Hi there, was on a site this week with OWSJ framing between larger steel trusses. The joists support a v-pan and concrete roof slab. Pictures are attached. Apparently, this was built in the 80's. For context, the joists are 12" deep @ 2' spacing, and the trusses are 5' deep @ 8' spacing.

I haven't seen this framing combination that I can recall. Would the concrete be designed to span one way between the OWSJ or would they be there to support the roof when it's curing and now the slab spans 2 ways?

Also, any thoughts on what the plastic mesh under the v-pan is for?




Thanks!