U.S. patent number 3,590,544 [Application Number 04/874,138] was granted by the patent office on 1971-07-06 for support structure.
This patent grant is currently assigned to Wilson Lighting Limited. Invention is credited to Charles G. Shepherd.
United States Patent |
3,590,544 |
Shepherd |
July 6, 1971 |
SUPPORT STRUCTURE
Abstract
A grid support structure comprising a pair of collinear first
support beams of thermally expandible material, and a pair of
collinear second support beams of thermally expandible material
which are perpendicular to the first support beams and the adjacent
ends of which are secured to the adjacent ends of the first support
beams. Longitudinal slits are formed in the first beams, each slit
extending from the end of the appropriate beam to a position
between the ends thereof with the portions of the beam bounding the
slit disposed in different planes. Corresponding slits are formed
in the second beams or, alternatively, outwardly directed lugs, by
means of which the second beams are secured to the first beams are
presented by each first beam and are secured to the second beams at
positions spaced from the first beam. Longitudinal thermal
expansion of the second beams causes the portions of each first
beam bounding the slit therein to be urged into overlapping
relationship, longitudinal thermal expansion of the first beams
similarly causing the portions of each second beam bounding the
slit therein to be urged into overlapping relationship, or causing
the lugs to flex relative to the first and second beams, as the
case may be.
Inventors: |
Shepherd; Charles G. (Oakville,
Ontario, CA) |
Assignee: |
Wilson Lighting Limited
(Toronto, Ontario, CA)
|
Family
ID: |
25363060 |
Appl.
No.: |
04/874,138 |
Filed: |
November 6, 1969 |
Current U.S.
Class: |
52/506.06;
403/217; D25/61 |
Current CPC
Class: |
E04B
9/14 (20130101); Y10T 403/44 (20150115) |
Current International
Class: |
E04B
9/06 (20060101); E04B 9/14 (20060101); E04b
001/68 (); E04b 005/52 () |
Field of
Search: |
;52/232,573,664,484,666,720,475,DIG.5 ;287/189.36A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Burke; Sam D.
Claims
What I claim as my invention is:
1. A support structure comprising a first support beam, and at
least one second support beam which is formed of thermally
expandible material and an end portion of which is secured to an
end portion of the first support beam, a slit being formed in the
first support beam and extending longitudinally thereof from the
end of the first support beam presented by said end portion thereof
to a position between the ends of the first support beam, the
portions of the first support beam bounding the slit being in
different planes and the direction of the longitudinal axis of the
second support beam having at least a component which is
perpendicular to the longitudinal axis of the first support beam
and to the plane containing the slit, thereby to permit said
portions bounding the slit of the first support beam to be urged
into overlapping relationship by longitudinal thermal expansion of
the second support beam.
2. A support structure according to claim 1, wherein at least the
first support beam is of inverted channel form in cross section,
and comprises a web portion and two substantially parallel
depending limb portions, the slit being formed in the web portion
of said beam.
3. A support structure according to claim 1, wherein the end of the
slit remote from said end of the first support beam is in
communication with an enlarged opening formed in the first support
beam.
4. A support structure according to claim 3, wherein a support tie
member is disposed through said enlarged opening, the first support
beam being in supported engagement with said member.
5. A support structure according to claim 1, wherein the first
support beam is formed of thermally expandible material and the
securement between said end portions of the first and second
support beams comprises outwardly projecting lug means which is
presented by said end portion of the first support beam and which
is secured to the second support beam at a position spaced from the
first support beam, the lug means being capable of flexing relative
to the first support beam and relative to the second support beam,
thereby to permit longitudinal thermal expansion of the first
support beam.
6. A support structure comprising a pair of collinear first support
beams which are formed of thermally expandible material and which
are disposed in spaced relationship, and a pair of collinear second
support beams which are formed of thermally expandible material and
which are disposed in spaced relationship with the space
therebetween constituting the space between the first support beams
and with the second support beams being substantially perpendicular
to the first support beams, the adjacent ends of the first support
beams each presenting outwardly directed lugs which are secured to
the second support beams at positions spaced from the first support
beams, each lug being capable of flexing relative to the first
support beam from which it is presented and relative to the second
support beam to which it is secured thereby to permit longitudinal
thermal expansion of the first support beams, slits being formed in
the first support beams and extending longitudinally thereof from
the adjacent ends of said first support beams to positions between
the ends thereof, the portions of each first support beam bounding
the slit therein being in different planes, and the second support
beams being substantially perpendicular to the plane containing the
slit in each first support beam, thereby to permit said portions of
each first support beam to be urged into overlapping relationship
by longitudinal thermal expansion of the second support beams.
