[TowerTalk] Bearing plate for pier pin foundation?

[Brian Machesney]

To the tower knowledgeable:

Rohn's mechanical drawing of concrete bases for guyed towers shows a
"bearing plate" on top of the concrete base, apparently concentric with the
pier pin. I can't find such an article - the only references I find to a
"bearing plate" are mounting arrangements for a thrust bearing.
Is this a drawing error?
Do I need to place something between the pier pin base assembly and the
concrete?
Can someone recommend a substitute?

I finally had concrete poured last week, so I'm gearing "up" for some fun!

Thanks,

Brian K1LI