[L_D (OP)]

We are told that on 9/11 the Towers, after being struck by planes, redistributed the load from the damaged columns and remained standing upright until fire softened the steel columns enough to initiate collapse. One of the first things I thought looked wrong when re-examining the collapses was the speed at which the collapses initiated, both the Towers went from basically standing upright into virtual freefall.

Steel is ductile, especially when softened by fire, so shouldn't this property of steel be reflected by a much slower collapse initiation? Why don't we see any significant amount of buckling occuring in the structure as the buildings fail? Isn't it true that the way the Towers failed is more indicative of explosives taking out the steel columns rather than fire softening them? This short clip shows the start of the North Towers demise.

The Windsor Tower in Madrid had a partial collapse of the upper floors during an inferno, this partial collapse took over 2hrs and buckling of the steel columns was observed throughout.
http://www.elmundo.es/documentos/2005/02/windsor/album1/02.html

In scratching the surface of this subject I have seen many examles of fire buckling steel columns without it leading to complete collapse, and I have seen no examples of fire causing steel columns to fail instantly except for WTCs 1,2, and 7.

For those of you who are bewildered how anyone can believe this conspiracy theory I ask you to look at Building 7 which collapsed on the same day, two professors of structural engineering have said with "large probability" WTC 7 was a controlled demolition. It is certainly good cause to go and have a closer, more critical look at how the Towers fell.

[paul.fr]

seriously, does anyone really believe that explosives were placed at the base or anywhere on the tower?
As far as conspiracy theories go, this has to be one of the most ridiculous.

Considering that this topic seems to be about a conspiracy theory, i will move it to new theories. If anyone objects it can always be moved.

[L_D (OP)]

seriously, does anyone really believe that explosives were placed at the base or anywhere on the tower?
As far as conspiracy theories go, this has to be one of the most ridiculous.

Considering that this topic seems to be about a conspiracy theory, i will move it to new theories. If anyone objects it can always be moved.

I consider that the thread has a valid engineering question to it in relation to the collapse of the Towers, and it isn't a "new theory" at all. (my 2c)

With regards to whether people "really believe" that explosives were used the answer is yes, in fact many millions of people throughout the world believe it including Professors, Architects, Engineers, intelligence specialists......

[ukmicky]

Its got nothing to do with engineering, its a conspiracy theory as there is no evidence to prove otherwise.

For explosives to take out the towers would mean that somehow they knew that two planes were going to fly into the towers at the same floor that the explosives were planted which is ludicrous. What would have happened if one of the planes missed or was shot down or crashed ten floors higher or lower

How would any one get access to both buildings to plant them and be so sure they wouldn't get found planting them.And don't say the American secret services because do you really think they could trust Bin Laden to work with them and keep it quiet.

Do you also realise how much explosive it would have taken and how much demolition it would have taken to plant the explosives in the exact places required to ensure a colapse.

What happened to the explosions taking out the steel girders in the seconds before the towers collapsed.  i didn't see any

Also the initial colapse was probably concrete on to concrete and then once enough floors had collapsed on top of each other the metal framework of the building would have crumpled as it did ,you have got to remember each floor was made out of thousands of tons of concrete. Drop a thousand tons and nothing gonna stop it.

 

[_Stefan_]

Could the terrorists have put bombs in the planes, instead?

[L_D (OP)]

Its got nothing to do with engineering, its a conspiracy theory as there is no evidence to prove otherwise.

There is plenty of evidence and the rapid onset that this thread is about is one of many very unusual features that can be explained by explosives but not by a gravity fed collapse. Have you seen WTC 7 collapse?

For explosives to take out the towers would mean that somehow they knew that two planes were going to fly into the towers at the same floor that the explosives were planted which is ludicrous. What would have happened if one of the planes missed or was shot down or crashed ten floors higher or lower

The second plane certainly should have been shot down, there were some very convenient military exercises going on that day for whoever planned this.

Noone can know all the logistics of how this was carried out except the actual perpetrators, but I believe the planes were autopiloted or remotely controlled and they knew with a fair degree of accuracy where they would hit, and just had a default system in place for any explosives that were destroyed by the impacts (pure speculation of course)

How would any one get access to both buildings to plant them and be so sure they wouldn't get found planting them.And don't say the American secret services because do you really think they could trust Bin Laden to work with them and keep it quiet.

Bush family members were directors of the company that ran security for the WTC in the build-up to 9/11 (a brother and a cousin iirc). The CIA has worked with BinLaden in the past but I really don't know what to make of him, whether he's dead or alive, an agent or an adversary?


 

What happened to the explosions taking out the steel girders in the seconds before the towers collapsed.  i didn't see any

Also the initial colapse was probably concrete on to concrete and then once enough floors had collapsed on top of each other the metal framework of the building would have crumpled as it did ,you have got to remember each floor was made out of thousands of tons of concrete. Drop a thousand tons and nothing gonna stop it.

