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CarlNelson

The Impossible Fast Collapse of The Towers

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According to the 1964 white paper cited above, a Tower would still be able to withstand a 100-mile-per-hour wind after all the perimeter columns on one face and some of the columns on each adjacent face had been cut. [8]

Also, John Skilling is cited by the Engineering News Record for the claim that "live loads on these [perimeter] columns can be increased more than 2000% before failure occurs." [9]

[8] City in the Sky, Times Books ..., , page 133

[9] How Columns Will Be Designed for 110-Story Buildings, ENR, 4/2/1964

You can quote-mine as much as you like. I can do the same. Here's Leslie Robertson, WTC structural engineer:

We designed the towers to resist the accidental impact of a Boeing 707, perhaps lost in the fog while seeking to land. The impact of the Boeing 767s, commandeered by the terrorists, even though larger and flying much faster, was still unable to bring down the towers. The fire-resistive systems, however, did not and could not have contemplated the subsequent fire fueled by thousands of gallons of jet fuel.

http://www.lera.com/sep11.htm

I'm an engineer, I've seen how predictive methods have developed over the years. There is no way that the effects of 911 could have been modelled in detail when the towers were built. A much cruder calculation would have shown that the towers would likely have resisted an impact, as indeed they did, but the fire effects would be far more complex. A rough estimate might have been done, but it would almost certainly have neglected the unexpected but critical fact that the impact took the fire protection layer from the structure.

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And how exactly is this supposed to be a valid comparison to the WTC being hit by a plane?

A pencil poking a screen netting? Really? You find this comparison to be compelling and accurate?

Its what he said and i have no reason to doubt the man and his expertise. I do think it is an apropriate analogy, and i think he is more credible in this instance than you and me

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Are you sure you understand physics? They give a table of position numbers, so you take differences to get a table of velocity numbers. If you take second differences you get acceleration numbers:

0 1 0 1 1 0 2 0 2 -1 1 1 1 0 1 1 1 0

With their pixel distance of 0.88 ft and time interval of 1/6 sec, those pixel-based accelerations are close to 1g for a value of 1 in my series. Once again, you get an idea of the uncertainty in their numbers, all you can say is they measure something between -1 and +2 g.

I've already shown (post #109) that their claimed size of jolt is grossly overestimated because of errors in their method. With a better method you get a much smaller jolt, easily lost in the scatter of their measurements.

Incidentally, you seem to be confusing impulse and acceleration. I suggest you take that physics course again.

"Bazant claims that a minimum force amplification of 31g, or 31 times the static weight of the upper stories, could have occurred in a collision between the upper and lower blocks of the Twin Towers after a fall of one story"

"The fact that a 31g impulse requires a deceleration of 997.4 ft./s2 is unassailable, and it does not matter whether the collision is elastic or inelastic. With a velocity reduction of 17.38 ft./s and a 997.4 ft./s2 deceleration, the duration of this impulse would have been 17 milliseconds. This rapid deceleration associated with the 31g impulse would necessarily show itself as an abrupt negative slope change in the velocity curve."

http://www.journalof911studies.com/volume/2008/TheMissingJolt7.pdf

so you are saying that 31g deceleration or 997.4 ft/s2 would be hidden in those measurements?

and an abrupt negative velocity of -17.38 ft/s (20 pixels per second) would be hidden in the velocity measurements?

when you say "their claimed size of jolt is grossly overestimated" you are referring to Bazant et al, right? in which case why did you present Bazant as support for your position?

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Posted (edited)

You can quote-mine as much as you like. I can do the same. Here's Leslie Robertson, WTC structural engineer

With several differences...

