This is probably a stupid question, but I can't figure it out.

My plans call for a steel center beam in the basement to support the floor joists of the 1st floor. The I-beam will be below the floor joists (not flush). It seems straightforward enough to frame a beam pocket in the ICF wall, but of course I have to pour the wall as high as the tops of the joists so that the floor joist hangers are embedded in the concrete. So do I simply make an extra-deep beam pocket? 10" for the depth of the beam, plus 12" on top of that for the depth of the joists? This seems workable, but leaves quite a large concrete-less gap in the wall. Or is there a better way to do all this?

Also, how is a beam fastened to the concrete after it is installed? It seems like people just leave it sitting there, but surely that can't be right...?

3 options

1 - use scraps of ICF and cut the wall, placing them in to create a beam pocket (Void), Cut them out the following day and you have a beam pocket

2 - Use end caps to create a void on either side of the beams location to place the beam

3 - Set up a bracing system and set the beam prior to pour and cast the concrete around it in place (My preference)

Options 1 & 2 will require you to get it level and grout around it

Option 3, you have to get it 100% perfect before the pour, once the concrete is in you cannot adjust it's height

nysharps,

If you decide to use either option 1 or 2 as outlined by Chris, then read the following:

How much bearing on the concrete wall will will the steel beam require?  If the bearing is only two or three inches, then there could be some concrete left in the wall behind the beam.  For example, if you have a 6" thick concrete core and the beam required 3" of bearing, then it would appear that 3" of concrete could be left in the wall.  However, that would be for a perfect world.  I would make the beam pocket 4" into the concrete core on each end of the beam.  This would allow some extra space while placing the beam.

Now if you use option 3, that is, cast the beam in place, then you may not need the extra 1" of maneuvering space.  That is, the concrete could flow all around the beam.  My only concern about that method is whether the temperature will ever change enough in the basement to expand the steel and crack the concrete.  Since the beam will be in the basement, I think it is unlikely that the steel will expand enough to crack the concrete in the walls.  If there was any concern, then 1" of EPS could be placed at the ends of the beam to absorb the expansion.

Another thing:

If headroom in the basement is reduced too much with the beam being under the floor trusses, then the beam could be embedded (hidden) in the floor trusses.  If doing this blocks the flow of HVAC and plumbing lines, then beams like Metwood that have holes through them could be used.  See:  http://www.metwood.com/products/throughspan   The throughSpan type of beam will allow some utilities to pass through.  I think the hole size will be governed by the height of the beam.

nysharps
If you make the pocket as Chris describes, most people leave the void all the way across the wall. In some cases it is easier to cut out the out side foam panel as well so that you can slide the beam through the wall and then back into the pocket on the other side. When the beam is in place, refit the foam and pour in a high strength grout to totally fill the void.

I'm with Chris, I prefer to cast the beam in place, but than I usually cast the floor in place as well. Everything is neat, level and square before you pour, plus you have the whole floor to walk on when you pour.

Also we often use a partially dropped beam. We will drop the beam around 6 or 7" below the top of the joists. This allows room for heat duct etc. to go over the beam. It also allows for a higher lighter beam which is usually cheaper and easier to handle.
In your case if it is only a 10" deep beam, the engineer has probably spec'ed a fairly heavy one. If he can use say a 14 inch deep beam, you will still have the same head room but because the web is 4" taller, therefore stiffer, the engineer can use a beam that weighs quite a bit less per foot and still get the same stiffness.

FBBP, how does a partially dropped beam work? What kind of floor joists do you use with it?

nysharps - you can use any type that you would use with a flush or drop beam.

The two most often used when you have a steel beam and wood I joists are blocking in the web and adding a ledger to the side of the beam for the joists to sit on or install a 2 x on top of the steel beam and use top mounted joist hangers. With a filled web, you can also use side mount hangers.

The other thing you might want to check is if the steel beam is being used just to get the headroom required. If instead of only having ten inches to work with, you now have 14 or 16 inches, will a LVL beam work and will it be more cost effective? If yes than again you have the choice of a side mounted ledger or side or top mounted hangers. LVLs tend to be more cost effective and more comforting to the framing crew. Most framing crews have a severe allergic reaction when they see steel beams in the drawings (;=)