AWWA D100 and API-650 are the common standards used for tanks of that size in the US.
Generally, the shell would be able to handle a fair bit of vertical load but not a lot of radial load or rolling moment.
For straight vertical load, add a vertical stiffener, assume load distributes out at 30 degrees either side, and adjust length to get adequate load capacity at bottom.
For rolling moment, design as if you had an anchor bolt chair, see "Steel Plate Engineering Data" Vol 1&2 (combined) from AISI/SPFA.
For radial load, it gets more involved- see various vessel design handbooks or WRC-297.