Would the WTC Twin Towers have collapsed from fire alone, without plane impact?

[Mendel]

it seems totally plausible from recent history and eyewitness accounts that they may have used bombs in addition to planes to attack the towers on 9/11.

didn't you just exhort us to not go by first impressions?

it did not seem plausible to NIST

it did not seem plausible to the 9/11 commission who researched how the terrorists prepared

you, on the other hand, acknowledge that there were many indicators of impending collapse as WTC7 burned, and that the collapse would look the same no matter how column 79 lost strength, but still find it plausible that this involved a bomb

it doesn't seem plausible that the terrorists would use both aircraft and bombs; if they could bomb the buildings, why do the aircraft thing, which cost lots of money, time, effort, and lives?

and if it's not plausible that the terrorists would do both, we go to "government conspiracy", which is unprecedented and even less plausible.

 

[benthamitemetric]

No, justify why NIST wouldn't test for explosive residue in the steel when it seems totally plausible from recent history and eyewitness accounts that they may have used bombs in addition to planes to attack the towers on 9/11.

First, there is no audio or visual evidence of explosive or thermitic devices. Second, the entire world trade center site was hand picked over by the FDNY, the NYPD (including its arson and explosives squad), FEMA, the FBI, the NTSB and many others as they searched for the remains and plane pieces. Much of the debris was then again sorted by hand on Staten Island in a years' long project. Third, the debris was also cleared by professional construction and engineering crews, many of whom were actually demolition experts. And, fourth, there are thousands upon thousands of photos of the debris (see this thread generally). In all of that, no one on the ground has reported there being evidence of steel attacked by explosive blast events, no one on the ground has reported witnessing the remnants of explosive devices, and no one has reported seeing anything such as pre-cutting of any structural elements by thermite, and none of the photographic evidence, much of which we ourselves can review to our heart's content today, includes any of the foregoing. Moreover, for a fifth point, as NIST documented in great detail, the damage that was seen to the elements of the towers was entirely consistent with the fire-damaged floors failing and the triggering a runaway collapse of the top block. NIST demonstrated this several ways, including by contrasting the damage to components from the upper blocks to damage to the components of the lower blocks (and, again, none of those components evinced damage from a blast event or an attack by thermite). There thus isn't just no evidence of demolition devices, there is very strong evidence that they were not present.

 

[deirdre]

No, justify why NIST wouldn't test for explosive residue in the steel when it seems totally plausible from both recent history and eyewitness accounts that Al-Qaeda may have used bombs in addition to planes to attack the towers on 9/11.

Article:

NIST did not test for the residue of these compounds in the steel.

The responses to previous questions demonstrate why NIST concluded that there were no explosives or controlled demolition involved in the collapses of the WTC towers.

....
Analysis of the WTC steel for the elements in thermite/thermate would not necessarily have been conclusive. The metal compounds also would have been present in the construction materials making up the WTC towers, and sulfur is present in the gypsum wallboard that was prevalent in the interior partitions.

Source: https://www.nist.gov/world-trade-center-investigation/study-faqs/wtc-towers-investigation

 

[Henkka]

First, there is no audio or visual evidence of explosive or thermitic devices. Second, the entire world trade center site was hand picked over by the FDNY, the NYPD (including its arson and explosives squad), FEMA, the FBI, the NTSB and many others as they searched for the remains and plane pieces. Much of the debris was then again sorted by hand on Staten Island in a years' long project. Third, the debris was also cleared by professional construction and engineering crews, many of whom were actually demolition experts. And, fourth, there are thousands upon thousands of photos of the debris (see this thread generally). In all of that, no one on the ground has reported there being evidence of steel attacked by explosive blast events, no one on the ground has reported witnessing the remnants of explosive devices, and no one has reported seeing anything such as pre-cutting of any structural elements by thermite, and none of the photographic evidence, much of which we ourselves can review to our heart's content today, includes any of the foregoing. Moreover, for a fifth point, as NIST documented in great detail, the damage that was seen to the elements of the towers was entirely consistent with the fire-damaged floors failing and the triggering a runaway collapse of the top block. NIST demonstrated this several ways, including by contrasting the damage to components from the upper blocks to damage to the components of the lower blocks. (and, again, none of those components evinced damage from a blast event or an attack by thermite). There thus isn't just no evidence of demolition devices, there is very strong evidence that they were not present.

Wow, so much work only to not do the final and most conclusive step, which would be to simply test the steel. Even if you have reason to think bombs weren't necessary to collapse the building, why not just check? Does it cost like a billion dollars to check the steel for some explosive residues? Especially when you have eyewitness testimony like this:


Source: https://www.youtube.com/watch?v=SVgYnVcPTzs

No-click: Firefighter recounting his experience of an explosion in the lobby.

When there is a terrorist attack, and you have firefighters on tape telling you they experienced an explosion in the lobby, you check for explosive residue. There is no excuse not to.

 

[Gamolon]

No, justify why NIST wouldn't test for explosive residue in the steel when it seems totally plausible from both recent history and eyewitness accounts that Al-Qaeda may have used bombs in addition to planes to attack the towers on 9/11.

Is there recent history that Al-Qaeda had terrorists sneak into a building, secretly gain access to steel columns, plant explosives on selected columns without anyone knowing, leave, then at a later date, coincide plane impacts with setting off those explosives?

 

[deirdre]

Even if you have reason to think bombs weren't necessary to collapse the building, why not just check? Does it cost like a billion dollars to check the steel for some explosive residues?

they said. because the testing wouldn't even be conclusive.
your shock that the experts didnt perform to your personal standards, is a bit odd sounding.

youre shocked. we get it. you don't understand the answers. even i, lay person extraordinaire, know you are wrong to be shocked. maybe it's time to move on.

