web on the other side
thereof and with the member located generally coplanar with the
supporting flange for sliding within tile kerfs on said other side,
said splines having lengths smaller than the tile dimensions
supported by the supporting flange for tile removal upon the
longitudinal movement of a spline along the supporting flange, the
web of each of said supporting beams being provided with a
laterally extending protrusion protruding from said other side of
said web from said flange, said protrusion being located at tile
height on the web on one side only for lateral displacement of the
joint between tiles by a preselected distance toward said other
side to facilitate insertion of a thin blade in said joint for
longitudinal movement of splines from below of the ceiling
structure.
16. The acoustic ceiling assembly as claimed in claim 15 wherein
the longitudinal protrusion is located on the other side of the web
opposite of the flange side.
17. An acoustic ceiling assembly formed of selectively removable
acoustic tiles having peripherally located kerfs comprising
horizontally mounted parallel-spaced longitudinal supporting beams,
each beam having a longitudinal web and a horizontally disposed
longitudinal tile-supporting flange extending generally
transversely from one side of the lower edge of the web and sized
to fit within tile kerfs to support a plurality of tiles,
supporting splines slidably mounted on the tile-supporting flange
for sliding movement therealong and within tile kerfs, each of said
splines having a tile-supporting member extending generally
transversely from the web on the other side thereof and with the
member located generally coplanar with the supporting flange for
sliding within tile kerfs, said splines having lengths smaller than
the tile dimensions supported by the supporting flange for tile
removal upon the longitudinal movement of a spline along the
supporting flange, the web of each of said supporting beams being
provided with a laterally extending rectangular cross-sectional
shaped protrusion on the web and located at tile height for lateral
displacement of tiles by a preselected distance to facilitate
longitudinal movement of splines from below of the ceiling
structure, the upper part of the beam terminating in a rectangular
enlargement sized to define with the rectangular protrusion an open
longitudinal splice-retaining channel, and a splice sized to snugly
fit within the splice channel to maintain beams in horizontal
alignment.
18. In an acoustical ceiling assembly formed of selectively
removable acoustic tiles having peripherally located kerfs and
including horizontally mounted parallel-spaced longitudinal
supporting beams, each beam having a longitudinal web and a
horizontally disposed longitudinal tile-supporting flange extending
generally transversely from one side of the lower edge of the web
and sized to fit within tile kerfs to support the tiles on said one
side thereof and with tile-supporting splines longitudinally
slidably mounted on the flange for sliding movement therealong and
within tile kerfs, the splines each having a tile-supporting member
extending generally transversely from the web on the opposite side
thereof from said flange for supporting tiles on said opposite
side, the improvement comprising a lateral protrusion extending
laterally of the web of the longitudinal supporting beams on one
side only of the web, said protrusion being located on the opposite
side thereof from said flange, said lateral protrusion being sized
and located to engage the end surfaces of the tiles above the kerf
on said opposite side for producing a slight offset of the joint
between the tiles on said one side and opposite side of said web,
said offset of the joint being in a direction toward said opposite
side to enable insertion of a thin blade upwardly through said
offset joint and beside said web for engagement with a spline to
produce sliding movement thereof for selective removal of acoustic
tiles.
19. In an acoustical ceiling assembly, the improvement as claimed
in claim 18, in which said lateral protrusion extends
longitudinally of the web of the supporting beams.
20. In an acoustical ceiling assembly, the improvement as claimed
in claim 18, in which said lateral protrusion is a rib extending
continuously longitudinally of the web of the supporting beams on
one side only of the web and positioned above the lower edge of the
web to be engaged by and thereby to limit the upward insertion of a
thin blade through said offset joint.
21. In an acoustical ceiling assembly, the improvement as claimed
in claim 18, in which the lateral protrusion is positioned below
the upper edge of the web of the supporting beams and extends
continuously longitudinally of the web, the upper edge of the web
has an enlargement extending longitudinally therealong, and said
enlargement, said lateral protrusion and the web extending
therebetween define an open channel located above said protrusion,
said open channel facing toward said other side of the web and
being adapted to snugly receive a beam-splicing element extending
longitudinally therein, said open channel providing longitudinal
alignment and vertical support of such beam splice element fitting
snugly therein.
