|Publication number||US3350125 A|
|Publication date||Oct 31, 1967|
|Filing date||Mar 24, 1966|
|Priority date||Mar 24, 1966|
|Publication number||US 3350125 A, US 3350125A, US-A-3350125, US3350125 A, US3350125A|
|Inventors||George C Adams|
|Original Assignee||Rollform Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (8), Classifications (13)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Oct. 31, 1967 Filed March 24, 1966 G. C. ADAMS SY TEM 2 Sheets-Sheet INVENTOR.
Oct. 31, 1967 c, ADAMS 3,350,125
EXPANSION CONNECTION FOR FIRE RATED CEILING GRID SYSTEM Filed March 24, 1966 2 Sheets-Sheet 2 INVENTOR.
// W, pflawgf United States Patent EXPANSION CONNECTION FOR FIRE RATED CEILING GRID SYSTEM George C. Adams, Ann Arbor, Mich., assignor to Rollform, Incorporated, Ann Arbor, Mich., a corporation of Michigan Filed Mar. 24, 1966,'Ser. No. 537,100 1 Claim. (Cl. 287--189.36)
ABSTRACT OF THE DISCLOSURE The instant invention comprises a pair of main T-bars or T-members butted end-to-end in a grid system and held in this position by a splicer which is attached thereto by suitable clip and slot means in a manner permitting controlled expansion of the T-members when exposed to fire or similar conditions and without disrupting the ceiling assembly. To this end, at least one of the main T-members is provided with a cut-out area in the vertical flange thereof adjacent its butted end and within the portion lapped by the splicer. In order to make the T-member adequately strong under normal conditions and at the same time permit it to collapse smoothly and uniformly Without disrupting the ceiling, the cut-out area extends downwardly from the upper edgejof the vertical flange to a point adjacent to but spaced above the horizontal bottom flanges. This arrangement leaves a narrow portion of the vertical flange between the cut-out area and the horizontal flanges which serves a stilfening and strengthening function under normal service conditions. A single generally V-shaped notch provided in the narrow vertical flange portion intermediate the opposite sides of the cutout area causes the portion of the T-member below the cut-out area to fold downwardly under thermal expansion conditions with the apex of the fold at the notch. Movement of the T-member into the cut-out area and relative to the splicer under expansion conditions is permitted by special clip and elongate slot means interconnecting the splicer and the vertical flange of the T-bar.. The integrity of the grid assembly in normal service is enhanced by providing the splicer in the area of the cut-out area with means for attachment of a cross T-member; and, in order to permit elongation of the main T-member under thermal expansion conditions without opening up the ceiling and without interference from the cross T-member, the attaching means is located generally in line with the V-notch and disposed at a substantial distance from the side of the cut-out area remote from the butted end and the remote side of the cut-out area is caused to extend transversely of the T-member in substantially a straight line from the bottom of the cut-out area.
This invention relates generally to ceiling structures, and particularly to an improved expansion connection for a suspended ceiling component.
In general, suspended ceilings, of the type to which the present invention relates, include a plurality of normally disposed interconnected grid members suspended from a conventional ceiling or overhead structure of an enclosure. These grid members conventionally include parallel spaced main grid members which extend one full dimension of the enclosure and which may be of integral construction but which preferably are of end-to-end spliced construction and cross grid members which extend normally to and interconnect the main grid members. The main and cross grid members each are of generally inverted T-shape in vertical cross section and together form a latticedefining a plurality of rectangular openings. A rectangular acoustical tile is positioned in each opening in the lattice and is supported on the bottom flanges of the grid members and provides a generally aesthetically pleasing and acoustically superior ceiling for the enclosure.
One of the problems arising in these ceiling structures relates to maintaining the integrity thereof under high ambient temperature conditions. Thus, when a fireoocurs in the enclosure, the metallic grid members expand and buckle so that the acoustical tiles in the grid openings are disturbed and tilted sometimes to such an extent that they fall through the openings. When this occurs, the elfectiveness of the suspended ceiling is destroyed and the overhead ceiling and related structure is exposed to the fire so that the latter can spread more easily and quickly through the entire structure.
From the foregoing, it is readily apparent that suspended ceiling structures desirable should maintain their integrity and hold the individual tiles in place as long as possible under any elevated temperature or fire condition. In this manner, fire within the enclosure is delayed and perhaps prevented from spreading to the overhead structure and therefore to other parts of the building.
The main object of the present invention therefore is to provide an improved grid member assembly for a suspended ceiling structure which is adapted to isolate and control thermal expansion thereof to a particular area and thereby maintain the integrity of the suspended ceiling under elevated ambient temperature conditions.
Further objects include a grid member assembly of the above character which is relatively inexpensive to manu facture, sturdy in construction and reliable in use.
Other objects and advantages of the present invention will become more apparent from a consideration of the following detailed description taken in conjunction with the drawings in which:
FIGURE 1 is a perspective view illustrating a main grid constructed according to the present invention and shown with a pair of cross grid members before assembly thereof;
FIG. 2 is a sectional view of FIG. 1 taken along the line 2-2 thereof; and
FIG. 3 is an exploded perspective view of the grid member of FIG. 1.
' Broadly described, the present invention comprises a grid assembly including an elongated grid member of generally inverted T-shape vertical cross section defining a vertical flange and a pair of horizontal flanges, said vertical flange having a rectangular slot therein intermediate its ends and extending to an area adjacent said horizontal flanges, a generally V-shaped notch in the bottom of said slot intermediate the ends thereof whereby thermal expansion of said grid member causes said slot to collapse and said horizontal flanges to bend downwardly in the area below said slot forming an apex opposite said notch.
Referring now more specifically to the drawings, a main grid member assembly embodying the present invention is illustrated generally at 11 in FIG. 1 and is seen to include a grid member 13 commonly referred to in the trade as a T-member because of its generally inverted T-shaped vertical cross section. As shown, the T-member 13 has a vertical flange 15 and a pair of horizontal bottom flanges 17, 19 at opposite sides of the flange 15. The grid member 13 is shown in aligned and abutting end-to-end relation with another grid member 21 having a vertical flange 23 and horizontal flanges 25, 27 identical to the flanges 15 and 17, 19, respectively, of the grid member 13. The main grid members 13, 21 are releasably held together by a splicer 29 and permit using a standard length main grid member, e.g., 12 feet, in various multiples or parts thereof to accommodate different enclosure sizes.
The main grid members are installed in parallel rows spaced apart a distance substantially equal to or slightly greater than one width dimension of the ceiling panels (not shown) to be used whereby these panels rest upon the horizontal flanges 17, 19 and 25, 27. The rows of main grid members are interconnected by cross grid members 31, 33 which also are generally inverted T-shaped in vertical cross section defined by a vertical flange 35, 37 and horizontal flanges 39, 41 and 43, 45, respectively. The extremities of the cross grids 31, 33 are formed with tabs 47, 49 receivable in a set of apertures 51, 53 formed in the vertical flange 15 of the main grid 13. Additional sets of apertures are formed in the main grid vertical flange 15 (not shown), the splicer 29 as at 50, 52 and the main grid vertical flange 23 as at 54, 56 to receive projecting tabs on other cross grids (not shown) and these sets of apertures are spaced apart a distance substantially equal to or slightly greater than the other width dimension of the ceiling panels (not shown) which are supported thereon so that the grid system formed by the main grids and the cross grids defines substantially a rectangular lattice and together with the panels supported thereon present an aesthetically pleasing and acoustically superior ceiling for the enclosure. The details of the interlocking relation between the main grids and the cross grids do not form a part of the present invention and are not described further here. Reference, however, may be made to my copending application Ser. No. 537,055, filed Mar. 24, 1966, for a detailed explanation thereof as well as for an illustration and explanation of the grid system formed thereby.
