Collapse of the WTC

The Fireheat and the collapse of the World Trade Center

On Tuesday the September 11th 2001 at 8:45 o'clock as a Boeing 767 on the aluminum-disguised front of the World trade center (WTC) hit, was sealed the fate of the north tower. That stood for still 102 minutes 417 meters high sysmbol New Yorks. But from the first moment on it was dying. The impact of the airplane itself did not give the excursion: The kidnapped machine was started with filled tank (approx. 90,000 litres) in Boston and weighed far more than 100 tons. Force was sufficient, in order about 20 steel girders of the external skeleton too smashed and at least three floors to devastate. The statics of the Towers however the collision could have worn
alone to nothing. Because the towers were prepared to defy enormous forces. In the case of the impact of the Boeing freely becoming the kinetic energy of approximately 750 million joule was not larger than the load, which rested with storm on the WTC front. In that 63 meters broad building must have stopped then stealing vines, cross-beams and tubes of elevators, possibly also one of the central elevator columns, the passenger jet. At this time was at the most one quarter of the carriers splits. It could have been even half, without the house would have collapsed. Then the explosion of the airplane tanks followed. Estimated 50 tons kerosene transformed into a fire ball, which blazed by the splintering windows of the external facade. A pressure wave rests by the building. But also the energy of this detonation left heavy north tower only short to the 900,000 tons vibrate. It seemed, as if the architects right should keep, who had once protested, only one atom bomb could the symbol of western resource destroy.
To the final calamity the multistoried building only the heat, released by the burning wreck, that approximately on height of the 80. Floor puts. Already with 400 degrees Celsius loses structural steel at firmness; with 800 degrees it "is in plastic" softly like kneading rubber, it, as the experts say. Kerosene fires however produce temperatures of more than 1,000 degrees. In order to offer a minimum of protection, the metal bases of the World Trade Center had been encased by the building firm Tishman Construction with concrete and the building material Vermiculit. Such materials are established to standard fires, as they result from cable fires or ignited furniture. Against the hell heat kindled by the kerosene such fires are restraining materials however powerlessly. Result: The linkages began glowing, the props deformed. The Northtower, as the first rammed, withstood the flames accurately 102 minutes. Its southern Twin, 18 minutes later approximately in 60. Floor met, collapsed still more quickly. Because the weight of approximately 50 floors rested here on the stealing vines softening under the glow heat. Which happened then, reminds of a domino effect: The entire building part lying above fell jerkily around few meters downward. It broke with such force on the underlying floor that this broke in for its part. Thus it continued to go into the lower floors.
The terrorists knew obviously exactly, where they had to meet the buildings, in order to destroy it surely, because would have them higher floors headed for, would be the impact of the breaking down floors been too weak, in order to bring the entire building to the collapse. With an impact in deeper floors the fire-brigade could possibly have deleted the fire. The impact of the rubble of the collapsing buildings shook the soil so much that strong oscillations developed and close of convenient buildings damaged the foundations. One (building number 7 of the WTC) collapsed already, several different must according to data by experts due to from tears in the foundation and other damage in the built volumes be probably torn off.

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