  • Quote you posted is post-911. And on the top of the page you linked to, it says, 'Our Comments Concerning The Events of September 11th, 2001'.
    The neutrality of this article is questionable.
  • Roberts acknowledged the molten metal at first, but later denied it in a debate with Prof. Steven Jones. His inconsistency is interesting and His motivation remains unclear in many instances
  • Leslie Robertson was not the Chief engineer for the Twin Towers, John Skilling was, he hired Robertson. You should look into what both John Skilling and Frank A. Demartini had to say about the towers. Frank A. Demartini was hired in 1993 after the 93 bombings as building manager unfortunately died in the attacks. Also in 1998 John Skilling passed. They both say that planes could not take down Twin Towers.
  • Given the differences in cruise speeds, a 707 in normal flight would actually have more kinetic energy than a 767, despite the slightly smaller size. Also, the 767s used on September 11th were estimated to be carrying about 10,000 gallons of fuel each at the time of impact, only about 40% of the capacity of a 707.

Here's Leslie Robertson, WTC structural engineer:

We designed the towers to resist the accidental impact of a Boeing 707, perhaps lost in the fog while seeking to land. The impact of the Boeing 767s, commandeered by the terrorists, even though larger and flying much faster, was still unable to bring down the towers. The fire-resistive systems, however, did not and could not have contemplated the subsequent fire fueled by thousands of gallons of jet fuel.

http://www.lera.com/sep11.htm

John Skilling who was the head structural engineer for the World Trade Center said in a 1993 interview 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]

Source - Twin Towers Engineered To Withstand Jet Collision, The Seattle Times, 2/27/93 [cached]

Edited by SolarPlexus

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--

John Skilling who was the head structural engineer for the World Trade Center said in a 1993 interview 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]

Source - Twin Towers Engineered To Withstand Jet Collision, The Seattle Times, 2/27/93 [cached]

This reminds me a lot of another bold claim of structural integrity; "as far as it is possible to do so, these two wonderful vessels are designed to be unsinkable."

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Posted (edited)

With several differences...

I note you only reply to the first part of my post about the quotes, even though I imply that the quotes are not important. How about addressing the important part: that no matter what they claim, they could not have predicted the outcome with the methods available at the time.

Edited by flyingswan

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"Bazant claims that a minimum force amplification of 31g, or 31 times the static weight of the upper stories, could have occurred in a collision between the upper and lower blocks of the Twin Towers after a fall of one story"

"The fact that a 31g impulse requires a deceleration of 997.4 ft./s2 is unassailable, and it does not matter whether the collision is elastic or inelastic. With a velocity reduction of 17.38 ft./s and a 997.4 ft./s2 deceleration, the duration of this impulse would have been 17 milliseconds. This rapid deceleration associated with the 31g impulse would necessarily show itself as an abrupt negative slope change in the velocity curve."

http://www.journalof911studies.com/volume/2008/TheMissingJolt7.pdf

so you are saying that 31g deceleration or 997.4 ft/s2 would be hidden in those measurements?

It is only the ends of the columns that meet that feel the full deceleration. The columns compress and then buckle, so that the bulk of the descending block feels a much smaller deceleration spread over a much longer time. Whether it's 31 g peak and a spread of a few milliseconds at the meeting point or 0.3 g peak and a spread of most of a second at the roof, the deceleration over the time integrates up to the same velocity change, which will only be around 2 ft/s. Such a small change will be easily missed in the uncertainty of the measurements, which we've already seen have an uncertainty of at least a pixel/time step, or 5 ft/s.

and an abrupt negative velocity of -17.38 ft/s (20 pixels per second) would be hidden in the velocity measurements?

No, that is a ridiculously incorrect value.

when you say "their claimed size of jolt is grossly overestimated" you are referring to Bazant et al, right? in which case why did you present Bazant as support for your position?

No, MacQueen and Szamboti, see my post #109.

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No, that is a ridiculously incorrect value.
why is that a ridiculous value?

such a deceleration is measurable in all verinage demolitions, why doesn't it exist with the north tower?

