My 30x40 tf was built on grade beam over pier wit 3 ' stone wall and I live in northern NY , 35 BELOW LAST NIGHT. The first winter the barn wasn't up and no cracks or movement. I don't regret for a minute getting so elaborate. For a thickened slab that is frost free look in FineHomebuilding magazine about 1999. There was an article on a frostfree slab that was developed by the scadinavins I believe. It never caught on here because it was difficult to form. It involved a insulated concrete skirt just below grade. It used geo-thermal heat to keep frost from penetrating under the slab. I've never tried it but but it was a proven design , but so is grade beam on pier. I'll try to find the exact issue.
