U.S. patent number 3,778,947 [Application Number 05/195,237] was granted by the patent office on 1973-12-18 for fire-rated grid member with controlled expansion means.
This patent grant is currently assigned to Flangeklamp Corporation. Invention is credited to Gale E. Sauer.
United States Patent |
3,778,947 |
Sauer |
December 18, 1973 |
FIRE-RATED GRID MEMBER WITH CONTROLLED EXPANSION MEANS
Abstract
A fire-rated grid member having a plurality of cut-out sections
in the web thereof defining connecting portions for controlling
deformation of the grid member to predetermined areas upon
expansion. The bead surmounting the web is deformed to create a
weakened portion deformable upon grid member expansion. The
opposite ends of the grid member are provided with a slot and
tongue arrangement for splicing adjacent grid members together.
Inventors: |
Sauer; Gale E. (Williamsville,
NY) |
Assignee: |
Flangeklamp Corporation
(Buffalo, NY)
|
Family
ID: |
22720592 |
Appl.
No.: |
05/195,237 |
Filed: |
November 3, 1971 |
Current U.S.
Class: |
52/232;
52/506.07; 52/664; 52/DIG.5; 403/252 |
Current CPC
Class: |
E04B
9/08 (20130101); E04B 9/067 (20130101); E04B
9/122 (20130101); F16B 2200/20 (20180801); Y10S
52/05 (20130101) |
Current International
Class: |
E04B
9/06 (20060101); E04B 9/08 (20060101); E04B
9/12 (20060101); E04c 002/52 (); E04c 002/42 ();
E04b 005/52 () |
Field of
Search: |
;52/232,664,665,667,573,484,475,DIG.5 ;287/189.36A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Braun; Leslie A.
Claims
I claim:
1. A grid member for supporting grid systems and the like
comprising: a support member having a web and flanges extending
laterally outwardly on opposite sides of said web, said web being
formed with at least one generally horizontally extending cut-out
section having a portion terminating in close proximity to said
flanges and at least a pair of vertically extending slots adjacent
opposite sides of said cut-out section in closely spaced relation
thereto and terminating at ends in close proximity to said flanges,
relatively narrow connecting portions of said web remaining between
said slot ends and said flanges and between said cut-out section
and said slots for strengthening said web under normal conditions
of usage and severable upon expansion for permitting controlled
deformation of said flanges and certain portions of said web.
2. A grid member as defined in claim 1 wherein said cut-out section
comprises an elongated slot extending generally parallel to the
longitudinal axis of said web and a V-shaped notch extending from
said slot intermediate the opposite ends thereof and terminating in
an apex in close proximity to said flanges.
3. A grid member as defined in claim 1 wherein said adjacent slots
extend in a direction normal to the longitudinal axis of said web
and have V-shaped portions each terminating in an apex in close
proximity to said flanges.
4. A grid member as defined in claim 1 including a bead surmounting
said web, said bead having a deformed portion forming a
continuation thereof to provide a pair of longitudinally spaced
weakened portions for controlling deflection of said bead upon
expansion of said support member.
5. A grid member as defined in claim 4 wherein said web is provided
with an opening below said deformed portion of said bead and
extending partially thereinto.
6. A grid member as defined in claim 4 wherein said deformed
portion has a double wall thickness of lesser width than the major
portion of said bead.
7. A grid member as defined in claim 1 wherein said cut-out section
comprises an elongated slot extending generally parallel to the
longitudinal axis of said web and a V-shaped notch extending from
said slot intermediate the opposite ends thereof and terminating in
an apex in close proximity to said flanges, said adjacent slots
extending in a direction normal to the longitudinal axis of said
web and having V-shaped portions terminating in apices in close
proximity to said flanges, a bead surmounting said web and having a
deformed portion controlling deflection of said bead upon expansion
of said support member, and said web being provided with an opening
below said deformed portion of said bead for controlling deflection
of said web upon expansion.
8. A grid member as defined in claim 1 together with means on
opposite ends of said web for interlocking engagement with adjacent
grid members.
9. A grid member as defined in claim 8 wherein said interlocking
means comprises a tab extending laterally outwardly at an angle of
approximately 45.degree. from one end of said grid member web and
insertable into an adjacent grid member slot.
10. A grid member as defined in claim 9 wherein said interlocking
means comprises a slot in said web adjacent the other end thereof
for receiving an adjacent grid member tab.
11. A grid member as defined in claim 10 including an extension
projecting longitudinally outwardly from said other end of said
grid member web in a plane laterally offset therefrom and parallel
thereto, said extension having an abutment shoulder engageable with
an adjacent grid member stop.
