If you are looking for a standard model that exactly reflects your staircase, the answer is "No".
If you are looking for a model that may do the trick, try this one. Load it in Sketchup and export it as a DAE model that can be imported in SH3D.

If you want something better, you can build it yourself from small parts using all the tricks described in the forum and several tutorials. Of course you can also use a different program such as Blender, Art of Illusion or Sketchup.

Hans