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Title: 9/11 demolition theory challenged
Source:
BBC
URL Source: http://news.bbc.co.uk/2/hi/science/nature/6987965.stm
Published: Sep 11, 2007
Author: staff
Post Date: 2010-07-17 17:31:29 by buckeroo
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Keywords: None
Views: 18969
Comments: 1209
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 study suggests a different explanation for how 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 to be 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. Man stands amid rubble of the World Trade Center, AFP/Getty 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. 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.
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Begin Trace Mode for Comment # 426.
#237. To: buckeroo (#0)
This is just a little longer than a free-falling coin, dropped from the top of either tower, would take to reach the ground. Actually a free fall from the 110th floor would have taken 9.22 seconds. Wow, the towers fell FASTER than free falling objects, like being sucked into a huge vacuum cleaner. Amazing.
Show me your calculation and/or source material.
Oh man, are you REALLY that stupid? Besides it being stated in virtually every report that exists in terms of free fall comparisons, here's the basic physics, which you apparently never learned in school. You can look up the formula, it's t = SQRT(2d/g) t = time, d = distance, g = acceleration due to gravity (32.2 feet per second/second) The roof heights of the WTC towers were 1368 ft for WTC1, 1362 feet for WTC2. Acceleration due to gravity is (32.17 feet per second)/second For WTC1; t = SQRT(2*1368/32.17) = 9.222 seconds For WTC2; t = SQRT(2*1362/32.17) = 9.202 seconds So there you go buck, try looking things up yourself next time before you make a fool of yourself.
Why do you think that your height measurement for the "top" of each of the WTC towers is correct? The towers were hit on the 96th and 81st floors, this means that "free fall" time values were 8.61 and 7.91 seconds respectively because this is the location of initial forces (de plane! de plane!) that buckled the upper floors. So, you are incorrect by throwing your silly brick off the 110th floor... for a publick demonstration of your astounding assumptions to thwart otherwise serious study and investigation into and about a tragic issue. This notion of "free fall" has always been used by the TWOOFERS and it is an incorrect assumption for the top of either of the building for the calculation; it is utter nonsense.
Hahahahhaa. More back pedaling after they themselves use 9.22 seconds as evidenced on Rosie's video clip. Where she's obviously parroting something she doesn't understand the least from a CT website.
Rosie is obviously brighter than you. You don't judge collapse time for only PART of the building collapsing, you INCLUDE the ENTIRE building from the very top. Do they give you stupid pills on your job?
You're the people bantering around the "9.22 seconds," "physical impossibility" phrases. You've had over 8 years and still can't come up with coherent, supportable, verifiable versions of events. Take another few years to get your stories straight. It's not like anybody will be holding their breaths.
Yep, the building SHOULD NOT HAVE collapsed as if it were falling through a vacuum, yet buck's expert "calculated" precisely that. Do you and he subscribe to "Junk Science Monthly"? Or do you just make this shit up as you go?
There is a very good reason why real world controlled demolition uses so much time, energy, and materials to create conditions getting as close to free fall speeds as possible. And the consequence of this reason is, if the collapse does not approach free fall speeds, it wasn't done by professional controlled demolition experts. The reason is, it is known with complete certainty that the force of gravity, if unobstructed by other forces, will pull the building straight down into its own footprint. Where it can be neatly disposed of without damage to anything else not intended to be destroyed. When the structure is not sufficiently prepared by getting rid of any and all remaining obstacles in the way of straight down vertical collapse, there are additional uncertainties introduced of timing, and rerouting gravitational forces in lines other than straight up and down. So professional demolitions people take extra time to make sure the fall will be as close to vertical free fall speeds as possible to avoid introducing other variables which may cause unpredicable unmanageable results. If a building doesn't fall at close to free fall speeds, its fall has not been set up by controlled demolition. Fifeeen seconds vs. nine seconds for a collapse is not even close to free fall speeds. The controlled demolition theory is debunked by actual and observed free fall speeds indicating lack of thorough setup for a building collapse many times larger than the largest recorded CD.
Wrong. All the demolition has to do is START the collapse, and with strategically placed charges and computer aided timing, the collapse can take however long they want it to in terms of structural collapse below the initial point of failure. Thing is, it collapsed WAY too fast for gravity to have done it alone, where a falling body meeting resistance slows down, and the resistance may eventually give way, but it takes some finite amount of time for that to happen. You're saying it took 6 seconds to smash and break EVERY iota of resistance, since the 9 seconds of falling through a vacuum doesn't correlate with the time it took to overcome the resistance.
But a demolition did not start the collapses. The jet crashes did.
Er, no buckie. The buildings did NOT start to fall down when they were hit. They did NOT start to fall till the precise time they collapsed.
So there was no debris scattered around immediately after the impacts? Not much time... it was amazing they stood for so long ... but it took time for the central structure to lose stress capability that caused the later crush down phase.
Not amazing at all, what's amazing is that they fell at all, never mind disintegrate into dust while coming down close to free fall speeds.
ROTFL .... no building is designed to withstand that kind of impact.
So what IS your excuse for WT7? Also the architect for those buildings claims they were indeed made to endure the impact of a 747. Also, this architect calls BS on much of the story......he has far more experience in this field than you do Buck.
Your story is FALSE or fabricated. The twins were designed for a 707 as in a FOG with a velocity well below 550mi/hr. (For you, that means much less inertial force as what occurred on 9/11 by the relative impacts caused by terrorist crashes)
You prove, once again, that you don't know wtf you are talking about. Statements by Engineers Engineers who participated in the design of the World Trade Center have stated, since the attack, that the Towers were designed to withstand jetliner collisions. For example, Leslie Robertson, who is featured on many documentaries about the attack, said he "designed it for a (Boeing) 707 to hit it." 2 Statements and documents predating the attack indicate that engineers considered the effects of not only of jetliner impacts, but also of ensuing fires. John Skilling John Skilling was the head structural engineer for the World Trade Center. In a 1993 interview, Skilling stated that the Towers were designed to withstand the impact and fires resulting from the collision of a large jetliner such as Boeing 707 or Douglas DC-8. Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed, ... The building structure would still be there. 3 A white paper released on February 3, 1964 states that the Towers could have withstood impacts of jetliners traveling 600 mph -- a speed greater than the impact speed of either jetliner used on 9/11/01.
Thank you for verifying my earlier post. You are dynamite!
LOL. The scenario they're quoting to support their CT says the fuel gets dumped inside the building, While elsewhere they argue against thermal energy from the 767's by saying the jet fuel mostly burns harmlessly outside the outer walls.
I know. They are actually agreeing with the FACT that no demolitions were used.
Liar. According to AGovShill's rules, you LOSE.
Where were the demolitions placed? Where is the timing of the demolitions? Who performed the demolitions? Who paid for the demolitions? Why were the demolitions placed? How and what kind of demolitions were placed? Until you can answer these simple questions, you should look at yourself, pal.
Until you can answer these simple questions, you should look at yourself, pal. Who screwed up the Deepwater Horizon? What was his name? Who gave him his orders? Who told the Coast Guard to drive journalists away from the oil cleanup sites? What were their names? Don't get cute with me there bucko. Just because the people who are SUPPOSED to investigate these things DIDN'T, and instead played a game of high stakes geopolitical conquest and clamped down on the US People with their draconian new laws, doesn't mean there isn't a guilty party behind it all.
ROTFL ... Where is at least one teeny, weenie, little ittsy-bitsy, tiny fact supporting any demolitions were used?
The TEENIEST little fact is found in the NANO THERMITE found withint the WTC debris. That's a nano fact..... Read all about it in Professor Steven E. Jones' peer reviewed paper.....here's a little taste: Iron-rich sphere, found in the dust of the World Trade Center, as documented by the United States Geological Survey and RJ LeeGroup, Inc. As noted by RJ Lee in its report, the iron-rich spheres, which are a common component of the WTC dust, are indicative of molten iron, which forms the spheres due to surface tension. The spheres are of interest to the 9/11 Truth movement in its study of the WTC building failures, as they are indicative of the presence of temperatures much hotter than office fires, and they are also a common end product of thermitic reactions, as discussed in the paper 'Active Thermitic Material Discovered in Dust from the 9/11 World Trade Center Catastrophe', by Niels H. Harrit, et. al. The paper describes how nano-scale thermitic material can be chemically tailored to function as an explosive, and it illustrates how iron-rich spheres are an end product from the ignition of thermitic materials. According to Steven Jones, a co-author of the "Active Thermitic Material" paper and a leading figure in the 9/11 Truth movement, NIST did not look for evidence of explosive residue.
Here is another way to see your idea is dispelled: Clearly the BLDGS buckled under the weight of the upper floors. Your reference to nano-thermite is ludicrous... link, please.
Really? Where's the buckling in the above image buck? There is total, complete, symmetric, and sudden collapse, as if there WERE nothing between the bottom red line and the falling upper structure. It's like the internal core columns and external columns magically disappeared, all at once. Not just the floors that were damaged suffered total and sudden collapse, as if they weren't there at all, but the section of the upper tower between the two red lines appears to disappear and collapse as well, resulting in a black puff of smoke. Now that I look at it closer, apparent the uppermost floor suffer the same fate. Buckling my ass.
Oh it fell down all by itself? Or with an explosive charge? Yet, at precisely where the plane struck, the building BUCKLED..... of course your ass wasn't there that day to buckle it. We know, because it is self evident that you are here today.
