But these floors were lightweight concrete on a sixty-foot truss system and were not designed for heavy loads, yet here we see what must be dozens of tons of debris, some of which fell 20 feet, to land in a heap on this floor. Comparatively the mechanical floors required I-beams to be able to support the big elevator motors and other heavy equipment, so what’s holding up this pile? Why didn’t the multi-ton wall panels plunge through this floor and every floor beneath it? Clearly this floor was heavily reinforced and I believe this is because they needed a big pile of debris to fill the hole so people wouldn’t notice the empty tower and the lack of jet parts behind it.