 

[Gamolon]

Wow, so much work only to not do the final and most conclusive step, which would be to simply test the steel. Even if you have reason to think bombs weren't necessary to collapse the building, why not just check? Does it cost like a billion dollars to check the steel for some explosive residues? Especially when you have eyewitness testimony like this:


Source: https://www.youtube.com/watch?v=SVgYnVcPTzs

No-click: Firefighter recounting his experience of an explosion in the lobby.

When there is a terrorist attack, and you have firefighters on tape telling you they experienced an explosion in the lobby, you check for explosive residue. There is no excuse not to.

See parts in red...

28. Why didn't NIST consider a "controlled demolition" hypothesis with matching computer modeling and explanation like it did for the "pancake theory" hypothesis?
NIST conducted an extremely thorough three-year investigation that included consideration of a number of hypotheses for the collapses of the WTC towers.

Some 200 technical experts—including about 85 career NIST experts and 125 leading experts from the private sector and academia—reviewed tens of thousands of documents, interviewed more than 1,000 people, reviewed 7,000 segments of video footage and 7,000 photographs, analyzed 236 pieces of steel from the wreckage, performed laboratory tests, and created sophisticated computer simulations of the sequence of events that occurred from the moment the aircraft struck the towers until they began to collapse.

Based on its comprehensive investigation, NIST concluded that the WTC towers collapsed according to the scenario detailed in the response to Question 11.

NIST's findings do not support the "pancake theory" of collapse, which is premised on a progressive failure of the floor systems in the WTC towers (the composite floor system—that connected the core columns and the perimeter columns—consisted of a grid of steel "trusses" integrated with a concrete slab; see diagram). Instead, the NIST investigation showed conclusively that the failure of the inwardly bowed perimeter columns initiated collapse and that the occurrence of this inward bowing required the sagging floors to remain connected to the columns and pull the columns inwards. Thus, the floors did not fail progressively to cause a pancaking phenomenon.


Diagram of the Composite WTC Floor System
NIST's findings also do not support the "controlled demolition" theory since there is conclusive evidence that:

• the collapse was initiated in the impact and fire floors of the WTC towers and nowhere else, and;
• the time it took for the collapse to initiate (56 minutes for WTC 2 and 102 minutes for WTC 1) was dictated by (1) the extent of damage caused by the aircraft impact, and (2) the time it took for the fires to reach critical locations and weaken the structure to the point that the towers could not resist the tremendous energy released by the downward movement of the massive top section of the building at and above the fire and impact floors.

Video evidence also showed unambiguously that the collapse progressed from the top to the bottom, and there was no evidence (collected by NIST or by the New York City Police Department, the Port Authority Police Department, or the Fire Department of New York) of any blast or explosions in the region below the impact and fire floors as the top building sections (including and above the 98th floor in WTC 1 and the 82nd floor in WTC 2) began their downward movement upon collapse initiation.

In summary, NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives. NIST also did not find any evidence that missiles were fired at or hit the towers. Instead, photographs and videos from several angles clearly show that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward until the dust clouds obscured the view.

 

[benthamitemetric]

Wow, so much work only to not do the final and most conclusive step, which would be to simply test the steel. Even if you have reason to think bombs weren't necessary to collapse the building, why not just check? Does it cost like a billion dollars to check the steel for some explosive residues? Especially when you have eyewitness testimony like this:

[video omitted]

No-click: Firefighter recounting his experience of an explosion in the lobby.

When there is a terrorist attack, and you have firefighters on tape telling you they experienced an explosion in the lobby, you check for explosive residue. There is no excuse not to.

So much work that it completely obviated the need for that step and left no rational reason to demand it. Why would one test for explosive residue on pieces of the building that do not display any damage from explosives, especially given all of the other affirmative evidence that there were no explosives?

As for the "explosions" that are being described in the video, it seems in context likely that the firefighters were in the lobby of the north tower when the south tower collapsed and did not yet piece together exactly what happened given the utter confusion and pandemonium that such a dramatic event caused. They obviously did not hear or see actual explosions that were actually bringing down the building they were in, or else they would not be alive to talk about it, right?

 

[Henkka]

Is there recent history that Al-Qaeda had terrorists sneak into a building, secretly gain access to steel columns, plant explosives on selected columns without anyone knowing

Sigh, no, try to remember what I said? It was only on the last page:

It is pretty strange to not look for explosive residues after a terrorist attack on a building that has been bombed before, yes. "Explosives" doesn't even immediately imply some sort of highly technically advanced demolition of the building. It could just be that Al-Qaeda also snuck car bombs into the basement, like it was done in 1993. That could explain why so many people thought they witnessed an explosion. But no, better not check at all.

As for the "explosions" that are being described in the video, it seems in context likely that they were in the lobby of the north tower when the south tower collapsed and did not yet piece together exactly what happened given the utter confusion and pandemonium that such a dramatic event caused. They obviously did not hear or see actual explosions that were actually bringing down the building they were in, or else they would not be alive to talk about it, right?

I'm not sure, but I don't think your version is very plausible. They would have to have gotten out of the north tower, leave the area, and sit down to be interviewed without realizing what they experienced was the south tower collapsing. The last firefighter is so sure of what he experienced, that he immediately starts speculating that there could be bombs planted in other buildings. He says, "Any one of these buildings could fucking blow up", not "There could be more planes coming". But it would be nice to know for sure which lobby they were in.

