BYU Professor: Explosives Used To Bring Down WTC

[JayUtah]

Has the WTC janitor William Rodriguez been discussed on this board before?

Perhaps not here, but he has been discussed on an another forum I frequent. Rodriguez claims 13 other people can corroborate his testimony, but he does not name them nor has anyone come forward to say he is one of the 13. There is no physical, eyewitness, or documentary evidence to support his claims.

Essentially Rodriguez is a man with an extraordinary story who immediately tried to shop himself around to all the media outlets in the post-9/11 feeding frenzy. The media generally refused, and so far the only people willing to print his tales are the fringe and alternative media. I don't really consider him to be a very credible witness because he seems so eager to get on television, but not very eager to help people confirm his claims. I suspect this is why the other media left him alone. Of course there has been the persistent claim that the media disregards Rodriguez because they are being told to ignore him by the Powers That Be, but it's more straightforward to conclude that the media is able to recognized a press hound from their prior experience with such people.

[JayUtah]

Not true. According to demolitions expert Van Romero, "It could have been a relatively small amount of explosives placed in strategic points,"

That's true if all we had to account for was the failure of the structure. But we're discussing Hoffman's alleged "energy deficit", which is concerned with much more than just failing the structure. Hoffman claims a certain amount of energy was available in the form of gravitational potential energy, and that a certain amount of energy was required to pulverize the materials to the extent he says was evident, and that the gravitational potential energy was not enough to satisfy the pulverization requirement. Therefore some other source of energy must have been present in order to cause the observed degree of pulverization.

Hoffman and his followers theorize that this extra energy came from explosives. However, Hoffman fails to realize how much mass of high explosives are required to produce the energy he attributes to them. It turns out that very large amounts of high explosives are required to supply the makeup energy, and it is understandably impractical to have placed so much energy clandestinely.

The real problem, of course, is that Hoffman's method is just something he made up, and he didn't undertake any effort to show that this is a valid method of analyzing structural collapses; then there is the additional question of whether his analysis of the pulverization is based on appropriately representative samples.

[JayUtah]

On a physics forum the calculation for the building collapsing was worked out ;

Well, the "physics forum" you refer to seems to house people with an interest in physics, not necessarily people who are qualified in it or have pertinent experience.

Does anyone see a problem with the math or applications.

Other than the complete disregard for structural dynamics? Physics and engineering are not the same thing.

What it implies is that the building offered no resistance.

Possibly, but what it implies is that the lower portion of the building offered less resistance than was possible to measure in the video records as a discrepancy from "free fall". The hidden assumption is that the building should have offered considerable resistance such that the upper, falling portion would have been slowed to a certain degree noticeable or measurable in the videos. This assumption has never been substantiated, and has been contradicted by every licensed structural engineer that I have consulted, including those with decades of experience in structural dynamics of collapses and failures.

[JayUtah]

Actually it was less than 1% of the total steel...

Irrelevant. The point of recovering specimens is not to recover every piece, nor any particular "smoking gun" piece. The NIST harvesting had specific criteria, which Turbonium and I have discussed, and there is no presumption that some minimum percentage of total steel has to be recovered in order to

...and less than half of that was identified. I've already shown how most of the WTC1/2 steel was likely from the upper levels, where the extreme temperatures supposedly existed.

So NIST was unable to identify half the steel, but you're able to identify "most" of it?

I fear you're trying to simplify this problem down to averages or prevalences. You cannot do that and discuss the true nature of the problem. That's like plunging one hand in a pan of boiling water at 100 C and freezing the other hand in a block of ice at -50 C and then saying that "on average" your hands feel fine.

It was not learned if the steel was exposed to those temperatures before or after the collapse...

Not true. Steel that bends and breaks when hot looks different than steel that bends and breaks when cool, and is then heated. That also looks different than steel that gets hot and bends, then cools and breaks.

...and the vast majority of simulations were based on photographic rather than material evidence

Total hogwash. The models were based on standard practice and well-established techniques that date back 25 years as commercial methods and back to the early 1970s as experimental techniques. Finite-element analysis for fire propagation, heat transfer, structural dynamics, and fluid dynamics are well established in the engineering community and have, in most cases, supplanted empirical methods.

