concrete slab inserts sizes

[wicked]

hi
i am a duct designer and i want to specify hanger insert sizes to be embeded in a 7 1/2" slab on 3" metal deck. i need to use 3/8" and 1/2" threaded rod droped thru the deck before the pour. is there a reference standard that will tell me accepable sizing of the upper attachment "insert". the duct reference SMACNA shows typical configurations for strap and rod but no sizes.
thanks

 

[Teguci]

Your insert size should be based on the anticipated load to be hung. Check the manufacturer's website to get allowable loads for their insert product.

Are you sure you want to pre-install? I've seen a few buildings with post installed anchors right next to the pre-installed anchors.

 

[wicked]

the hangers are shop fabricated and should be stronger than the manufactured insert that is placed after the conc pour. our structural eng at this project has required this type of hanger but wont give any details of how to size the bent rod or plate/washer assembly in the slab.