12. A grid member assembly comprising: at least two coaxially
aligned grid members each having a web, connecting means on
adjacent ends of said webs for splicing said grid members in an
abutting end-to-end relation, said connecting means comprising a
tongue extending longitudinally outwardly from the abutting end of
one web in a plane laterally offset from said one web and parallel
thereto, a tab projecting laterally outwardly from the end of said
tongue remote from said web at an angle of approximately
45.degree., said web having stop means projecting outwardly
therefrom and disposed longitudinally inwardly from the abutting
end thereof, a slot provided in said other web adjacent the
abutting end thereof for receiving said tab, an extension
projecting longitudinally outwardly from the abutting end of said
other web in a plane laterally offset from said other web and
parallel thereto, said extension having means adjacent the free end
thereof engageable with said stop means in the assembled relation
of said grid members.
13. A grid member assembly as defined in claim 12 wherein said stop
means comprises a laterally projecting finger struck out of said
other web.
14. A grid member assembly as defined in claim 13 wherein said
extension is provided with a pair of axially extending, vertically
spaced projections defining an abutment shoulder therebetween
engageable with said finger in the assembled relation of said grid
members whereby said projections prevent vertical displacement of
said grid members relative to each other.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to fire-resistant tile supporting
grid systems and the like and, more particularly, to tile
supporting members capable of absorbing expansion without
substantial buckling of the ceiling tiles during abnormally
elevated temperatures, thereby preserving the integrity of the
ceiling as a barrier under such conditions.
The present invention is particularly adapted for use in ceiling
tile supporting grid systems of the type comprising a plurality of
parallel spaced main grid members and cross grid members extending
transversely between the main grid members and having end portions
interlocking therewith. These interconnected grid members generally
are suspended from a conventional ceiling or an overhead support
structure.
One of the critical problems encountered in these ceiling tile
supporting grid structures is to maintain the integrity thereof
under abnormally elevated temperatures, such as accompany a fire.
Under these high temperature conditions, the metallic grid members,
which generally are fixed at opposite ends, expand and buckle
whereby the supported ceiling tiles are displaced and sometimes
tilted to such an extent that they drop through the openings formed
by the intersecting grid members. As a result, the effectiveness of
the suspended ceiling as a barrier is destroyed and the overhead
ceiling and related support structure is exposed to the fire
whereby the latter can spread more easily and rapidly through the
entire structure.
SUMMARY OF THE INVENTION
Accordingly, a primary object of this invention is to provide an
improved fire-rated grid member which accommodates expansion
resulting from extreme heat and controls deformation of the grid
member upon expansion to predetermined areas to preserve the
integrity of the ceiling under elevated ambient temperature
conditions.
Another object of the present invention is to provide an improved
fire-rated grid member having especially configurated cut-out
sections in the web thereof providing weakened connecting portions
adapted to influence deformation of the grid member at
predetermined areas.
A further object of this invention is to provide the foregoing grid
member with a deformed bead surmounting the web and having weakened
portions to control deflection thereof upon expansion.
Still another object of the present invention is to provide splice
means at the opposite ends of the foregoing grid member for
interlocking adjacent grid members in an abutting end-to-end
relation and thereby extending the effective length of the main
grid support member.
The foregoing and other objects, advantages and characterizing
features of the present invention will become clearly apparent from
the ensuing detailed description of an illustrative embodiment
thereof, taken together with the accompanying drawings wherein like
reference characters denote like parts throughout the various
views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary, perspective view of intersecting grid
members incorporating a fire-rated main grid member of this
invention;
FIG. 2 is a fragmentary, perspective view of two main grid members,
shown in an interconnected, abutting, end-to-end relation;
FIG. 3 is a fragmentary, perspective view of one end of a main grid
member constructed in accordance with this invention;
FIG. 4 is a fragmentary, perspective view of the other end of the
main grid member shown in FIG. 3;
FIG. 5 is a side elevational view of a fire-rated main grid member
of this invention, being broken away for ease of illustration;
FIG. 6 is a top plan view, of the fire-rated grid member shown in
FIG. 5, being broken away for ease of illustration;
FIG. 7 is a vertical, cross-sectional view, on an enlarged scale,
taken about on line 7--7 of FIG. 5;
FIG. 8 is a fragmentary, side elevational view, on an enlarged
scale, showing the cut-out sections in the grid member web and the
deformation of the grid member bead for controlling expansion of
the grid member;
FIG. 9 is a vertical, cross-sectional view, on an enlarged scale,
taken about on line 9-9 of FIG. 5;
FIG. 10 is a fragmentary, horizontal sectional view, on an enlarged
scale, taken about on line 10--10 of FIG. 2;
FIG. 11 is a fragmentary, side elevational view, on an enlarged
scale, illustrating the actual deformation of the grid member of
this invention upon the application of heat; and
FIG. 12 is a fragmentary top plan view of the deformed grid member
of FIG. 11.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now in detail to the illustrative embodiment depicted in
the accompanying drawings, there is shown in FIG. 1 a ceiling tile
supporting grid system incorporating a main T support member,
generally designated 10, detachably connected to a pair of cross T
support members, generally designated 12. Main T member 10 can be
conveniently fabricated from a single piece of any suitable
material, preferably an inexpensive, lightweight metal such as soft
steel for example, and is formed to provide a generally vertical
web portion 14 upstanding from laterally projecting, tile
supporting flanges 16 on opposite sides thereof and surmounted by a
generally boxshaped, longitudinally extending, reinforcing member
or bead 18.