Description
This invention generally relates to an access-providing suspended
acoustic ceiling assembly with removable locked-in tile sections
and more particularly to a suspended acoustic ceiling structure
wherein sections of acoustic tiles are selectively removable for
enlarged access to a plenum area above the ceiling or for receiving
light fixtures, the supporting structure for the acoustic tile
sections being hidden from view of the persons in the room
below.
In my U.S. Pat. No. 3,381,437 I have described a suspended ceiling
with an invisible support structure whereby access to the plenum
area above the ceiling becomes possible at any desired location by
the convenient removal of a ceiling tile located below the plenum
area of interest. Such individual tile removal capability is
obtained by the employment of tile-supporting splines which can be
snapped onto the flanges of main supporting beams to be slidingly
mounted on the flanges and to fit within longitudinal slits or
kerfs in tile edges to support the tile. An easily accomplished
longitudinal movement of splines along the flange of a supporting
beam will drop any desired tile out of its position in the
ceiling.
Among the advantages of this invention are those resulting from the
fact that it enlarges the ceiling sections that may be conveniently
removed from a suspended ceiling structure utilizing the
aforementioned splines, to provide large clearance access into the
plenum space above the ceiling for maintenance personnel and
enabling light fixtures to be supported directly from the
beams.
It is a further advantage of the invention to provide a hidden
supporting structure for a suspended ceiling wherein large ceiling
sections are removably supported without sagging.
Further advantages of the present invention result from the fact
that it enables the selectively shaped horizontal parallel beams to
be held rigidly parallel in predetermined spaced relationship so
that these beams can be suspended on wires directly from the
building structure above. That is, the horizontal beams and spacer
bars provide a rigid grid without the necessity of employing the
heavy structural channels which conventionally are installed in the
prior art ceiling structures.
The ceiling produced by this invention is durable, rigid and strong
and hides the acoustic tile supporting elements from the viewer
located below the ceiling. The ceiling of this invention further
has the advantage that fewer supporting beams are needed, larger
tiles may be employed, and correspondingly larger access areas are
provided upon the removal of tiles.
In the practice of my invention, the ceiling supporting beams are
horizontally aligned parallel to one another supported on wires
directly from the building's structure and are selectively spaced
from each other and rigidly held in spaced parallel relationship by
spacer bars. The distance between the spaced parallel beams may
span several smaller tiles or a single large tile. Each of the
supporting beams has a longitudinally extending vertical web which
has as its lower edge a tile-supporting flange extending generally
transversely, i.e., horizontally, from one side of the web.
Slidable splines are snapped into place onto the supporting flange,
as described in my patent, to provide movable support members for
the acoustic tiles located on the other side of the web where there
is no flange. Removable tile sections are assembled by employing
crossbars fitting into slits or kerfs in the peripheral edges of
the acoustic tiles. The crossbars are angled sections with a cross
flange and are selectively shaped at the ends thereof to allow free
passage of the slidable splines. Removable tile sections are formed
by placing the cross flanges of two crossbars into oppositely
located kerfs of the tile or tiles used in a section. Thereupon,
the assembled tile section is inserted from below onto the main
supporting beams where it is supported by beam flanges and slidable
splines. The resulting acoustical ceiling includes large removable
sections sufficiently sturdy to present a horizontal ceiling free
from sagging tiles and the spaced main ceiling beams are
sufficiently strong for directly receiving light fixtures.
Another feature of the invention contemplates a suspended ceiling
structure stabilized by the employment of spacer bars. The spacer
bars are provided with accurately placed slots sized to engage the
supporting beams and rigidly hold and accurately space the beams
from one another. The spacer bars are easily installed to form a
quickly assembled rigid suspended ceiling structure, all of which
can be suspended on vertical wires running down from the building
structure above, e.g., such as the floor girders or floor slab
above.
A further advantage provided by the horizontal beams employed with
the invention is their increased load-carrying capability. This is
obtained with an upper edge enlargement and a longitudinal rib
along the vertical web of the beam. The rib provides a selected
spacing between tiles to facilitate movement of splines to remove a
tile and advantageously adds rigidity as well as load-bearing
capacity to the beam.
