Support Mezz

[JStructsteel]

Anyone ever seen anything like this? Anyone know a manufacture?

Someone wants to use this as a mezz, support a wood floor on it. 2x6's over the top.

 

[mmarlow]

I'm not aware of a manufacturer. It's interesting how the top and bottom chords are completely different profiles Do you know what the prior use of this framing was? What type of loading will go up there? Light storage?

I know this isnt your questuon, and Its hard to see from the photo, but I'd look into the connection from the steel to the wood ledger on the wall.I've never done anything like this, but I find with wood framed decks, the ledger connections can be tough. Depending on your LL, it might be worth checking those connections. The longer spans between the truss carriers could give high reactions.

-MMARLOW EIT

 

[JStructsteel]

From what I understand its a support structure for assembly lines, hanging air, electrical, etc lines.

Its been communicated not a good idea to use. He wants to use the joist between columns to carry the load. Capacity aside, deflection will be the killer (if it stands)

 

[jayrod12]

My opinion on deflection is although it is important to meet requirements, it's not mandatory.

I've had some clients who were hell bent on using something, so I explain to them the drawbacks of not meeting the code prescribed deflection requirements, how the structure is still stable but occupant comfort and potential for damage to finishes will be affected etc. Once they sign off on my discussion with them, I'll let deflection requirements slide to a point.

 

[Ron247]

The vertical connection between "sections" is odd looking. In your first picture, there are 4 of these within 3' of the column. I am assuming it is a completely bolted connection and not a partially welded connection. Note the upper portion has bolts on each side of the top chord but the bottom does not. Unless the bottom chord is welded, I do not see great connection to transfer any bottom chord tension axial force. If that is true, then it appears that the connection locations are intended to have the bottom chord in compression. And if that is true, they may be "modeling" this as fixed over the columns. Again, welding the bottom would change this opinion.

Wonder why they made the diagonals on each side of the top chord not align to each other?

 

[Ron247]

I'll bet some type of really light trolley ran on the bottom chord. That open C-shape looks like a trolley guide. Is the bottom chord cold-formed? Don't look for a truss supplier, look for a trolley supplier.

 

[JAE]

That is a weird joist system. Never seen it before - looked through the "Antiquated Structural Systems" articles from Structure Magazine and nothing matches in there.



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[JStructsteel]

I just wonder if its a custom built one off system?

 

[Ron247]

jrisebo,
I just saw your comment about hanging air line lines and electrical. Based on that, I even more think these were very light loads that moved. You could move your air and electrical as you worked. They would not travel beyond that vertical connection plate that is less than 3' from the column. They were suspended from the bottom chord. Why else have an open channel turned down for a bottom chord? That is a shear connection between the hanging load portion and the portion that is centered over the column. What looks like a round pipe for the top chord may be nothing more than a "snuff can" thickness.

The whole system was possibly designed around very light moving loads. I would not assume the top chord is very thick. I would want to confirm that for sure. It also may be cold-formed.

 

[JStructsteel]

thanks all. I think its a given its not a proprietary system, or if it is, a rare one.

Hopefully the hammer mechanic that wants to support his mezzanine with this will reconsider, or hire the proper engineer to analyze.