7. A support structure according to claim 6, wherein coverplate is
mounted over the space between the adjacent ends of the first
support beams and the adjacent ends of the second support beams,
the coverplate extending over the adjacent end portions of the
first support beams and being connected thereto.
8. A support structure according to claim 7, wherein slits are
formed in the portions of the coverplate which extend over the
adjacent end portions of the first support beams, a portion of the
coverplate bounding each slit formed therein being in engagement
with the slit formed in the adjacent first support beam to maintain
the portions of said first support beam bounding the slit therein
in different planes.
9. A support structure according to claim 6, wherein the securement
between each lug and the second support beam to which it is secured
comprises an upwardly projecting tab presented by the lug and
disposed through a slot formed in said second support beam, the tab
being disposed out of the plane of the slot on the side of the slot
remote from the lug.
10. A support structure comprising a pair of collinear first
support beams which are formed of thermally expandible material and
which are disposed in spaced relationship, and a pair of collinear
second support beams which are formed of thermally expandible
material and which are disposed in spaced relationship with the
space therebetween constituting the space between the first support
beams and with the second support beams being substantially
perpendicular to the first support beams, the adjacent ends of the
first support beams being secured to the adjacent ends of the
second support beams, slits being formed in the first and second
support beams and extending longitudinally thereof from the
adjacent ends of the beams to positions between the ends thereof,
and the portions of each first and second support beam bounding the
slit therein being in different planes, thereby to permit said
portions of each first and second support beam to be urged into
overlapping relationship by longitudinal thermal expansion of the
second and first support beams, respectively.
11. A support structure according to claim 10, wherein a coverplate
is mounted over the space between the adjacent ends of the first
support beams and the adjacent ends of the second support beams,
the coverplate extending over the adjacent end portions of the
first support beams and being connected thereto.
12. A support structure according to claim 11, wherein slits are
formed in the portions of the coverplate which extend over the
adjacent end portions of the first support beams, a portion of the
coverplate bounding each slit formed therein being in engagement
with the slit formed in the adjacent first support beam to maintain
the portions of said first support beam bounding the slit therein
in different planes.
Description
This invention is concerned with a support structure such as a
structure constituted by a plurality of first support beams which
are all disposed in the same direction and a plurality of second
support beams which are likewise all disposed in the same
direction, this latter direction being, for example, perpendicular
to the direction in which the first support beams are disposed. In
such a structure the first and second support beams are
interconnected so that the structure is in the form of a grid which
may be horizontally mounted below a support deck, such as a
flooring deck, in a building structure for supporting, for example,
the elements of a ceiling, such as a plurality of lighting
units.
The support beams constituting a support structure of the type
referred to above are generally formed of a thermally expandible
material, such as metal, with the result that provision must be
made in such structures for accommodating thermal expansion of the
support beams caused by these beams being subjected to a high
temperature, such as by a fire in the room space or the like below
the support structure. If provision is not made for accommodating
such thermal expansion of the support beams there is a considerable
danger that, in the event of the beams being subjected to fire
heat, the beams will buckle and warp longitudinally with the result
that fire insulation panels or the like which are normally
supported by the beams will no longer be so supported. The result
is, of course, that the first may travel from the room space or the
like below the support structure to the space above this structure
and hence throughout the entire building structure.
Various arrangements have hitherto been proposed and used with the
view to overcoming this disadvantage, the most relevant prior
arrangement of which the inventor is aware being that disclosed in
U.S. Pat. No. 3,242,628 which issued on March 29, l966 to Jahn. In
this patent there is disclosed a ceiling panel supporting grid
structure comprising comprising main and cross beams each of which
is of approximately T-form in cross section. The flanges of each
main beam are formed with a plurality of longitudinally extending
slots which are in alignment with the position of attachment of the
crossbeams to said main beam so that when the crossbeams are
subjected to thermal expansion, as a result for example of a fire,
the appropriate portions of the flanges of the main beams are
caused transversely to buckle thereby to accommodate the expansion
of the crossbeams.
This arrangement of Jahn suffers from the disadvantages that the
above-mentioned transverse buckling of the flanges of the main beam
caused by thermal expansion of the crossbeams, results almost
inevitably in spaces being formed between the flanges of the main
beam and the tiles or the like supported thereby, these spaces
permitting the fire in the room space below the structure to travel
to the region above the structure. Thus, the fire or the like is
not contained within the room space in which it originates with the
result that the fire damage is likely to be much more extensive
than would otherwise be the case. As will be appreciated,
therefore, the structure disclosed by Jahn suffers from
substantially the same disadvantage as support structures, in which
no provision is made for accommodating thermal expansion of the
support beams constituting the structures.
