The software was completely retired in December 2017.
It is important to note that in 2015.
Because the product is retired, you cannot buy a new license or download a trial. However, there are specific ways existing users can still access it: AutoCAD Structural Detailing discontinued - Autodesk Download AutoCAD aSD
AutoCAD Structural Detailing (often referred to as ) is a legacy software program previously used for structural drafting, steel fabrication drawings, and concrete reinforcement detailing. Critical Status Update: Discontinuation The software was completely retired in December 2017
Autodesk now recommends Autodesk Advance Steel for steel detailing and Autodesk Revit for concrete and rebar detailing. How to Access/Download ASD Today steel fabrication drawings