Web portion 14 is provided at spaced intervals with rectangular,
normally vertical slots 20 (FIG. 5) for the reception of the end
portions of cross T members 12. Slots 20 are generally H-shaped,
being formed with downwardly and upwardly projecting center tabs 22
and 24, respectively, at the top and bottom of the slot which serve
as partitions or separators between the two cross T members 12 in
the assembled joint. While slots 20 are shown as being H-shaped in
the illustrative embodiment, it should be understood that slots 20
may take any shape compatible with the end portions of cross T
support members 12 so that such end portions will be snugly
received in the associated slots.
Cross T members 12 can be similarly fabricated from a single piece
of any suitable material, such as soft steel by way of example, and
formed to provide a normally vertical web portion 26 upstanding
from laterally projecting, tile supporting flanges 28 and
surmounted by a generally box-shaped, longitudinally extending,
reinforcing member or bead 30. It should be appreciated that
reinforcing members or beads 18 and 30 can take various shapes in
cross-section, such as a rounded or bulbous shape, as desired.
Cross T support members are provided at their opposite ends with
tongue portions generally designated 32, extending axially
outwardly from said opposite ends of said cross T member 12 and
slightly offset from web portion 26 in opposite lateral directions.
Any suitable locking means can be provided on tongue portions 32
for interlocking engagement behind web portion 14 of main T support
member 10. As shown in FIG. 1, two cross T support members 12
extend perpendicularly to main T support member 10 on opposite
sides thereof with their respective tongue portions 32 inserted
into slot 20 for passage therethrough and for interlocking
engagement with web portion 14. It will be understood that main T
support member 10 includes throughout its length at predetermined
spaced intervals a plurality of slots 20 with corresponding pairs
of cross T members insertable therethrough in the assembled
relation. Various interlocking cross T tongue arrangements can be
utilized, as will be readily understood by those skilled in the
art. For additional details of the illustrated arrangement,
reference is made to pending application Ser. No. 178,893, filed
Sept. 9, 1971 and assigned to the same assignee as the present
application.
In accordance with the present invention, main T support member 10
is formed in such a manner as to confine expansion thereof under
abnormally elevated temperatures to predetermined areas of such
member 10 in an effort to preserve the integrity of the suspended
ceiling. To this end, a series of cut-out sections, generally
designated 36, are provided in web portion 14 of main T support
member 10. As seen in FIG. 8, each cut-out section 36 comprises a
horizontally elongated slot 38 of trapezoidal shape in outline
defined by an upper, horizontally extending wall 40 generally
parallel to the longitudinal axis of web portion 14, a lower
horizontally extending wall 42 in substantial parallelism with
upper wall 40 and a pair of side walls 44 joining lower wall 42 to
upper wall 40 and inclined upwardly in a converging relation. A
generally V-shaped notch 46 is cut into web portion 14 extending
downwardly from each slot 38 intermediate the opposite ends thereof
and terminating in an apex 48 disposed slightly above flanges 16.
While three such slots 38 are shown in the illustrative embodiment,
it should be understood that more or less than three slots can be
utilized in the present invention.
A series of elongated, vertically extending slots 50 are cut into
web portion 14, the slots 50 being disposed adjacent opposite ends
of horizontally extending slots 38 and spaced therefrom at the
narrowest dimension therebetween approximately one-sixteenth of an
inch. Slots 50 terminate at their lower ends in V-shaped portions
52 having apices 54 disposed in substantially the same horizontal
plane as apices 48 of V-shaped notches 46. It will be seen that a
plurality of narrow, connecting portions 56 of web portion 14 (FIG.
8) remain between slots 38 and 50 and between apices 48, 54 and
flanges 16 and serve to influence or concentrate deformation at
these weakened connecting portions 56 upon expansion or elongation
of main T support member 10. While the removal of material to
provide slots 38 and 50 somewhat weakens web portion 14, they are
so arranged and proportioned to only negligibly weaken web portion
14 whereby main T support member 10 possesses the requisite
rigidity and strength to withstand the stresses imparted thereto
under normal conditions of handling, installation and usage. A
plurality of ribs 58, constituting remaining parts of web portion
14 after slots 38 and 50 are cut-out, disposed below slots 38
between V-shaped notches 46 and 52 and joined by web portions 56,
aid in reinforcing web portion 14 under normal conditions.
In order to provide for the expansion of the upper portion of main
T support member 10, a portion of web 14 is cut out to form an
opening 60 which extends into the lower edge of bead 18. Also, bead
18 is deformed above opening 60 to form an embossment 62 in one
side of bead 18. In the fabrication of main T support member 10, as
by a roll forming operation for example, bead 18 is initially
formed into a box-shaped configuration (FIG. 9) comprising a top
wall 64, a bottom wall 66, and a pair of side walls 68 and 70. In
forming embossment 62, a portion of side wall 70 is pressed against
side wall 48, as shown in FIGS. 7 and 8, to form a wall portion 72
of double thickness having opposite ends which serve as
longitudinally spaced, vertically extending fold lines 74 and 76 to
influence relative movement between the portions of bead 18
adjacent embossment 62 upon expansion of main T support member 10.
Opening 60 and embossment 62 are formed by a single punching
operation, together with an opening 61 through top wall 64, the
opening 61 being of the same length, and depth into bead 18, as
opening 60. As a result, side wall 70 of bead 18 is deformed
slightly inwardly at spaced points toward fold lines 74 and 76
defining curved surfaces 78 and 80 (FIG. 6).
While the deformation of bead 18 to form embossment 62 somewhat
weakens bead 18 to permit deformation thereof during thermal
expansion, the double thickness wall portion 72 possesses the
requisite strength and rigidity to provide the necessary resistance
against bending under normal conditions of handling, installation
and usage. Embossment 62 serves as a connecting link between the
box-shaped portions of bead 18 to provide a continuous bead 18
throughout the length of support member 10 to provide a strong and
rigid compression member under normal conditions.
Means are provided for releasably securing a pair of main T support
members 10 in an abutting, end-to-end relation to form a splice
therebetween. Such means comprise a tongue 84 extending axially
outwardly from one end of main T support member 10 and formed
integral therewith as shown in FIG. 4. Tongue 84 is slightly offset
from web portion 14 (FIG. 10) but lies in a plane parallel to the
plane of web portion 14. A tab 86 extends laterally inwardly from
the end of tongue 84 at an angle of approximately 45.degree. to the
plane of tongue 84 and is joined thereto along a vertical fold line
88. Tab 86 is trapezoidal in configuration having a progressively
decreasing width from tongue 84 to the free end of tab 86 for
facilitating insertion of tab 86 into its associated opening 100. A
finger 90 is struck out from web portion 14 adjacent the end
thereof, in spaced relation to tongue 84, and is bent laterally
outwardly for a purpose hereinafter explained.
The other end of main T support member 10 is provided with an
extension 92 (FIG. 3) projecting axially outwardly from said other
end and slightly offset in the opposite direction from the plane of
web portion 14. Extension 92 is provided with a forked end having
two axially extending projections 94 and 96 defining an abutment
shoulder 98 therebetween adapted to engage with finger 90 of the
adjacent main T support member 10. An axially elongated opening 100
is provide in web portion 14 of main T support member provided
adjacent the end having extension 92, in spaced relation thereto,
for receiving tab 86 of the adjacent main T support member 10 in
assembled relation.
In assembling a pair of main T support members 10 in an end-to-end
relation, the end edges of web portions 14, flanges 16, and beads
18 of adjacent main T support members 10 which are coplanar, are
brought into abutting relation with tongue 84 overlying extension
92. In these relative positions of tongue 84 and extension 92, tab
86 is in registry with opening 100 and can be inserted therein.
Finger 90 of one member 10 engages abutment shoulder 98 of the
other member 10 preventing further axial inward movement of tongue
84 relative to extension 92. The upper and lower edges of finger 90
fit snugly between projections 94 and 96 to prevent relative
vertical movement therebetween. Tab 86 can then be reversely bent
about fold line 88 to extend along web portion 14 of the adjoining
main T support member 10 in order to firmly secure members 10
together, as shown in FIGS. 2 and 10. In this secured position, tab
86 is oriented generally parallel to tongue 84 and spaced therefrom
a distance approximating the thickness of web portion 14 of the
adjacent main T support member 10 for sandwiching the latter
therebetween.