It is a primary object, therefore, of the present invention to
provide a support structure in which the above-mentioned
disadvantages of the structure disclosed by Jahn is substantially
overcome and in which, more specifically, thermal expansion of the
beams constituting the structure results in no significant
longitudinal or transverse buckling or warping of the beams, and
hence in the formation of no spaces through which fire may travel
from below to above the structure.
Furthermore, the structure disclosed by Jahn accommodates thermal
expansion of only the crossbeams. Clearly, if both the main and the
crossbeams are formed of a thermally expandible material, the main
beams, as well as the crossbeams, are subjected to longitudinal
thermal expansion when, for example, a fire occurs and it is,
accordingly, an object of the preferred embodiments of the present
invention to provide a support structure in which thermal expansion
of all the beams constituting the structure is accommodated without
buckling or warping of the beams.
A support structure according to the present invention comprises at
least one first support beam and at least one second support beam
which is formed of thermally expandible material and an end portion
of which is secured to an end portion of the first support beam. A
slit is formed in the first support beam, the slit extending
longitudinally of this beam from the end of the beam presented by
said end portion thereof to a position between the ends of said
beam. The portions of the first support beam bounding the slit are
disposed in different planes, and the direction of the longitudinal
axis of the second support beam has at least a component which is
perpendicular to the longitudinal axis of the first support beam
and to the plane containing the slit, thereby to permit said
portions of the first support beam to be urged into overlapping
relationship by longitudinal thermal expansion of the second
support beam.
In order that the invention may be more clearly understood and more
readily carried into effect the same will now, by way of example,
be more fully described with reference to the accompanying drawings
in which:
FIG. 1 is a perspective view from above of a portion of a support
structure according to the invention, lighting units mounted on the
support structure being shown diagrammatically in chain-dotted
lines;
FIG. 2 is an isometric view from above of a part of the support
structure shown in FIG. 1, this view showing the adjacent end
portions of a pair of first and a pair of second support beams;
FIG. 3 is a top plan view of the part of the support structure
shown in FIG. 2, the beams being shown in their condition when the
second support beams are subjected to thermal expansion;
FIG. 4 is a view corresponding to FIG. 3 but showing the beams in
their condition when the first support beams are subjected to
thermal expansion;
FIG. 5 is a sectional view on the line 5-5 of FIG. 2, but with the
coverplate which is shown in an exploded condition in FIG. 2
disposed in its operative condition;
FIG. 6 is a view corresponding to FIG. 2 but showing an alternative
embodiment of the invention; and
FIG. 7 is a view corresponding to FIG. 3 but of the alternative
embodiment shown in FIG. 6.
Throughout the various views of the drawings like reference
numerals are used to denote like parts.
With reference to the drawings, and in particular FIG. 1 thereof,
10 denotes generally a support structure which comprises a
plurality of first support beams 11 and a plurality of second
support beams 12, the form and construction of the support
structure 10 being hereinafter disclosed in greater detail with
reference to the remaining views of the drawings. 13 denotes
generally each of a plurality of lighting units which may
operatively be supported by the support structure 10. The lighting
units 13 form, however, no part of the present invention and the
details of construction of these units are, therefore, not further
described or illustrated in this application.
With particular reference to FIG. 2, there is therein illustrated a
pair of collinear first support beams 11 of thermally expandible
material which are disposed in spaced relationship, i.e. which are
so disposed that the adjacent ends 14 thereof are spaced apart.
FIG. 2 also shows a pair of collinear second support beams 12 of
thermally expandible material which are likewise disposed in spaced
relationship, the space 15 between the adjacent ends 16 of the
second support beams 12 also constituting the space between the
adjacent ends 14 of the first support beams 11.
While in the preferred embodiments of the invention as herein
described with reference to the accompanying drawings there is a
plurality of first support beams 11 and a plurality of second
support beams 12, it is to be understood that in alternative
embodiments (not shown) there may be only one first support beam 11
and only at least one second support beam 12.
Each first support beam 11, and each second support beam 12, is of
inverted channel form in cross section and comprises a web portion
17 together with two substantially parallel depending limb portions
18. The limb portions 18 of each beam 11 or 12 present outwardly
directed flange portions 19 which are disposed in a plane
substantially parallel to the plane containing the web portion 17
of said beam 11 or 12.
