---In [email protected], <noozguru@...> wrote :
On 05/20/2015 01:46 PM, TurquoiseBee turquoiseb@... mailto:turquoiseb@... [FairfieldLife] wrote: From: "anartaxius@... [FairfieldLife]" mailto:anartaxius@...[FairfieldLife] <[email protected]> mailto:[email protected] I was having lunch with some relatives in Rhode Island a few years ago and the topic of the World Trade Towers coming down came up. One said it was an inside job. The other, who worked for a large insurance firm that insures buildings like that (and had 250 adjusters working under her) they knew pretty well how those buildings would fare if hit by aircraft and there was no doubt in their minds that the plane took them down. I know a few high iron architect/engineers, the kind who build skyscrapers, and none of them ever had any problem with the WTC buildings being brought down by the planes. Except that after the planes hit you can see people on adjacent floors looking out of the building wreckage. The original architect designed the building to take such crashes. The buildings did take the impact. It was the intense heat from the ignited jet fuel that weakened the structures. The medical examiner who was responsible for identifying bodies got some flack for suggesting to the bereaved that some would never be identified because they were vaporised from the intense heat. The buildings would probably be still standing today if the planes' fuel tanks were empty upon impact. Most of the people in those buildings were still alive after the impact. 'The structural integrity of the World Trade Center depends on the closely spaced columns around the perimeter. Lightweight steel trusses span between the central elevator core and the perimeter columns on each floor. These trusses support the concrete slab of each floor and tie the perimeter columns to the core, preventing the columns from buckling outwards.' 'After the initial plane impacts, it appeared to most observers that the structure had been severely damaged, but not necessarily fatally.' 'It appears likely that the impact of the plane crash destroyed a significant number of perimeter columns on several floors of the building, severely weakening the entire system. Initially this was not enough to cause collapse.' 'However, as fire raged in the upper floors, the heat would have been gradually affecting the behavior of the remaining material. As the planes had only recently taken off, the fire would have been initially fuelled by large volumes of jet fuel, creating potentially enormously high temperatures. The strength of the steel drops markedly with prolonged exposure to fire, while the elastic modulus of the steel reduces (stiffness drops), increasing deflections.' 'Modern structures are designed to resist fire for a specific length of time. Safety features such as fire retarding materials and sprinkler systems help to contain fires, help extinguish flames, or prevent steel from being exposed to excessively high temperatures. This gives occupants time to escape and allow fire fighters to extinguish blazes, before the building is catastrophically damaged.' 'It is possible that the blaze, started by jet fuel and then engulfing the contents of the offices, in a highly confined area, generated fire conditions significantly more severe than those anticipated in a typical office fire. These conditions may have overcome the building's fire defenses considerably faster than expected.' 'Eventually, the loss of strength and stiffness of the materials resulting from the fire, combined with the initial impact damage, would have caused a failure of the truss system supporting a floor, or the remaining perimeter columns, or even the internal core, or some combination. Failure of the flooring system would have subsequently allowed the perimeter columns to buckle outwards. Regardless of which of these possibilities actually occurred, it would have resulted in the complete collapse of at least one complete story at the level of impact.' 'Once one story collapsed all floors above would have begun to fall. The huge mass of falling structure would gain momentum, crushing the structurally intact floors below, resulting in catastrophic failure of the entire structure.'
