We're thinking of moving a 24'x48' pole barn. Previous owner placed it in the middle of a pasture to serve as a loafing shed. Well, we've no cattle and could get much better use of it in Zone 1.
The posts are roundwood, creosote treated, 8" diameter. Frost line is 30". Ground is expansive clay, cracks open when it's dry, makes you taller walking on bare ground when it's wet. We experience some strong straight line winds from thunder storms, tornadoes are a possibility.
My first thought was to cut the posts at ground level, drill and epoxy some threaded rod into the posts, then attach those to sonotube concrete piers coming up above ground level. However, I'm a bit concerned about the shear strength of that rod. Also, I've had a look at this thread: Attaching roundwood posts to poured foundation piers and was curious if there was a more environmentally friendly foundation system that would be appropriate to my soil and wind load constraints.