This invention relates generally to arrangements for restraining building elements from perimeter supporting structures. More particularly, this invention relates to methods and components for seismically restraining suspended ceilings from perimeter walls, bulkheads or the like.
Ceilings are typically made from a suspended metal grid of intersecting structural rails, wherein ceiling panels or tiles are laid in or fastened to the grid.
The ceiling grid may run on a single plane with mechanically interlocking rails (e.g. interlocking T-rails) or may be installed on two different levels with a mechanical device connecting the intersecting rails, such as wherein lower furring channels are connected to orthogonal top cross rails with locking keys.
These ceilings may be seismically restrained by connecting their perimeter to an abutting structure, such as a wall or bulkhead. According to this method, horizontal seismic actions within the ceiling system are transferred to the perimeter structure.
‘Perimeter restraint’ requires that every primary and secondary grid member shall have one end fixed (to provide seismic restraint) and the other end floating (to provide seismic isolation) at the perimeter.
As is shown in
For flush-grid ceilings (e.g. ceilings comprising intersecting T-rails), the seismic load path along the grid members is provided by the mechanically interlocking rail connections. Current industry practice involves the use of proprietary perimeter seismic clips 129 as is illustrated in
At the fixed end 121, seismic loads within the ceiling system are transferred to the perimeter supporting structure via the axial stiffness of grid members. At the floating end 120, the ceiling system is seismically isolated from the perimeter structure to avoid unwanted load swaps, as required. Seismic clips prevent the spreading of grid ends and provide stability at ceiling perimeters. Also, seismic clips prevent grid ends from sliding off at the edges. These clips are connected discretely at each terminal end of each grid member. When connecting to a cavity wall (e.g. dry-wall), an additional noggin member 130 is required to be installed within the wall cavity, to provide fixing support for the perimeter clips. This imposes additional labour and material cost and effort.
For the case of ceiling grids having over-crossing rails (e.g. ceilings comprising lower furring channel and orthogonal top cross rail-type grids), the intersections 131 between the upper and lower grid members must be restrained by additional means, as conventional devices such as locking keys are typically designed to provide gravity support only, not lateral restraint.
Failing to restrain grid intersections may result in sliding between intersecting grid members under horizontal loads, which defeats the purpose of seismic restraint, or may result in disengagement of the lower furring channel from the top cross rail and subsequent progressive collapse of the entire ceiling, a phenomenon commonly known as ‘blanket collapse’ which compromises life safety and may result in catastrophic fatalities. Provision for such intersection restraint incurs additional labour and material cost and effort.
It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.
There is provided herein a continuous ceiling perimeter restraint member that acts as both a perimeter trim and a connector for either fixed or floating connections, without requiring additional structural support/backing such as noggins.
For T-rail ceilings, the use of a continuous track rather than discrete clips reduces the number of fasteners required to connect to the perimeter structure. As such, in effect, the perimeter trim, seismic clips, and supporting noggin are integrated into a single, continuous, face-fixed member, saving time and money.
As such, the continuous ceiling perimeter restraint member having integrated connectors allows for fixed or floating connections at the terminal ends of ceiling grid members and which does not require additional support noggins.
For ceilings having top cross rails crossing over furring channels, the ceiling perimeter restraint member provides lateral restraint in both orthogonal directions in the ceiling plane, without the need for lateral restraint at grid intersections.
In essence, the ceiling is restrained in both orthogonal directions only by the lower furring channels, whilst maintaining floating sides, as required. Seismic loads within the ceiling system are transferred to the perimeter structure via the axial, flexural and shear stiffnesses of the furring channels.
As such, the present method of perimeter restraint of ceilings with over-crossing two-way grids eliminates the requirement for additional horizontal restraint at ceiling grid intersections.
Furthermore, the present arrangement provides restraint in both orthogonal directions by the lower furring channel, without relying on the top cross rail, saving time and money.
