Abstract:
A perimeter clip attached to a wall molding that supports a beam in a suspended ceiling intended to survive seismic disturbances. The clip is capable, during an earthquake, of permitting an end of a beam at one end of a connected line of beams, in a grid, to slide while being supported in the clip, or, in the alternative, to secure an end of a beam to the wall molding.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     (1) Field of the Invention  
         [0002]     The invention relates to ceilings capable of surviving seismic disturbances. The ceilings are of the suspended type that have a grid of interconnected metal beams hung from a structural ceiling. Panels are supported in the grid openings.  
         [0003]     (2) Description of the Related Art  
         [0004]     Suspended ceilings have a grid of beams hung from a structural ceiling by wires. Panels are supported in the grid openings. An angle wall molding runs around the perimeter of the ceiling and supports the ends of the grid beams. Such a ceiling is shown in U.S. Pat. No. 4,827,681, incorporated herein by reference.  
         [0005]     The beams are roll formed of strip steel bent, in cross section, into a vertically extending web, horizontally extending flanges at the bottom of the web, and a bulb at the top of the web. The beams are interconnected into a grid. The grid is hung with wires from the structural ceiling, within the vertical walls of the individual rooms of a building. Such walls include structural walls as well as interior partition walls. A wall molding having an angle cross section supports the ends of the beams of the grid. An upper extending leg of the angle forms a face that is fastened against the wall, and the horizontal extending leg of the angle forms a ledge which receives and supports the beams. The end of the beam may simply rest on the ledge, or the beam flange may be secured to the ledge as by a self-tapping screw. The width of the ledge is usually about equal to the width of the beam flange, so, when viewed from below, the visual effect is a pleasing one.  
         [0006]     In some instances, a perimeter clip is used to secure the ends of the beams to the wall molding. Such a clip is shown in U.S. Pat. No. 5,046,294, incorporated herein by reference. Such a perimeter clip is fixed on the wall molding at each end of a line of beams, and an end of a beam at the end of a line is fixed in a clip.  
         [0007]     In a ceiling approved for an installation where a seismic event may occur, it is required that the beams in a grid be allowed to move relative to the side walls. Wires and the angle wall molding were relied on to keep the grid of beams supported in the ceiling, while allowing the beams to slide on the wall molding. To permit a beam to shake while supported on a ledge of a wall molding, seismic building codes often require a minimum two inch ledge on the wall molding to permit the beam end to slide on the ledge, without sliding off the ledge, during a quake. In such seismic codes, one end of a line of connected beams in the grid is required to be fixed to the wall molding; the other end must be free to slide back and forth longitudinally of the line of beams on the two inch ledge. Such a two inch wide ledge, however, is visually incompatible with the rest of the grid ceiling, when viewed from below, since the flanges on the beam are generally less than 1 inch wide.  
       SUMMARY OF THE PRESENT INVENTION  
       [0000]     (1) In General  
         [0008]     The present invention relates to a new use for the perimeter clip of the &#39;294 patent, as modified herein.  
         [0009]     The new use of the modified &#39;294 clip eliminates, in a suspended ceiling subject to seismic forces, the need for a 2 inch wide horizontal ledge on the angle wall molding that supports the ends of the grid beams. The invention permits the use, in such a ceiling, of a wall molding ledge of about ⅞ inch, as is now used in non-seismic ceilings, that is usually compatible with, and in harmony with, the beam flanges, which are visible from below.  
         [0010]     The perimeter clip, as shown in the &#39;294 patent as modified herein, is desirably formed from a single, stamped flat piece of sheet metal, bent into the finished shape.  
         [0011]     The beam end, in a line of connected beams in a grid, is not fixed, or secured, to a perimeter clip at both ends of the line of connected beams, as taught in the &#39;294 patent, but one end of the line of connected beams is free to slide lengthwise of the line, in the clip, in the event of seismic occurrence.  
