• After defining your stair in the position and geometry it should be in your project, activate the Set Stair Boundary Conditions command in the Stair auxiliary toolbar.

  • The Set Boundary Conditions dialog will open.

  • After marking the solution with building system title, make your arrangement so that only the option/options that are supported on each side of the staircase will remain active.

If you want to solve the staircase element with the structure, it would be a better solution to select the Semi-rigid diaphragm option from the Analysis Settings/General tab.