 

[benthamitemetric]

I'm not sure, but I don't think your version is very plausible. They would have to have gotten out of the north tower, leave the area, and sit down to be interviewed without realizing what they experienced was the south tower collapsing. The last firefighter is so sure of what he experienced, that he immediately starts speculating that there could be bombs planted in other buildings. He says, "Any one of these buildings could fucking blow up", not "There could be more planes coming". But it would be nice to know for sure which lobby they were in.

Again, in hindsight, we know that the lobby he was in was not being blown up by actual explosives that were bringing down the north tower, right? Otherwise, those explosives detonated in the lobby and left the north tower standing, meaning they did not contribute to the collapse, which, in any case, we can all see happened from the top down a significant time after the south tower collapse. (And we know he wasn't in the south tower lobby when explosives were bringing down that building (which in any case, we can also see happened from the top down) or else he'd be dead.) Instead, everything he said is consistent with being in the north tower lobby when the south tower collapsed and your theory that there were actual explosives in the north tower lobby that were going off at that time is incoherent. I'm sure it felt like the north tower lobby was being hit by explosives when the south tower collapsed, however.

 

[LilWabbit]

Wow, so much work only to not do the final and most conclusive step, which would be to simply test the steel....

When there is a terrorist attack, and you have firefighters on tape telling you they experienced an explosion in the lobby, you check for explosive residue. There is no excuse not to.

@Henkka, please give me a brutally honest answer which I know you're capable of producing as you've given me one before:

Do you not see from the above citation and earlier ones that your undercurrent attitude towards the NIST report is negative and even condescending?

If you do, you must honestly acknowledge that such an attitude is called bias. It prevents you from studying the NIST report with thought, a posture of learning and attention to detail (please note that I didn't say "with naive acceptance of everything as divine truth"). As a result of this bias, you either:

(1) Ignore the bits which address the very questions you raise, some of which have been repeatedly cited for you on this thread; or

(2) Summarily dismiss them as inadequate without the benefit of the doubt that maybe NIST had valid and intelligent reasons for not observing what you, as a layperson, regard as simple, obvious and necessary steps in the investigative process.

This underlying anti-NIST bias, which seems to have been further fuelled by your immersion into truther literature, prompts you to regard your own lay reasoning on how a proper investigation ought to be conducted as a competent universal standard.

If you pause and reflect on the above, you will understand how funny and obstinate such hubris about something so evidently amateur looks like to the rest of us. As a result of such honest self-reflection, you would cease to engage in 1 and 2, and adopt a humbler posture of learning at MB, in order for us to be willing to continue any conversation with you and to take you seriously.

We reserve the right to judge for ourselves if you fulfil these basic and fair criteria of constructive dialogue.

Thank you if you took the trouble to read this post seriously.

 

[Henkka]

This part has been quoted a few times now, thought it was kind of interesting:

Some 200 technical experts—including about 85 career NIST experts and 125 leading experts from the private sector and academia—reviewed tens of thousands of documents, interviewed more than 1,000 people, reviewed 7,000 segments of video footage and 7,000 photographs, analyzed 236 pieces of steel from the wreckage, performed laboratory tests, and created sophisticated computer simulations of the sequence of events that occurred from the moment the aircraft struck the towers until they began to collapse.

And yet...

"NIST carried its analysis to the point where the buildings reached global instability. At this point, because of the magnitude of deflections and the number of failures occurring, the computer models are not able to converge on a solution…. [W]e are unable to provide a full explanation of the total collapse." — p. 3-4, NIST Response to Request for Correction

https://www.ae911truth.org/evidence/near-free-fall-acceleration

 

[Mendel]

Why would one test for explosive residue on pieces of the building that do not display any damage from explosives

my impression is that the rationale for this testing is in situations where a bombing is known to have taken place, and it's now of forensic interest to find out what kind of bomb it was

the other, much rarer rationale is when an aircraft disappeared over the open sea, and all we have is some drifting / drifted ashore parts. but in most situations, the damage pattern already provides conclusive evidence of the cause of the event

is my impression correct?

 

[Mendel]

And yet..

... you have conveniently forgotten every response to this, made days ago in this very thread

 

[LilWabbit]

If a choice must be made between:

A. Sloppy reasoning and near venomous bias by nameless internet warriors constantly failing to appreciate the complexity of the facts on the scene by spouting gross simplifications and out-of-context data snippets to the exclusion of a vast range of other data which inconveniently complicate their preferred state-of-play.

B. Imperfect but by and large expert public investigation by established professionals employing lots of time, resources and methodological rigour, while using neutral, dispassionate and articulate language to describe comprehensively, and yet with great detail, the process, the hypotheses, the evidence and the findings.

It's not hard to choose whose findings are more plausible to the neutral observer. Even if B were wrong. Which is the less likely scenario.

 

[Landru]

The FACT that NIST did not test for explosives has been discussed ad nauseum https://www.metabunk.org/search/530235/?q=nist+test+explosive&o=relevance. Please do not talk about it here. It is off topic.

 

[FatPhil]

Article:

Here, for example, is this statement as written in Forbes by professor Richard Muller at the University of California, Berkeley. It opens as follows: "According to the general theory of relativity, the Sun does orbit the Earth. And the Earth orbits the Sun." I invite you to read the rest of it; it's not long.

What's his point? In Einstein's theory of gravity ("general relativity"), time and three-dimensional space combine together to form a four-dimensional shape, called "space-time", which is complex and curved. And in general relativity, you can choose whatever coordinates you want on this space-time.

