Here you can find links to many interesting proffesional sites for steel design industry. Design and developmnet.

Tekla Free Viewer
Free Download
Tekla Structures Model Reviewer
Free Download
IPROBLUE™ - build digitally, build responsibly
National Institute of Steel Detailing
Steel Joist Institute

Tekla - Building Information Modeling (BIM) software
Steel Deck Institute
American Institute of Construction