The models were not "based on" photographic material. They were based on the engineering construction drawings and records of the construction. They were validated against photographic evidence by showing that they predicted -- to within a high degree of correlation -- the observed damage. They were not derived from the observations in the sense that they were worked backwards from the observation.

...so how reliable are the models that you claim were 'validated' with so little material evidence?

Extremely. The nature of the models does not require a significant portion of the findings to be empirically verified in order to validate the model. This is because the models produce highly complex results; the probability that the model is wrong, yet still satisfies a small handful of spot-verification points, is negligibly small.

These were state-of-the-art FEA models.

Let me give you an example. It's not related to WTC or any actual structural analysis; it's just abstract.

Let's say you have an irregularly shaped piece of steel. You place one end of it in a gas fire at, say, 1000 C and sustain this heat loading until the steel comes to equilibrium. The heat will travel along the steel, but the temperature of the steel will not be the same at all points -- it will be progressively colder as you approach the end that's not in the fire. But according to what schedule?

FE methods can work here. You model the steel's geometry as a very small number of regular elements, establish the heat load in the model at the appropriate end, and then simultaneously solve for all the boundary conditions between your small (say 1 cubic millimeter) adjacent elements. This requires enormous computing power, especially if we relax the assumption that the piece is at equilibrium. Now you know that the model will give you the temperature of each point on the surface of the steel, and indeed within it. So how do you validate the model? Well, you can take the temperature of the steel at several points along its surface. But how many points are necessary? A hundred? A thousand? Two?

You can probably validate the model with only two or three temperature measurements. If the model accurately predicts the steel temperature at those points, the chances of the model being wrong and yet getting those randomly chosen points correct is practically nil. And because you have validated the method of the model, the same kind of model can be used for steel shapes that don't exist anymore in real life. The model deals only with the interactions between tiny adjacent pieces of metal. So anything that can be modelled as tiny adjacent pieces of metal (i.e., everything) can be submitted to this kind of analysis.

So let's say you had a photograph of the actual piece of steel being heated as described, and you noted that it glowed orange in certain places. And since you can look up how hot steel has to be in order to glow a certain color, you can use that photograph to validate your model. You didn't set the model up to duplicate the photo. You just modeled the small-scale physics of the problem, replicated it billions of times inside the supercomputer, and then verified that it predicted what occurred in real life.

So when you see the "drawings" produced by the impact FEM put up next to photographs of the actual impact holes, you're not seeing a model that was built specifically to produce those results. You're seeing a model that captures the fine-grained physics of the collision reasoned from first principles, and noting that it does indeed produce the results that were seen. This is verification that you have a good handle on the physics.

Could the models have allowed for significant tweaking?

Of course. Any finite-element solution is sensitive to initial conditions. And that's why the NIST report describes the various procedures used to control and investigate the initial conditions. They put upper and lower bounds on each parameter, then ran the models to see how much of an effect that particular parameter had on the outcome. For parameters with little effect, there was no need to study the variance. For parameters with great effect, the model was run at various settings of those parameters to see which settings were the most predictive.

NIST claimed to have found some of the beams actually hit by one of the planes; how would the temperature be almost twice as great anywhere else than the point of impact?

Why do you assume the point of impact should be the point of greatest heat? The jet fuel burns off rapidly. Its burning is of great concern not because it constituted the main fuel load that created the most heat, but because it started widespread fires in material that was already present in the building and other solid combustibles that were brought in by the airplanes. That fuel load is what burned for a long time and through which the fires propagated. That type of combustion, not the rapid deflagration of the jet fuel, is what creates the dangerous heat transfer.

Which Cardington tests, can you supply a source? All of my search hits concern tests done well before 9-11.

Yes, so what? These are tests that are not in any way connected with 9/11, so you can't accuse them of being tampered with in order to provide empty support for the prevailing 9/11 theory. I read the studies in print, but I'm sure there are links to the salient findings.

Here is a page[/URL] that uses some Cardington tests as counter-evidence.

I don't consider anonymous lay analysis to be evidence or serious argumentation.

The conspiracy theorists consider the Cardington full-scale tests to be counterevidence because the structure in that case did not collapse. That is a simplistic view based on a relative ignorance of structural and thermal behavior. It takes a trained expert to discuss the differences between Cardington and WTC and therefore which results are generalizable between them and which are not.

The Cardington building first did not sustain any mechanical damage whereas the WTC did. But more importantly the Cardington building is of a different type of construction. It was a relatively pedestrian type of construction that is well-known for structural redundancy, whereas the WTC structural system was more exotic and allowed for less overall redundancy and less uniform redundancy. You can, for example, remove all the floor slabs from a Cardington-type building without affecting its structural integrity. The floors are dead loads to the steel framework. However you cannot do the same with the WTC structure; its floors were part of an overall system.

So those are the basic differences. The similarities involve various mechanical responses to heating and evidence of thermal profiles. In the Cardington building the floor slabs sagged as the result of heating. In that type of construction it's no problem. In the WTC construction it's a big problem. In the Cardington fires the sagging slabs put extreme tension loads on the structures at each end. They sagged and therefore created tension, then when they cooled and shrank in the sagged shape, they added to the tension. You can have 10 kips or more of tension in such a circumstance. That's not enough to seriously damage a Cardington-type structure, but it's enough to cause serious damage to a WTC-type structure that relies on the floor slabs for bracing.

The Cardington investigators measured temparatures up to 1,200 C in the upper layer of air on floors fired using only standard Class B combustible fuel loads. This validates the NIST model saying that layers of air near ceilings in WTC fires reached 1,000 C. Steel immersed in those temperatures loses its strength. It lost its strength in the Cardington tests, but the building's overall redundancy prevented a global collapse. The steel was simply plasticly deformed but generally still serviceable. The surviving columns of the WTC cores were already overloaded, and could not have survived plastic deformation as easily.

Finally the Cardington tests confirm the relationship between radiance, convection, and stoichiometrics. It is argued that the WTC fires were cool fires because they were starved of oxygen. This is inferred from the color of the smoke and the (wrong) presumption that it is jet fuel burning. In fact the combustibles are the office contents (which produce that color of smoke in any stoichiometric), and the alleged oxygen starvation is largely irrelevant. At Cardington they showed that fires actually burned cooler if they removed the building skin. This is because the radiant heat from the fire is lost and not reflected back into the structure, and because incoming cool air cools the fire convectively. So even though an unlimited air supply improves the stoichiometrics of the combustion, it has a secondary effect to the geometry of the fire container. The radiant return and the lack of convection dominate the problem.

Where is video evidence of these extreme raging fires just prior to collapse?

Why will you only accept video evidence?

From what I read in that report, their simulations assumed that the core supports in the upper levels of the towers were damaged until they were weak enough that collapse was imminent, at which point the simulations ended.

I may have misunderstood your argument. I took you to argue that the impact alone was said to have weaked the core columns to the point at which collapse was "imminent". This is not the case. The impact alone did not damage either structure to the point that would have failed inevitably. The resulting fires further weakened the structure.

But you are correct in stating that the models end at the point collapse initiated and did not attempt to model the behavior of the structure beyond that point. This was for two reasons. First, the software (ANSYS/LS-DYNA) does not provide algorithms for large-scale collision/impact simulation at that magnitude, and there is no computer available to NIST that would support modeling of the entire structure to the degree of resolution. And second, there's no point. Global collapse is inevitable at that point, and this is the unanimous opinion of every licensed structural engineer I have consulted on this topic. (I have consulted dozens.) It is also my opinion. Only the conspiracy theorists who lack expertise and training seem surprised that the buildings collapsed entirely.

It hasn't even been agreed upon what sorts of explosives could have been used and where they could have been planted, so how can anyone know so much about which bombs were placed where?

It doesn't matter. If you take the most powerful explosives available at the time and use those for the energy computations, it would still take a very conspicuous amount of them. If you tell me there's an elephant hidden in my house, it doesn't matter that you didn't give me hints whether he was in the kitchen or in the hall closet -- he's going to be noticeable no matter where he is.

I've claimed explosives could have been planted in the basement levels, which many eyewitnesses claim was true...

There are no witnesses to bombs. There are only witnesses to loud noises. Have you ever heard a substantial piece of steel snap?

...and shown that NIST et al. barely even considered damage in the basements contributing to the collapse.

Why should they? If you have a house fire whose burn pattern radiates outward from the gas stove in your bedroom, there's no point checking to see whether the electric space heater in the basement was plugged in or not. There is no evidence in the collapse that anything initiated in or was helped by the basement.