So you are perfectly free to choose a set of coordinates, according to this point of view, in which the Earth is at the center of the solar system. In these coordinates, the Earth does not move, and the Sun goes round the Earth. The heliocentric picture of the planets and the Sun merely represents the simplest choice of coordinates; but there's nothing wrong with choosing something else, as you like.

Source: https://profmattstrassler.com/2022/05/04/sun-around-the-earth-or-earth-around-the-sun-did-einstein-say-its-all-the-same/

Article:

General relativity allows the use of any coordinate system. Pick a system in which the center of the Earth is fixed; indeed, it can be a system in which the Earth is not even rotating about its axis. Then you can derive all the equations of motion in this system. In this system, the Sun is moving, not the Earth.

Of course, that is a very ponderous approach, and although the equations will work, in principle, they will be very awkward and tricky. So scientists never use them.

So it is not wrong to say that the Sun orbits the Earth. It just leads to much more complicated equations that give you no good intuition for the behavior of gravity.

Source: https://www.forbes.com/sites/quora/2018/03/12/how-general-relativity-complicates-what-we-know-about-earths-orbit/

The ability to chose your own coordinates predates relativity. I first encountered it when studying Lagrangian Mechanics (which was certainly an influence on Einstein's way of thinking, it's pretty fundamental to most physics of the last century or so)

Suppose there exists a bead sliding around on a wire, or a swinging simple pendulum, etc. If one tracks each of the massive objects (bead, pendulum bob, etc.) as a particle, calculation of the motion of the particle using Newtonian mechanics would require solving for the time-varying constraint force required to keep the particle in the constrained motion (reaction force exerted by the wire on the bead, or tension in the pendulum rod). For the same problem using Lagrangian mechanics, one looks at the path the particle can take and chooses a convenient set of independent generalized coordinates that completely characterize the possible motion of the particle. This choice eliminates the need for the constraint force to enter into the resultant system of equations. There are fewer equations since one is not directly calculating the influence of the constraint on the particle at a given moment.

-- https://en.wikipedia.org/wiki/Lagrangian_mechanics

However I think it's wrong to only consider the choice of the coordinate system being flexible as being the thing that permits us to make statements about the physical world, we have to consider the context surrounding, and other implications of, what we are saying. To state "the sun orbits around the earth" is not a statement about coordinate systems, it's a statement about gravity. The sun is the important driver of the gravitational behaviour - without it, we'd fly off into space - and we are practically unimportant - without us, the sun would wobble ever so slightly differently (about the same as a beachball moving the width of a grain of fine sand). There's no symmetry in this relationship. Gravitationally, the sun simply is more important as that's where the barycentre is, and I repeat, "the [sun|earth] orbits around the [earth|sun]" is a statement about a particular gravitational interaction, not abstract coordinates. If it's a statement about abstract coordinates, it's a statement about nothing.

To the accuracy we care about, the barycentre is the centre of the sun (the sun's radius isn't even defined to such precision). The most useful coordinates for describing the gravitational behaviour of the system are the barycentric ones. Which, at the precision that is meaningful, are the heliocentric ones.

 

[Mendel]

To state "the sun orbits around the earth" is not a statement about coordinate systems, it's a statement about gravity.

For one, that's why I qualified it as 'technically' true.

But also, it's something we can see and have evidence of (the sun rises and sets etc.), and this evidence aligns with physics if you model the situation from the observer's coordinate system. The observer can see that the sun revolves around them, and not be wrong.

But no observer can see that Earth is flat, or that it does not move or rotate, or that "water seeks its level". These are false interpretations of what we actually see.

 

[Mendel]

But no observer can see that Earth is flat, or that it does not move or rotate, or that "water seeks its level". These are false interpretations of what we actually see.

@FatPhil Remember, I'm making this distinction because of Henkka's claim that "what seems 'evident' is an incredibly poor way to figure out what's actually true", which sounds like the first step to brainwashing, and is often the first step down the rabbit hole.

What is evident is most often an excellent way to figure out what is true, if you can divorce the observation from the "first impression", aka the interpretation that goes along with it.

"It's evident because I see it" trumps "it's evident because I can't disprove it".

 

[econ41]

Collapsing high rises from what ever the initial cause will look similar.

So true @Jeffrey Orling. Despite the so often repeated false claims. A collapsing building collapses the way its structure allows it to collapse. IF that collapse started because beams 23, 56, 79 and Columns 5, 7 and 12 failed THAT is how it will collapse. Whether those failures resulted from heating, motor vehicle impact or explosive cutting.

Despite truther false claims "Free Fall" does not prove CD. The building does not have to make a decision: "Ooops, I'm collapsing, and I've been CDed so I had better collapse faster".

OR "I can collapse slower because I'm only collapsing from fire!"

 

[Mendel]

Come on... Something that feels frustrating about these conversations sometimes, and what I already said in a PM to LilWabbit, is that you guys can't seem to concede even a little bit, on anything.

this isn't about conceding, this is about keeping your argument straight.

I responded to "But with WTC 7, it does not seem evident at all that we're looking at a natural collapse from office fires" with "no".

This means I think there is obvious evidence that this was a collapse from fire. (I have explained why, a few posts back.)

You should be able to concede that it at least looks like a demolition,

The fact that the collapse looks like a demolition to the layman rest on the observation that "the breakdown of column 79 will always result in the same ensuing collapse sequence", which is a quote from the post you are having issues with.

This means I have already conceded it!

Your problem is that you continue to insist that demolition and fire-induced collapse must look different, so for you, the collapse looking like a demolition is evidence it wasn't the fire. But this is not evident at all! Your claim lacks evidence in every way!

