SpaceBase does not include any readers for any specific formats, but you're free to read them yourselves and insert the objects into SpaceBase as you see fit. This way you can choose if and how you want to break down shapes into multiple SB objects.
We've successfully (and easily) imported Open Street Map into SpaceBase. Most of it was done for customers, so we can't just release the code, but it was a simple matter of reading the map file with a SAX parser, and inserting roads into SB.