In order to understand an important detail of the collapse of each tower, especially WTC2, it is necessary to identify the lowest bolted column-to-column connections along each perimeter just above the MER levels. This is how it is done:



First, take the NIST graphic and duplicate the step pattern along the top face every 3 floors as shown.


The orange line show where a straight row of welded connections are just above the MER panels so the yellow line cannot be correct. The red step pattern is the lowest pattern that is correct, and below that ther are a straight line of welded connections along the orange line.

There is only one way to fit the lowest panels between the red line and the orange line, and it is like this:


Using these steps anyone can verify that the purple step pattern is along the lowest bolted connections just above the 75-77 MER panels.