The idea that the collapse looks similar to a demolition does not contradict that we're evidently looking at a fire collapse.

The fact that a Ferrari is red like a fire truck does not change the fact that it's evidently a sports car.

 

[econ41]

Your problem is that you continue to insist that demolition and fire-induced collapse must look different, so for you, the collapse looking like a demolition is evidence it wasn't the fire. But this is not evident at all! Your claim lacks evidence in every way!

This is complementary to the point that I have made several times. We saw three WTC Towers collapse on 9/11. We saw and still have access to visual records and details from which we can explain the observed mechanism. BUT it is the same mechanism whether it was started by unfought fires or had a bit of help from CD.

There should be no disagreement over the main features of those collapses. The Twin Towers had two main stages viz "initiation" (Something caused the top block to start falling) and "progression" (it kept going and didn't stop.) We know that for WTC7 Col 79 failed because we saw the EPH collapse. There are a lot more details that should be common ground. Agreed by proponents of CD or supporters of "unfought fires did it".

Because CD is only a trigger. If CD is needed it MUST be needed to start the collapse. Whether or not it is needed to ensure "progression" does not halt.

The collapses we saw are the collapses that resulted from CD or from unfought humongous fires and a bit of initial damage. There are NOT two different-looking sets of three collapses. Only one set. Three individual collapses. Whatever started them.

So, my second oft-repeated point. Understand each of those mechanisms. They may look superficially similar to CD. But, if you understand the mechanism, you will know that CD was not needed. And why.

The idea that the collapse looks similar to a demolition does not contradict that we're evidently looking at a fire collapse.

Which we can be assured of if we understand the mechanism. Not forgetting the status of debate. No truther has ever proved that CD was needed or that CD was performed.

 

[Henkka]

So true @Jeffrey Orling. Despite the so often repeated false claims. A collapsing building collapses the way its structure allows it to collapse. IF that collapse started because beams 23, 56, 79 and Columns 5, 7 and 12 failed THAT is how it will collapse. Whether those failures resulted from heating, motor vehicle impact or explosive cutting.

Despite truther false claims "Free Fall" does not prove CD. The building does not have to make a decision: "Ooops, I'm collapsing, and I've been CDed so I had better collapse faster".

OR "I can collapse slower because I'm only collapsing from fire!"

I don't really agree with this... Of course a building that has all its supports cut by precisely placed and timed explosives will fall faster, smoother and more symmetrically than a building that collapses for some other reason. That's why those explosives are used. There's not that many videos of buildings collapsing due causes other than CD since it rarely happens, but I think this video is pretty illustrative:


Source: https://www.youtube.com/watch?v=FQQ8X97EYu0

No-click: Video of buildings collapsing from airstrikes during recent conflict in Gaza.

So these buildings are collapsing from explosives instead of fire, but it's not CD. The airstrike is targeted at the base of the building yeah, but it's nowhere near as precise as CD. The thing that I want to draw your attention to here is the tumbling, halting manner in which the buildings collapse. So for example at 0:40, the building starts collapsing, but then decelerates, and then tips over like a tree. Then at 1:30, you can see the same thing happen to a different building. They decelerate because while the airstrike does massive damage, it's not systemically cutting every support simultaneously like CD would. So the lower structure still puts up resistance, and the building halts and tumbles.

The question that everyone has to answer to their own satisfaction is, is it possible for a building to fall as if all its supports had been cut by explosives, but actually do so because of randomly scattered fires? I'm not so sure that's possible.

 

[benthamitemetric]

The question that everyone has to answer to their own satisfaction is, is it possible for a building to fall as if all its supports had been cut by explosives, but actually do so because of randomly scattered fires? I'm not so sure that's possible.

If column 79's collapse is induced by a fire, the rest of the building reacts to the collapse of that column based on the loads that are shifted from column 79 and the manner in which the rest of the building was designed and constructed.

If column 79's collapse is induced by an explosive or by thermite, the rest of the building reacts to the collapse of that column based on the loads that are shifted from column 79 and the manner in which the rest of the building was designed and constructed.

The rest of the building can't know or care why column 79 collapsed; all it can do in any case is react in accordance with its constructed state. There is thus no reason why a controlled demolition of WTC7 that started at column 79 would necessarily look different than a fire induced failure that started at column 79, except that we'd except to see large fires at the time of the latter and we'd expect some auditory or visual indicia of the former.

And look how far off topic we are again.

 

[Henkka]

The rest of the building can't know or care why column 79 collapsed; all it can do in any case is react in accordance with its constructed state. There is thus no reason why a controlled demolition of WTC7 that started at column 79 would necessarily look different than a fire inducted failure that started at column 79, except that we'd except to see large fires at the time of the latter and we'd expect some auditory or visual indicia of the former.

Are you including the debris damage here? The simulations NIST did without debris damage where only column 79 failed looked very different from the real collapse. In those, the top of the building basically folds in on itself.

 

[benthamitemetric]

Are you including the debris damage here? The simulations NIST did without debris damage where only column 79 failed looked very different from the real collapse. In those, the top of the building basically folds in on itself.

All of the simulations that NIST ran looked different than the real collapse. If NIST simulated a CD-induced collapse, it would look different than in real life too. Divergence is expected in a simulation, which is the simplified calculation millions of interdependent variables over time based on approximated inputs, but that's another off topic tangent.