No, MacQueen and Szamboti, see my post #109.

they are looking for the jolt that Bazant claims should be there, and they don't find it.

you said "They use the actual velocity (at less than 1g) after a drop of one floor as the measure of input energy. However, the actual potential energy available corresponds to a 1g acceleration, so a lower velocity means that some of the energy has already gone into deforming the structure.

well of course they use the measured acutal velocity, the kinetic energy available when the top block collides with the bottom strcuture should be calculated using the measured velocity not freefall.

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Posted (edited)

why is that a ridiculous value?

such a deceleration is measurable in all verinage demolitions, why doesn't it exist with the north tower?

they are looking for the jolt that Bazant claims should be there, and they don't find it.

you said "They use the actual velocity (at less than 1g) after a drop of one floor as the measure of input energy. However, the actual potential energy available corresponds to a 1g acceleration, so a lower velocity means that some of the energy has already gone into deforming the structure.

well of course they use the measured acutal velocity, the kinetic energy available when the top block collides with the bottom strcuture should be calculated using the measured velocity not freefall.

Can I just ask - how that velocity was actually measured ?

Was it guestimated from video ?

Br Cornelius

Edited by Br Cornelius

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Whether it's 31 g peak and a spread of a few milliseconds at the meeting point or 0.3 g peak and a spread of most of a second

the building could withstand millions of 0.3g peaks over a second, you are denying Newtons third law again. The building withstood 1g since it was built. it was built with a safety factor of 5 on the perimeter, so would require 6g to realistically fail the top story of the bottom block. a 6g impulse would be seen in the data.

I do not believe that you are an engineer.

look at figure 6, a 6g impulse would result in 17.38 m/s reduction in velocity, such a reduction would be visible in the velocity time graph, it would take at least 6 datapoints (0.8 seconds) to recover to preimpact velocity. it would show in the graph.

"Consider a velocity graph with a 6g deceleration, very likely the minimum load amplification necessary to overcome the reserve capacity of the perimeter columns, which had a minimum factor of safety of 5.00 to 1"

"A 6g impulse requires a deceleration of 193 ft./s2. With a velocity reduction of 17.38 ft./s and a 193 ft./s2 deceleration, the duration of this impulse would have been 90 milliseconds. As the graph shows, there would still be a quite obvious abrupt negative slope change, which is not seen in the velocity curve determined from the measured data."

http://www.journalof911studies.com/volume/2008/TheMissingJolt7.pdf

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How did the "team" of demolition experts determine where the planes were going to hit and hence where to begin the progressive demolition ?

All controlled demolitions of tower blocks are initiated from the bottom up, so why was this one initiated from the top where the result would be much more unpredictable ?

Where is the seismic evidence of the explosions necessary to initiate such a collapse ?

Where is the evidence that shows a demolition team at work in the towers (not in the basement) in the lead up to the collapse ? It would not have been possible without extensive modifications of structure such as opening of office walls.

Just a few basic questions which seem a crucial first step to acceptance of a controlled demolition hypothesis.

Br Cornelius

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I note you only reply to the first part of my post about the quotes, even though I imply that the quotes are not important.

How about addressing the important part: that no matter what they claim, they could not have predicted the outcome with the methods available at the time.

The outcome? They did predict plane impacts if thats what you mean. Twin Towers Engineered To Withstand Jet Collision, The Seattle Times, 2/27/93 (cached)

I do not believe that you are an engineer.

Flyingswan is an engineer, but his branch is aerospace engineering i.e. engineering of aircraft and spacecraft, not skyscrapers.

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Posted (edited)

Whole thing was a show from start, everything was planned. Burning wires were already set-up, where the designated hit would occur. When the planes took off the thing started...And you dont need to open any walls lol! You just roll this wiring around a support column anywhere that is located, and leave it to suprise of "terorist act". By the way your NSA should know the second the planes were kidnaped and no response was giving to control tower. Fighter jets should be scrambled and planes should be shot down. But wait i didnt see any fighter or even alert that this is about to happen. On radar the controller knew 10min or more before the plane changed its course, and note the pilot has turned off the transponder, at this point i would take this as a threat, especially when i see the planes course...

