The Nodes ribbon is there to help you calculate the many forces that will be acting on your structures, in this ribbon you can either work with nodes on a complete model or choose a specific area of interest to focus on. The node point (ie axis where your elements are connected to each other, two or more elements) will share, distribute or support the structures load, here we are getting into the stress analysis of the structure. In any given point (let’s say a selected node point) you can have your My and Mz (your bending moments), your Nx (normal forces), Vy and Vz (your shear forces). In AS, if you decide to create one of these node points and each created point is identified under forces tab in case and description column (ex: LC1) and you can also add new load sets if needed for comparison, you will have the advance properties as any other advance feature and in that window you have the possibility to specify the applied forces.
[refer to “stress analysis”] on the AS forum.
http://www.graitec.com/en/forum_search.asp?search=stress+analysis&method=2