Info. on old C-channel steel joists?

[zstructural]

I'm analyzing an existing structure that has what appears to be cold-formed steel joists. They are 8" deep, with a 2" flange width, and a return lip, similar to standard SSMA joists/studs. The odd thing is that the punchouts are spaced 6" o.c. The punchouts are "football" shaped - 4.5" wide (along the joist's length) and 2.5" high. There is only 1.5" between punchouts, along its entire length.

I'm wondering if anyone has any design information on these joists? How do I analyze these joists to determine their capacity?

Thanks!

 

[ishvaaag]

A photo or sketch might help. In any case the capacity may be analyzed by cold formed steel codes such AISI. You can also get appraisal of the capacity by modeling the geometries with 3D able analysis programs, modeling the plates themselves and introducing some initial imperfections. RISA-3D, Algor Simulation could be informative on that. Models can be drawn in Autocad, Spaceclaim, respectively.