Seismic adapter

Abstract

A seismic adapter for attachment to a steel web joist. The joist includes a pair of angled elements which extend parallel to one another with a cord space therebetween. The adapter includes an anchor plate juxtaposed with the upper surface of the element pair and an engagement plate engaging the parallel edges of the legs of the element pair. A threaded stud attaches to the anchor plate and extends through the engagement plate. The extension of the stud provides for the attachment to a hanger adapter brought together by a nut on the stud. The engagement plate includes a flat anchor portion and upstanding engagement portions having distal edges with interlocking engagement profiles including a tongue and outwardly extending shoulders to receive the parallel edges of the angle element pair.

What is claimed is:  
     
         1 . A seismic suspension system comprising 
 a steel web joist including a beam with two angle elements, each having a first leg and a second leg, the first legs being parallel with a cord space therebetween and the second legs extending in opposite directions;    an anchor plate extending across the cord space and in juxtaposition with each second leg and including a first hole therethrough;    an engagement plate including a flat anchor portion having a second hole therethrough and upstanding engagement portions to either side of the flat anchor portion, the engagement plate extending across the cord space opposite the anchor plate, each upstanding engagement portion being at an obtuse angle substantially greater than 90° to the flat anchor portion and having a distal edge with an engagement profile abutting and being in interlocking engagement with the first legs;    a stud extending from the first hole to and beyond the second hole, the stud being adapted to secure the anchor plate and the engagement plate to the beam of the steel web joist.    
     
     
         2 . The system of  claim 1 , the stud being threaded and the anchor plate being a square flat plate with the first hole therethrough being centrally positioned and threaded to engage the threaded stud.  
     
     
         3 . The system of  claim 1 , each engagement profile including a tongue extending between the first legs of the steel web joist in the cord space and shoulders to either side of the tongue.