Gamolon, it is very likely you simply don't understand what is going on. The NIST hypothesis of a walk-off to the west cannot possibly work with girder A2001 at 500 degrees C and the western side plate of column 79 in its way. When the girder expands it will go up against the flange of column 79, which faces the end of the girder. Then after 3 inches of lateral travel to the west, due to the five beams to its east expanding and pushing it to the west, it will be trapped behind the side plate and unable to fall off its seat at column 79. NIST ignored the column side plate being in the way and ARUP did not.