Creative Speculation

... or to resist progressive collapse, once it started. In particular, the interior girder connections to the columns were only designed to handle the anticipated gravity loads, not lateral forces from thermal expansion or moment forces from falling girders. Doing so would have made construction much more expensive, but there wasn't (and still isn't) any code requirement to do so, so they didn't. That's one of the serious issues raised by the collapse, since it implies that a great many other steel structures would also be vulnerable in a prolonged, unfought fire. The argument that if it never happened before 9/11 then it couldn't happen on 9/11 either is as bogus as the argument that if it looked like a controlled demolition then it must have been a controlled demolition.

Richard Gage's "over 1500 architects and engineers" should know this if they actually read the NIST report and actually have even rudimentary knowledge of structural mechanics, but they don't seem to think that the construction details are of any significance. Regardless of how impressed Ed Asner is, Gage & Co. present neither a credible technical argument against the NIST theory nor a credible, substantiated alternate theory.