The various features, aspects and advantages of the present
invention will be more fully understood from a consideration of the
following detailed description in conjunction with the accompanying
drawings in which:
FIG. 1 is a perspective view of the access-providing suspended
ceiling structure with removable locked-in tile sections as seen
from the plenum area above the ceiling.
FIG. 2 is an enlarged perspective view of a portion of the ceiling
structure of FIG. 1 showing the selectively shaped main beams which
are directly suspendible on wires and are held rigidly in spaced
parallel relationship by the spacer bars, with portions of the
acoustical tile broken away to reveal details.
FIG. 3 is a sectional view taken along the line 3--3 in FIG. 2 and
shown on further enlarged scale.
FIG. 4 is an end view of a direct-wire-suspendible supporting beam
having a predetermined configuration.
FIG. 5 is a sectional view taken along the line 5--5 in FIG. 1,
drawn on enlarged scale and showing an assembly of acoustical tiles
and crossbars.
FIG. 6 is a sectional view taken along the line 6--6 in FIG. 5
showing details of the crossbar.
FIG. 7 is a perspective view of the ceiling structure as seen from
the plenum area above showing the removal of an assembled pair of
tiles from their locked-in position between adjacent supporting
beams.
FIGS. 8A and 8B are respectively an end view and a side view of a
spacer bar utilized in rigidly spacing and aligning the main
supporting beams of the ceiling structure according to the
invention.
FIG. 9 shows the flexibility of installation capabilities of a
ceiling structure embodying the present invention. If structural
channels are available, then the main supporting beams can be
fastened to such channels by a supporting clip engaged with the
beam and channel as shown.
FIG. 10 is an elevational view taken along the line 10--10 in FIG.
9 showing further aspects of the beam-to-channel clip.
FIG. 11 is an elevational view of a beam-to-channel clip of
extended length.
FIG. 12 is a perspective view of a main supporting beam and a beam
splicing spline for interconnecting the ends of two beams.
With reference to FIG. 1 there is shown a direct-wire-suspended
acoustical ceiling structure including a light fixture resting on
the main beams of the suspended ceiling, with a plenum area 10 seen
above the suspended ceiling 12. The ceiling 12 is conveniently and
inexpensively supported by a plurality of vertical wires such as 14
attached to the building structure above (not shown), such as floor
girders, toggles or shots, known as inserts, in the floor slab
above. The wires 14 are attached to main supporting beams 16 which
are horizontally mounted in spaced parallel relationship with one
another and rigidly held with predetermined spacing. In the ceiling
of FIG. 1, the beams are so spaced that pairs of square acoustic
tiles may be supported between beams such as tiles 18--18' or an
enlarged double-length rectangular tile 20 may be employed. A light
fixture 22 is shown positioned between and resting with brackets 23
on the beams 16. In addition, there are spacer bars 24 extending
across and engaged with the beams 16 to maintain their
predetermined spacing and generally provide rigidity to the
direct-wire-suspended structure. The spacer bars 24 are spaced at
intervals longitudinally of the beams 16.
FIG. 2 illustrates a typical portion of the suspended ceiling of
FIG. 1 showing a pair of square acoustical tiles 18--18' mounted
between a pair of main supporting beams 16--16. Each supporting
beam 16 has a tile-supporting horizontal flange 26 (see also FIG.
4) on which is mounted a plurality of longitudinally slidable
splines 28 of the type described in the above-identified patent.
The slidable splines 28 effectively provide the opposite sides 30
of the beams 16--16 with supporting members 32 generally located in
coplanar relationship with the flanges 26 of the beams. This
supporting member 32 fits within tile kerfs such as 33 so that one
side of tile 18 is supported by the slidable spline 28. The sliding
of the spline 28 along the flange 26 from the kerf 33 in tile 18
will thereby remove support from that tile thus permitting one edge
of the tile to be lowered for removal from below. The sectional
cutout region of a tile as shown in FIG. 2 illustrates that the
flange 26 of the beam also fits within a tile kerf 33.
