In February 2012 this team discovered that NIST had left out critical structural elements from its WTC7 model reported in NCSTAR 1-9 (Nov. 2008)

GIRDER STIFFENERS

There were two girder web stiffeners at the connection where NIST claims the collapse initiated.  Frankel shop drawing 9114  shows them prominently. (I highlighted them in red and added labels)

 

Col79 Stiffeners2

 

Col79 Stiffeners

 

These stiffeners strengthen both the web and bottom flanges of the girder.  Here is a video showing the various scenarios under which the girder could have been found.

Here is a detailed description of the stiffeners: