Can anyone please direct me to a design guide for cantilever stairs in steel? I'm looking at one at the moment and any help on this topic will be appreciated.
Where are you located? I think this is more of a "scissor stair" than a cantilevered stair. I would be concerned about vibrations for this case. The strength design should be pretty straightforward, especially if you can model it in Advanse or Risa.
These stairs rely both on fixity at the floor levels and truss action between the stringers and torsion in the members connecting the stringers together.
A 3D model should be sufficient for you to determine stresses, rotations and deflections. In addition to 100% loading on both flights, I also recommend using full loading a one flight with zero on the other to look at maximum torsion.
jike is correct. Modeling the staircase as described is the way to do it. Detailing is the next key. If you are in a seismic region or a heavy wind region you will also need to add lateral loads to the model. I would recommend some members be added to the floor framing to drag loads from the stringers into the building diaphragm for gravity and lateral loads.
StructIET - yes you are right, it is a scissors stairs, I'm based in Eire. The stair is cantilevers off link bridges between two blocks and is a feature in the atrium space.
Done a similar design with a solid concrete stair and followed guidance in Reynold's Concrete Designer's Manual.
I dont have the 11th edition but from what i hear they have cut a few things out of it and its not as involved at the 10th edition?...might just their personal view though!