Steel Floor Joist Bridging

[ATSE]

Consider an electrical room inside a larger industrial area. That is, room is "self-standing" with stud wall terminating below the ceiling (not at the floor or structural roof above).
Walls and ceiling are cold formed steel, Cee shapes.
Ceiling is 8" tall Cee shape spanning 18'. It has 9/16" Vercor metal deck on top of joists, bracing top flange with #10 SMS at 24" oc.
5/8" type X gypboard fastened to btm flange at 12" oc.
Walls are 6" tall Cee shape, 11' tall, with gypboard both sides.
A cold formed manufacturer's design guide that recommends bridging at third points (6' from each wall for this case).
If the top flange and bottom flange are fully braced at no more than 24", what benefit is bridging?
Is this a 2007 AISI code requirement, or a good idea, or a waste of time and money, or a miscommunication in the design guide?

 

[hokie66]

If nothing else, the bridging would be a safety aid during construction. Cold formed members are flimsy out of plane and can easily twist without the required bracing. Put it in.

 

[msquared48]

Not installing it, when it is a requirement of the manufacturer, will void the warranty for the joists. Your call...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ATSE]

I am thinking that the cold formed manuf is showing bridging for a floor, where the floor is a 1st story raised floor where no sheathing is below. The document is from SSMA - a collective of manufacturers. Their technical documents are fairly useful, but here they are vague regarding bridging.
For no sheathing below, bridging is certainly required - just like roof joists. But for an elevated floor, like 2nd story or ceiling with access above, seems like no benefit.

 

[MiketheEngineer]

And don't step on unbraced C-sections - unless you like falling!!