If you can properly develop the torque with the slot maybe an expansion anchor will work fine. It might be in my 2006 Hilti Tech Guide, but I couldn't find it.
Stairmaster,
I agree with DaveAtkins. In my openion, for expansion anchors to work, there should be a very small deformation in the base material. Expansion anchors really work in concrete and natural stone. Try using adhesive anchors.
If you use Hilti, try not to use cementitious products (HY 150). Try RE 500 but I doubt whether technical details are available when the base material is steel.
I am assuming that you are talking about using a post-installed anchor into a normal hole and then slotting the base plate hole. If this is the case, any type of post-installed anchor could be used. This is a common method of taking care of those nasty edge distance reduction factors for close edges. When doing your design, slot the holes in the direction of the shear force near the edge and only have the shear acting on the non-slotted hole anchors. You may need a big diameter to handle the extra shear on the remaining anchors. All anchors can be used to resist tension. Just make sure the contractor puts the base plate slots in the right direction (easier said than done).
