One way to build a suitable superstructure would be to do so in discrete, pod-like units - placed end-to-end/side-by-side with space between them to accomodate raft flexing. Flooring between units to be fixed to one unit but free floating over the next - bridging the gap required for flexing. If required to provide for a closed external wall the the same idea could be employed here(ie: the walls would look something like the scales on a fish from the outside).
Yes, from a modern standpoint but totally unfeasible for a bronze aged people whose "knowledge" was a flat earth, a water canopy, the sun & moon as lights and the feasibility to reach Heaven by building a tower.
There is no better love between 2 people than mutual respect for each other WT Young, 2002
Who gave anyone the authority to call me an authority on anything. WT Young, 1969
Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008