How do you distribute weight on a concrete slab?

Can you please provide more information about your project? We are moving our fulfillment facility to the second floor of our main building. Approximately 150 40 x 48 pallets with various weights along with approximately 600 (40lb) cartons that will be put onto metal shelfing. The concrete floor was tested for the following: Dead Load - 41 pounds per square foot. Live Load - 122 pounds per square foot. We are trying to determine if we can double stack pallets (40 x 48) by putting up racking. Do we put one pallet directly on the floor and the other pallet on the rack itself. My concern is how do we determine how to do this with weight distribution. Is there a easy method to determine which way to go and be safe. What do we keep the pallet and it material weight to on the floor and what do we keep the pallet and material to that would go on the rack. Maybe the racking is out of the question and we can only put one pallet on the floor with a total amount of weight. The same goes with putting metal shelving up (2' x 3'). How much weight can we put on the shelves that will have 4 legs to distribute the weight. We are told we might have to put plywood down to distribute the weight. How do i calculate this properly and how thick should the plywood be? Each metal racking will have a number of shelves depending on the weight aloud.