         [0012]     The clip is in general a right-angle form, wherein one leg of the right angle is hooked over the vertical web of the wall molding and secured to the wall by self-tapping screws, and the other leg of the clip extends at right angles to the wall to receive the end of the grid beam. In the clip of the invention, it is this leg of the &#39;294 clip that is modified to extend from the wall about 2⅜ inches. The beam, at one end, of a line of connected beams, as stated above, and as required by the seismic code, is suitably secured in the clip. In the clip of invention, this occurs by tightening up a self-tapping screw in a slot. On the beam, at the other end of the line of connected beams, the self-tapping screw in the slot is not tightened, and the beam is free to slide in the clip on the screw that serves as a slidable pin, so that the beam is not fixed to the wall molding.  
         [0013]     In the invention, the clip of the &#39;294 patent, with the modification disclosed herein, is used on an angle wall molding, as shown in the &#39;294 patent, that extends around the perimeter of a suspended ceiling. With the clip of the invention, the angle wall molding can have a ledge of about ⅞ inch wide, and still satisfy the seismic code requirements, which generally, as set forth above, require a two inch ledge on the wall molding, to keep the end of a beam from sliding off during a quake.  
         [0014]     In a normal rest position, the flange at the end of the beam end is above, and close to or in contact with the ledge, so that there is a pleasing view from below, with no vertical or horizontal gaps between the beam flange, and the ledge.  
         [0015]     The perimeter clip itself is hidden from view from below by the wall molding, the beam flanges, and the ceiling panels in the grid openings. The clip permits the width of the horizontal ledge of the wall molding to conform to the width of the flanges of the grid beams, to yield a pleasing and harmonious visual effect from below.  
         [0000]     (2) The Modification  
         [0016]     The leg of the perimeter clip of the invention, in which the end of the beam rests, is extended in the &#39;294 clip, to at least 2⅜ inches from the wall, beyond the wall molding ledge. In forming the ceiling grid, a beam is installed in the leg of the clip, with the end that is free to slide, spaced about ¾ inches from the wall, at a rest position. The other end of the line of connected beams is secured to the clip, and is not free to slide. During an earthquake, the end of the beam in the clip of the invention, that is free to move, can move up to ¾ inches away or toward the wall, while still being supported by the perimeter clip of the invention, which is attached to the wall molding.  
         [0017]     Under normal conditions, at a rest position, the ledge of the wall molding continues to provide an attractive covering below the ends of the beams, as well as a covering below the clip, around the perimeter of the room, but the actual vertical support of a beam end, though the beam end is permitted to slide during a quake, is given by the perimeter clip of the invention, which is hooked onto the face of the wall molding.  
         [0000]     (3) The Slot  
         [0018]     The leg of the clip, in which the end of the beam slides during a quake, has a continuous slot that, from the beam rest position, toward the wall, is horizontal, and away from the wall, is inclined. A self-tapping screw is passed through the slot and the beam, piercing the end of a beam, at a right angle thereto. The screw, which acts as movable pin, rides in the slot, and lifts the beam end above the ledge as the beam moves away from the wall during a quake. As the beam moves back toward the wall, in its reciprocating movement during a quake, the beam end clears the edge of the ledge of the wall molding, so there is no interference between the beam end and the edge of the wall molding ledge.  
         [0019]     The end of a line of beams can be fixed in the clip by tightening up the self-tapping screw, in the slot, so that it binds the web of a beam in the extended leg of the clip.  
         [0020]     The slot in the leg forward of the slot mid-position, toward the wall molding face, is horizontal, so that as the beam moves toward the wall in its reciprocal motion during an earthquake shake, the beam end movement is kept horizontal, by the screw, which acts as a movable pin, riding in the slot. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is an isometric exploded view of the clip of the invention, with mounting screws, and a segment of an angle wall molding.  
         [0022]      FIG. 2  is a fragmentary isometric view, illustrating a portion of drywall construction to which a segment of an angle wall molding is secured. The clip of the invention is hooked to the vertical face of the perimeter angle wall molding, in the desired position. One end of a grid beam is inserted into a leg of the clip at its normal rest position, where it is free to slide in the event of a seismic disturbance, or in the alternative, is secured in the clip.  
         [0023]      FIG. 3  is a view similar to  FIG. 2  showing the end of a beam, during a seismic event, at a position toward the wall, from its rest position, where the beam is free to slide.  