Since the spacing, such as S indicated in FIG. 1, between a pair of
main supporting beams 16--16 is equal to twice the size of a single
tile 18, a natural tendency of the pair of tiles 18--18 would be to
sag under their own weight in the middle at their juncture line 34.
Such sagging would become unsightly when viewed from below, and the
crossbars 36 serve to provide tile support for pairs of tiles
18--18' spanned between main supporting beams 16--16. These
crossbars 36 have angled L-shaped sections as seen in FIG. 5,
including a vertical web 38 for spacing between the main beams and
a cross flange 40 sized and shaped to fit within the tile kerfs.
The cross flange 40 extends transversely from the web 38 of the
crossbar 36 and on one side thereof so that a pair of crossbars
36--36' (see FIG. 7) engaged in the kerfs on opposite sides of the
pair of tiles 18--18' define a removable ceiling section.
Each of the crossbars 36 is further selectively shaped at the ends
thereof so that slidable splines 28 may be longitudinally moved
without interference or obstruction by the crossbars. For this
reason the lower portion of the crossbar webs 38 and its flange 40
are selectively notched out to a depth D (FIGS. 3 and 6) sized to
permit a spline to freely pass underneath. Thus, the crossbar
flanges 40 terminate short of the end of the webs 38 by a distance
E selected to allow the entire spline including its supporting
member 32 to freely slide by it. It is noted in FIG. 3 that the
upper portions of the crossbar webs 38 terminate closely adjacent
(distance A) to the sides of the main supporting beam 16 to prevent
any significant sliding motion of the crossbar 36 such as would
cause interference with the longitudinally slidable splines 28.
In order to stabilize the ceiling structure, spacer bars 24 (see
FIG. 2) are employed at spaced intervals along the supporting beams
16 to maintain the spacings S between the beams as well as to hold
and lock the main beams against twisting or displacement. A spacer
bar 24 is illustrated in FIG. 2 and is shown to snugly fit and
engage in locking relationship about an upper box beam section 42
of a pair of main supporting beams 16. The spacer bar is an angled
bar of inverted L-shape which at the ends thereof is provided with
slots which are generally T-shaped, having an enlarged head sized
to engage the box beam enlargement 42 of the beam 16 and for
engaging the sidewalls of the beams in locking engagement as will
be described in relation to FIG. 8.
With reference to FIG. 4, the main supporting beam 16 configuration
is clearly illustrated. It includes an upper enlargement 42 in the
form of a rectangular box beam section. A vertical web 44
interconnects the box beam enlargement 42 with the horizontal
supporting flange 26. The web 44 is further provided with an offset
protrusion 46 laterally extending on the side of the web 44
opposite from the side to which the flange extends to slightly
offset the joint line between the tiles as is more clearly
illustrated in the adjoining FIG. 3. This lateral protrusion, i.e.,
longitudinally extending rib section 46, is shown as having
generally a rectangular channel shape, and it advantageously
cooperates with the flange 26 to stiffen the lower portion of the
web 44 against twisting or deflection. The beam 16 is lightweight
but strong and stiff, having sufficient strength for direct
suspension from vertical wires 14 without the use of structural
channels. Moreover, these beams 16 have sufficient strength for
supporting the light fixtures 22 having a width S, which in this
example is 2 feet. Apertures 48 are formed at spaced intervals
along the web 44 for the attachment of direct supporting wires 14,
as seen in FIGS. 2 and 3.
In the FIG. 3 it may be observed that tiles 18 are each provided
with a peripheral kerf 33 separating upper sections 50--50' from
lower sections 52--52'. The upper sections 50--50' are slightly
recessed at their end surfaces 54--54'. Normally, therefore, the
lower sections 52--52' of the tiles tend to contact one another
leaving a small space between the upper sections 50--50'. The
spline 28 is longitudinally slidable along the main beam flange 26
by the employment of a very thin strong steel blade 53 as shown in
FIG. 3. The joint between lower sections 52--52' of the tiles is
advantageously offset slightly (to the right of the beam portion 47
below rib 46) by the laterally protruding rib section 46 which
engages the upper tile section 50. Therefore, when the thin blade
53 is inserted, it can conveniently extend upwardly alongside of
the portion 47 of the web 44 until it reaches the rib section 46
and in this way the user is assured that the edge of the blade 53
has secured a mechanically positive engagement with the end of the
slidable spline 28. Thus, the user can conveniently push the
slidable spline along the flange 26 without fear that the blade 53
may suddenly skid past the spline 28.
