mich verwundert:
Warum wird weiterhin die freie Fallgeschwindigkeit angezweifelt, obwohl selbst NIST schreibt "the building section above came down essentially in free fall".
Noch ein paar Fakten:
die Beschädigung durch das Flugzeug betrug lediglich 15 %.
According to NIST’s base case computer model, three of the core columns are severed and another ten suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 189 ] If this is accurate, it means that the impact damage to the core reduces the Tower’s strength by another approximately 7.5 percent, meaning that the building loses about 15 percent of its strength in total,
Das Kerosin
Über um wieviel Kerosin reden wir da überhaupt?
AA11 hatte ca. 40 Kubikmeter Kerosin an Board. NIST geht davon aus, dass 40% (16.000 Liter) die „core columns“ beschädigten. Die Fläche der 47 core columns im inneren der Türme erstreckte sich auf eine Fläche von 20 x 20 Meter. Wenn wir mal großzügig annehmen, dass sich dort 20.000 l Kerosin verteilten dann kommen wir auf folgende Zahl: Das Kerosin stand in der Höhe von 5 cm auf einer Fläche von 20x20 Meter. Und diese 5 cm machten sich dann auf den Weg nach unten, durch die Fahrstuhlschächte, 230 m tiefer explodierte es in der Lobby. Aber nicht nur da – das Kerosin soll an verschiedensten Stellen explodiert sein. Darunter –zufälligerweise- in den Sicherheitszentren im 22. Stock und tief im Untergrund der Türme. Diese Explosionen hatten verheerende Folgen für die Arbeit der Feuerwehrleute.
War das WTC nicht konzipiert für einen Brand?
Die World Trade Center wurde von den Ingenieuren Robertson und Skilling erbaut.
Aussage Robertson
"And then of course with the 707 to the best of my knowledge the fuel load was not considered" in the design, and indeed I don't know how it could have been considered."
Dagegen sagt der andere Ingenieur, Skilling:
"We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side," said John Skilling, head structural engineer."
Nun steht bei Wiki Amerika Folgendes, dass wohl die Entscheidungsfindung, wer die Wahrheit spricht, erleichtert:
Fire and aircraft potentials
Like all modern skyscrapers, WTC towers were designed to survive major fires, but not necessarily those that involved aviation fuel. Though fireproofing had been incorporated in the original construction, more was added after a fire in 1975 that spread to six floors before being extinguished.[2] Early tests conducted on steel beams from the WTC show they generally met or were stronger than design requirements.[7]
Designers had also considered the consequences of aircraft impact. In 1993, John Skilling, who had been in charge of the structural design of the buildings, said that an aircraft impact would cause a great deal of damage and loss of life, mainly because of the ensuing fires, but the structure would not collapse.[8] After the 2001 attacks, Leslie Robertson, who had participated in the structural design of the towers, said that the towers had in fact been designed to withstand the impact of the largest airliner of the day, the Boeing 707-320, in the event one was lost in fog while looking to land. According to Robertson, the modeled aircraft weighed 263,000 lb (119 metric tons) with a flight speed of 180 mph (290 km/h), as in approach and landing. As FEMA pointed out in its report, this implies a slower and smaller plane than those involved in the actual impacts of 9/11.[2] Robertson also said that they lacked a good understanding of the effects of such large fires on the structures.[9]
The National Institute of Standards and Technology, however, was unable to document the study reported by Robertson and FEMA. Instead it found a reference to a study of the effects of a Boeing 707 carrying 23,000 US gallons (87 m³) of fuel hitting the buildings at 600 mph (1,000 km/h), which would not only be faster than either of the two planes that hit on 9/11 but with twice the fuel quantity. In line with Skilling's remarks, this study apparently found that the buildings would not collapse in that event. But NIST was unable to find any further details about the study and stated that without the original calculations which were used to render such conclusions, any attempt to compare the performance of the buildings to design expectations would be "speculation". In examining the collapse of the towers, NIST also stated that, "No building code in the United States has specific design requirements for impact of aircraft, and thus, buildings are not specifically designed to withstand the impact of fuel-laden commercial aircraft."[10]
Wikipedia: Collapse of the World Trade Center# note-Bazant07
Leider ist Skilling bei der Explosion der WTC gestorben.
