Let us focus first on NIST’s statement that “the steel framing heated more quickly than the concrete slab.” How much more quickly? Even though this is presumably a scientific document, NIST provides no quantitative assessment. We need to know, however, what NIST had in mind. If its vague statement meant only that the steel heated up 0.5 percent more quickly than concrete, then the difference in the thermal expansion would be too trivial to have mentioned. But if NIST meant that steel heated up much more quickly—say 50 percent more quickly—this would imply, contrary to fact, that reinforced concrete would not be useful. But NIST’s report gives no figure. Nevertheless, NIST’s entire case for shear stud failure rests on its vague claim about differential thermal expansion, as the following statement illustrates:
Shear stud failures in WTC 7 were found to be primarily due to differential thermal expansion effects as the floor beams heated more quickly than the concrete slab.
(The Mysterious Collapse of World Trade Center 7: Why the Final Official Report about 9/11 is Unscientific and False by
David Ray Griffin)
