Determining stress or load on a beam

looking for extension or plugin to help with determining stress on structures

Good luck. Doesn’t really sound like a CAD related thing.

There is this
However, it’s been dormant for a few years…
Not sure about its compatibility…
There’s also this

The beam equations are handily presented online in the form of a calculator:

Some of the solids modeling programs I’ve used in the past allowed you to specify the material and its mechanical properties and then use the 3D geometry to dynamically simulate various supports and loads (SDRC Ideas, for example). Not sure how a SketchUp plugin would offer much more than the geometry (which can be created in SketchUp and then imported into some structural analysis software).

I think that a simple calculator for something like a wooden beam could be embedded even in a dynamic component.