What I said above had nothing to do with NIST's simulations. So I ask: Why would a controlled demolition that was accomplished by destroying column 79 with explosives look different to an outside observer than a failure of the building that resulted from a fire induced failure of column 79 (again, putting aside the presence of fires)? How or why would the rest of the building know or care what felled the column and then behave differently in the two scenarios?

 

[Henkka]

Why would a controlled demolition that was accomplished by destroying column 79 with explosives look different to an outside observer than a failure of the building that resulted from a fire induced failure of column 79 (again, putting aside the presence of fires)?

I guess it wouldn't. But now we would need to establish it would look anything like the observed collapse.

 

[benthamitemetric]

I guess it wouldn't. But now we would need to establish it would look anything like the observed collapse.

But what difference does it make if the same collapse could come from a fire or explosives? You could spend years of your life building an even more detailed model of WTC7 than NIST that collapses even more realistically when you fail column 79 than did NIST's model. Or maybe you find that column 78 failing first leads to a result that was closer to real life. But you are still just reflecting in your model that an element failed, which says nothing about why it failed. There is thus almost no utility to looking at the problem this way if you always hold out as an alternative hypothesis that some unspecified demolition device, instead of the fires, was actually what failed the column. That can never be disproven. For all we know, there was a team of 10 people working column 79 over with angle grinders on the third floor and we've all been fooled. But there's no evidence for that and we know that, even if they had not been doing that, the building could have still collapsed as it did, which makes the idea that they would undertake a demolition pretty silly in hindsight.

 

[Henkka]

But what difference does it make if the same collapse could come from a fire or explosives? You could spend years of your life building an even more detailed model of WTC7 than NIST that collapses even more realistically when you fail column 79 than did NIST's model. Or maybe you find that column 78 failing first leads to a result that was closer to real life. But you are still just reflecting in your model that an element failed, which says nothing about why it failed. There is thus almost no utility to looking at the problem this way if you always hold out as an alternative hypothesis that some unspecified demolition device, instead of the fires, was actually what failed the column. That can never be disproven. For all we know, there was a team of 10 people working column 79 over with angle grinders on the third floor and we've all been fooled. But there's no evidence for that and we know that, even if they had not been doing that, the building could have still collapsed as it did, which makes the idea that they would undertake a demolition pretty silly in hindsight.

I don't know that a failure of column 79 would collapse the building at all. This is only based on computer simulations by NIST, which are of dubious quality.

 

[benthamitemetric]

I don't know that a failure of column 79 would collapse the building at all. This is only based on computer simulations by NIST, which are of dubious quality.

Weidlinger Associates came to the same conclusion, actually, but you're at least focused on the real question now, so hopefully we can avoid getting so hung up on what the WTC7 collapse "looked like". In any case, this is not the thread to rehash whatever lingering objections you may have about the technical analysis of the WTC7's collapse progression. So maybe this thread has run its course?

 

[Henkka]

So maybe this thread has run its course?

Yeah, I would say so

 

[LilWabbit]

I don't know that a failure of column 79 would collapse the building at all.

You would if you'd make an unbiased comparison between the scientific merits of the NIST report and your truther sources. Which, in turn, is impossible since you've already immersed yourself deeply in truther sources while merely glossed over the NIST report with the biased motivation of selectively pinpointing isolated passages and errors in order to confirm your truther stance (i.e. confirmation bias). 'Errors' which would be somewhat comfortably resolved by a more comprehensive, non-selective and attentive study of the NIST report. That's essentially why we're stuck where we are.

This is only based on computer simulations by NIST

No, it's not. Read the NIST report more attentively, as well as earlier contributions to this thread, on the evidence for column 79 failure rather than being based on mere simulations. NIST not examining physical samples of WTC 7 steel does not equate with NIST lacking in reliable evidence on the column 79 failure (namely, critical structural vulnerabilities such as "long-span floor systems, connections that cannot accommodate thermal effects, floor framing that induces asymmetric forces on girders, and composite floor systems, whose shear studs could fail due to differential thermal expansion") which seems to be your go-to reasoning. Neither does it equate with a suspicious motive or a skipping of an important investigative step.

which are of dubious quality.

You have demonstrated neither the credentials nor the competence to pronounce such a verdict on simulations. There's a reason why the simulation is not identical with the observed collapse while still fully valid for the purpose it was designed.

 

[Mendel]

I don't know that a failure of column 79 would collapse the building at all. This is only based on computer simulations by NIST, which are of dubious quality.

No.
4 different outfits, at least, simulated this. I posted on Torero's "WTC7 revisited" paper before, where they're summed up.

 

[Landru]

Henkka has been banned from replying to this thread for continued posting guidelines violations.

 

[econ41]

@LilWabbit -we have two more attempted derails into topics that could be worthy of their own threads. I'll identify the topics and post a brief overview of the status of the issues. This one first:

You have demonstrated neither the credentials nor the competence to pronounce such a verdict on simulations. There's a reason why the simulation is not identical with the observed collapse while still fully valid for the purpose it was designed.

Engineering models or simulations fall into two broad classes viz (a) those that visually "look like" the real thing, and (b) Those that don't for reasons of scaling distortions to ensure valid engineering outcomes. The NIST WTC7 sim doesn't "look like" because it is of that second type of sim. BUT truthers have been encouraged to believe that a sim that does not "look like" is false. (Note that the Hulsey sim was a faked result to "look like" - probably to fool the supporters.)

Then this issue - two of them actually:

I don't really agree with this... Of course a building that has all its supports cut by precisely placed and timed explosives will fall faster, smoother and more symmetrically than a building that collapses for some other reason. That's why those explosives are used. There's not that many videos of buildings collapsing due causes other than CD since it rarely happens, but I think this video is pretty illustrative:

The first issue is the process issue - the "spin" or "moving the goalposts" debating trick which @Henkka engages in is SOP so no further comment is needed - I made a specific statement which @benthamitemetric has supported. IF a building is caused to collapse by certain members failing the collapse will be the same whether the members fail by explosive cutting "CD" or any other method. That is the real topic and I doubt it warrants separate debate in its own thread once we remove the mendacious "spin" of @Henkka's goalpost shifting.

And, on the marketing practice of "buy two - get one free" - here is the 3rd of my "two more" :

The question that everyone has to answer to their own satisfaction is, is it possible for a building to fall as if all its supports had been cut by explosives, but actually do so because of randomly scattered fires?

And, again, set aside the implied loaded question false premise "randomly scattered fires" (It has been responded to on at least one previous occasion) (The collapse that resulted from the fires was the collapse that those fires caused. IF the "scattering" had been different then a different collapse could ensue. The collapse that the other fire caused.) Then his logic is also "arse about". IF fires were to cause a collapse by failing certain members THEN cutting those members without the fires would create the same collapse. An explosive attack can be planned post hoc to model an actual "random" fire. There is no way that a random fire would match any hypothetical explosive cutting collapse. By definition of "random" - not "planned".

I'm not so sure that's possible.

I am. Once the question is framed legitimately.

 

[Oystein]

Spurred by @Oystein, inspired by @Henkka, and challenged by @Mendel, I'd like to make the argument for why it's hard to believe that fire alone (or a small amount of explosives at the top) could have brought down the towers.

Imagine two very large box columns, one inside the other. The outer column represents the perimeter shell of the WTC towers, the other represents the core. Make the shell 3" thick at the base (tappering upwards) and the core 6" thick. Make the perimeter a 200' square and the core an 80' square.

Bolt them directly to the bedrock.

These columns will have their own Euler self-buckling limit individually, but they can be strengthened (as the towers were) by connecting the perimeter to the core at regular intervals with trusses. So imagine putting eight trusses every 10' feet, connecting the perimeter to the core, each corner to each corner and each face to each face.

Next, we're going to have to load those floors. Imagine a square donut concrete slab resting on those eight trusses at every story.

What we need, in the first instance, is to determine a height and load (per floor) for this structure that would allow it to stand up in hurricane force winds. (This is not a "scaled down" model; it's just a very simplified one. Its actual dimensions are roughly similar to the WTC towers.)

Next we need to tweak it so that sustained fires (for a few hours) on three floors would cause the trusses to sag sufficiently to pull in the outer shell, initiating collapse.

Finally, we need this to cause the total collapse of the building. I realize this is just a constrainted version of the Hoffman challenge, which has already been dicussed (see this thread), and I'm not asking you to solve it (which would require math that, as I understand it, none of us are capable of doing).

What I'm asking you to understand is that the difficulty you (hopefully) have imagining this structure collapsing totally to the ground by fire (given that it wouldn't collapse by hurricane or earthquake) is the difficulty that I (and, I presume, @Henkka) have understanding how fires alone could have brought down the WTC.

I cannot imagine there's a height / load / connection strength distribution that makes it both strong enough under ordinary circumstances to stand and weak enough when on fire to fail. And I really do believe I'm providing the basic design concept of the WTC towers. This is how it is described by people like Guy Nordenson in a video that I've mentioned before where he talks about the design of the outer shell of the WTC in some detail. The relevant portion is 5 minutes (from where I've cued it up). At 17:56 he says:



And by people like Leslie Robertson (I think that's who it is) in this video, who describes the shell as a "box":


Finally, I promised Oystein I would find the place where Uwe Starossek uses a similar thought experiment to present a "design concept" using a massive tube (rather than a system of columns). I believe he used it in the book Progressive Collapse of Structures, but I don't have those pages on hand. Instead, I found it in a journal article he published in Structural Engineering International 18(3), 2008, called "Avoiding Disproportionate Collapse of Tall Buildings". Here's the key passage:
View attachment 52856
Source: https://www.tandfonline.com/doi/abs/10.2749/101686608785096577

I'm not sure it's what you're looking for, but that's the argument for my "incredulity". There are plenty of ways to poke holes in it. And it is my sincere hope that you do poke enough holes in it to make it collapse in a manner that is comparable to ROOSD. I have not been able to do it.

The obvious strategy is to put windows in the shell. But converting the outer shell faces from single plates of 3" (at the base) steel into 60 box columns with 3" walls connected with spandrel plates seems to me to produce a structure of (at least) the same strength (which was, I believe, the point).

I also don't see how just adding more (and weaker) trusses would change anything substantially. And I don't think the problem changes if we imagine the weakening at the top to be brought about by well-placed charges on the initiating floors. But I'm all ears.

Sorry I reply six days later - had a killer week at work and no energy left to follow this thread.

What can I say - I am close to thinking you must be a Poe.

Here is a very brief summary of your argument (quote marks indicate actual quotes, bolding is mine):
"Imagine two very large box columns, one inside the other." [more specifics of an imaginary structure that is totally not the WTC] "[...] I cannot imagine there's a height / load / connection strength distribution that makes it both strong enough under ordinary circumstances to stand and weak enough when on fire to fail. And I really do believe I'm providing the basic design concept of the WTC towers."

So there we have it - argument from imagination and incredulity. Dismissed.

