No they are not. They are 3 feet deep holes dug with a 24" post hole digger. That is the only way I have seen steel farm sheds built around here. We have a commercially built 60x96 that is on piers that are a little deeper but those trusses are 18' apart so not nearly the concrete that we are using. May be different up as far north as you are. I don't know of any that have failed built this way around here.

 John