A bomb was planted in the basement levels in '93, so this scenario certainly has precedence.

Sure -- a precedence of failure. The 1993 bomb failed to destroy the structure as planned. So why would it suddenly work in 2001? In any case, the visible damage and failure behavior revolve around the impact points, not the basement. A bomb in the basement won't fail a building at the 90th floor, or pulverize dust that was up that high.

[JayUtah]

Nobody has even answered dinAlt's basic question about the symmetry of collapse from an asymmetric fire. You apparently know quite a bit about these things, could you enlighten us?

Sure; it's easy. First, the WTC 7 collapse was not "symmetric". Second, there's no presumption in structural mechanics that assymmetric loading or localized failure must produce an "asymmetric" response in the structure.

You have to realize that homespun expectations and ad hoc analysis methods are not really going to arrive at a defensible conclusion, or even poke substantial holes in someone else's conclusion.

Unfortunately 99% of the material evidence was destroyed, so is it your simulation against mine?

What simulation do you have?

I don't see how these simulations can be as definitive as you claim.

But you don't know anything about them. How can you be so sure about something you aren't familiar with?

This is the problem with conspiracy theorists. They are generally johnny-come-latelys to sciences and techniques that have been used by experts successfully for a long time, and don't have the familiarity they should have with accepted practices before they delve into criticizing those practices. So the arguments end up looking like unconvincing FUD (fear, uncertainty, and doubt) that seems more aimed at fostering disbelief than in arriving at a real answer.

The hard evidence taken from the site remains the most credible...

No. Engineering has not thought this way for at least a decade. Computer models have evolved generally to the point where they are more predictive and useful than physical models. This is not to say that we ignore physical evidence or eschew empiricisim. But it is to say that we do not require extensive empiricism in order to draw defensible conclusions.

...it does not conclusively show high enough temperatures existed before the collapse.

It does not have to. It only has to show that a certain temperature existed in a certain place. You cannot presume that the few documentable temperatures represent the maximum temperature. As I told Turbonium, we have a well-documented method of reasoning from basic principles and with the aid of those specimens to arrive at a holistic model. You are proposing instead that we simply -- without any justification of any kind -- suppose that the steel got no hotter than what was observed.

If we go back to the FEM example earlier, you're asking me to say that because I measured the steel in only one place along its length and it was only 300 C, that the entire mass of steel can nowhere be hotter than 300 C -- and this in spite of the fact that I have a good idea about the steel's general heat loading. If the model predicts that the temperature at that point should be 302 C, and the actual measurement is 300 C, then the model is validated. And if the model predicts that the temperature elsewhere should be 1,200 C then I can be reasonably sure that it won't be 300 C. It may not be exactly 1,200 C, but it won't simply be the hottest temperature I measured at some particular point.

Plus, you have to explain the symmetric collapse if only certain "hot spots" ever got hot enough to weaken the steel; how did the entire steel core in WTC1 collapse almost in unison under your "hot spot" model?

Because it is natural to do so. Why do you suppose otherwise? You keep bringing up intuitive expectations without considering that they might be wrong.

Let's say I have a structural system of eight columns arranged in a non-uniform plan. Each column has a rated axial load of 100 kg with a 1.5X margin so that each column can really take an axial load of 150 kg before it buckles. Let's say I load the entire system to 750 kg -- comfortably within the design limits. But the distribution is non-uniform, so I can't simply assume that each column takes a load of 750 / 8 = 94 kg. Some columns may be loaded only to 50 kg while others may be loaded to 110 kg. (Yes, such overloading actually occurs in real structures -- this is partly why we use margins.)

Now let me fail three of those columns by, say, an impact and further damage a fourth by seriously denting it. Let's say those three columns together held up 290 kg and the fourth held a load of 50 kg. The damaged column can still bear a load in deflection (i.e., while it's bent) but usually only a fraction of its load. So we can assert that its critical load is now down to 60 kg. But those 290 kg have to go somewhere. Since this loading (and most real-world loading) is not uniform, you can't just divide the 290 kg among the remaining six (or seven, depending on your perspective) columns and add that to their existing load. In fact it's usually the case that one or two columns will bear the vast majority of the redistributed load.

