Wasn't there a video in this thread that answered your question?? That bldg collapsing in the video didn't produce much dust at all. But all of this is armchair quarterbacking unless we get the bldg plans for the WTC. Now why can't we get that? Is bldg design now some kind of national secret?
Here is one of those news media provided explanations that turns out to be as wrong as it is right.http://www.usatoday.com/graphics/news/gra/wtccollapse/flash.htm
The numbers are off. The claim of heat melting the steel has already been dispelled by engineers. They say "100% steel" which is misleading. The columns were "box steel", and probably 1/2 inch thick steel plates welded to form a box.
Another site by a couple of engineers has a really good, and appears to be correct, explanation.http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html
Has a good explanation why the USA Today stuff is just not correct. It is physically impossible for the type of fire in the WTC to reach 2000 degrees C. Sorry. Can't argue with thermodynamics.
But even they don't get it 100% right. They say the aircraft impact did not take out that many of the outer columns BUT if you look at the hole in the bldg it looks like >half a side was taken out. There were 244 columns. Sounds like a good number of columns to me, 40+.
The floors were 4 inch concrete poured over the joists that connected the outer columns. Multiply this by the number of floors, 110, and area, 64 m square, and there is your concrete content, 14,700 cu.ft. Don't forget to factor in the center core and factor out the dead space. Don't forget the 7 other bldgs besides the towers.
More wrong stuff by the media. Seems to be a pattern.http://news.bbc.co.uk/2/hi/americas/1540044.stm