If the building is in tornado alley, I would think it would be mandatory for a qualified SE to do the design.
Will there be a "safe room"? I haven't done any designs in tornado land but realizing the huge wind velocities, flying debris, and low air pressure tending to "explode" closed structures, and the design of building structures being less accurate and predictable than aerospace structural design, I would hire a SE.
At any rate, a free resource is attached (it is a large .pdf file), but keep in mind this is not complete such as the NDS.