Adjustable Ceiling Strut

Abstract

Office buildings commonly have a false ceiling comprising a grid of inverted T-shaped runners, a plurality of ceiling panels insertable in the grid and supported thereby, and vertical and diagonal wires suspending the grid from a true ceiling. The present invention provides a telescopic strut running from the true ceiling to a runner in the false ceiling, and having a slot on the lower end which engages the runner. Means are provided for fixing the length of the telescopic strut after the runner has been engaged by the slot so that the strut prevents vertical translation of the ceiling during seismic disturbances.

Description

BACKGROUND OF THE INVENTION

The present invention relates to false ceiling assemblies, and in particular to means for preventing vertical translation of a false ceiling during an earthquake.

It has become quite common of office buildings to provide a false ceiling beneath the true ceiling to hide the presence of heating ducts, electrical wires, and other unsightly features. These false ceilings usually comprise a grid of inverted T-shaped runners with a plurality of ceiling panels, usually light-weight sound insulative materials, insertable in the grid and supported thereby. Flourescent lighting fixtures and heating ducts are also usually supported by the grid. The grid is suspended from the true ceiling by wires, some of which run diagonally from the true ceiling to the grid to prevent swaying of the false ceiling. This type of ceiling is light, easy to construct, absorbs noise and hides unsightly structural features in the building and is thus quite popular.

The false ceiling construction described above exhibits an undesirable tendency during an earthquake, namely, the diagonal wires induce an exaggerated vertical translation of the ceiling. The vertical translation of the ceiling is actually accentuated by the diagonal wires, which induce a snapping up and down motion in the false ceiling when the building sways back and forth. The vertical translation of the ceiling dislodges the ceiling panels, including the light fixtures, from the grid, causing them to fall. Since the diagonal wires accentuate the effect of swaying motion of the building, even a slight earth quake is sufficient to cause the ceiling panels and light fixtures to fall.

Allowing the light fixtures and heating ducts to fall presents an extreme danger to persons in the building. Allowing the ceiling panels of insulation material is also a serious problem, since a major cause of death to persons trapped in a building after an earthquake is suffocation from dust caused by parts of the building falling. This problem is greatly accentuated when a false ceiling is used and the ceiling panels are allowed to fall since a large volume of dust will have collected on the false ceiling. Also, the psychological trauma induced by having the ceiling fall, even in a minor earthquake, can result in severe emotional distress to sensitive individuals.

SUMMARY OF THE INVENTION

The present invention provides a simple structural device which can be used in combination with current methods of constructing false ceilings. A hollow cylindrical rod has an upper end adapted to abut the true ceiling. A hollow square sleeve fits slidably over the lower end of the rod, and has a slot in its lower end adapted to engage a runner in the false ceiling. A set screw is provided which prevents relative sliding of the sleeve and the rod after the runner has been engaged by the slot, so that the false ceiling cannot translate vertically. In combination with the diagonal wires, the present device also prevents lateral translation of the false ceiling relative to the true ceiling.

The present invention provides a simple means for rigidly inter-connecting the false ceiling and the true ceiling. This prevents the exaggerated vertical motion of the false ceiling which is induced by the diagonal rods as the false ceilings are presently constructed. The false ceiling merely sways from side to side along with the true ceiling. By reducing the exaggerated motion of the false ceiling, there is less likelihood of the light fixtures falling, or the other ceiling panels becoming dislodged. Hence, the false ceiling is far safer during seismic disturbances, but does not lose the advantages of current false ceiling construction.

By providing a square sleeve overlying a cylindrical rod, a telescopic strut is provided which can be easily manufactured without a requirement for close tolerances. If two overlying cylindrical members or two overlying square members were used, there would be much difficulty in controlling the tolerances of the two pieces to allow them to slide with respect to each other without becoming jammed together. Using a cylindrical rod with an overlying square sleeve minimizes the frictional surfaces between the two members so that the members will not jam even if cruedly constructed. Hence, the struts can be manufactured quite inexpensively with little concern over close tolerances.

By utilizing a hollow rod, the rod can be easily jammed into the insulation usually found on the true ceiling so that the rod does not become dislodged. The slot on the lower end of the square sleeve fits over the vertical portion of the runner so that the runner is firmly engaged by the strut and does not become dislodged during an earthquake. Since the strut is hollow, it can be placed over a vertical support wire to further insure that it will not become dislodged. Only a few such struts are required to prevent movement of the false ceiling during earthquake, and use of one strut for every 150 square feet of ceiling has been found quite acceptable. Hence, the cost of using the struts of the present invention in the construction of a false ceiling is minimal, both in the cost of the strut itself and the effort involved in placing the strut in position.

The novel features that are believed to be characteristic of the invention, both as to organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purposes of illustration and description only and are not intended as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the ceiling strut of the present invention utilized with a standard false ceiling.

FIG. 2 is a top view of the ceiling strut illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The use of the present invention in a traditional false ceiling construction is illustrated by way of reference to FIG. 1. The false ceiling comprises a grid of inverted T-shaped runners 10. Ceiling panels (not shown), including rectangular sections of acoustic material and rectangular fluorescent light fixtures, are supported by the outwardly flanged lower portions 12 of runners 10. The ceiling panels are merely placed on flanges 12, and are not fixed to the grid of runners 10 in any manner. Runners 10 are suspended from the true ceiling 14 by means of a plurality of wires. The basic support for the grid of runners 10 is provided by vertical wires 16 which are attached to runner 10 and connect to eyelets 18 in the true ceiling. In order to prevent lateral motion of the false ceiling during very minor disturbances, such as a person walking across the floor above, oppositely directed diagonal wires 20 and 22 are also provided for support of runners 10.