         [0024]      FIG. 4  is a view similar to  FIG. 2 , showing the beam end being supported at a position away from its rest position and away from the wall, beyond the ledge of the wall molding, during a quake, where the beam is free to slide. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     As seen in  FIG. 2 , a vertical dry, or plastered, wall  20  is supported from a wood post structure  21 . The wall  20  forms one side of a room within a building and generally extends from the floor to a structural ceiling.  
         [0026]     A suspended ceiling of the grid type as shown, for instance, in the &#39;681 patent referred to above, has a beam  22  in the form of an inverted T. Beam  22  integrally has a flange  23 , a web  25 , and a bulb  26 . Beam  22  is roll formed from a longitudinally extending flat strip bent to form the beam elements. A cover piece  27  is wrapped around the flange  23  of the beam and is painted a desired color. Such beams  22  are well known in the art and are interconnected to form the grid structure for the panels that are laid in the grids.  
         [0027]     An angle wall molding  30  is secured to wall  20  by screws or fasteners  31 . The wall molding  30  extends horizontally along the wall  20  at the desired suspended ceiling height. Wall molding  30  forms an angle in cross section having a wall molding vertical face  32  and a wall molding horizontal ledge  33 . The wall molding  30  is formed of a continuously extending strip bent into folds  35  to form smooth edges, and bent at a right angle along the longitudinal center line to form face  32  and ledge  33 . The face  32  and ledge  33  each are of a width approximately equal to the width of the flange portion  23  of beam  22 , for instance, so when the ceiling is in place, the wall molding ledge  33  and flange portion  23  are uniform in appearance.  
         [0028]     The beam  22  does not have an offset portion as taught in the &#39;294 patent, since this would interfere with the free sliding of the beam  22  in the clip  40 , as described later, during an earthquake.  
         [0029]     The perimeter clip  40  of the invention is used to firmly secure the end of beam  22  to wall molding  30  at one end of the beam  22 , in a line of connected beams, and to slidably support end of the beam  22  at the other end of the line, independently of wall molding ledge  22 .  
         [0030]     The perimeter clip  40  of the invention is that shown in the &#39;294 patent, with modifications.  
         [0031]     Clip  40  is in the form of a right angle having legs  41  and  42 . Leg  41  is of a single thickness of sheet metal and has a tab or ear  43  lanced out in a U-shape with the top of the U at  45  remaining integral with leg  41 . Holes  44  receive screws  79 . A space, slightly smaller in thickness than the thickness of face  32  of wall molding  30  is formed by tab  43 .  
         [0032]     Relatively small, pointed barbs  47  are lanced on each side of the tab  43 . The points of barbs  47  are pointed upward in the clip. Leg  41  is generally rectangular in shape. An edge of leg  41  has extending therefrom one opposing web  52  of leg  42 . Web  52  has at its top thereof, offset  53 .  
         [0033]     Leg  41  has formed at the top thereof bent portion  60  extending toward leg  42 . Section  61  of portion  60  has an edge  62  that is connected to opposing web  63  of leg  42 . Web  63  has an offset portion  65  corresponding to offset  53  on web  52 .  
         [0034]     A slot  70 , extends in leg  42 . The slot  70  extends through both sides of leg  42 , in registry. The slot can be, for instance, {fraction (3/16)} inch wide.  
         [0035]     The slot has a combined length of about 2 inches, with a 1 inch long horizontal segment  91  forward from the mid-rest position  90 , and a one inch long inclined segment  92  rearward from the rest position  90  and the wall  20 . The inclined segment  92  of the slot  70  can, for instance, rise a distance of about ⅜ inch over its length to provide the required rise and fall for the flange  23  on the beam  22  to clear the ledge  33  on the angle wall molding  30  as beam  22  slides back and forth during an earthquake.  
