How to read the analysis of the axial stress beam view?

I’m trying to analyze the axial stress of Weald and Downland Structure for my research but i don’t know the reason why is it red (compress) and why is it blue (tension), isn’t the one in the bottom of the corrugated barrel vault should be in tension (blue)?

Here’s the file if u guys need the rhino and gh
GH Final Weald and (251.4 KB)
Model Fix Weald and Downland.3dm (2.5 MB)

The colour mapping you showed indicates axial forces in the beam cross section. If you want to see the axial forces, use the secion forces in the BeamView component, where orange indicates compression and blue tension.

Thanks for the help Matthew, is there any theory that describe why all of them are in compression, and all the bracing are in tension? Is it because the basic geometry created by arch (pure compression)

Hi, i am not too sure about the theory, but the forces seem to make sense. All the loads need to be brought down to the supports and this can only be down through the main elements.