And if you think this was really a "terorist" act, explain to me why no defensive measures were taken, even thou the NSA and Cia and probably some other agency knew about this... And why would a terorist attack with an airplane and not with a nucler device if he has terrorising plans... They would just leave themselves for powerfull counter attack by US...? And later US attacks whole Afganistan why not send a deep cover operative to take only Bin Baden out??? Sounds like a resourse mission to me, under flag of "vengance".

I dont know how this wire is called but it was actualy shown on discovery!

http://www.oredigger61.org/?p=1509

Edited by Nuke_em

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Whole thing was a show from start, everything was planned. Burning wires were already set-up, where the designated hit would occur. When the planes took off the thing started...And you dont need to open any walls lol! You just roll this wiring around a support column anywhere that is located, and leave it to suprise of "terorist act". By the way your NSA should know the second the planes were kidnaped and no response was giving to control tower. Fighter jets should be scrambled and planes should be shot down. But wait i didnt see any fighter or even alert that this is about to happen. On radar the controller knew 10min or more before the plane changed its course, and note the pilot has turned off the transponder, at this point i would take this as a threat, especially when i see the planes course...

And if you think this was really a "terorist" act, explain to me why no defensive measures were taken, even thou the NSA and Cia and probably some other agency knew about this... And why would a terorist attack with an airplane and not with a nucler device if he has terrorising plans... They would just leave themselves for powerfull counter attack by US...? And later US attacks whole Afganistan why not send a deep cover operative to take only Bin Baden out??? Sounds like a resourse mission to me, under flag of "vengance".

I dont know how this wire is called but it was actualy shown on discovery!

http://www.oredigger61.org/?p=1509

These are the aspects which leave the situation open to suspicion as I said before.

As to you comments about high explosive wires which could take out the support beams - show us what high explosive is capable of that. Test have been carried out and shown that thermite, as postulated, could not take out the main beams. Also the main beams are most definitely behind walls and would need to be accessed.

Are you positive that the flying skills of any pilot (let alone a rank amateur) were up to the job of locating a specific floor within the towers. I do not think so.

As to why attack the twin towers with planes. The twin towers are highly resonate and symbolic symbols of American Imperialism (both their design and function) and so they are almost the best symbolic target of the country. These things are not lost on people making symbolic statements to the world.

However, as you pointed out, the response on the day was highly dubious and leaves me suspecting that there was definitely complicity involved. The actual collapse is entirely plausible as a response to the impacts however and a controlled demolition requires far to many leaps of the imagination to become credible.

Br Cornelius

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Posted (edited)

Damn you made some good points too, and yes the wiring was called thermite ( thanks )! :lol: Well they made a test on show that was broadcasted on Discovery, and it went around and thru the test column. Well i think that pilot would hit the designated spot on skycrapper easily, probably they practiced before and even so there are no amatuer pilots in major sky transportation services. How to get to the beam, well i dont know that one...i would need to see the inside of WTC, and i mean inside, there were probably access shafts like they are everywhere, just dont know how big they are.

I'm just saying that this event was no teror act, and i'll stick to that until i die, or your gov. tells the thruth

( which they wont,like many many times before ).

Answers to your questions should be given by many foreign experts, which dont work for your gov. Otherwise they would just lie on...

Edited by Nuke_em

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Damn you made some good points too, and yes the wiring was called thermite ( thanks )! :lol: Well they made a test on show that was broadcasted on Discovery, and it went around and thru the test column. Well i think that pilot would hit the designated spot on skycrapper easily, probably they practiced before and even so there are no amatuer pilots in major sky transportation services. How to get to the beam, well i dont know that one...i would need to see the inside of WTC, and i mean inside, there were probably access shafts like they are everywhere, just dont know how big they are.

I'm just saying that this event was no teror act, and i'll stick to that until i die, or your gov. tells the thruth

( which they wont,like many many times before ).