So if we say that one column takes 90 kg of additional load and another column takes 200 kg of additional load -- beyond the loads they were already carrying, that's a sure bet that those two columns will exceed their critical loads and buckle. To keep things simple let's say our buckled column was one of the ones that failed. So now we have five failed columns. And the original orphaned load of 290 kg has increased by however much the two newly failed columns held up. We said the bent column was loaded to 50 kg, and let's say the other failed column had a load of 85 kg. So our load to be redistributed has increased to 425 kg.

Evenly distributed, that would still add 85 kg to each of the five remaining columns. Our total load was 750 kg, so the five survivors are collectively holding up 325 kg, or an average of 65 kg each. With a fairly apportioned share of 85 kg from the orphaned load, we're at 150 kg per column -- the columns' actual critical load. Now our structure has passed the point of no return. It will fall. We know that our structure is non-uniform, so the 425 kg will actually be distributed rather unfairly over the remaining columns, concentrating on two or three.

I'm not trying to mire you down in numbers. The abstract point I want to get across is that each time a column fails, the load to be redistributed gets bigger while the number of columns to which it can be transfered gets smaller. That's a recipe for progressive failure -- and the kind of progressive failure that gets worse the more it progresses. Since the problem gets worse as time goes on, progressive failure frequently (but not always) becomes global failure.

This simplistic kind of collapse doesn't happen all the time in real life because we try to make structures that accept loads more uniformly. It's not easy, and it leads to structural inefficiency. In the terminology of the engineer, we establish redundant load paths. That is, we provide multiple ways in which loads can be accepted and transferred for each specific load, so that if one of them breaks, the load can be redirected to many alternate paths. But the problem for designers is that if you have multiple paths for any one load, you have load-bearing capacity that you're not actually using at any given moment. Load-carrying capacity comes at a price: dead load. Redundant load paths means you have beams and columns that are doing little more than taking up space and inflicting their own weight on the underlying structure. That's a problem for high-rise building designers because tall buildings are very heavy if built with normal techniques. So they have to have systems that are very light and also very strong. Making them light means eliminating some of the redundancy. That means each individual part -- like the columns in our example -- is more responsible for doing its job as part of the overall system.

There are other techniques for stopping progressive collapse, usually highly dependent on the geometry of the structure. You can have shear walls, for example, that provide a sort of built-in weakness that makes material fracture instead of transferring a load. In aircraft we use crack-stoppers that limit the progression of a fuselage fracture and redirect it in a way that minimizes the effects.

The NIST report mentions progressive collapse generally only in its recommendations to adopt more failure resistant structural systems. It is a thinly-veiled accusation that the original WTC designers did not provide for enough redundancy, although many will argue that the building exceeded the redundancy that would normally be expected from that type of construction.

But to answer (at last) your question, "hot spots" lead to global collapse in some structural systems by failing already overloaded columns. Any structural system needs a quorum of members to retain its strength; it's not a matter of the entire building remaining standing as long as one column is still in place. If you destroy a certain number of columns and overheat certain other columns to the point of failure, all that orphaned load can be transferred to columns that are perfectly intact, but are now simply loaded beyond their critical loads. Perfectly straight, intact, cold columns can fail under these circumstances. And once columns start to fail in sequence, the mathematics of load redistribution often impose increasingly excessive loads on a decreasing number of surviving columns such that the global failure actually accelerates from initiation to global failure.

[Musashi]

I have been wondering, if it was a conspiracy, why did the "bombers" bring the buildings straight down? Wouldn't it have raised fewer eyebrows if they had just haphazardly knocked it over?

[SynKronoS]

I have been wondering, if it was a conspiracy, why did the "bombers" bring the buildings straight down? Wouldn't it have raised fewer eyebrows if they had just haphazardly knocked it over?

cost! its cheaper and faster to clean up a pre cut neat pile

[Baloo]

I have been wondering, if it was a conspiracy, why did the "bombers" bring the buildings straight down? Wouldn't it have raised fewer eyebrows if they had just haphazardly knocked it over?

cost! its cheaper and faster to clean up a pre cut neat pile

On the contrary, is easier to stuck in one place the necessary amount of explosives and detonate it all at once than evenly distribute it and synchronously detonate it in order to assure a controlled demolition.
And there is more: had the WTC buildings fall down on a side and not straight down the destruction around them had been much greater... I thought that this is exactly what the conspiracysts wanted to do, so why they didn't do it?

