Open Web Steel Joist Walkable Ceiling Attachment? 2

[SteelPE]

I am currently working on a project that is under construction and has a “walkable” ceiling applied under the roof structure. The roof utilizes open-web steel joists spaced at 6’-8” o.c.

The are in the process of installing the walkable ceiling today when I get a frantic call from the site in regards to the hanger detail we show on our drawings. We currently show a rod being fit though the bottom chord with a plate washer to distribute the load to the two chord members. We also give a web reinforcing detail for when these loads are applied more than 6” away from a panel point.

The contractor is proposing an alternate detail with a J plate that will be installed on the top chord (see attached). The plate is quite thick; however, it appears as if there will be quite an eccentric load placed on the joist.

I am told that this is a standard detail, but in designing open-web joist systems for 22 years this is the first time I have ever seen the detail (so I don’t think it’s as standard as they think it is). Has anyone used this detail before?

 

[XR250]

Never seen one either and it seems like a bad idea

 

[phamENG]

Might be 'standard' (or, at least, acceptable) for an acoustical drop ceiling grid...not for a "walkable" ceiling. If they want to do something like that, then maybe a steel angle with a large vertical leg between two joists (like an RTU frame) with a hanger coming down from the vertical leg.

You are quite justified in your concentric loading concern. And I'd be skeptical of that 5/16" plate taking the load anyway.

 

[JLNJ]

Looks like a hanger for a small firewater line, not a walkable ceiling.