 

Plenty of witnesses saw flashes and heard explosions, the squibs that jet out beneith the collapse zone are also very graphic examples of explosives.

The collapse sequence you are describing is the pancake theory which has been widely dismissed even by the NIST final report because, among other reasons, steel buildings don't pancake at anywhere near freefall speed, and the core should have remained if it was the trusses that failed.

Could the terrorists have put bombs in the planes, instead?

That wouldn't cause the whole buildings to collapse, in order for the whole building to fail in the way it did the integrety of the strong undamaged lower section had to have been undermined with explosives.

[DoctorBeaver]

I think Elvis planted the explosives during his lunchbreak from Walmart where he works in the underwear section. He acquired the explosives from an old man in Argentina known as Adolf.

Apparently there was documentary evidence in the basement to do with the deaths of Marilyn Monroe & JFK that the CIA didn't want being brought to light.

[Bored chemist]

Here's adefinition of the word theory cribbed from wiki.
Science
In scientific usage, a theory does not mean an unsubstantiated guess or hunch, as it can in everyday speech. A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena. It originates from or is supported by experimental evidence (see scientific method). In this sense, a theory is a systematic and formalized expression of all previous observations which is predictive, logical and testable. In principle, scientific theories are always tentative, and subject to corrections or inclusion in a yet wider theory.

This fairy tale about the explosives isn't a scientific theory by this definition. Can we set up a suitable place for it to be moved to?

[L_D (OP)]

Here's adefinition of the word theory cribbed from wiki.
Science
In scientific usage, a theory does not mean an unsubstantiated guess or hunch, as it can in everyday speech. A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena. It originates from or is supported by experimental evidence (see scientific method). In this sense, a theory is a systematic and formalized expression of all previous observations which is predictive, logical and testable. In principle, scientific theories are always tentative, and subject to corrections or inclusion in a yet wider theory.

This fairy tale about the explosives isn't a scientific theory by this definition. Can we set up a suitable place for it to be moved to?

I originally posted this in general science as it was an engineering question relating to the most surprising engineering failure this century, not a new theory.

The question of how steel columns fail under fire conditions is not new, and this observation is certainly "logical and testable". All the testing I've examined shows that steel columns do not fail without buckling and that this is a relatively slow process (compared to if the columns were taken out with explosives). Yet on 9/11 three massive steel framed buildings failed at near freefall speed ultimately due to fire, or so we are told.

[DoctorBeaver]

What was holding the girders together? Ordinary bolts. There's your answer. You don't need buckling of the girders themselves if the bolts break.

[L_D (OP)]

What was holding the girders together? Ordinary bolts. There's your answer. You don't need buckling of the girders themselves if the bolts break.

I understand that girders can fail suddenly but what I'm talking about here is the vertical steel columns, in order for the Towers and Building 7 to fall the way they did, and at the speed they did, the columns had to fail more or less instantly.

It is, as far as I can tell, unprecedented for steel columns to fail in this way due to fire because of the ductile nature of steel. I am particularly interested in what happened to the core columns of the Towers.

[DoctorBeaver]

I saw a program on TV some time ago about this. A Japanese engineer/architect was explaining what happened. I can't remember the exact details but it was something to do with the lagging.

[L_D (OP)]

I have resurrected this old thread rather than start a new one because the subject matter is the same, except now I am more interested in the third high-rise that fell on 9/11 (WTC 7).

Please look at this short youtube video of WTC 7s collapse if you haven't already seen it:

The official NIST account of this collapse has recently been released and it admits that freefall occured for 2.25 seconds early in the collapse, or approximately 8 stories.

So now not only does WTC 7 fall in a manner only previously seen through controlled demolition, but it also has the key feature of freefall where the buildings structure offers no resistance to the collapsing building at all.

It is now at the point where anyone who believes those 3 buildings completely collapsed because of isolated fire and damage is in danger of becoming a laughing stock.

http://www.ae911truth.org/info/49

[Bored chemist]

I don't mind being laughed at by fools.

[Chemistry4me]

I'm a fool. I laughed.

[Don_1]

There always seems to be conspiracy theories, JFK, Monroe, moon landings..............

[dentstudent]

Yes - It's odd how they don't think their conspiracy theory through. If you work them through to their logical conclusions, they invariably collapse. With or without explosives.

And surely it should be conspiracy hypothesis, not theory?

[Don_1]

I was just going along with popular phrase. I'm not even so sure that 'hypothesis' would fit the bill! In some cases I think 'conspiracy fairy story' might be the best.

[dentstudent]

Sorry Don - I wasn't commenting about your usage, more the general term.

[Don_1]

No problem mate, I guessed that was the case.