[SynKronoS]

Has the WTC janitor William Rodriguez been discussed on this board before? He is the best eyewitness to whatever explosions occurred in the basements because he was down there when it happened and dragged a few people out, and was also perhaps the last person out of the towers alive, so I'd suggest the explosions happened whenever he says they did. He claims it was just before the first plane hit. There's also been evidence of smoke coming from the railway underneath the towers before the first attack. (I'll look up sources later tonight when I have some time)

well i have mentioned his name here but no one seems too interested in discussing his story-- here is an image from the naudet documentary that collaberates with his story with some background--
IMAGE

Damage to the North Tower Lobby

The damage to the parking garage and lobby simultaneous with the first plane impact are also indicative of the effects of high explosives, with widespread blast damage and fine dust covering the entire scene. Below is a link to a video clip of the WTC-1 lobby area just after the first plane crash, as seen in the documentary "9/11" made by Jules and Gedeon Naudet:

The narrator claims that he "later learned" that there had been an explosion caused by fuel pouring down an elevator shaft, but the lobby shows none of the soot or fuel residue we would expect from such an explosion. Instead we see blown-out windows and a fine dry dust covering the entire lobby, very much the signature of high explosives. Similar damage to the parking garages and subbasements can only be explained by pre-placed explosive charges that were detonated at the moment of the plane's impact.

Another account of underground blasts
Construction worker Phillip Morelli describes being thrown to the ground by two explosions while in the fourth subbasement of the North Tower. The first, which threw him to the ground and seemed to coincide with the plane crash, was followed by a larger blast that again threw him to the ground and this time blew out walls. He then made his way to the South Tower and was in the subbasement there when the second plane hit, again associated with a powerful underground blast. This is one of a series of interviews with WTC survivors done by NY1 News: LINK
LINK

[SynKronoS]

And there is more: had the WTC buildings fall down on a side and not straight down the destruction around them had been much greater... I thought that this is exactly what the conspiracysts wanted to do, so why they didn't do it?

please-- again the common denominator is cost-- only the buildings insured by silverstein collapsed that day-- any other damage would not have been covered

[JayUtah]

here is an image from the naudet documentary that collaberates with his story with some background

Rodriguez is not unique in claiming subterranean "explosions". He is unique in claiming that the explosions were from below his position and that they were "definitely" bombs. He also claims he heroically rescued people who, for some unknown reason, have disappeared and cannot be located for interviews. None of this is corroborated by your evidence.

And again, Rodriguez is discounted not so much because of the incredible nature of his story, but because his behavior is more consistent with that of a media hound than of a survivor.

The damage to the parking garage and lobby simultaneous with the first plane impact are also indicative of the effects of high explosives, with widespread blast damage and fine dust covering the entire scene.

Why is this considered distinctive and particular to "high explosives"? I read this account quite a while ago and was not surprised to learn that the author had no experience in high explosives or their results.

...the lobby shows none of the soot or fuel residue we would expect from such an explosion.

The author offers no substantiation or explanation for his expectation that a fuel-air explosion would produce soot or "fuel residue". The author says this scene is anomalous simply because it contradicts his personal opinion.

Instead we see blown-out windows and a fine dry dust covering the entire lobby, very much the signature of high explosives.

Why would this not be produced by a fuel-air explosion?

Similar damage to the parking garages and subbasements can only be explained by pre-placed explosive charges...

Begging the question. The author offers only a vague suggestion of an indirect proof. "Can only be explained..." is the typical argument offered when there is actually no direct evidence of any kind.

...that were detonated at the moment of the plane's impact.

To what effect? If you want to fake a demolition by intentional aircraft impact, why would you think it wouldn't be suspicious to set off explosive charges 1,000 feet away from the point of impact? And what role are those explosives supposed to play in the overall scenario?

Construction worker Phillip Morelli describes being thrown to the ground by two explosions while in the fourth subbasement of the North Tower.

First "explosion" = pressure wave created at impact. This was seen at several floors.

Second explosion = fuel-air explosion from fuel that passed down the elevator shafts.

Tower and was in the subbasement there when the second plane hit, again associated with a powerful underground blast.

Pressure wave created by second impact; the towers had a common sublevel comprising a shopping mall.

