To begin with, the "thousands" of specialists you're referring to seems to reference a petition that was posted earlier in the thread, which represents an extremely small minority of the overall community -- and which could easily have a large quantity of false signatures, or signatures from self-proclaimed specialists that actually know very little in terms of structural engineering and architecture in general. The overall consensus is that the towers could've indeed "fallen like they did" as per the official conclusion to the investigations following the tragedy, and what I've stated thus far has yet to be comprehensively, analytically refuted. Again, "got'cha!" rhetoric that's entirely devoid of substance isn't substantive evidence, and certainly doesn't warrant a reconsideration of the official account.
You've stated that the McCormick building and the WTC's towers are a flawed comparison. They are. Contextually, I was responding to Deadtosin's assertion that "no other steel-framed building in history" has collapsed due to "fire alone," which is demonstrably untrue. The McCormick Place's exposition hall was at the time largely thought to have been fireproof due to its steel and concrete construction -- it clearly wasn't. It demonstrates that steel is clearly prone to the effects of fire, and that it doesn't have to reach its melting point in order to substantially weaken. Here's an excerpt from SteelConstruction, an informational encyclopedia on steel as it's used in structural engineering.
All materials weaken with increasing temperature and steel is no exception. Strength loss for steel is generally accepted to begin at about 300°C and increases rapidly after 400°C. By 550°C the most common grades (S275 and S355) of hot rolled structural steel retain about 60% of its room temperature yield strength.
Popular Mechanics, a widely-acclaimed engineering magazine, cites an estimate that most of the steel exposed to the fire would've lost over half its strength under direct contact with the inferno that ensued after the planes impacted the towers.
"Steel loses about 50 percent of its strength at 1100°F," notes senior engineer Farid Alfawak-hiri of the American Institute of Steel Construction. "And at 1800° it is probably at less than 10 percent." NIST also believes that a great deal of the spray-on fireproofing insulation was likely knocked off the steel beams that were in the path of the crashing jets, leaving the metal more vulnerable to the heat.
But jet fuel wasn't the only thing burning, notes Forman Williams, a professor of engineering at the University of California, San Diego, and one of seven structural engineers and fire experts that PM consulted. He says that while the jet fuel was the catalyst for the WTC fires, the resulting inferno was intensified by the combustible material inside the buildings, including rugs, curtains, furniture and paper. NIST reports that pockets of fire hit 1832°F.
Again, this has to be taken into context with my original response to Deadtosin, who again asserted that "fire alone" couldn't have brought the structure down -- a claim that simply doesn't stand up to scrutiny. Fire's potential for structural damage in all types of buildings should never be overestimated, and this doesn't take into account the tremendous force and subsequent damage imparted by the initial impact of the airliners, or the structural damage imparted by falling debris that impacted WTC 7 that caused the structure's south facade to fail.