Further, as for this passage:
"Finally, I promised Oystein I would find the place where Uwe Starossek uses a similar thought experiment to present a "design concept" using a massive tube (rather than a system of columns). I believe he used it in the book Progressive Collapse of Structures, [...] I found it in a journal article he published in Structural Engineering International 18(3), 2008, called "Avoiding Disproportionate Collapse of Tall Buildings". Here's the key passage:"
[For "key passage" see quote above]

Thomas Thomas! From the Abstract that you link to (my bolding):

[...] an arrangement of independent primary and secondary load transfer systems is arrived at where the primary system consists of a compact reinforced-concrete tube forming the vertical spine of the building. Based on the isolation approach, a vertical segmentation accomplished by strengthened floor slabs is suggested where a commencing pancake-type collapse is arrested by dissipating energy in shock-absorbing devices.

It occurs to me that you did not show us the "key passage" at all, and failed to understand that Starossek's design is NOT a simile for the WTC designs!
You suggest a design with a tube in a tube - Starossek only suggest a core tube. What's the relevance? There is none! You suggest dimensions (3" / 6" thickness at the bottom, tapering off with height) - but based on what? You simply make stuff up! And then ask us to IMAGINE how that totally irrelevant design performs.

That is not an argument - that is high-level obfuscation.

 

[Oystein]

Why was the control needed?

I know Henkka has been banned from posting in this thread, and I assume with confidence that this question has been answered in the meantime, several times probably, but since (s)he asked me, I'll answer again:

To avoid damage to neighboring buildings and infrastructure.
You know, the kind of damage inflicted by the WTC collapses to the entire WTC collapse and all buildings around its perimeter, causing many billions in damages in addition to the collapses of two towers that were directly attacked.

What a question!

 

[Oystein]

...WTC 7 went down in an eerily "controlled" fashion despite zero explosives being used to initiate or control the fall.
...

I am sure this has been answered already, but I'll chime in anyway:

NO - TOTALLY FALSE!
WTC7 did not - I repeat: NOT!!!! - go "down in an eerily 'controlled' fashion".

How can Henkka no know the HUGE damage inflicted when WTC7 twisted and turned and fell all over a couple of streets and slammed INTO the Verizon building to cut a gash, and even fell ON TOP of Fiterman Hall ACROSS THE STREET, with such mass and force that Fiterman Hall was TOTALED and had to be torn down in an expensive procedure?!?!

I guess that happens when you get your information from professional liars like AE911Lies, who withhold very important information from you, so you never see the LIES they feed you.

 

[Oystein]

Or consider "shear lag":

View attachment 52871
Source: Ali & Moon (2007). Structural Developments in Tall Buildings: Current Trends and Future Prospects, Architectural Science Review, 50(3).
https://www.researchgate.net/public...Buildings_Current_Trends_and_Future_Prospects

Anyway ... I have come to the reluctant conclusion that the expertise here is more apparent than real. Sorry. I think the consensus on this forum about how the outer shells of the WTC towers (to name just one component) worked is simply wrong. Here's how they are described by Feng Fu in Advanced Modelling Techniques in Structural Design (Wiley, 2015).

View attachment 52872
View attachment 52875
pp. 30-31

Ali and Moon (2007) is the same paper I quoted the shear lag passage from. This is what they say about perimeter tubes. (They go on to mention WTC as a specific example.)

View attachment 52874
Source: Ali & Moon (2007). Structural Developments in Tall Buildings: Current Trends and Future Prospects, Architectural Science Review, 50(3).
https://www.researchgate.net/public...Buildings_Current_Trends_and_Future_Prospects

At this point there is no doubt in my mind that the perimeter shells could stand on their own in a hurricane (and an earthquake) even when hollow. They'd be like a giant empty box (or a cup).

Let's cut off here:

No.
The WTC floor trusses had the specific role of transferring lateral loads (i.e. mainly wind loads) to the core. (The trusses on the the other side would continue to transfer some of that load to the far side of the perimeter).
This is what the author you quote means by "increae their structural depth".

As for the load paths you sometimes ask for: It would go from a column nearer the center of a wall upon which a strong wind is blowing directly through numerous floor trusses to the core, then through the beams interconnecting the core, then from core to center of the perimeter on other side again straight through trusses.
In the alternative, where you hollow out the perimeter and take away all trusses, the load path would go through the spandrels left and right, orthogonally to wind load, to the corners, then through adjacent walls, to far side of perimeter, while leaving the core entirely unused and of no use.

It seems glaringly obvious that the structure WITH trusses is a "million" times (orders of magnitude) stiffer and more stable than the same structure without.

Remember the towers were DESIGNED with the trusses playing a major role in the overall structural action and not just for holding slabs, people and furniture.

 

[Oystein]

...

Source: https://www.youtube.com/watch?v=SVgYnVcPTzs

No-click: Firefighter recounting his experience of an explosion in the lobby.

...
As for the "explosions" that are being described in the video, it seems in context likely that the firefighters were in the lobby of the north tower when the south tower collapsed and did not yet piece together exactly what happened given the utter confusion and pandemonium that such a dramatic event caused. They obviously did not hear or see actual explosions that were actually bringing down the building they were in, or else they would not be alive to talk about it, right?

benthamitemetric is mistaken - and Henkka even more so:

These firefighters were actually in the lobby of WTC3 - the Marriott Hotel, which was the staging area of their company before the first tower collapsed. What they describe is the effects of the South Tower's debris raining down upon the hotel and destroying its upper floors. They then retreated, without having understood what had happened.

So after 21 years, a truther still has to resort to a piece of "evidence" that is NOT evidence for "explosives" in the twin towers. Why? Because there really is absolutely NO such evidence anywhere to be found.

It's a fantasy.