Notes on the cathedrals

Note the vertical gaps in the box columns of the perimeter wall. Gaps in the box columns do not seem to be a sensible feature in a supposedly load bearing wall. Is this because the perimeter wall was not actually meant to be a load bearing wall as such, but a feature designed to give the WTC its required rigidity (against wind loading)? In the left photo note the yellow and red lines in the concrete. In the right photo note the three parallel light-colored lines (about 4 inches wide) in the concrete. One also wonders why the pile of steel in the foreground was hoisted up the building, unless it was to be incorporated in the structure. An answer to this question may be provided by the following photo. Between the workers cutting up a couple of WTC core columns, is a column with concrete still attached to the beams that are welded/bolted to it. These U-shaped beams look suspiciously like the lengths of steel in the foreground of the picture of the trussing. Is it possible that floor slab was some eight inches thick ...»