The lateral protrusion 46 in the web of the main supporting beam 16
is so sized that it will abut the upper section 50 of the adjoining
tile 18 and actually force a slight offset of the joint between the
lower sections 52--52' just sufficiently to enable insertion of the
thin blade 53 and yet not so much as to lose aesthetic appeal of
the ceiling. The protrusion 46 as shown in the FIGS. 3 and 4 is
rectangular in form and extends longitudinally along the web. It is
possible to utilize an effectively similar protrusion of somewhat
different shape, but the rectangular shape is preferred as will be
explained in relation to FIG. 12.
A further feature illustrated in FIG. 3 is the selective spacing of
the crossbars 36 from the main supporting beam 16. Note that each
crossbar 36 is provided with a cutout sized to permit longitudinal
movement of the spline. In addition, the crossbar web ends 56
terminate short of the main beam 16 by the distance A, which is
less than the spacing B between the crossbar flange and the spline
28.
Thus, in the event a crossbar creeps up to the main beam 16,
sufficient space remains for the spline 28 to slide without
interference along the flange 26 of the beam. On the other hand, it
is desired that the crossbar flange 40 commences its support of a
tile as closely as possible to the spline 28. The reason for this
resides in the nature of most tiles, which generally are brittle
and do not readily withstand a tensile stress. Since the midsection
of tiles located between beams is essentially supported by
crossbars 36 and since the crossbars do not directly rest upon the
beam 16 a concentrated tensile force is applied to the tile such as
at support point 58 thereof. This supporting force at 58 results in
a force applied along a moment having a length approximately as
indicated by the spacing L. By making L as small as possible, tile
rupture is avoided.
FIG. 5 illustrates back-to-back mounting of a pair of crossbars 36
between removable sections. It is noted that each crossbar flange
40 is provided with a plurality of protrusions 60 which are sized
and shaped to snugly fit the cross flanges 40 with reduced vertical
play within each tile kerf and thus maintain the tiles between the
main beams 16 in horizontal alignment.
FIG. 6 illustrates that the protrusions 60 are not continuous, but
composed of discrete bumps. Although a longitudinal protrusion
could be employed, the use of discrete protrusions 60 facilitates
insertion of a cross flange 40 into the tile kerfs 33, which due to
production tolerances of acoustical tiles are not always exactly
uniform in cross section.
FIG. 7 illustrates the removal of a tile section as defined by a
pair of tiles 18--18' and a pair of crossbars 36--36'. First by the
employment of the thin blade 53 as shown in FIG. 3, the two splines
28 in FIG. 7 are slid along the respective flanges 26 of the main
supporting beams 16--16, thereby permitting the left portion of the
ceiling section to drop free of the left supporting beam 16 as seen
in FIG. 7. As soon as the left end of the removable tile section
has lowered enough to clear the supporting beam 16, the tile kerf
at the other end of the ceiling section may be cleared from the
flange 26 of the right supporting beam 16 by applying a transverse
motion as indicated by arrow 62. In this manner, both tiles 18--18'
along with both crossbars 36--36' are removed and an enlarged
access space to the plenum area above the ceiling is provided. In
this example this access space is 2 feet wide, corresponding to "S"
in FIG. 1, and the access space can be made as long as may be
desired by removing more than one of the ceiling sections in the
manner as described.
It is to be understood that when these ceiling sections are held in
place by the slidable splines 28, they are locked in place so that
they can neither be lifted up by hand nor by differential air
pressure or drafts of wind and they cannot be lowered. In other
words, they are positively locked in place when they are in their
installed positions, and yet an enlarged access can be obtained
wherever desired by building maintenance personnel.
Spacer bars 24, as previously explained, both maintain accurate
spacing between the supporting beams, as well as rigidly holding
the beams 16 against twisting. The spacer bars are located at
intervals along the main supporting beams. For instance, in
practical dimensions the spacer bars may be located every 10 to 15
feet, whereas the removable ceiling sections are generally 2 feet
wide.
