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.

1 . A seismic suspension system for a web joist, comprising 
 an anchor plate including a first hole therethrough;    an engagement plate including a flat anchor portion having a second hole therethrough and two flat upstanding engagement portions, one to either of two opposed sides of the flat anchor portion, each upstanding engagement portion being at an obtuse angle substantially greater than  900  to the flat anchor portion and having a distal edge with an engagement profile including two shoulders with a tongue therebetween, the tongue and the shoulders defining concavities therebetween;    a stud extending from the first hole and threadably engaged therewith to and beyond the second hole with a threaded engagement beyond the second hole.    
   
   
       2 . The seismic suspension system of  claim 1 , the tongue and the shoulders being tapered to define the concavities as V-shaped concavities.  
   
   
       3 . The seismic suspension system of  claim 1  further comprising 
 a nut threadably engaged with the stud at the threaded engagement.    
   
   
       4 . The seismic suspension system of  claim 1 , each engagement profile having a terminal edge substantially perpendicular to the flat upstanding engagement portion.  
   
   
       5 . A seismic suspension system comprising 
 the anchor plate, engagement plate and stud of  claim 1;     a 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, the anchor plate extending across the cord in juxtaposition with each second leg, the engagement plate being positioned with the first legs extending into the concavities and the stud extending through the cord space to engage the anchor plate and the engagement plate.    
   
   
       6 . The seismic suspension system of  claim 5  further comprising 
 a nut threadably engaged with the stud at the threaded engagement.    
   
   
       7 . The seismic suspension system of  claim 6  further comprising 
 a bracket positioned over the threaded engagement between the flat anchor portion and the nut.    
   
   
       8 . The seismic suspension system of  claim 5 , each engagement profile having a terminal edge substantially perpendicular to the flat upstanding engagement portion.  
   
   
       9 . The seismic suspension system of  claim 4 , the tongue and the shoulders being tapered to define the concavities as V-shaped concavities.