RC slab supported on steel columns mid height 2

[nivoo_boss]

Hey everyone!

I'm designing an RC slab that is preferably 220 mm thick and is supported by RHS steel columns mid height. All the columns are at the edges of the slab, the mid columns don't continue through the slab. Now I know punching shear is probably the most important aspect of the slab design on mid columns, but what about the areas on edges where the columns should support the slab?

The first issue is - how should I model it? Should the joint be pinned where the slab is supported mid columns? I'm not even sure how to input that into to the model. When detailing it as something I drew below, it should be pinned.

This a screenshot from the model:

And this is sketch of the detail. I've seen something like this before.

As for the column, is it correct to assume that shear is transferred to column via this compression strut I sketched? How should the L bracket be designed?

 

[nivoo_boss]

"I was thinking of this mechanism. Once you commit to the angles supporting the vertical load, I feel that logic has to be carried through the entire connection, creating the need for an HSS wall buckling check as shown. It sort of depends on whether you see the slab pushing against the top of the angle or pulling away from it. I'm thinking the latter in light of the potential for hogging moments."

I don't know, the RC slab is so stiff in bending I can't see it acting this way to the L bracket. The rotation would be minimal, nearly all shear should go the welds around the L bracket instead of bending it.

 

[jayrod12]

The rotation would be minimal, nearly all shear should go the welds around the L bracket instead of bending it.

That doesn't satisfy statics. And on a 6m spanning 220mm slab the rotation will not be negligible. Especially when the bearing length is only what, 150mm maybe?

You have multiple people telling you this is a bad idea, and then the one person who is willing to entertain your idea (KootK) informs you of the critical issues he sees and you appear to be dismissing him and us.

In the end, you're free to do what you want, and it appears you want to see this idea through to the end. Let's just hope that we don't end up reading about your building here next, forum815.