         [0036]     In the clip  40  of the present invention, the length of the leg  42 , in the direction normal to leg  41 , is about 2 and ⅜ inches, whereas, in the clip of the &#39;294 patent, the length of leg  42  was not critical, in that there was no concern with a sliding beam during an earthquake. In the &#39;294 patent, the beam  22  was secured in clip  40  at both ends of a line of connected beams  22 , preventing any movement of the line. The present invention does not secure the beam  22  at one end of a line of connected beams, so that the end of the beam  22 , and thus the line of connected beams, is free to slide at one end of the line with respect to the wall molding  30  during a quake, and still be supported on the wall molding  30 . The leg  42  of the clip that supports the end of the beam is extended to about 2⅜ inches to support the end of the beam during the sliding that results from the quake.  
         [0037]     As with the &#39;294 clip, the perimeter clip  40  of the invention is applied to the vertical face  32  of wall molding  30  by snapping tab  43  downward on the face until barbs  47  ride over upper fold  35  and, tab section  45  rests on the upper fold  35 , as seen, for instance, in  FIG. 2 . Self-tapping screws  79 , as seen in  FIG. 1 , secure the clip  40  through holes  44  to board  20 , so the clip  40  cannot move horizontally along the wall molding  30  at rest or during a quake.  
         [0038]     Clips  40  are positioned along the angle wall molding  30  at points predetermined by the intended position of the suspended ceiling grid. For instance, where the beams  22  are interconnected to form a 2 foot×4 foot grid, the clips  40  will be spaced at 4 foot intervals along one set of opposing walls, and at 2 foot intervals on the other set of opposing walls, in a rectangularly shaped room.  
         [0039]     The end of the beam  22  is inserted into a clip  40  as seen in  FIG. 2 . Web  25  of beam  22  is inserted between opposing webs  52  and  63  of leg  42 , and bulb  26  of the beam engages opposing ofsets  53  and  65 . The webs  52  and  63  are so spaced from one another as to provide a snug, springy fit about the beam. The end of the beam  22  is held by the clip  40  above the ledge  33  of wall molding  30  so that virtually no weight of the beam  22  rests on the ledge  33 . The end of beam  22 , as seen in  FIG. 2 , is inserted into the clip  40  as described above, so that it rests at a position about ¾ inch away from the vertical face  32  of molding  30 . As seen in  FIG. 2 , a self-tapping screw  71  is inserted through the slot  70  in web  63  of leg  42 , into web  25 , at the end of beam  22 . The screw  71  pierces through the web  25  of beam  22  and then out through the slot  70  on the other web  52  of leg  42 . The screw  71  has a diameter slightly smaller than the width of slot  70 , so that the screw is free to travel along the slot during a quake, in the form of a sliding pin, as will be described. The screw  71  is not tightened at the end of the beam that is intended to slide.  
         [0040]     In the event that it is desired to fix and secure the end of beam  22  in the clip  40 , as discussed above, it is simply necessary to tighten screw  71  so that it fixes the beam  22  to the clip  40 .  
         [0041]     During an earthquake, the end of a line of connected beams  22  that is fixed in a clip  40 , by tightened screw  71 , will not move relative to molding  30  and wall  20 . However, at the other end of the line of connected beams  22 , the end of beam  22  is free to slide in clip  40 , since screw  71  is not tightened. The movement of the end of beam  22  in clip  40  is a reciprocal one, forward toward the wall from rest position  90 , and rearward from the wall and away from rest position  90 .  
         [0042]     As the end of beam moves toward the wall from rest position  90 , as seen in  FIG. 3 , it is supported in the horizontal segment  91  of slot  70  by screw  71 , and its movement remains horizontal. As the end of beam  22  reciprocates rearward, away from the wall  20 , it travels again in a horizontal movement, until screw  71  reaches mid-position  90 , at which point the end of the beam  22  is elevated as it moves toward its outermost position as shown in  FIG. 4 . In the segment  92  of the slot  70 , the end of beam  22  is elevated as it moves beyond the ledge  33  of molding  30 , as seen in  FIG. 4 .  
         [0043]     As the end of beam  22  reverses direction and travels back toward the wall  20  and molding  30 , the flange  27  on beam  22  is lowered until it reaches the rest position  90  as seen in  FIG. 2 . The action then repeats as the seismic event continues.  
         [0044]     The action of the clip in elevating the end of beam  22  as it travels beyond ledge  32  of molding  30 , as seen in  FIG. 4 , prevents interference between the beam and molding during the quake.