I am currently working on a screen project for a staircase descent.
A rather imposing all-aluminum set '-'.
And I'm looking to make a little simulation that will allow me to see if my outfit will bear the weight of the snow next winter and any kind of bad weather.
Unfortunately for this kind of design, for a study by SimulationXpress it must not be an assembly. So I remodeled the whole thing in one piece. SLDPRT
Simulation Xpress does not manage the beam mesh, which seems to be the case of your aluminum structure, for me Xpress simulation is not made for that, you need the simulation tools present in a Premium license of SolidWorks, which will be able to manage the beams, the screwed connections, well clearly a complete static analysis tool.
You can stay in assembly with SImulation, no need to switch to parts.
In the folder of the bodies of the simulation, you have to convert the beam into a beam mesh (right click) unless you have worked in mechanically welded because in this case it will be automatic.
I am attaching a similar file to help you in mechanically welded parts.
Be careful, no volume combination! We remain as in reality in multi-body.
Also look at the tutorials integrated into SolidWokrs or the ones here in Lynkoa:
@+
Edit: here is a video https://www.youtube.com/watch?v=C-Fqy-VsKcU