The study by a Cambridge University engineer demonstrates that once the collapse of the twin towers began, it was destined to be rapid and total.
One of many conspiracy theories proposes that the buildings came down in a manner consistent with a “controlled demolition”.
Many conspiracy theories? It is the main scientific theory thank you.
The new data shows this is not needed to explain the way the towers fell.
Over 2,800 people were killed in the devastating attacks on New York.
Thanks for reminding us. A refreshing dose of trauma, anyone?
After reviewing television footage of the Trade Center’s destruction, engineers had proposed the idea of “progressive collapse” to explain the way the twin towers disintegrated on 11 September 2001.
Which has been thoroughly researched, here. And by the way, since when did buildings have enough energy to collapse at free-fall speed, eject 80% of its mass hundreds of yards away (exploding) and also disintegrate the vast majority of matter in the buildings, that is, to dust?
This mode of structural failure describes the way the building fell straight down rather than toppling, with each successive floor crushing the one beneath (an effect called “pancaking”).
Dr Keith Seffen set out to test mathematically whether this chain reaction really could explain what happened in Lower Manhattan six years ago. The findings are published in the Journal of Engineering Mechanics.
Previous studies have tended to focus on the initial stages of collapse, showing that there was an initial, localised failure around the aircraft impact zones, and that this probably led to the progressive collapse of both structures.
Once the collapse began, it was destined to be “rapid and total” In other words, the damaged parts of the tower were bound to fall down, but it was not clear why the undamaged building should have offered little resistance to these falling parts.
“The initiation part has been quantified by many people; but no one had put numbers on the progressive collapse,” Dr Seffen told the BBC News website.
Dr Seffen was able to calculate the “residual capacity” of the undamaged building: that is, simply speaking, the ability of the undamaged structure to resist or comply with collapse.
His calculations suggest the residual capacity of the north and south towers was limited, and that once the collapse was set in motion, it would take only nine seconds for the building to go down.
This is just a little longer than a free-falling coin, dropped from the top of either tower, would take to reach the ground.
‘Fair assumption’
The University of Cambridge engineer said his results therefore suggested progressive collapse was “a fair assumption in terms of how the building fell”.
“One thing that confounded engineers was how falling parts of the structure ploughed through undamaged building beneath and brought the towers down so quickly,” said Dr Seffen.
The south tower of the World Trade Center collapses, AP Conspiracy theorists see evidence of a “controlled detonation” He added that his calculations showed this was a “very ordinary thing to happen” and that no other intervention, such as explosive charges laid inside the building, was needed to explain the behaviour of the buildings.
That’s why it happened when the Empire State Building was hit by a plane, and all the other buildings that have caught fire have also exploded and collapsed into dust.
The controlled detonation idea, espoused on several internet websites, asserts that the manner of collapse is consistent with synchronised rows of explosives going off inside the World Trade Center.
Several internet websites eh. Would make one think this whole 9/11 truth movement is limited to some nutjobs in a basement!
Zogby Poll Finds Over 70 Million Voting Age Americans Support New 9/11 Investigation
That’s a lot of basements…
This would have generated a demolition wave that explained the speed, uniformity and similarity between the collapses of both towers.
Conspiracy theorists assert that these explosive “squibs” can actually be seen going off in photos and video footage of the collapse. These appear as ejections of gas and debris from the sides of the building, well below the descending rubble.
Other observers say this could be explained by debris falling down lift shafts and impacting on lower floors during the collapse.
Would it explain the explosions reported in the buildings before and during the impacts?
William Rodriguez account summary.
9/11 Commission Ignored Firefighter’s Account of Explosions Inside WTC
And for intense fires weakening the structure…Officials put the time of the outbreak of the fire at 4pm and said that was extinguished by about 6pm. The south tower of the WTC burned for just 56 minutes before collapsing, while the north tower lasted around an hour and 45 minutes. According to the official transcripts of the firefighter tapes, fires in both towers were almost out immediately before the collapses. Read more…
Dr Seffen’s research could help inform future building design.
Or they could just ask the BBC, which had an amazing ability to predict the collapse of buildings.
And what about building 7 eh? Wasn’t hit by a plane. Experienced the same third-in-history demolition type collapse at almost free-fall speed. I wonder if he factored in the size and strength of the internal columns. All of those floors providing zero resistance? Come on now.
The 9/11 commission report said the collapses were due to fires. Kind of like this one:
Ground Zero Building Catches Fire, Doesn’t Collapse
The 40 story Deutsche Bank building next to the ground zero site in New York, where the world trade center once stood, caught fire yesterday and burned intensely for seven hours without collapsing… Read more
You won’t get answers unless you are prepared to ask questions…
