Post thrust failure calculation

[fromrfarm]

Good morning all.

  I am trying to learn more about posts and their failures with regards to high posts and various roof pitches.

  I was looking through the tools and various books I have but even in Tedd Bensons Building The Timber Frame House, I do not see any calculations or calculators for such a thing.

  An example is always best. So I had an old barn with 3 bays/4 bents. Each bent had a high post that was 5' to the top plate above the tie beam below. The posts were 8x8 spruce and hemlock and the tie beam was a through tenon with shouldered mortise and an 8x10. The high posts had no struts and had 6x6 queen posts to a height of 8' sitting on the tie beams for each bent that supported the principle rafters. The width of the old barn was 17' and the rafters were all 4x6 with a roof pitch of 10/12. 

  What I am interested in learn is how to calculate not just the outward thrust(which is easy with https://forestryforum.com/members/donp/RafterThrust.htm), but the failure point on the posts themselves. I have yet to be able to find anything that does this but perhaps I am googling the wrong terms. 

   A tree fell on the barn and smashed the roof collapsing it about ten years ago and I tore it down a year or so ago. Would like to rebuild to its historical accuracy but not before I understand the mechanics. Yes I will have an engineer review but I want to learn this myself. Any guidance would be greatly appreciated.

All the best and hope everyone is staying healthy.

Matthew

[fromrfarm]

Aaaa HA

 Found https://forestryforum.com/board/index.php?topic=94227.0

 and just grabbed the timber framers workshop book so think I am set. 

M