On an Alaska trip with my son last summer I had a chance to spend a day in Whittier, AK which is a rail center for ocean-going cargo. Just outside our hotel was the railyard and a pretty cool structure made out of shipping containers and refrigerated truck trailers. This structure appeared to be on the same property as a seafood processing plant next door. The roof was steel and the trusses wood. The containers were the outside 'walls' and the truck trailers were set in place between the containers.
Iin addition to this structure there was a much larger structure builit out of stacked containers and the roof was made out of containers, too. Because I didn't want to trespass I didn't walk over to the large building but I'm assuming it acts as a covered maintenance or parking building for the large lift trucks that are used to pick up double stacked containers and load them on ocean going barges. The only logical reason I can see for having a building made out of containers stacked four high is to give enough head room to raise the lift trucks during maintenance.
Either structure would be easy to bash together and as you can see, there is a prototype! If space is at a premium on your layout you could easily build a structure like the small one using the short 20' containers.
One of the interesting things about the barge is that the containers weren't being set on the barge deck but rather on a framework above the deck. I'm guessing that the space under the containers is reserved for railroad cars and they can't load the rail cars until the containers are loaded.
Enjoy!
Bob
The small building:
The large building:
Barge loading operation: