Interstitial Seismic Resistant Support for an Acoustic Ceiling Grid

Abstract

Ceiling suspension system including a plurality of rigid, elongated seismic joists interposed between opposing walls of a room, spaced selected distances apart along a horizontal support plane, and hangers suspended from the respective joists to support a grid from the respective lower ends thereof.

I claim: 
     
         1 . A seismic suspension apparatus to suspend a ceiling grid between a first wall and a second wall that is not perpendicular to and is spaced a distance apart from the first wall comprising:
 a ceiling grid;   a first track supported from the first wall;   a second track supported from the second wall;   wherein the first track and the second track are positioned to open toward one another;   a plurality of transversely projecting metal seismic joists spaced apart along the first track and second track, each of said seismic joists comprising a tubular steel beam;   a plurality of transversely projecting metal conventional joists spaced apart along the first track and second track;   a plurality of seismic hangers, each of which comprises a metal hanger bracket rigidly affixed to a metal rigid lever arm projecting downwardly from the metal hanger bracket;   a plurality of conventional hangers;   wherein each of said metal hanger brackets is attached by a slack-free connection to one of the respective seismic joists and each of the downwardly projecting rigid lever arms is affixed to the ceiling grid; and   wherein each of said conventional hangers are attached to one of the respective conventional joists and is affixed to the ceiling grid.   
     
     
         2 . The seismic suspension apparatus of  claim 1  wherein at least one conventional joist is positioned between each seismic joist. 
     
     
         3 . The seismic suspension apparatus  claim 1  wherein each of the seismic joists further comprises a box beam. 
     
     
         4 . The seismic suspension apparatus of  claim 1  further comprising a cable tray affixed above one or more of the respective seismic joists and conventional joists. 
     
     
         5 . The seismic suspension apparatus of  claim 1  wherein the seismic joists are at least six feet in length. 
     
     
         6 . The seismic suspension apparatus of  claim 1  wherein each of the conventional joists further comprises a C-channel support joist. 
     
     
         7 . The seismic suspension apparatus of  claim 1  further comprising:
 a plurality of ceiling tiles; 
 wherein one of the plurality of ceiling tiles is inserted into and supported by the ceiling tile grid. 
 
     
     
         8 . A seismic suspension apparatus to suspend a ceiling grid between a first wall and a second wall that is not perpendicular to and is spaced a distance apart from the first wall comprising:
 a first track supported from the first wall;   a second track supported from the second wall;   wherein the first track and the second track are positioned to open toward one another;   a plurality of transversely projecting metal seismic joists spaced apart along the first track and second track, each of said seismic joists comprising a tubular steel beam;   a plurality of seismic hangers, each of which comprises a metal rigid lever arm attached by a slack-free connection to one of the respective seismic joists and projecting downwardly from the respective seismic joist; and   wherein each of said seismic hangers is rigidly affixed to the ceiling grid.   
     
     
         9 . The seismic suspension apparatus of  claim 8  wherein each of the rigid lever arms further comprises a steel angle. 
     
     
         10 . The seismic suspension apparatus of  claim 8  wherein each of the rigid lever arms further comprises a steel channel. 
     
     
         11 . The seismic suspension apparatus of  claim 8  wherein each of the rigid lever arms further comprises a steel stud. 
     
     
         12 . The seismic suspension apparatus of  claim 8  wherein each of the rigid lever arms is welded to the respective seismic joist. 
     
     
         13 . The seismic suspension apparatus of  claim 8  wherein each of the rigid lever arms is rigidly affixed to the respective seismic joist with self-tapping screws. 
     
     
         14 . The seismic suspension apparatus of  claim 8  wherein each of the plurality of hangers is constructed of steel with a thickness of between 12 and 18 gauge. 
     
     
         15 . A seismic suspension apparatus for supporting a ceiling grid from opposite walls of a room or corridor and having respective spaced apart confronting surfaces and comprising:
 tracks supported from the confronting surfaces of the respective walls and opening inwardly toward one another;   a plurality of transversely projecting seismic joists spaced apart selected distances along the tracks and wherein each seismic joist is constructed of box-shaped steel beams; and   a plurality of hangers formed by vertical steel angles rigidly affixed to and projecting downwardly from the respective seismic joists; and   wherein the plurality of hangers are each rigidly connected to the ceiling grid.   
     
     
         16 . The seismic suspension apparatus of  claim 15  wherein each of the plurality of hangers is welded to the respective seismic joist. 
     
     
         17 . The seismic suspension apparatus of  claim 15  wherein each of the plurality of hangers is rigidly affixed to the respective seismic joist with self-tapping screws. 
     
     
         18 . The seismic suspension apparatus of  claim 15  further comprising:
 wherein each of the plurality of hangers comprises a steel angle having cross-sectional dimensions of at least 2-inches by 2-inches and a thickness of between 12 and 18 gauge steel.