Answers to your questions should be given by many foreign experts, which dont work for your gov. Otherwise they would just lie on...

The planes were hijacked by amateurs with very limited flying experience - they were in control of the planes at the time of impact. I very much doubt that they had the expertise to pinpoint a rigged floor. Did they rig every upper floor and only detonate the impacted one. This is where it starts to get ridiculousness - after nearly an hour of intense fire what do you think were the chances that the detonations could be reliably controlled to happen in such a manner as to initiate the initial drop. Very unlikely.

These are the basic common sense questions which have to be addressed before even attempting to venture into speculation about the nature of the drop itself.

Br Cornelius

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The planes were hijacked by amateurs with very limited flying experience - they were in control of the planes at the time of impact.

This is what you been told from your gov. and it ends here...You should realize that much of your gov. information is false,disinformative,a lie and i dont need to prove that. Its already been proven by histroy itself...Like i said we need foreign expert to make hes own conclusions.. With answer to one simple question,

" Could this collapse be the work of a man? " And if expert will say yes then we have a starting point...if he says no we cn close the topic...simple :rofl:

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Posted (edited)

How did the "team" of demolition experts determine where the planes were going to hit and hence where to begin the progressive demolition ?

All controlled demolitions of tower blocks are initiated from the bottom up, so why was this one initiated from the top where the result would be much more unpredictable ?

Where is the seismic evidence of the explosions necessary to initiate such a collapse ?

Where is the evidence that shows a demolition team at work in the towers (not in the basement) in the lead up to the collapse ? It would not have been possible without extensive modifications of structure such as opening of office walls.

Just a few basic questions which seem a crucial first step to acceptance of a controlled demolition hypothesis.

Br Cornelius

you are looking for reasons to ignore the evidence, rather than looking at the evidence.

to answer your questions, you simply have to ask yourself "how would I have done it". if you don't have the imagination or knowledge to realise that computers control planes these days to exacting precision, then again, you are only looking for reasons to confirm your belief, rather than look at the evidence or pretending you don;t have that knowledge or imagination. demolitions can occur any way yo want them to occur, youtube "top down demolition", ordinary thermite can cut through structural steel beams, youtube "john cole 911 experiments". why would there be evidence of a demolition team, ask youself "how would I have done it", the answer is you would not wear "demolition team" labels on your uniform, sorry to be overly sarcastic but come on, 50,000 people were in those buildings, nobody knew what everybody was doing and you could access the columns from inside the elevator shafts, ask yourself how would you have done it, a reasonable person would say "rent floor space and shut the doors", even bin laden could have done that.

all these speculative questions have been waived a million times.

you are asking good questions, but what you are doing is asking the wrong side for proof before investigating. the only questions to answer is "is a new investigation warranted".

when your questions are anlaysed logically we find they are not questions, they are statements. you are stating "this is impossible", "that is impossible", in order to show those statements false, it is sufficient to show through speculation that it is possible which has been done. it is not required to know exactly how it was done in order to answer those questions. if you are stating something is impossible then the burden of proof is on you to prove something is impossible, otherwise you are just appealing to incredulity - a logical fallacy.

Edited by Little Fish

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Posted (edited)

Whole thing was a show from start, everything was planned. Burning wires were already set-up, where the designated hit would occur. When the planes took off the thing started...

BBC even reported the collapse of WTC7 in advance !!

i mean the building was still standing when they reported the collapse!

Edited by SolarPlexus

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why is that a ridiculous value?

Because they derived it by subtracting not only the momentum loss but also the energy required to destroy the next two floors from the kinetic energy lost in the impact. This energy is not absorbed instantaneously, but gradually as those two floors deform during the next part of the drop, and by the time that energy is absorbed, a lot more potential energy is available from that drop.

they are looking for the jolt that Bazant claims should be there, and they don't find it.

you said "They use the actual velocity (at less than 1g) after a drop of one floor as the measure of input energy. However, the actual potential energy available corresponds to a 1g acceleration, so a lower velocity means that some of the energy has already gone into deforming the structure.

