Unkown Open Web Steel Joist - No Top Chord

[guanorican]

Has anybody come across this type of open web steel joist? See attached. U shape bottom chord, tube web members, and no top chord. At every panel point there is a steel member running perpendicular. Take a look and let me know. I need to figure out the capacity of these joist. I already sent it to SJI and they had no clue. Tks

 

[dik]

I recall the Hambro (sp?) from decades back that didn't have a top chord; it utilised the concrete deck over.

 

[KootK]

Wow, just when you thought you'd seen everything... thanks for sharing this.

Using the deck itself as the top chord is pretty aggressive. I'd be curious to know the erection procedure. All of the joists seem to land at the decking joints so perhaps some of the decking was installed on the ground and the joists were erected at double tee-ish units.

Sadly, I've never seen this system before and so cannot help with identification / evaluation.

Is there a decking lap joint along the length of the joists? You'd think that you'd have to transfer a whack of deck compression there.

 

[ANE91]

For what purpose? I’m assuming that the building owner is contemplating adding/replacing RTUs.

I don’t see “perpendicular members” at every panel point; I only see them every so often, consistent with bridging.

Unless you measure every cross-section and know what kind of steel it is, you’re gonna have a hell of a time figuring this out. Been there; done that.

Ask to load test it with a big bladder and a water pump.

EDIT: Oh, at the top chord. Or whatever that is instead of a top chord.

 

[dik]

They may still be in play...

hambro system at DuckDuckGo

DuckDuckGo. Privacy, Simplified.

duckduckgo.com

 

[jerseyshore]

Thanks for sharing. Never seen anything like this either. Where is this building located? Year built?

I've always said that those pesky top chords are a waste.

 

[guanorican]

Thanks for sharing. Never seen anything like this either. Where is this building located? Year built?

I've always said that those pesky top chords are a waste.

Built in the 1960s in the Chicago suburb area.

 

[guanorican]

For what purpose? I’m assuming that the building owner is contemplating adding/replacing RTUs.

I don’t see “perpendicular members” at every panel point; I only see them every so often, consistent with bridging.

Unless you measure every cross-section and know what kind of steel it is, you’re gonna have a hell of a time figuring this out. Been there; done that.

Ask to load test it with a big bladder and a water pump.

EDIT: Oh, at the top chord. Or whatever that is instead of a top chord.

The client wants to add solar panels to the roof. Yes, I can confirm that at every top panel point there is a perpendicular member running joist to joist

 

[guanorican]

Thank you all for your responses! Greatly appreciated! I will keep looking.

 

[jerseyshore]

Built in the 1960s in the Chicago suburb area.

If Kenny C doesn't have a clue then I'd guess it was a more local supplier. I'd start searching for local shops that were open around that time period.