[Baloo]

please-- again the common denominator is cost-- only the buildings insured by silverstein collapsed that day-- any other damage would not have been covered

Oh, come on...why should a evil government who's willing to kill 3000 of it's citizens be worried about some insurance companies?

[twinstead]

please-- again the common denominator is cost-- only the buildings insured by silverstein collapsed that day-- any other damage would not have been covered

Okay, now this layman is confused.

So let me get this straight; is this a plot by Silverstein to collect insurance money, or a plot by the evil government to garner support for a war on terrorism?

In one breath it is said that the attacks were done for maximum death to rally the American people to do the evil GWB's bidding, and then in another it is said they were careful not to damage and non-Silversteen building so they meticulously wired the buildings and manged an absolutely perfect in the footprint demolition as a favor to him.

And anyway, both the staggering amount of cash that a plot (if true probably the most complex black ops operation in the history of the Earth) like this must have cost to put together, along with the trillions of dollars in economic cost, you'd think an extra few million for cleanup over a wider area would be more than worth it for the extra effect.

Is Silverstein supposed to have come to the government and asked them to help him get some insurance money, and they said, "sure, and that will allow us to kill 2 birds with one stone", or did the government come to him and tell him they are going to demolish his buildings and wink wink if you don't say anything about it well let you collect the insurance money?

I've read both sides of this issue. Contrary to many CTs beliefs, even rational people when faced with ALL the evidence can still lean towards the official story as the more plausible.

[Cl1mh4224rd]

Okay, now this layman is confused.

So let me get this straight; is this a plot by Silverstein to collect insurance money, or a plot by the evil government to garner support for a war on terrorism?

I have to second this confusion. Additionally, if this was meant as a trigger to invade foreign countries for "trillions" of dollars worth of oil, and carried out by a government who not-so-secretly wastes tons of money, why is cost suddenly an issue?

What; is there a conspiracy to save money now?

[Wolverine]

heres the new york times piece on it-- ask ralph blumenthal about his work as the original archive link from the times no longer works-- the fact that it occured is beyond doubt
************************************************
NEW YORK TIMES

Thursday October 28, 1993 Page A1

"Tapes Depict Proposal to Thwart
Bomb Used in Trade Center Blast"

By Ralph Blumenthal

[Moderator note: Copyrighted material deleted.]

LINK

SynKronoS, your unwillingness to abide by the forum rules and heed the previous warnings issued leave me with no alternative but to terminate your account. Your post I've quoted above from the New York Times originally contained better than four paragraphs of copyrighted material. Fair warning was given, it's unfortunate you chose not to comply.

Apologies to other members who undertook substantial effort to address this user's claims.

[Wolverine]

B) No one will ever mistake anyone who can spell, punctuate, and capitalize as being your sock puppet.

While I wholeheartedly appreciate your desire to preserve the English language, this comment was rather snide and unnecessary. Please refrain from posting similar things in the future.

[dougreed]

WHY DID THE WTC FALL more or less VERTICAL and not topple over? BECAUSE no material exsists that could support a stucture of those dimensions at an angle that would allow it to topple. It IS that simple! It was a building meant to stand upright like every other building. The forces that come into play as it would lean would cause it to split and drop just as it did. The same as an aircraft is meant to fly with it's wings fixed, introduce too much flex and the components fail. A building is just not designed or constructed to withstand falling over like a tree. AND if you look at the one Hi8 video you do indeed see the top portion of one of the buildings does indeed topple at quite an angle before gravity and stresses below take it vertical and into the dust cloud.

[akirabakabaka]

Actually it was less than 1% of the total steel...

Irrelevant. The point of recovering specimens is not to recover every piece, nor any particular "smoking gun" piece. The NIST harvesting had specific criteria, which Turbonium and I have discussed, and there is no presumption that some minimum percentage of total steel has to be recovered in order to

Where was this recent 2005 NIST sample taken from if all of the steel was destroyed years ago?

...and less than half of that was identified. I've already shown how most of the WTC1/2 steel was likely from the upper levels, where the extreme temperatures supposedly existed.

So NIST was unable to identify half the steel, but you're able to identify "most" of it?

I fear you're trying to simplify this problem down to averages or prevalences. You cannot do that and discuss the true nature of the problem.