Proving my point that the deforming energy doesn't go instantaneously. They make this mistake, so they grossly overestimate the jolt they are looking for, so of course they don't find it.

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Posted (edited)

you are looking for reasons to ignore the evidence, rather than looking at the evidence.

to answer your questions, you simply have to ask yourself "how would I have done it". if you don't have the imagination or knowledge to realise that computers control planes these days to exacting precision, then again, you are only looking for reasons to confirm your belief, rather than look at the evidence or pretending you don;t have that knowledge or imagination. demolitions can occur any way yo want them to occur, youtube "top down demolition", ordinary thermite can cut through structural steel beams, youtube "john cole 911 experiments". why would there be evidence of a demolition team, ask youself "how would I have done it", the answer is you would not wear "demolition team" labels on your uniform, sorry to be overly sarcastic but come on, 50,000 people were in those buildings, nobody knew what everybody was doing and you could access the columns from inside the elevator shafts, ask yourself how would you have done it, a reasonable person would say "rent floor space and shut the doors", even bin laden could have done that.

all these speculative questions have been waived a million times.

you are asking good questions, but what you are doing is asking the wrong side for proof before investigating. the only questions to answer is "is a new investigation warranted".

when your questions are anlaysed logically we find they are not questions, they are statements. you are stating "this is impossible", "that is impossible", in order to show those statements false, it is sufficient to show through speculation that it is possible which has been done. it is not required to know exactly how it was done in order to answer those questions. if you are stating something is impossible then the burden of proof is on you to prove something is impossible, otherwise you are just appealing to incredulity - a logical fallacy.

If I were to accept your position I would have to accept a whole raft of maybe's. As it is I want evidence for those maybes and not imaginative speculation. The burden of proof is firmly on your side.

Show me where a floor was rented for rigging.

Show me the planes were rigged for remote control.

Show me that there were no records from door personnel showing traffic in and out of the buildings.

Controlled demolitions do not rely on thermite alone - they involve weakening the support members enough that the force of thermite is adequate to sever the remaining part.

Speculations without evidence are not adequate and discredit your position.

The objective of the hijackers was achieved without the twin towers falling - they would have been demolished anyway - why go to all the extra trouble of rigging them ?

I refuse to throw basic common sense out just because I have a suspicion that there was an element of Government collusion.

Br Cornelius

Edited by Br Cornelius

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the building could withstand millions of 0.3g peaks over a second, you are denying Newtons third law again. The building withstood 1g since it was built. it was built with a safety factor of 5 on the perimeter, so would require 6g to realistically fail the top story of the bottom block. a 6g impulse would be seen in the data.

There is a large peak g at the point of impact, but since that overloads the columns that hit each other, those columns deform, and in deforming they act like shock absorbers to protect the bulk of the building which therefore sees a much lower g over a longer time.

I do not believe that you are an engineer.

Then go ask your nearest university engineering department.

look at figure 6, a 6g impulse would result in 17.38 m/s reduction in velocity, such a reduction would be visible in the velocity time graph, it would take at least 6 datapoints (0.8 seconds) to recover to preimpact velocity. it would show in the graph.

MacQueen and Szamboti make an incorrect assumption that means these numbers are wrong, see my post above or post #109.

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BBC even reported the collapse of WTC7 in advance !!

i mean the building was still standing when they reported the collapse!

This proves what exactly? How does it help a conspiracy to tell the media in advance?

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Posted (edited)

BBC even reported the collapse of WTC7 in advance !!

i mean the building was still standing when they reported the collapse!

And people don't make mistakes ?

The building was damaged by debris and by fire and there was speculation that the building would either fall down or have to be pulled at some point.

The fact that the BBC misreported is compelling evidence of NOTHING.

Let me say however that if there was a remote possibility of a building been demolished on the day then it would have to be WTC7.

Br Cornelius

Edited by Br Cornelius

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