If you have no supports on any sides of your landing, I can see 2 options but they will produce large torsional moments on your supporting beams. Option 1: model each upper and lower staircase as a cantilever. Assign the landing to either cantilever. Option 2: model the upper staircase as simply supported between the upper floor and landing. Design the lower staircase and landing as a cantilever. There is also option 3: continuously harass your architect until he or she agrees to let you put in hangers or supports for the landing.

Agree with Motor City. I've only seen a handful of stairs with an unsupported switchback landing. Puts large torsion on the supporting structure

All I know is P/A and Mc/I

I did a fairly large one of these a long time ago... My initial model was as shown in the attached sketch. I'll dig up a photo and post it...

Dik

• http://files.engineering.com/getfile.aspx?folder=ac8ae230-b46e-4ad4-b3b7-e1

Photo Cornwall Centre in Regina, Canada:

The curved beams were from a design book by Reynolds (sp?)... a British publication from way back when...
Dik

• http://files.engineering.com/getfile.aspx?folder=6b0855c0-b195-4d58-8839-e4

It's a truss.

Can you not design the stairs as continuous through the landing? That would take out any torsional moments to the supporting beams.