FSD with concrete slab simply supported on bottom flange of beam

[madcowscarnival]

I'm looking for design references for the following situation:

Client needs to maximize height below a suspended slab in a residential garage. Is it possible to support the slab on the bottom flange of the beam? The beam would be the same depth as the slab and decking, and would be exposed at the surface. Quickly, it is a 12"x35# beam, 20' span, 4" FSD, 8" slab above, 11' spacing between beams. The beam is over-sized, but something the client has on hand (or available). I have found plenty of references for supporting a beam on the lower flange of a girder, but that would not be the situation here. I skimmed through a thesis on deflection of the outer edge of the flange, but that scenario would not apply here either. Any suggestions appreciated.

 

[KootK]

This shouldn't be a problem. Similar systems have been used with precast and deep deck systems plenty in the past. You may or may not be able to call the beam flange uniformly loaded depending on the spacing of your ribs and whether or not you've got enough solid concrete up against the beam webs to call it a distribution member parallel to the steel beam.

You're going to have combined flange tension, bending, and shear to contend with. Depending on your philosophical bent, you may or may not want to perform a Von Mises check. You'll need a flange deflection check too but that ought not be an impediment. As the flange deflects, the load will move closer to the beam web. Some mundane stuff to keep an eye on:

1) General durability issues when using steel in a parking area.
2) Make sure the beams can't roll over when individual decks are poured.
3) Since you won't have a continuous topping, make sure that you've secured diaphragm action somehow.
4) Watch out for unbalanced loads and concentrated loads.


I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.