Realistically, I think such a massive structure falling from space to a planet surface would either break up in the atmosphere or essentially vaporize on impact in a huge explosion, or at the very least collapse under its own weight. Although I guess the case could be made that their frames employ some hyper-advanced engineering techniques to withstand accelerations of thousands of gs, as they would need to do routinely in order to travel and maneuver at high fractions of lightspeed or travel via space warp. Or that their inertial dampers and structural integrity fields remain powered throughout the descent and afterward.