As described briefly above, a fire within the enclosure in which the ceiling is suspended heats the grid members and causes them to expand. If these grid members are rigidly confined, this expansion causes at least some of the grid members to buckle whereupon the ceiling panels supported thereby are either raised, tilted or fall out of the grid system and the fire is permitted to spread quickly to the overhead structure. In an effort to maintain the integrity of the grid system, means may be provided whereby the cross grid members 31, 33 are permitted to expand without buckling or causing the main grid members to buckle. One such means is that illustrated in FIG. 1 and illustrated and described in detail in my copending application, Ser. No. 537,055, filed Mar. 24, 1966. In addition to the cross grid members, the main grid members 13, 21 and therefore the grid assembly 11 also expand under this heat. Because of the relatively great length of the grid assembly 11, expansion thereof, if left uncontrolled, causes the main grid assembly to buckle and dislodge the ceiling tile and thereby speeds the spread of the fire.
It has been discovered that if a particular area or areas of the main grid member assembly 11 be weakened in a novel manner, expansion thereof can be confined to this area or areas and integrity of the system can be maintained. To this end, the main grid member 13 is seen to have a generally rectangular cut-out area or slot 55 formed in the vertical flange 15. The cut-out area 55 opens through the upper edge of the flange 15 and extends downwardly therefrom to a point adjacent to but spaced above the horizontal flanges 17, 19 leaving a relatively narrow portion 57 of the vertical flange 15 which serves a strengthening and stiffening function in the normal use of the T-member 13. A generally V-shaped notch 59 is formed in the narrow flange portion 57 at substantially the midpoint thereof. The purpose of the notch 59 is to weaken the flange portion 57 sufficiently so that the lower portion of the T-mernber 13 will fold at this point under forces of compression due to expansion of the member in the event of fire or the like. To this end, the notch 59 need not extend all the way to the horizontal flanges 17 and 19 although it may do so if the loss of strength and stiffness resulting therefrom is not critical.
When the main grid member 13 is he e a d caused to expand, it collapses first at the area of the slot 55 since this portion of the grid member 13 is substantially weaker than the rest of the grid member. In addition, because of the notch 59, the flange portion 57 and the flanges 17, 19 bend in a fashion forming an apex at the notch 59, substantially as shown in dot-dash lines in FIG. 1. The bending of the flange portion 57 and the flanges 17, 19 is prevented from occurring in a lateral direction both by the relatively great strength of the flanges 17, 19 in this direction and because of the presence of the ceiling panels (not shown) which rest thereon. Further, this bending is prevented from occurring upwardly by the presence of the splicer 29, in a manner to be described, and is caused to occur in a vertical downward direction substantially as shown in the figure. In this way, the adjacent panel or panels seated thereon are not lifted therefrom and tend to remain in place so that the integrity of the ceiling is maintained.
It has been discovered that by utilizing a generally elongate slot 55 and by providing only one notch 59 which is disposed centrally of the bottom flange portion 57, the overall force required to bend the horizontal flanges 17, 19 and the flange portion 57 and therefore collapse of the T-member 13 at the slot 55 is substantially less than if a plurality of notches 59 are provided. Tests have demonstrated particularly that significantly less force is required to start the bending and collapsing action which occurs at the slot 55 when the member 13 is under compression of a magnitude developed in case of a fire for example. Apparently, under these conditions, the forces of compression are concentrated at the single notch 59 in such a way that collapsing begins to occur sooner than if a plurality of notches are used according to conventional practice even though some tearing of the metal at the corners of the notch must occur in order for the bending action to progress. The single notch 59, when located as shown and described, concentrates the forces of compression in the T-member 13 in such a way that bending always occurs first at the notch. The portion of the member 13 below the notch 55 begins to fold downwardly into a V-form as shown by broken lines in FIG. 1, and it continues to collapse in this manner as long as the forces of compression continue to build up in the member. Thus, the single notch 59 provides a construction that is desirably normally stronger and more rigid than a similar construction having more than one notch but unexpectedly yields more readily to initial bending. This assures a more effective control of the collapsing action under fire conditions and maintains the integrity of the ceiling for a longer time than otherwise would be the case.