This arrangement is particularly suitable for restraining ceilings in long corridors, which is generally challenging to achieve by conventional perimeter restraint methods, as the length at which the ceiling can be restrained is limited by the connection capacity at the adjoining wall at the corridor end, whereas according to the present method, a finite seismic mass is attributed to a single furring channel which can be repeated along the length of the corridor, virtually without limitation.
The fixed connection apertures and floating connection slots may provide both floating and fixed connections and may be on both flanges of the track. Furthermore, the unequally sized flanges allow the bottom flange to provide ledge support for the grid, making grid installation easier, and the upwardly-inclined edge of the upper flange prevents the grid member from jamming when sliding back and forth under seismic excitation.
Other ceiling types may be restrained similarly.
According to one aspect, there is provided a seismic restraint system for suspended ceilings, the system comprising longitudinal ceiling perimeter restraint members each having a longitudinal web, a longitudinal bottom flange extending orthogonally from the web, integrally formed fixed connection apertures and floating connection slots orthogonally orientated with respect to the web wherein, in use, a pair of ceiling perimeter restraint members are installed horizontally at opposite sides of a suspended ceiling, the suspended ceiling comprising a grid of intersecting structural rails, each ceiling perimeter restraint member installed with the web attached to a respective adjacent structure with the bottom flange thereof extending away therefrom and with respective ends of the structural rails resting thereatop, wherein each structural rail running longitudinally between the ceiling perimeter restraint members is fixed in place at one end using at least one of the fixed connection apertures and slidably affixed at an opposite end using at least one of the floating connection slots.
The ceiling perimeter restraint member may be installed without additional noggin support therebehind.
Each ceiling perimeter restraint member may further comprise a longitudinal upper flange at an opposite side of the web from the bottom flange and extending orthogonally from the web to the same side as the bottom flange.
The bottom flange may extend beyond the upper flange.
The upper flange may comprises a lip inclined away from the bottom flange.
The upper flange and bottom flange may be spaced apart according to the height of a structural rail such that an end of the structural rail wedges therebetween.
Each ceiling perimeter restraint member may comprise a plurality of punched out tabs, each being orthogonal with respect to the web and the bottom flange.
Each tab may have an outer edge extending beyond the bottom flange from the web.
Each tab may have a respective floating connection slot therealong and at least one fixed connection aperture adjacent to the floating connection slot.
Each tab may comprise a pair of fixed connection apertures.
The pair of fixed connection apertures may locate respectively adjacent to either end of the floating connection slot.
The structural rails may be a flush grid of T-rails and wherein webs thereof are connected to respective fixed connection apertures and floating connection slots.
The bottom flange may have the integrally formed fixed connection apertures and floating connection slots formed therethrough.
The bottom flange may comprise an alternating pattern of at least one fixed connection aperture and floating connection slots.
The bottom flange may comprise a pair of fixed connection apertures between adjacent floating connection slots.
The pattern may be an equidistant pattern.
The structural rails may comprise top cross rails crossing over furring channels and wherein webs of the furring channels are connected to respective fixed connection apertures and floating connection slots.
At least one furring channel may be fixed in place at one end using at least one of the fixed connection apertures and slidably affixed at an opposite end using at least one of the floating connection slots.
Opposite ends of the top cross rails may be left floating away from respective adjacent structures.
According to another aspect, there is provided a longitudinal ceiling perimeter restraint member for seismic restraint of ceilings having a web and an orthogonal bottom flange and integrally formed fixed connection apertures and floating connection slots orthogonally orientated with respect to the web.
The ceiling perimeter restraint member may further comprise a longitudinal upper flange at an opposite side of the web from the bottom flange and extending orthogonally from the web to the same side as the bottom flange.
The upper flange and bottom flange may be spaced apart according to the height of a structural rail such that an end of the structural rail wedges therebetween.
The ceiling perimeter restraint member may further comprise a plurality of punched out tabs, each being orthogonal with respect to the web and the bottom flange and wherein each tab has a respective floating connection slot therealong and at least one fixed connection aperture adjacent to the floating connection slot.
The bottom flange may have the integrally formed fixed connection apertures and floating connection slots formed therethrough.
According to another aspect, there is provided a method of restraining a ceiling comprising top cross rails crossing over furring channels, the method comprising forming a fixed connection to an adjacent structure at one end of at least one furring channel thereof and a laterally-restrained floating connection to a respective adjacent structure at an opposite end thereof and leaving ends of the respective top cross rails spaced away from respective adjacent structures.
Other aspects of the invention are also disclosed.
Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:
A longitudinal ceiling perimeter restraint member 100 comprises a web 101 and a bottom flange 102 extending orthogonally from the web 101.
The restraint member 100 comprises integrally formed fixed connection apertures 103 and floating connection slots 104 orthogonally orientated with respect to the web 101. In the manner illustrated in
The suspended ceiling 105 comprises a grid of intersecting structural rails 106 which may be suspended from ceiling wires 107 attached to adjustable ceiling clips 108 thereof.
Each ceiling perimeter restraint member 100 is installed with the web 101 thereof attached to a respective adjacent structure 109, such as a wall, bulkhead or the like, and with the bottom flange 102 thereof extending away from the structure 109. In the embodiment shown, the structure 109 is a dry-wall comprising face board 112 and vertical supportive wall studs 110 therebehind.
Each structural rail 106 running longitudinally between the ceiling perimeter restraint members 100 rests atop respective bottom flanges 102 at either end thereof.
Furthermore, each structural rail 106 running longitudinally between the ceiling perimeter restraint members 100 is fixed in place (i.e. a fixed perimeter connection) at one end using at least one of the fixed connection apertures 103 and slidably affixed (i.e. a floating perimeter connection) at an opposite end thereof using at least one of the floating connection slots 104.
As is illustrated in
Each ceiling perimeter restraint member 100 may further comprise an upper flange 114 at an opposite side of the web 101 from the bottom flange 102 and extending orthogonally from the web 101 to the same side as a bottom flange 102.
The upper flange 114 may further comprise a lip 115 inclined away from the bottom flange 102. The upper flange 114 and the bottom flange 102 may be spaced apart to accommodate an end of a rail 106 therebetween whilst minimising vertical movement. In a preferred embodiment, the upper flange 114 and the bottom flange 102 are spaced apart according to the height of the rail 106 such that an end of the rail 106 wedges therebetween.
Furthermore, the bottom flange 102 may extend beyond the upper flange 114 and wherein the inclined lip 115 guides the top of the rail 106 in under the upper flange 114 whilst the bottom of the rail 106 slides across the bottom flange 102 orthogonally with respect to the web 101.
Each tab 119 may have a respective floating connection slot 104 therealong and at least one fixed connection aperture 103 adjacent to the floating connection slot 104. Each tab 119 may also comprise a pair of fixed connection apertures 103. Furthermore, the pair of fixed connection apertures 103 may locate respectively adjacent to either end of the floating connection slot 104.
Seismic ceiling restraint using the ceiling perimeter restraint member 100 of the first embodiment is illustrated in
As is illustrated in
In accordance with this embodiment, the bottom flange 102 has integrally formed fixed connection apertures 103 and floating connection slots 104 therethrough. In the embodiment shown, the bottom flange 102 comprises an alternating pattern of at least one fixed connection aperture 103 and floating connection slots 104.
The particular embodiment shown has a pair of fixed connection apertures 103 between adjacent floating connection slots 104. Furthermore, the alternating pattern may be an equidistant pattern.
As is also illustrated in
Furthermore, with reference to
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practise the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed as obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.
The term “approximately” or similar as used herein should be construed as being within 10% of the value stated unless otherwise indicated.
Filing Document | Filing Date | Country | Kind |
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PCT/AU2021/050041 | 1/25/2021 | WO |