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Ursprungligen postat av MaxDL
ex. simulationen som står i nist är baserad på uppskattningar. modellen som simulationen innehöll av byggnaderna är inte som byggnaderna i verkligheten. simulationer i dagsläget är helt enkelt inte tillräckligt verkliga för att kunna återskapa en sådan här händelse helt korrekt. det finns så otroligt många faktorer som spelar med och att få med alla dessa i en simulation för att sedan dra slutsatser från simulationen är högst spekulativt. den kan i bästa fall visa vissa indikationer men aldrig hur någonting verkligen sker utanför simulationen. dessutom så användes för höga uppskattningar av skada i simulatoinen med 900 % i vissa fall vilket gör den ytterligare missledande.
Du spekulerar ju bara fritt nu! Du menar att NIST är uppbyggd på uppskattningar men att "trutherrörselsens" rapport är ren och konkret fakta?
Simulation hit och dit, det är ju bara trams. Att det inte funnits byggnader av liknande korrelation som WTC är ju inte så konstigt. Hur många byggnader har egentligen "erövrats" av stor andel jet fuel? Eller blivit påsmackad i maximal hastighet?
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Jet fuel burns at 800° to 1500°F, not hot enough to melt steel (2750°F). However, experts agree that for the towers to collapse, their steel frames didn't need to melt, they just had to lose some of their structural strength — and that required exposure to much less heat. "I have never seen melted steel in a building fire," says retired New York deputy fire chief Vincent Dunn, author of The Collapse Of Burning Buildings: A Guide To Fireground Safety. "But I've seen a lot of twisted, warped, bent and sagging steel. What happens is that the steel tries to expand at both ends, but when it can no longer expand, it sags and the surrounding concrete cracks."
"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.
"The jet fuel was the ignition source," Williams tells PM. "It burned for maybe 10 minutes, and [the towers] were still standing in 10 minutes. It was the rest of the stuff burning afterward that was responsible for the heat transfer that eventually brought them down."
Redan postat, men värt att läsa, om man nu är intresserad.
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Once each tower began to collapse, the weight of all the floors above the collapsed zone bore down with pulverizing force on the highest intact floor. Unable to absorb the massive energy, that floor would fail, transmitting the forces to the floor below, allowing the collapse to progress downward through the building in a chain reaction. Engineers call the process "pancaking," and it does not require an explosion to begin, according to David Biggs, a structural engineer at Ryan-Biggs Associates and a member of the American Society of Civil Engineers (ASCE) team that worked on the FEMA report.
Like all office buildings, the WTC towers contained a huge volume of air. As they pancaked, all that air — along with the concrete and other debris pulverized by the force of the collapse — was ejected with enormous energy. "When you have a significant portion of a floor collapsing, it's going to shoot air and concrete dust out the window," NIST lead investigator Shyam Sunder tells PM. Those clouds of dust may create the impression of a controlled demolition, Sunder adds, "but it is the floor pancaking that leads to that perception."