The adjacent ends 14 of the first support beams 11 each present
outwardly projecting lugs 20 which are each of approximately
triangular form. Each lug 20 is connected to the appropriate limb
portion 18 of the beam 11 from which it is presented, the lug 20
preferably being integral with said beam 11, and having a lower
edge 21 which is upwardly inclined in the direction away from said
beam 11 and an upper edge 22 which, in the preferred embodiments
illustrated in the drawings, is disposed in a plane substantially
parallel to the plane containing the web portion 17 of said beam
11. The edge 22 of each lug 20 presents, at a position spaced from
the beam 11 from which said lug 20 is presented, an upwardly
projecting tab 23 which is disposed through a slot 24 formed in the
web portion 17 of the appropriate one of the second support beams
12, the underface of the web portion 17 of said second support beam
12 being supported on the edge 22 of lug 20 when the tab 23 is so
disposed. Each tab 23 is twisted, out of the plane of the slot 24
through which it is disposed, on the side of the slot 24 remote
from the lug 20 thereby to maintain in secured interrelationship
the adjacent end portions of the first and second support beams 11
and 12. In FIG. 2, the two left-hand tabs 23 are shown in their
condition prior to this twisting, the two right-hand tabs 23 being,
however, shown in the twisted condition.
The flange portions 19 of each second support beam 12 are each, at
the end 16 of the beam 12, off set in the upward direction thereby
to overlie, in the manner shown at 25 in FIG. 2, the adjacent
flange portion 19 of the appropriate one of the first support beams
11, the flange portions 19 of the beams 11 being at the end 14
thereof of chamfered form.
Each lug 20 is capable of flexing relative to the second support
beam 12 to which it is secured, and also relative to the first
support beam 11 from which it is presented.
A slit 26 is formed in the web portion 17 of each first support
beam 11, the slit 26 extending longitudinally of the beam 11 from
the end 14 thereof to a position between said end 14 and the other
end (not shown) of the beam 11. The portions of the web portion 17
of each beam 11 which bound the slit 26 formed therein are disposed
in different planes, for example, by downwardly deflecting one of
these portions as indicated at 27 in FIG. 2.
The end of each slit 26 remote from the end 14 of the beam 11 in
which said slit is formed is in communication with an enlarged
opening 28 formed in the web portion 17 of said beam. The openings
28 may be of circular form as shown at the left-hand side in FIG.
2, or may be of elongated form disposed transversely to the
longitudinal axis of the beam 11 as shown at the right-hand side of
FIG. 2. Particularly in the latter case, the openings 28 serve so
to weaken the end portions of the beams 11 in which they are formed
that overlapping of the portions of the web portion 17 of each beam
11 which bound the slit 26 formed therein is facilitated, such
overlapping being caused by longitudinal thermal expansion of the
beams 12 as is hereinafter more fully described. Furthermore, in
both cases, the opening 28 serves to prevent longitudinal creepage
of the end of the slit 26 remote from the end 14 of the beam 11 in
which it is formed.
As shown at the right-hand side of FIG. 2, a support tie member
constituted by a rod 29 may be disposed through the opening 28, the
lower end of the rod 29 being screw-threaded and having a washer 30
and a nut 31 mounted thereon below the web portion 17, thereby to
support the beam 11 by the rod 29, the upper end (not shown) of
which is secured to, for example, a flooring support deck.
As an alternative to supporting the beam 11 by the rod 29 and the
associated washer 30 and nut 31, the beam 11 may be supported by
means of a tie wire 32 and a strap 33 as shown at the left-hand
side of FIG. 2, the strap 33 being disposed through aligned slots
34 formed in the limb portions 18 of the beam 11, with the lower
end portion of the wire 32 being secured through openings 35 formed
in the end portions of the strap 33.
The second support beam 12 are disposed substantially perpendicular
to the first support beams 11, and to the plane containing the
slits 26 in the web portions 17 of the first support beams 11, i.e.
with the plane containing the slits 26 and disposed perpendicular
to the plane containing the web portions 17 of the beams 11. It is
not essential, however, that the second support beams 12 be so
disposed provided that the direction of the longitudinal axis of
each second support beam 12 has at least a component which is
perpendicular to the longitudinal axis of each first support beam
11 and to said plane containing the slits 26 in the web portions 17
of the first support beams 11. Thus, in alternative embodiments
(not shown) of the invention, each second support beam 12 may be so
disposed that the direction of the longitudinal axis thereof forms
an acute angle with the longitudinal axis of one of the first
support beams 11 and additionally, or alternatively, forms an acute
angle with said plane containing the slits 26 in the web portions
17 of the first support beams 11.
