Check out Steel Mountable Stairs with Landing Free 3D model on CGTrader for free. High-quality mesh by Modconcepts. Textured.
DWG (AutoCAD, filesize: 569 KB), DXF (DXF, filesize: 4.88 MB), RFA (Autodesk Revit, filesize: 2.11 MB), MAX (Autodesk 3ds Max, filesize: 3.36 MB)