Unknown Proprietary Steel Joist Identification

[smintun]

I visited a site today to take some field measurements of steel joists in a St. Louis warehouse building built in the early 1960s. The chord profile of the joists is unlike anything I have seen before. The top and bottom chords are composed of bent steel plates as shown in the photo below. Please ignore the wide flange that is welded to the top of the chord member. This was a special case where the chord was cut for catwalk access, but it allowed me to get a good clear photo of the chord section. The web members were all cold formed tubes with un-welded seams.

Has anyone ever dealt with this type of joist before? I assume this was a proprietary design and couldn't find much of anything with a Google search. I am generally looking for some historical joist tables to back out allowable design loads based on field measurements. Any guidance is appreciated.

 

[TugboatEng]

I'm going to guess that it is metal repurposed from another application such as guardrail or sheet pile.

 

[TomLee777]

It looks like a bottom chord so that the web members can be welded in the slot at the middle of the profile. All commercial joists should have a tab on each joist (typically at an end diagonal web member), and that would give you some information.