As shown in FIGS. 1 and 3, the splicer 29 is substantially S-shaped in vertical cross section and includes a vertical web 61 adapted to overlie the vertical flange 15 of the main grid 13 and a lower horizontal flange 63 which seats against the horizontal flange 19. The splicer 29 is secured to the main grid members 13, 21 by butterfly type clips 65, 67, 69, 71, 73 which are receivable in key-shaped openings 75, 77, 79 in the vertical flange 15 and key-shaped openings 81, 83 in the vertical flange 23. Conveniently, the butterfly clips 65, 67, 69, 71, 73 are struck out from the splicer web 61 and are formed by a punching operation during formation of the splicer 29.
The key slots 75, 77, 79 in the vertical web 15 are oriented oppositely with respect to the key slots 81, 83 in the vertical web 23 to permit easy assembly of the parts. Thus, after the splicer 29 is mounted on the main grid 13 with the clips 65, 67, 69 in place in the key slots 75, 77, 79, the main grid 21 is brought to position the clips 71, 73 in the slots 81, 83. The clips 65, 67, 69, 71, 73 and the slots 75, 77, 79, 81, 83 are of course positioned so that when the main grids 13, 21 are in end-to-end abutting relation, the clips and slots obtain as shown in FIG. 1.
In accordance with the present invention, the slot 55 is positioned between two of the key slots 75, 77, 79 and adjacent one end of the main grid 13. In addition, the key slots 75, 77 on one side of the slot 55 are considerably longer than the key slot 79 on the other side of the slot 55. The key slots 81, 83 in the main grid vertical flange 23 are substantially the same size as the key slots 79 so that when the parts are assembled as shown in FIG. 1, the clips 69, 71, 73 are precluded from further longitudinal movement in their key slots 79, 81, 83 while the clips 65, 67 and their slots 75, 77 can move longitudinally relative to each other. Thus, when the main grid 13 thermally expands, the abutting ends of the main grid members 13, 21 are held intact while the slot 55 collapses and the vertical flange portion 57 and the horizontal flanges 17, 19 bend as shown in dot-dash lines in FIG. 1. During this time, the clips 65, 67 and their slots 75, 77 slide longitudinally relative to each other. It will be understood that the other end (not shown) of the main grid member 21 can be formed similarly to the illustrated end of the main grid 13 to control and confine expansion thereof.
In addition to holding the main grids 13, 21 together, the splicer 29 controls the direction of bending of the vertical flange portion 57 and the horizontal flanges 17, 19. As shown, the splicer flange 63 seats against the grid horizontal flange 19 so that during heat expansion of the main grid 13, the flange 19 cannot bend upwardly. As described, the ceiling panels (not shown) which are in place in the grid system prevent lateral bending thereof so that bending must take place in a downward direction as shown by the dot-dash lines in FIG. 1. In this way, the supported ceiling panels can remain in place in the grid system for a longer time, sincedownward bending of the horizontal flanges 17, 19 will not unseat them, and a fire in the enclosure will be less apt to spread to the overhead structure. Also, where the main grids 13, 21 are used along one side edge of a ceiling so that ceiling panels are in place only on one of the horizontal flanges such as the flange 17, the splicer web 61 lends support to the main grid 13 on the other side and prevents lateral bending thereof.
