A small group of engineers is planning to sue NIST for the fraudulent 2008 report that was supposed to explain the 9/11 collapse of WTC7, in an effort that will presumably involve AE9/11Truth. Kevin Ryan exposed the fraudulent non-explanation in 2011, and newly uncovered data confirms Ryan´s conclusion: NIST´s progressive collapse theory relies on a "girder walk-off" premise that is demonstrably false, and without the toppling of the first domino, the theory is invalid.
NIST´s suspicious computer animation depicts thermal expansion of five floor-beams (under the north-east corner of the thirteenth floor) pushing one end of a girder off the seat that attaches it (and the floor that rests on it) to the critical vertical column (#79); This small section of the floor then collapses and takes down with it a few floors below it, which leads to the failure of column #79 because it is lacking the horizontal support from those floors (stop Ryan´s video at 2 min. to see the girder/column); The failure of this single column (#79) then allegedly leads to a domino-effect that results in the incredible implosion of WTC7. You will have to have faith in NIST, because no-one is allowed to verify the model input data.
NIST´s initial failure mechanism requires the heated floor-beams to push the critical girder 6.25 inches. To understand what happens at 6.25 inches it is important to note that the girder is an I-beam, and that the central vertical element is the "web", while the horizontal elements are the "flanges". NIST assumes that the girder falls off the seat because 6.25 inches is enough to move the web past the seat, and the flange alone is too soft to support the weight - see video.
Kevin Ryan pointed out in 2011 that NIST omitted the fact that it had calculated the maximum possible heat-expansion as 4.75 inches, and Kawika et al. are now revealing that the girder "walk-off" cannot happen, even given the impossible 6.25 inches: NIST omitted the stiffener plates at the end of the girder, which stiffen the bottom flanges and prevent this type of failure!
NIST has responded by stating that it was legit to omit the "web crippling plates" because analysis did not indicate web failure, which of course omits the fact that the plates also stiffen the flanges.
For more information about the debunked 2008 NIST report, read Chris Sarns´ 5-part article for AE9/11Truth:
Part One: No evidence for the fire responsible for the thermal expansion
Part Two: Magical Thermal Expansion
Part Three: Omitted Girder Sheer Studs
Part Four: Debris Damage Fiction
Part Five: Non-Existent Diesel Fuel Fire