When true ceiling 14 sways back and forth, such as during an earthquake, diagonal members 20 and 22 attempt to prevent lateral swaying of the false ceiling. However, during such a major disturbance, movement of the false ceiling will cause the runners 10 to rotate about one or the other of the diagonal wires 20 or 22. When the ceiling sways in one direction, wire 22 will be tensioned, and when the ceiling sways in the other direction, wire 20 will betensioned. Thus, swaying of the true ceiling 14 back and forth will alternately tension wires 20 and 22. The transferral of tension from on diagonal wire to the other oppositely directed diagonal wire will cause runner 10 to be snapped up and down. Hence, swaying of true ceiling 14 traditionally results in an exaggerated vertical up and down motion in runner 10.

The present invention provides a telescopic strut 24 adapted to prevent vertical movement of the grid of runners 10 relative to true ceiling 14. Strut 24 has a cylindrical upper portion 26 which is merely jammed into insulation 28 on the underside of true ceiling 14. Cylindrical portion 26 is preferably hollow so that it becomes firmly embedded in insulation 28, and can be fitted over one of the vertical wires 16, insuring that the strut cannot become dislodged. A rectangular sleeve 30 overlies cylindrical portion 26 and forms the lower portion of telescopic strut 24. Sleeve 30 has a slot 32 in the lower end thereof adapted to fit over the vertical portion of runner 10. A set screw 34 is threaded through a corner of the rectangular sleeve 32 and is adapted to engage cylinder 26 to lock the strut 24 at the desired length.

The construction of telescopic strut 24 is further illustrated by way of reference to the top view of FIG. 2. Sleeve 30 overlies cylindrical portion 26, with the interior surfaces of sleeve 30 in contact with the outer surfaces of cylindrical portion 26. In this manner, sleeve 30 and cylindrical portion 26 are in frictional contact so that sleeve 30 will not normally slide with respect to cylindrical portion 26 in the absence of an external force. However, since sleeve 30 is rectangular and cylindrical portion 26 is circular, the surfaces thereof in mutual contact are minimal, thus preventing the possibility of sleeve 30 becoming jammed relative to cylindrical portion 26. However, sufficient frictional force is available to prevent sleeve 30 from loosely sliding relative to cylindrical portion 26.

Set screw 34 is threaded through a corner of sleeve 30. Hence, a space is provided between the aperture through sleeve 30 for the set screw 34, and the contact of the tip of the set screw with cylindrical portion 26. Hence, set screw 34 can be fully engaged with sleeve 30, projecting completely through the aperture in the sleeve, without necessarily contacting cylindrical portion 26. This allows set screw 34 to be threaded completely through sleeve 30 prior to use of telescopic strut 24 so that there is little likelihood of the set screw becoming disengaged.

In operation, a grid of inverted T-shaped runners 10 is suspended from true ceiling 14 in the traditional manner. Telescopic strut 24 is then simply added to the traditional false ceiling construction. Cylindrical portion 26 is first jammed into insulation 28 on the underside of true ceiling 14. Rectangular sleeve 30 is then slid downwardly along cylindrical portion 26, and rotated if necessary, until slot 32 engages the top of runner 10. After sleeve 30 is in position, set screw 34 is turned until cylindrical portion 26 is engaged, thus locking telescopic strut 24 in the extended position. If the strut 24 is to be placed over one of the vertical wires, the strut must be slipped over the wire before attaching the wire to the grid. With telescopic strut 24 locked in position, vertical translation of the false ceiling is prevented. Since the false ceiling is supported by diagonal wires 20 and 22 as well as vertical wires 16, the false ceiling is firmly locked in position relative to true ceiling 14.

The present invention can be used with the traditional method of constructing false ceilings without interfering with that method. The telescopic strut of the present invention cooperates with the traditional wire suspension of the false ceiling to rigidly interconnect the false ceiling with the true ceiling. Use of one strut for every 150 square feet of ceiling has been found quite acceptable, so that use of the present invention adds little to the effort involved in constructing a false ceiling.

While a preferred embodiment of the present invention has been illustrated above, it is apparent that modifications and adaptations of that embodiment will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention, as set forth in the following claims.

Claims

I claim:

1. In a false ceiling comprising a grid formed of a plurality of inverted T-shaped runners, a plurality of ceiling panels insertable in the grid and supported thereby, and wires suspending the grid from a true ceiling, the improvement comprising:

a telescopic strut comprising a hollow cylindrical rod having an upper end adapted to abut the true ceiling and a hollow square sleeve adapted to end fit slideably over the lower end the rod in continuous frictional contact therewith, said sleeve having a slot spanning the width of the lower end thereof and adapted to engage one of the runners; and

means for fixing the length of the telescopic strut after engaging the runner with the slot,

whereby vertical translation of the false ceiling during seismic disturbances is prohibited.

2. A false ceiling as recited in claim 1 wherein the means for fixing the length of the telescopic strut after engaging the runner with the slot comprises a set screw threaded through a corner of the square sleeve and adapted to engage the rod to prevent relative sliding therebetween.

3. A false ceiling as recited in claim 1 wherein at least one of the wires suspending the grid from the true ceiling is vertical, and wherein the telescopic strut is hollow and is adapted to be placed over said vertical wire.

4. In a method for constructing a false ceiling comprising suspending a grid of inverted T-shaped runners from a true ceiling by means of vertical and diagonal wires, and inserting a plurality of ceiling panels in the grid to support said panels in said grid, the improvement comprising: placing a telescopic strut over one of the vertical wires intermediate the grid and the true ceiling, fastening said one vertical wire to the grid and the true ceiling prior to extending the telescopic strut, extending the telescopic strut to engage both the true ceiling and one of the runners of the grid, and locking the telescopic strut in the extended position to prevent vertical translation of the false ceiling.