I apologize if you stated this in an earlier post, but where did you buy your above ground shelter? Did they install it, or did you hire a contractor? ThanksBolted...with high-strength bolts. Mine uses eighteen 1/2" bolts that are about 4" into the concrete.
ETA: I should mention ours was installed on existing concrete. When they're installed with a new slab of concrete they usually will have a different type of anchor that's placed into reinforced concrete.