Each spacer bar 24 is easily attached to a beam for quick assembly
of the ceiling structure. This is accomplished by providing each
spacer bar, prior to assembly as shown in FIG. 8B with a pair of
T-shaped slots 64 having an enlarged rectangular headspace sized to
snugly enclose the box beam section 42 of the main supporting beam
16. As shown in FIG. 8B, after engagement of the spacer bar onto a
beam 16 the slot 64 also snugly clamps against a portion of the
beam web 44 below the rectangular beam section 42. This snug
enclosure of a beam 16 by the spacer bar 24 is accomplished by
initially providing the spacer bar with a bendable tab 66
originally in the bent-up position as indicated in FIGS. 8A and 8B
at 68.
With the tab 66 in the initial position at 68 the beam channel 42
can be engaged into the slot 64 and after such placement the tab 66
is bent down along multiple fold lines 70 and 71 to a generally
vertical planar position to firmly lock or capture the beam in
position relative to the spacer bar. This bending engagement is
easily accomplished with a metal gripping tool such as a pair of
pliers. It is noted that the tab 66 may be bent in place with a
single fold line 70 which may be placed at other locations for
minimum interference during bending. The T-shaped slot 64 is
further provided on the vertical stem portion of the T-shape with
opposed indentations at 73 to assure double pairs of web-gripping
points 75--75' on opposite sides of the web 44.
When desired, the main supporting beam may alternately be attached
to the conventional structural channels by employing easily applied
clips. FIGS. 9 through 11 illustrate such a clip 72 which is
attached to a structural channel member 74 which is either
suspended from or attached to the building structure. The clip 72
is formed with an upper bendable flange 76 which may be wrapped by
bending over the end of a flange 78 on the structural channel
member 74. The depending portion 80 of the clip is provided with a
T-shaped slot 64 (FIG. 8B) and sized to snugly engage the
rectangular channel section 42 of the beam 16 as well as a portion
of the beam web 44 similar to the spacer bar 24 of FIG. 8.
The clip 72 is thus provided with a bendable tab 83 initially bent
along the fold lines 84 and 85 to allow insertion of the beam 16 in
slot 82. Subsequently, the beam is captured in the slot by bending
the tab as indicated in FIG. 10. It is seen that the lower portion
86 of structural channel member 74 rests against the upper box beam
section 42, and in this manner the horizontal alignment of the
beams 16 is determined by the orientation of the channel member 74.
However, as illustrated in FIG. 11 at 72A, the clip may also be
elongated.
The advantage of utilizing a rectangular shaped protrusion 46 in
the web 44 of the main supporting beam 16 may be appreciated from
reference to FIG. 12. As shown in this figure a channel 88 is
effectively defined by the rectangular protrusion upper edge 89,
the planar portion of the web 44, and the lower surface 90 of the
rectangular box beam section 42. A beam splice 92 sized to fit in
snug relationship into this channel may be advantageously used to
reinforce the main beam 16 for interconnection with another main
beam aligned therewith. The splice 92 for this purpose is provided
with laterally extending tabs 94 which after insertion into
suitable apertures in the webs of beams 16 are bent to lock the
splice onto the beams 16. The splice-coupled main supporting beams
16 are rigidly held as well as maintained in proper alignment.
Having thus described a new ceiling structure, several advantages
thereof now readily appear. The employment of enlarged removable
tile sections facilitates assembly of the suspended ceiling.
Substantial access areas are possible with the ceiling structure of
this invention, yet without loss of rigidity with the employment of
spacer bars. The spacer bars both accurately locate main supporting
beams parallel to one another as well as clamp the suspended
structure in a mechanically rigid position. The main supporting
beams 16 having box beam sections 46 are strong, stiff and yet are
light in weight. Further horizontal alignment and rigidity are
obtained by selective shaping of the main supporting beams to
accommodate splices sized to fit in channels of the supporting
beams. The splices and spacer bars are easily installed to provide
an economic properly aligned, rigid suspended ceiling
structure.
* * * * *