Half W Beam embedded into Concrete Slab

[Vshah97]

So there is a condition where I have to use W beams, due to height restrictions, I am being asked if I can embed half of the top of W beam into concrete. Contractor does not want to do Deck Sheet and concrete over it. If we do flat concrete with shuttering at the base of it, how do I connect the bottom of the slab to W beam which avoids cracking and actually transfer the loads to W beam as required?

Any suggestions are welcome.

 

[jayrod12]

Weld angles to the web of the beam at the underside of slab elevation.

 

[cliff234]

being asked if I can embed half of the top of W beam into concrete.

This is going to be expensive. First off, what was the original detail? (beam depths and slab thickness) A formed slab spanning between beams is expensive because of formwork cost. We have always used composite metal deck. I have embedded beams several inches into the underside of slabs and detailed angles welded to the webs of the beams and embedded the tops of the beams several inches into the undersides of slabs (with the top flanges about 3" below the top of the slab. Add #4 closely spaced negative moment top bars over the beam to restrain cracks, otherwise you'll have serious cracking over the beam, but design the slab as a simply supported single span. What do you mean by "embed half of the top of W beam into concrete"? How deep are your beams? How thick is your slab? Why doesn't the contractor want to do it the easy and less expensive way (using composite metal deck)? The beams will no longer be composite - which means the framing will be heavier and more expensive. Were the beams originally composite? Can you just make the beams 3" or 4" heavier but shallower? How many inches of framing depth are you trying to save?

 

[BridgeSmith]

If the slab is supposed to be continuous over the beam, and designed to carry negative moment, without a lot of care in placing the concrete, it will be difficult to count on the effective depth to the bottom of the slab. There may be voids in the concrete under the flanges, so you may be limited to the thickness of the slab above beam as the structural depth of the slab, at least for moment continuity.