If you are looking for Autodesk AutoCAD Structural Detailing 2016 you will not find it. This program has been discontinued.
One of Autodesk recommendations is to use Advanced Steel instead.
Autodesk® Advance Steel software supports more advanced structural modeling and detailing capabilities, and provides tools that help drive fabrication. This fills an important gap in the steel design to construction workflow. Advance Steel is built on the AutoCAD® platform, providing a familiar user interface, helping to support a faster, smoother transition from AutoCAD® products.
Key benefits of Advance Steel:
- Integrates with Autodesk® Revit® and Autodesk® Navisworks® software products for building projects
- Integrates with Autodesk® AutoCAD® Plant 3D software with object-enabler technology and Navisworks for industrial projects
- Provides comprehensive modeling libraries of profiles and connection types
- Highly customized for local steel standards including steel connection design
- Helps reduce shop errors by producing NC & CNC files directly from the 3D model and connecting these models directly with leading MIS software.
- Supports collaboration in a multi-user 3D model environment
- Automatically updates and maintains revision control of documentation
For more information see the Autodesk KB article: