911 WTC collapse (only!)

[JJM 777]

I am interested in the technical details of the collapse of the WTC twin towers. I have heard several contradicting claims and theories, which I am not qualified to evaluate myself.

- The official story says that the burning gasoline of the airplanes melted the steel pillars of the towers, which then caused the buildings to collapse.

- The alternative theories claim that:

a) jet gasoline does not burn hot enough to melt steel (is this true or not?)

b) even if the fire were just hot enough to melt steel, the steel pillars would transfer the heat to other parts of the building, and the temperature would remain quite moderate at any location (is this true or not?)

c) the collapse took place faster than would be possible with a domino effect of a floor crushing the floor below and so on (is this ture or not?)

d) a controlled demolition of pre-installed explosives could have taken the towers down exactly in the manner witnessed in tv cameras (I expect this claim to be true)

---

If possible, focus on the technical side of the issue: what might possibly have caused the buildings to fall, and exactly how and why?

If possible, keep Al Qaida and CIA outside of this topic -- theoretically, any of these could have done the job in whichever way.

 

[pomeroo]

I am interested in the technical details of the collapse of the WTC twin towers. I have heard several contradicting claims and theories, which I am not qualified to evaluate myself.

- The official story says that the burning gasoline of the airplanes melted the steel pillars of the towers, which then caused the buildings to collapse.

- The alternative theories claim that:

a) jet gasoline does not burn hot enough to melt steel (is this true or not?)

b) even if the fire were just hot enough to melt steel, the steel pillars would transfer the heat to other parts of the building, and the temperature would remain quite moderate at any location (is this true or not?)

c) the collapse took place faster than would be possible with a domino effect of a floor crushing the floor below and so on (is this ture or not?)

d) a controlled demolition of pre-installed explosives could have taken the towers down exactly in the manner witnessed in tv cameras (I expect this claim to be true)

---

If possible, focus on the technical side of the issue: what might possibly have caused the buildings to fall, and exactly how and why?

If possible, keep Al Qaida and CIA outside of this topic -- theoretically, any of these could have done the job in whichever way.

I am told that material addressing these concerns can be found on the web.

 

[uk_dave]

JJM 777, welcome to the forum.

You're about 4 years too late.

The official account does not require the steel to 'melt'
Steel weakens considerably in fire and has to be protected against fire.

The 'pillars' were not the element affected by fire which resulted in the structural failure. It was the thin steel sections of the unprotected floor trusses which failed and pulled the columns inwards causing their failure.

The collapse was much slower than it would have been without resistance from the lower structure.

Don't know if a controlled demolition would have taken the towers down as witnessed because it has never been done before.

What caused the towers to fall?
A bloody great fuel leaden plane slamming into it at 500mph and subsequent fires.

It was on tv. You might have seen it.

 

[gumboot]

I am interested in the technical details of the collapse of the WTC twin towers. I have heard several contradicting claims and theories, which I am not qualified to evaluate myself.

- The official story says that the burning gasoline of the airplanes melted the steel pillars of the towers, which then caused the buildings to collapse.

False. Boeing 767's carry Jet-A fuel, not gasoline. The official account of the collapse does not contend that any steel in the buildings melted. The exterior columns were pulled inwards by the light weight floor trusses, which sagged due to heat.

a) jet gasoline does not burn hot enough to melt steel (is this true or not?)

Jets do not run on gasoline, they run on Jet-A fuel which is essentially kerosene. However neither gasoline, nor aviation gasoline (avgas), nor kerosene-based jet fuels can produce temperatures hot enough to melt steel.

b) even if the fire were just hot enough to melt steel, the steel pillars would transfer the heat to other parts of the building, and the temperature would remain quite moderate at any location (is this true or not?)

False. The floor trusses were very light weight, and connected to steel columns by only two bolts on every second exterior column. Steel is not as efficient a heat sink as some would imply.

c) the collapse took place faster than would be possible with a domino effect of a floor crushing the floor below and so on (is this ture or not?)

False. The above over-simplifies the collapse mechanism. Needless to say, the forces acting on the floor trusses exceeded their design limit by an order of magnitude, and failed almost instantaneously.

d) a controlled demolition of pre-installed explosives could have taken the towers down exactly in the manner witnessed in tv cameras (I expect this claim to be true)

False. No building implosion can explain a gradual bowing of exterior columns over time, as captured on video and in photographs.

If possible, focus on the technical side of the issue: what might possibly have caused the buildings to fall, and exactly how and why?

If possible, keep Al Qaida and CIA outside of this topic -- theoretically, any of these could have done the job in whichever way.

Simply put:

1) Each structure sustained a high speed impact from a large airliner. This caused:
A) Severe structural damage including the severing of exterior and core columns.
B) Stripping of fireproofing material from floor trusses.
C) Large fires starting simultaneously across multiple floors.

2) Fed by the jet fuel fires, and supported by the wind feeding into the gaping hole in each tower, the fires igniting the building contents, resulting in an inferno spreading across multiple floors.

3) The badly damaged, and unprotected floor trusses began to soften in the heat, sagging as they did so.

4) The sagging trusses pulled the exterior columns of the towers inwards across an entire face.

5) With additional loading on the exterior columns due to other severed columns, and increasing lateral loading due to bowing, the exterior columns failed across an entire face of each building.

6) The upper structure twisted and fell through the destroyed impact floors, hitting the first fully intact floor with 10 GJ (WTC1) or 30 GJ (WTC2) of energy. It failed virtually instantly, adding its own weight to the mass falling on the next floor.

7) The floor mass collapsed down inside the tube created by the exterior columns.

8) The force of the collapse forced exterior columns below the impact point outwards, peeling them away from the structure in multi-story sections.

9) The debris fell to the ground, leaving the badly damage core standing to at least its height.

10) The core section, unable to stand on its own, collapses.

-Gumboot

 

[Shrinker]

If possible, focus on the technical side of the issue: what might possibly have caused the buildings to fall, and exactly how and why?

If possible, keep Al Qaida and CIA outside of this topic -- theoretically, any of these could have done the job in whichever way.

Don't pretend you're new to these debates. These last two lines give away your experience.

Picking up from the last CDist. Who makes silent, fireproof demolition explosives that produce no shockwave? Or, if you're in the thermite crowd, how can thermite collapse 60-70 storeys, one at a time, to millisecond precision?

 

[beachnut]

I am interested in the technical details of the collapse of the WTC twin towers. I have heard several contradicting claims and theories, which I am not qualified to evaluate myself.

- The official story says that the burning gasoline of the airplanes melted the steel pillars of the towers, which then caused the buildings to collapse.

No steel was melted, you can look up the melting point of steel and figure this out yourself.

- The alternative theories claim that:

a) jet gasoline does not burn hot enough to melt steel (is this true or not?)

No the official story said jet fuel, which is not gasoline, usually does not burn hot enough to melt steel in ordinary pressure and in ordinary air. This is not an alternate, is a fact.

b) even if the fire were just hot enough to melt steel, the steel pillars would transfer the heat to other parts of the building, and the temperature would remain quite moderate at any location (is this true or not?)

This is stupid. Do you know what your heat sink on your computer is made of? It is not steel. Steel is not a good heat sink, and will not transfer heat good enough to save it from being weakened by fire. You could look this one up yourself too. To really get a feel for this idea, replace your heatsink with a piece of steel and see how long your computer runs. Or look up the facts about different metals, you can do that yourself. Why listen to the idiots of the truth movement, they make all this up as they go.

c) the collapse took place faster than would be possible with a domino effect of a floor crushing the floor below and so on (is this ture or not?)

No the collapse took exactly what a gravity collapse would take. Sorry, the truth movement is full of idiots, do not trust them, they are not very good at physics.

d) a controlled demolition of pre-installed explosives could have taken the towers down exactly in the manner witnessed in tv cameras (I expect this claim to be true)

False, there were no sounds of RDX. Sorry, the truth movement lied. Explosives would have noise, and blast effects. Did you know some people survived in the towers stair well where all the fantasy explosives were planted. Sorry, the liars of 9/11 truth have stuck again, or stuck out.

If possible, focus on the technical side of the issue: what might possibly have caused the buildings to fall, and exactly how and why?

Gee, you could ask the chief structural engineer. He said the aircraft impact were greater than designed for. Plus the jet fuel set fires which set off office fires which weakened the steel. The aircraft did major damage, the fires weakened the steel, the building fell. Gravity helped. Study physics and look up steel properties and you can figure this out all by yourself.

If possible, keep Al Qaida and CIA outside of this topic -- theoretically, any of these could have done the job in whichever way.

CIA is not allowed to operate in the USA. That takes care of that. UBL took credit as did the terrorist hijackers. Darn, end of that stuff.

 

[Gravy]

Hi, JJM.
You can learn about the engineering aspects of the collapses here. I suggest starting with the NIST FAQ at the top. You seem to have swallowed a whole load of misinformation from conspiracists.

 

[JJM 777]

No the collapse took exactly what a gravity collapse would take.

This is an excellent example of what I was looking for by starting this thread: "they" say that a domino collapse would have taken considerably more time than what happened, "you" say that the timing was perfectly natural for a gravity collapse.

I am looking for facts:
- how many seconds did the collapse take ("they" say that it was free falling speed -- true or false)?
- how many seconds would a typical domino collapse take?
- how many seconds would a typical controlled demolition take?
- what happens to the steel core of the building - the vertical steel pillars?

False, there were no sounds of RDX. Sorry, the truth movement lied.

Several people have been quoted describing "pops" and "blasts" and "explosions". I would ignore these details at this point, and focus on the physical nature of the collapse only.

CIA is not allowed to operate in the USA. That takes care of that.

I am (still) trying to keep CIA and AQ out of this thread, but please consider the validity of your statement: Al Qaeda is not allowed to operate in USA either. It is waste of time to mention any names here, it leads nowhere.

 

[The Doc]

- how many seconds did the collapse take ("they" say that it was free falling speed -- true or false)?

False. The first pieces of the building struck the ground 9 seconds (WTC2) and 11 seconds (WTC1) after the collapses. The rest of the towers (excluding the cores) followed a few seconds later. The cores of the buildings took upwards of 20-25 seconds to actually finish collapsing from the start of the collapse.

- what happens to the steel core of the building - the vertical steel pillars?

They stayed standing for around 10 seconds after the collapse of the rest of the structure.

 

[The Doc]

I think I'm going to opt out of this thread. Dealing with the same claims over and over is too much for me, and I don't really even do it as much as some of the others here. I don't know how you do it lol.

 

[MortFurd]

This is an excellent example of what I was looking for by starting this thread: "they" say that a domino collapse would have taken considerably more time than what happened, "you" say that the timing was perfectly natural for a gravity collapse.

I am looking for facts:
- how many seconds did the collapse take ("they" say that it was free falling speed -- true or false)?
- how many seconds would a typical domino collapse take?
- how many seconds would a typical controlled demolition take?
- what happens to the steel core of the building - the vertical steel pillars?


Several people have been quoted describing "pops" and "blasts" and "explosions". I would ignore these details at this point, and focus on the physical nature of the collapse only.


I am (still) trying to keep CIA and AQ out of this thread, but please consider the validity of your statement: Al Qaeda is not allowed to operate in USA either. It is waste of time to mention any names here, it leads nowhere.

Here's a link to some controlled demolitions. Watch and listen to them.

Note the methodical pounding of the charges going off in timed sequence. Note the hammering loudness. Note the flashes that ripple around the building before the collapse starts.

Now, watch a video of the collapse of WTC 1,2, and 7. Note the lack of the hammering sequential detonations. Note the lack of flashes.

Looks nothing like a controlled demolition. The only similarity is that the buildings collapsed.

 

[slingblade]

This is an excellent example of what I was looking for by starting this thread: "they" say that a domino collapse would have taken considerably more time than what happened, "you" say that the timing was perfectly natural for a gravity collapse.

I am looking for facts:

That's good. But, and I hope I phrase this well: why are you looking here, specifically?

What does this single sub-forum of the JREF forum have that draws you here to seek facts about this event?

A good portion of the information here is, while skillfully and carefully presented, based on the findings of others, not members of this forum. There is a certain amount of first-hand information, and a great deal of informational commentary by experts in several fields, yes. But given that so much here comes from forum-members' analyses of reports and investigations done by non-members, why seek facts here, in particular?

If you have not sought out the original reports and investigations, why not?

And if you have, in what way were they factually lacking that you seek to make up that lack here, of all places?

What's so special about the facts here?

 

[Belz...]

The official story says that the burning gasoline of the airplanes melted the steel pillars of the towers, which then caused the buildings to collapse.

You've had 5 years to research this subject, and you claim this ? The steel didn't melt, and the gasoline was burned up by then. Please research the subject.

d) a controlled demolition of pre-installed explosives could have taken the towers down exactly in the manner witnessed in tv cameras (I expect this claim to be true)

Then you expect wrong. Demolition charges tend to be visible and audible. These were not. Also, if you cared to look at pictures of 2 WTC right before the collapse, you can see the exterior columns bowing in. Why do you need explosives if the building's going to come down, anyway ?

 

[Dave Rogers]

JJM 777,

Material that relates to the answers to these, and many other related, questions can be found at the excellent http://www.911myths.com/ website. You will find discussions of a wide range of aspects of the WTC collapses together with links to a wide range of source material to back up any analysis presented on the site. I would thoroughly recommend you take a good look around the site.

Dave

 

[MortFurd]

This is an excellent example of what I was looking for by starting this thread: "they" say that a domino collapse would have taken considerably more time than what happened, "you" say that the timing was perfectly natural for a gravity collapse.

I am looking for facts:
- how many seconds did the collapse take ("they" say that it was free falling speed -- true or false)?

Pretty much irrelevant, since you can see pieces falling off of the buildings during the collapse. Those pieces are falling under the acceleration of gravity. They hit the ground before the part of the building they came from, therefore the building fell slower than "free falling speed."

- how many seconds would a typical domino collapse take?
- how many seconds would a typical controlled demolition take?

A typical CD is a "domino collapse." They destroy parts of the supports and let gravity take over and pull the building down. How fast the domino proceeds depends on how many (how much) of the supports the demolishers removed (among many other things.)
WTC 1 and 2 collapsed for two reasons:
1. The strucutural damaged caused by crashing airplane into them.
2. The buckling of internal stuctures caused by the heat of the fires after the crashes.
Those are two natural equivalents of the demolition charges used in a controlled demolition.

The collapse time of a controlled demolition is whatever the demolishers want it to be. You have to understand that these folks know their stuff pretty danged well. The Kingdome is one that provides a good example. They brought it down slowly so that is didn't hit the ground too hard. They even went so far as to cut the roof loose from the supports so that is had a huge air cushion under it when it fell - it fell inside of the external walls so that the air cushion was trapped. They also had charges set to weaken the roof so that it disintegrated when it hit the ground to lessen the peak impact load.

How long does a typical CD take? As long as they want it to.

- what happens to the steel core of the building - the vertical steel pillars?

Use google. You'll find plenty of pictures that show that the core stood for a bit (some seconds) longer than the rest of the buildings, and that they then collapsed as well.

Several people have been quoted describing "pops" and "blasts" and "explosions". I would ignore these details at this point, and focus on the physical nature of the collapse only.

Answered this one before, but I would add:
Take a good look at the CDI site. Note the materials and prep-time that they give for the various projects. Remember that every building CDI has ever done is far smaller than just one of the twin towers or WTC7, and consider the prep-time and materials that would be needed for such large buildings.

I am (still) trying to keep CIA and AQ out of this thread, but please consider the validity of your statement: Al Qaeda is not allowed to operate in USA either. It is waste of time to mention any names here, it leads nowhere.

ETA:Good plan, lest you accuse some of your fellow Americans of murder before finding just how baseless the stories are that you've heard.

 

[T.A.M.]

The mark is strong...we will see.

TAM

 

[Anti-sophist]

- how many seconds did the collapse take ("they" say that it was free falling speed -- true or false)?

It was measurably less then freefall. The collapse times were in the low 10s (11-13 seconds, or so), and freefall would be below 10 (in the 9 range). It is painfully obvious that it was less then freefall because the collapse wave moves behind the objects that have fallen to the side and are in actual freefall.

- how many seconds would a typical domino collapse take?

I don't know what a 'domino collapse' is and I certainly don't know what a 'typical' domino collapse is. If you want a theoretical estimate of the time of collapse, you're gonna need to consult the papers done by Greening and/or Bazant, etc.

- how many seconds would a typical controlled demolition take?

Typically, freefall.

- what happens to the steel core of the building - the vertical steel pillars?

They stood for many seconds after the collapse, before themselves collapsing. This would -never- happen in a CD, as they-d be the first thing cut with explosives. There are numerous videos of the core standing after the collapse.

 

[T.A.M.]

Funny, I recall Charles Pegelow (Ithink it was him) in a radio interview with Fetzer, claiming the whole Heat Sink thing. You would think AN ENGINEER would know what a horrible heat sink steel is...

TAM

 

[Dave Rogers]

Funny, I recall Charles Pegelow (Ithink it was him) in a radio interview with Fetzer, claiming the whole Heat Sink thing. You would think AN ENGINEER would know what a horrible heat sink steel is...

Yeah, even some of us physicists know that. Back in my graduate student days when I was working with liquid helium and superconducting magnets, anything that had to be immersed into a helium cryostat tended to be stuck on the end of a long steel rod. Since the latent heat of evaporation of helium is the square root of sweet Fanny Adams, we had to avoid heat transfer as much as possible, and stainless steel was both a relatively good insulator, and non-magnetic.

Dave

 

[T.A.M.]

I am sure chefs all over the world would concur...

TAM