God damnit, accidentally his back and lost the whole post I had written. It's going to be a bit more concise this time, I guess.
I was curious about this article the professor you seem to have copy and pasted most of your arguments from. After a bit of googling (his in-text citations weren't exactly the best) I was able to find the article he refers to.
http://wtc.nist.gov/pubs/NISTNCSTAR1Draft.pdf
His use of elipses and boldface font really do help his argument out.
Let's take a look one of those lines I saw particularly interesting when viewed with the rest of NIST's response.
Quote:
Of the more than 170 areas examined on 16 perimeter column panels, only three columns had evidence that the steel reached temperatures above 250ºC… Only two core column specimens had sufficient paint remaining to make such an analysis, and their temperatures did not reach 250 ºC. ... Using metallographic analysis, NIST determined that there was no evidence that any of the samples had reached temperatures above 600 ºC. (NIST, 2005, pp. 176-177; emphasis added.)
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So there's what he cited. But, perhaps conveniently, he left out the last part of that bullet.
Quote:
NIST did not generalize these results, since the examined columns represented only 3 percent of the perimeter columns and 1 percent of the core columns from the fire floors.
I'd also like to note that his page citation is incorrect, the previous paragraph actually occurrs at the bottom of page 88 of the report and nowhere else. Most certainly not page 176/177, though they do have some stuff I'll hit later
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And, let's look at the paragraph following that one.
Quote:
These results were for a very small fraction of the steel in the impact and fire zones. Nonetheless, these analyses indicated some zones within WTC 1 where the computer simulations should not, and did not, predict highly elevated steel temperatures.
(emphasis mine, obviously)
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Oh my, what's this? Finding that those beams weren't really hot actually
reinforces their predictions. Guess leaving parts of paragraphs out is a really good tactic.
Quote:
Further, FEMA states jet fuel fires are not enough to make a building collapse but the overall normal office fire is.
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Well, let's see why they say about that (pardon any typos, the FEMA document doesn't allow copy+pasting).
Quote:
However, as the burning jet fuel spread across several floors of the buildings, it ignited much of the buildings' contents, causing simultaneous fires across several floors of both buildings. The heat output from these fires is estimated to have been comparable to the power produced by a large commercial power generating station. Over a period of many minutes, this heat induced additional stresses into the damaged structural frames while simultaneously softening and weakending these frames. This additional loading and the resulting damage were sufficient to induce the collapse of both structures.
http://www.fema.gov/pdf/library/fema403_ch2.pdf
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As any person worth their salt that deals with materials knows, pure temperature alone isn't enough, time is crucial as well.
Oh, and as for your MIT professor, might want to read what he had to say in context as well.
Quote:
Even with its strength halved, the steel could still support two to three times the stresses imposed by a 650°C fire.
The additional problem was distortion of the steel in the fire. The temperature of the fire was not uniform everywhere, and the temperature on the outside of the box columns was clearly lower than on the side facing the fire. The temperature along the 18 m long joists was certainly not uniform. Given the thermal expansion of steel, a 150°C temperature difference from one location to another will produce yield-level residual stresses. This produced distortions in the slender structural steel, which resulted in buckling failures. Thus, the failure of the steel was due to two factors: loss of strength due to the temperature of the fire, and loss of structural integrity due to distortion of the steel from the non-uniform temperatures in the fire.
http://www.tms.org/pubs/journals/JOM...agar-0112.html
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He also decides to comment on the 'implosion issue' you're talking about.
Quote:
It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.
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So, yeah, please check your facts next time.
Also, lollin' at how the guy you're copying the original argument from doesn't even have support from anyone in the civil/structural at his own university.
Edit: Screw you guys for ruining the thread even more and making styphon close it. >=(
