mating posts to concrete sonotube

Folks,
Help me here. In one of the projects done by the Guild, the posts were placed on sonotube (brand?) columns about 3' high.
In these forums, I've noticed at least two members mentioning that they never have wood in contact with concrete.
How, then, does one mate a post with a concrete base?
Thanks,
Mark

There are various ways. One I like is to cut a pad of heavy rubber or plastic, maybe 1/4" thick, slightly smaller than the post. This is creates a nearly invisible shadow line under the post, and lifts it enough to avoid rot.

Steel connectors can be also be designed to provide a bit of vertical stand-off.

Another more common solution is to set the post on a square piece of pressure treated 2x8 as a plinth.

Any of these must be designed isolate the wood from the concrete and also avoid trapping rain, etc.

pete