1. Just design the vertical reaction from the mainframes for P/A, making sure the uplift is compensated for in the dead load of the footing/slab/grade beam. Don't forget to check the sidewall X brace and any portal frame reactions against the same footings. There may also be additional X brace reactions to design for at the endwalls.
2. Also, the thrust from the mainframes is taken by rebar hairpins -"usually #4,5 or 6 bars, bent in an open "U" shape, flared to the outside at 2:1, with the anchor bolt pattern inside of the U. I usually just use one 20 foot section of rebar and bend it accoringly. A grade beam tension tie can be used if the size gets too big.
There are other tricks, but those are the basics. Nothing fancy here.