During heating of the main grid members 13, 21, as during a fire, for example, some elongation occurs along substantially the entire length thereof. To accommodate this, the tabs 47, 49 on the cross grid members 31, 33 are relatively flexible so that they can bend laterally with elongation of the main grid members 13, 21 and hold the ceiling panels supported thereon in place. Flexibility of the tabs 47, 49 can be enhanced by cutting a slot 85 in the vertical webs 35, 37 of the cross grids 31, 33. In any event, unit elongation of the main grids 13, 21 between cross grids 31, 33 is not so great as to pose a serious problem and the flexibility of the tabs 47, 49 is sufiicient to maintain integrity of the system during a fire.
It will' be seen that by the present invention there is provided an improved grid member assembly for a ceiling grid system which controls and confines heat elongation thereof to a particular area thereof and while a preferred embodiment of the present invention has been illustrated and described above in detail, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention as encompassed by the appended claim.
What is claimed is: A control expansion grid member assembly comprising a pair of main T-members butted end-to-end and each having a vertical flange and horizontal bottom flanges, one of said T-members being provided in its vertical flange and adjacent the butted end thereof with a cut-out area which extends downwardly from the upper edge of the flange to a point adjacent to said horizontal flanges, the bottom of said cutout area being spaced above said horizontal flanges to define a relatively narrow portion of said vertical flange between the bottom of the cut-out portion and said horizontal flanges which serves a strengthening and stiffening function, said relatively narrow vertical flange portion having a generally V-shaped notch therein intermediate the sides of said cut-out area, whereby thermal expansion of said T-member causes the portion thereof below said cut-out area to fold downwardly in a V-shape with the apex of the fold at said notch, a splicer bridging the joint between said main T-members and extending across said cut-out area, and clip and slot means fastening said splicer to the vertical flanges of said T-members, certain of said clip and slot means being at the side of said cut-out area remote from the butted end of said one T-member and the slot portions of said certain clip and slot means extending from the clip portions thereof in a direction away from said cutout area to permit said one T-member to move relative to said splicer and into said cut-out area under thermal expansion conditions, the portion of said splicer extending across said cut-out area being provided with means for attachment of a cross T-member the remote side of said cut-out area extending transversely of the T-member in substantially a straight line from the bottom of said area and said cross T-member attachment means being located generally in-line with said V-notch and disposed a substantial distance from said remote side of said cut-out area.
References Cited UNITED STATES PATENTS EDWARD C. ALLEN, Primary Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3142367 *||Feb 16, 1962||Jul 28, 1964||Donn Prod Inc||Controlled expansion structural beam and grid structure including same|
|US3189138 *||Oct 24, 1961||Jun 15, 1965||Eastern Prod Corp||Ceiling construction|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3782055 *||Jan 27, 1972||Jan 1, 1974||Trend Ceilings Syst Co||Expansion joint assembly for ceiling grid system|
|US4128978 *||Apr 11, 1977||Dec 12, 1978||Ceiling & Drywall Products Limited||Controlled expansion suspended ceiling grid beam|
|US4206578 *||Jul 31, 1978||Jun 10, 1980||Donn Incorporated||Grid tee for suspension ceilings or the like|
|US4335973 *||Mar 20, 1981||Jun 22, 1982||Armstrong World Industries, Inc.||Runner splicer bar|
|US4422272 *||Dec 4, 1980||Dec 27, 1983||Lok Products Company||Cosmetic cover for channelled type grid systems|
|US4785595 *||Jan 29, 1988||Nov 22, 1988||Chicago Metallic Corporation||Fire-rated main runner|
|US6729100||Apr 30, 2002||May 4, 2004||Usg Interiors, Inc.||Main tee splice|
|USRE31528||Nov 12, 1981||Mar 6, 1984||Donn Incorporated||Grid tee for suspension ceilings or the like|
|U.S. Classification||403/28, 52/DIG.500, 52/506.7, 403/300|
|International Classification||E04B9/08, E04B9/12|
|Cooperative Classification||E04B9/122, E04B9/068, E04B9/08, Y10S52/05|
|European Classification||E04B9/08, E04B9/12B, E04B9/06F2D|