Explain why all four corners of the damaged section decided to give way simultaneously, along with the internal core, and the external vertical columns. Explain why the floors directly inbetween the roof and the damaged floors ALSO simultaneously failed in all quadrants, and why the upper floors nearest the roof ALSO failed in all quadrants.
Comparatively the inner core of the building held up the entire structure not the outer paper thin skeleton.
#430. To: buckeroo (#426)
(Edited)
Yet there WERE external columns across all 4 walls, yet they seemingly disappear all at the same instant in time, on at least 3 different floors, the top floors, the floors between the top and the damaged section, and the damaged section itself. Two of those floors weren't even damaged. How did they all disappear at once I wonder, along with total immediate failure of the inner multi-column core in 3 different locations, all at the same time...
Top • Page Up • Full Thread • Page Down • Bottom/LatestHis 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.
#246. To: FormerLurker (#237)
Actually a free fall from the 110th floor would have taken 9.22 seconds.
#247. To: buckeroo (#246)
Show me your calculation and/or source material.
#249. To: FormerLurker, AGAviator (#247)
#252. To: buckeroo (#249)
This notion of "free fall" has always been used by the TWOOFERS and it is an incorrect assumption for the top of either of the building for the calculation; it is utter nonsense.
#256. To: AGAviator (#252)
More back pedaling after they themselves use 9.22 seconds as evidenced on Rosie's video clip.
#260. To: FormerLurker, buckeroo, turtle (#256)
You don't judge collapse time for only PART of the building collapsing, you INCLUDE the ENTIRE building from the very top.
#263. To: AGAviator, buckeroo (#260)
You're the people bantering around the "9.22 seconds," "physical impossibility" phrases.
#309. To: FormerLurker, buckeroo, turtle (#263)
(Edited)
Yep, the building SHOULD NOT HAVE collapsed as if it were falling through a vacuum, yet buck's expert "calculated" precisely that.
#316. To: AGAviator (#309)
If a building doesn't fall at close to free fall speeds, its fall has not been set up by controlled demolition. Fifeeen seconds vs. nine seconds for a collapse is not even close to free fall speeds. The controlled demolition theory is debunked by actual and observed free fall speeds indicating lack of thorough setup for a building collapse many times larger than the largest recorded CD.
#318. To: FormerLurker, AGAviator (#316)
All the demolition has to do is START the collapse
#321. To: buckeroo (#318)
But a demolition did not start the collapses. The jet crashes did.
#323. To: FormerLurker (#321)
The buildings did NOT start to fall down when they were hit.
They did NOT start to fall till the precise time they collapsed.
#328. To: buckeroo (#323)
Not much time... it was amazing they stood for so long ... but it took time for the central structure to lose stress capability that caused the later crush down phase.
#331. To: FormerLurker (#328)
what's amazing is that they fell at all
#337. To: buckeroo (#331)
no building is designed to withstand that kind of impact.
#341. To: abraxas (#337)
Also the architect for those buildings claims they were indeed made to endure the impact of a 747.
#346. To: buckeroo (#341)
The twins were designed for a 707 as in a FOG with a velocity well below 550mi/hr. (For you, that means much less inertial force as what occurred on 9/11 by the relative impacts caused by terrorist crashes)
#350. To: James Deffenbach (#346)
John Skilling was the head structural engineer for the World Trade Center. In a 1993 interview, Skilling stated that the Towers were designed to withstand the impact and fires resulting from the collision of a large jetliner such as Boeing 707 or Douglas DC-8. Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed, ... The building structure would still be there.
#359. To: buckeroo (#350)
Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building
#361. To: AGAviator (#359)
#363. To: buckeroo (#361)
They are actually agreeing with the FACT that no demolitions were used.
#364. To: FormerLurker (#363)
Liar.
#367. To: buckeroo (#364)
Where were the demolitions placed? Where is the timing of the demolitions? Who performed the demolitions? Who paid for the demolitions? Why were the demolitions placed? How and what kind of demolitions were placed?
#371. To: FormerLurker (#367)
Don't get cute with me there bucko.
#403. To: buckeroo (#371)
Where is at least one teeny, weenie, little ittsy-bitsy, tiny fact supporting any demolitions were used?
#408. To: abraxas (#403)
The TEENIEST little fact is found in the NANO THERMITE found withint the WTC debris.
#418. To: buckeroo (#408)
(Edited)
Clearly the BLDGS buckled under the weight of the upper floors.
#421. To: FormerLurker (#418)
Buckling my ass.
#423. To: buckeroo (#421)
Yet, at precisely where the plane struck, the building BUCKLED.....
#426. To: FormerLurker (#423)
Explain why all four corners of the damaged section decided to give way simultaneously, along with the internal core, and the external vertical columns.
Replies to Comment # 426. Comparatively the inner core of the building held up the entire structure not the outer paper thin skeleton.
End Trace Mode for Comment # 426.