In my planned build the Hambro or equivalent OWSJ will be supported entirely on outer ICF walls. How are the interiors wood framed walls attached to the steel joists above in this case? Are the wood studs supposed to go up to the top chord of the joists and be attached to the concrete of the floor above?

Attach to bottom chord of OW, pre drill with 3/16" bit and then screw down through chord with 2" pan head screw

Thanks Chris.

I didn't realize that steel structures allow this kind of drilling, unlike wood.
I was thinking more like sandwiching the bottom chord between the top plate and another 2x4 passing over on top of the chord with 2x4 blocks on both sides of the chord and then screw the sandwich together. In that way the steel remains untouched.

But your solution is much simpler obviously.