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9/11 conspiracy theorists are wrong - bring on the science!
Don Rizzle:
9/11 demolition theory challenged
An analysis of the World Trade Center collapse has challenged a conspiracy theory surrounding the 9/11 attacks.
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".
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.
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.
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").
Resistance to collapse
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.
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.
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.
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.
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.
Dr Seffen's research could help inform future building design.
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6987965.stm
Published: 2007/09/11 01:45:47 GMT
© BBC MMVII
virtuoso:
Ah yes, very ordinary, if fire could bring down a building which was built to withstand attacks from aircraft, insurance companies would refuse to provide protection.
Building 7 was not struck by any aircraft and was instead hit by debris, yet other buildings in much closer viscinity to the towers were also struck and though sustained damage, the integrity of the structure held up to the impact.
The firefighters said there are bombs in the building everyone get out.
Bring on the science? ah so when respected architects and engineers cast doubt on how the towers fell, they to become conspiracy theorists do they?
Did you even know that up until very recently when the original blueprints were released publicly, no one was talking about the 20 central core columns, after all, it kind of upset the clear cut explanation.
What kind of collapse, brings forth an almighty ploom of smoke, so huge and powerful that it rockets down the streets far and beyond the immediate area.
What kind of collapse literally throws bodies onto the surrounding roofs?
I notice to how the new "official explanations" continue to contradict the previous one, for a long time they were happy to stick to the concept of a pancake collapse, however this can be deemed to be either shoddy investigation or evil deceit. This is because when you use the pancake collapse theory calculation, it would still have to taken much longer for the buillding to collapse than what actually occurred.
People know full well that many respected figures in the construction industry question the official story and people realise that popular mechanics is run by a guy whose first cousin is Michael Chertoff and is a part of the Hearst Publishing Group nuff said.
Twentytwofifty:
Only a nutjob would believe that something other than the airplanes were responsible for bringing the buildings down.
Don Rizzle:
--- Quote from: virtuoso on September 11, 2007, 11:44:25 AM ---
Ah yes, very ordinary, if fire could bring down a building which was built to withstand attacks from aircraft, insurance companies would refuse to provide protection.
Building 7 was not struck by any aircraft and was instead hit by debris, yet other buildings in much closer viscinity to the towers were also struck and though sustained damage, the integrity of the structure held up to the impact.
The firefighters said there are bombs in the building everyone get out.
Bring on the science? ah so when respected architects and engineers cast doubt on how the towers fell, they to become conspiracy theorists do they?
Did you even know that up until very recently when the original blueprints were released publicly, no one was talking about the 20 central core columns, after all, it kind of upset the clear cut explanation.
What kind of collapse, brings forth an almighty ploom of smoke, so huge and powerful that it rockets down the streets far and beyond the immediate area.
What kind of collapse literally throws bodies onto the surrounding roofs?
I notice to how the new "official explanations" continue to contradict the previous one, for a long time they were happy to stick to the concept of a pancake collapse, however this can be deemed to be either shoddy investigation or evil deceit. This is because when you use the pancake collapse theory calculation, it would still have to taken much longer for the buillding to collapse than what actually occurred.
People know full well that many respected figures in the construction industry question the official story and people realise that popular mechanics is run by a guy whose first cousin is Michael Chertoff and is a part of the Hearst Publishing Group nuff said.
--- End quote ---
What makes you so certain, may i see your engineering doctorate?
jeromechickenbone:
I don't know what happened on 9/11. I'm not a conspiracy nut at all, but I think there needs to be a full investigation and any inconsistencies need to be answered.
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