Forget the columns and pour the pad.    It keeps the weeds down under the bin and makes it much much easier to clean up spilled feed. 


All of our feed bins (5 ton 4 legs all the way to 12 ton 6 legs) are on concrete pads poured using 2x6 form boards.

If your base is good that concrete will never crack.


 

We've got 24+ ton ingredient bins that are sitting on 12" thick pads.