A cover plate 36 is mounted over the space 15 between the adjacent
ends 14 of the beams 11, and the adjacent ends 16 of the beams 12,
the cover plate 36 which is shown in an exploded condition in FIG.
2 extending over the adjacent end portions of the first support
beams 11 and being connected thereto by means of downwardly
projecting tabs 37 which frictionally grip the opposed limb
portions 18 of the beams 11 in the manner most clearly shown in
FIG. 5. Slits 38 are formed in the end portions of the cover plate
36 which extend over the adjacent end portions of the beams 11, a
portion 39 (FIG. 5) of the plate 36 bounding each slit 38 being in
engagement with the slit 26 formed in the adjacent beam 11 to
maintain the portions of the web portion 17 of said beam 11
bounding the slit 26 therein in different planes.
As is most clearly shown in FIG. 3, longitudinal thermal expansion
of the second support beams 12, i.e. longitudinal movement of the
end portions of the beams 12 shown in FIG. 3 in the directions of
the arrows A, results in the portions of the web portion 17 of each
first support beam 11 which bound the slit 26 formed therein, being
urged into overlapping relationship, as shown in FIG. 3, by the
arrows B.
As shown in FIG. 4, longitudinal thermal expansion of the first
support beams 11, i.e. longitudinal movement of the end portions of
the beams 11 shown in FIG. 4 in the directions of the arrows C,
results in the above-mentioned flexing of each lug 20 relative to
the support beam 11 from which it is presented and relative to the
support beam 12 to which it is secured by means of the tab 23. As
will be appreciated, the ends 16 of the second support beams 12
are, when the structure 10 is in normal use, preferably spaced a
short distance from the first support beams 11 thereby to
facilitate such flexing of the lugs 20. It is, however, not
essential that the ends 16 of the second support beams 12 be so
spaced, since the forces exerted during longitudinal thermal
expansion of the beams 11 are, in practice, so large that the
above-mentioned flexing of the lugs 20 will, in any event,
occur.
Although for clarity, the effect of longitudinal thermal expansion
of the beams 12 and of the beams 11 has been in two separate view
of the drawings, it will be appreciated that, in practice, these
effects occur together where, as will usually be the case, the
beams 11 and also the beams 12 are formed of thermally expandible
material, such as metal, and are operatively all subjected
simultaneously to fire heat.
Thus, longitudinal thermal expansion of the first and second
support beams 11 and 12 is accommodated in the structure according
to the present invention substantially without any longitudinal or
transverse buckling or warping of the beams 11 and 12 constituting
the structure, and hence without any substantial risk of spaces,
through which fire could travel from below to above the support
structure, being formed between the beams 11 and 12 and insulation
panels or the like operatively supported thereon.
The alternative embodiment of the invention illustrated in FIGS. 6
and 7, is substantially similar to that illustrated in the
preceding views of the drawings and differs therefrom substantially
only in that the lugs 20, and associated tabs 23, are omitted and
the end portions of the beams 11 are secured to the adjacent end
portions of the beams 12 by means of outwardly projecting,
hook-shaped members 40 which are presented by the limb portions 18
of the first support beams 11 at the ends 14 thereof and which are
engageable with similarly formed outwardly projecting, hook-shaped
members 41 presented by the limb portions 18 of the second support
beams 12 at the ends 18 thereof, each hook-shaped member 40 being
upwardly open and each hook-shaped member 41 being downwardly open
so that these members are interconnectably engageable in the manner
shown in FIG. 6. Furthermore, in the alternative embodiment
illustrated in FIGS. 6 and 7 the web portions 17 of all the beams
11 and 12 are formed with longitudinally extending slits
corresponding to the slits 26 formed in the web portions 17 of the
beams 11 in the first embodiment. In addition, in this alternative
embodiment the slits 38 formed in the coverplate 36 have been
omitted although it is to be understood that such slits could also
be provided in the coverplate 36 in this alternative
embodiment.
As shown in FIG. 7, longitudinal thermal expansion of the second
support beams 12 results in the portions of the web portions 17 of
the beams 11 which bound the slits 26 formed therein being urged
into overlapping relationship in the same manner as is described
above with reference to FIG. 3. In this alternative embodiment,
longitudinal thermal expansion of the first support beams 11
results in the portions of the web portions 17 of the beams 12
which bound the slits 26 formed therein being likewise urged into
overlapping relationship in an identical manner.
* * * * *