BBC's September 13th 2001 Article on How the WTC Fell
Still an amazing piece, how blatantly they lie about melted steel from jet fuel fires:
But as fires raged in the towers, driven by aviation fuel, the steel cores in each building would have eventually reached 800C - hot enough to start buckling and collapsing.Funny how that concrete core thing is always ignored...
The protective concrete cladding on the cores would have been no permanent defence in these extraordinary circumstances - keeping the intense heat at bay for only a limited timespan.
"It was the fire that killed the buildings. There's nothing on earth that could survive those temperatures with that amount of fuel burning," said structural engineer Chris Wise.
"The columns would have melted, the floors would have melted and eventually they would have collapsed one on top of each other." (snip) "But steel melts, and 24,000 gallons (91,000 litres) of aviation fluid melted the steel. Nothing is designed or will be designed to withstand that fire."
Once the steel frame on one floor had melted, it collapsed downwards, inflicting massive forces on the already-weakened floor below. (snip)
The building's design was standard in the 1960s, when construction began on what was then the world's tallest building. At the heart of the structure was a vertical steel and concrete core, housing lift shafts and stairwells.
Steel beams radiate outwards and connect with steel uprights, forming the building's outer wall.
All the steel was covered in concrete to guarantee firefighters a minimum period of one or two hours in which they could operate - although aviation fuel would have driven the fire to higher-than-normal temperatures. The floors were also concrete.
The building had to be tough enough to withstand not just the impact of a plane - and the previous bomb attack in 1993 - but also of the enormous structural pressures created by strong winds.
Newer skyscrapers are constructed using cheaper methods. But this building was magnificent, say experts, in the face of utterly unpredictable disaster.