In use, with the ends of main T support member fixed or restricted
with respect to movement in axial directions and upon the
application of heat to the ceiling structure, such as might be
caused by fire, main T support member 10 seeks to expand and
elongate and will buckle unless such expansion can be absorbed by
member 10. In the present invention, any such expansion or
elongation is accommodated, and controlled deformation of member 10
is achieved as follows:
The compressive reaction forces acting axially against the opposite
ends of main T support member 10 caused by expansion thereof are
transmitted through the body of member 10 including the narrow,
connecting portions 56. It should be realized that the lower
surfaces of flanges 16 are directly exposed to the heat and these
flanges tend to initially expand to a greater degree than the web
portion 14 thereabove which is somewhat insulated by flanges 16 and
the ceiling tiles. The narrow, connecting portions 56 of web
portion 14 offer less resistance to deformation than any other
portion of web 14 and influences the deflection of flanges 16 to
occur adjacent these connecting portions 56. Accordingly, flanges
16 will bend downwardly carrying ribs 58 therewith, the latter
deflecting about connecting portions 56. At full expansion of main
T support member 10, ribs 58 shear at these connecting portions 56
and, together with those portions of flanges 16 connected to ribs
58, assume a V-shaped contour, as shown in FIG. 11. FIGS. 11 and 12
illustrate the actual deformation imparted to a fire-rated grid
member of this invention which was exposed to fire. While FIG. 11
shows maximum deformation adjacent the right hand cut-out section
36, partial deformation adjacent the central cut-out section 36,
and substantially no deformation adjacent the left hand cut-out
section 36, it should be understood that any one or all of these
sections can experience this deformation depending on the direction
of movement of the fire and the duration of the exposure of these
areas to the fire.
As the upper portion of main T support member 10 expands, bending
of bead 18 occurs about the spaced fold lines 74 and 76 to cause
the spaced deformed end portions of bead 18 at opposite sides of
embossment 62 to by-pass each other as shown in FIG. 12. Curved
surfaces 78 and 80 on bead 18 facilitate the bending of wall
portion 72 of bead 18 into a generally S-shaped bend, as shown in
FIG. 12. The relatively narrow portion of web 14 disposed between
slot 38 and opening 60 is bent in a similar S-shaped pattern along
with bead 18.
The main T support member 10 of this invention satisfactorily
passed the two-hour A S T M Fire Endurance Test conducted in
accordance with the Standard Methods of Fire Tests on Floor and
Ceiling Constructions. In this test, a section of a ceiling
construction, including main and cross T support members and
ceiling tiles supported thereon, was exposed to fire at
temperatures ranging from 1000.degree. - 1900.degree.F. The main T
support member 10 of the present invention readily met the
fire-rated requirements consistent with the fire endurance time of
two hours. Flanges 16 of main T support member 10 did not deform
sufficiently, even at its maximum deflection during this two hour
period, to disrupt the continuity of the ceiling system, thus
maintaining the overall integrity of the ceiling structure.
Moreover, the specimen tested serves as a fire retarding and heat
transmission barrier to prevent the fire from spreading to other
superstructure. The specimen not only effectively withstood the
2-hour fire-rated test, but remained exposed to the fire for yet
another hour. While more pronounced deformation of the support
members took place during this third hour, flanges 16 were still
capable of supporting the ceiling tiles so that none were displaced
or dislodged to the extent that they fell through the openings
defined by the intersecting tile supporting members. FIGS. 11 and
12 depict actual deformation of the main T support member of this
invention after having been exposed to fire for three hours at
temperatures ranging from 1000.degree. - 1900.degree.F.
From the foregoing, it is apparent that the objects of the present
invention have been fully accomplished. As a result of this
invention, an improved fire-rated grid member is provided for
maintaining the integrity of a ceiling structure upon the
application of heat thereto and preserving the fire retarding
qualities thereof to prevent the escape of heat therethrough to the
superstructure. By the provision of a plurality of specially
configurated cut-out sections in the web portion of the grid
member, deflection of the flanges can be influenced in
predetermined directions to prevent buckling of the grid system
upon expansion. These cut-out sections tend to concentrate the heat
to certain predetermined areas to achieve the above action and also
interrupt the transmission of heat through the web portion. Also,
by providing an embossment in the bead of the grid member,
deflection of the upper portion of the grid member is effectively
controlled to absorb expansion. At the same time, the support
member possesses the strength and stability required in use for
this purpose.
A preferred embodiment of this invention having been disclosed in
detail, it is to be understood that this has been done by way of
illustration only .
* * * * *