I wasn't unable to identify any of it, since I've never seen it before. I was however able to make a case that much of it was likely taken from the upper levels of the towers, where the extreme temperatures supposedly existed.

It was not learned if the steel was exposed to those temperatures before or after the collapse...

Not true. Steel that bends and breaks when hot looks different than steel that bends and breaks when cool, and is then heated. That also looks different than steel that gets hot and bends, then cools and breaks.

Read the WPI report. The no-melted-steel group has largely ignored this report, which found evidence of liquified steel. If the sulpheric reactions were entirely due to fuel, either from the jets or from the building, that supports the case that they were heated during the attack. Comments from the scientists suggest they did not consider this a possibility, but maybe they overlooked it.

...and the vast majority of simulations were based on photographic rather than material evidence

Total hogwash.

I exaggerated, sorry.

Final Report of the National Construction Safety Team on the Collapses of the World Trade Center Towers (Draft): "The scarcity of physical evidence that is typically available in place for reconstruction of a disaster led to
the following approach: Accumulation of copious photographic and video material. With the assistance of the media, public agencies and individual photographers, NIST acquired and organized nearly 7,000 segments of video footage, totaling in excess of 150 hours and nearly 7,000 photographs representing at least 185 photographers. This guided the Investigation Team’s efforts to determine the condition of the buildings following the aircraft impact, the evolution of the fires, and the subsequent deterioration of the structure." -- since most of the evidence was destroyed, they have to verify their models using visual evidence.

"In some cases, assessment of enhanced photographic and video images of the towers enabled distinguishing between damage that occurred prior to the collapse and damage that occurred as a result of the collapse." (p.87) -- how reliable is that?

The models were not "based on" photographic material.

Agreed, bad choice of a word.

...so how reliable are the models that you claim were 'validated' with so little material evidence?

Extremely. The nature of the models does not require a significant portion of the findings to be empirically verified in order to validate the model. This is because the models produce highly complex results; the probability that the model is wrong, yet still satisfies a small handful of spot-verification points, is negligibly small.

These were state-of-the-art FEA models.

"NIST also used these global reference models to establish the baseline performance of the towers under gravity and wind loads. [...] The estimation of wind-induced loads on the towers emerged as a problem. Two sets of wind tunnel tests and analyses were conducted in 2002 by independent laboratories [...] The estimated loads differed by as much as 40 percent." (p.91-92) -- they appear to conclude that the wind load data is no good and so they don't use it?

6.6.3 explains how these global reference models weren't even used for the impact simulations. "the model had to “fit” on a state-of-the-art computer cluster and to run within weeks rather than months." (p.92) -- why such a limited time restraint after spending years on this investigation?

"The model of WTC 1 included floors 92 through 100; the model of WTC 2 extended from floor 77 through floor 85." -- you mentioned on the other 9-11 thread:

It's not like they made up their minds ahead of time what caused everything and embarked on a course of action designed to support only that hypothesis and make it sound credible.

Wasn't it decided that the impact and fires caused the collapse, end of story? The simulation wasn't inconclusive, but I would argue it had a high uncertainty and was open for significant tweaking of inputs.

Could the models have allowed for significant tweaking?

Of course. Any finite-element solution is sensitive to initial conditions. And that's why the NIST report describes the various procedures used to control and investigate the initial conditions. They put upper and lower bounds on each parameter, then ran the models to see how much of an effect that particular parameter had on the outcome. For parameters with little effect, there was no need to study the variance. For parameters with great effect, the model was run at various settings of those parameters to see which settings were the most predictive.

From what I can tell they only ran the impact simulation a single time. "The combined tower and aircraft model of more than two million elements, at time steps of just under a microsecond, took approximately two weeks of computer time" (p.92)

NIST claimed to have found some of the beams actually hit by one of the planes; how would the temperature be almost twice as great anywhere else than the point of impact?

Why do you assume the point of impact should be the point of greatest heat?

The fires all took place in the same area near the point of impact. Why was this fire damage so limited that they didn't find any steel exposed to those temperatures, yet found steel directly around that area, even the point of impact?

Which Cardington tests, can you supply a source? All of my search hits concern tests done well before 9-11.

Thanks, nice reply.

Where is video evidence of these extreme raging fires just prior to collapse?

Why will you only accept video evidence?

Because there's pictures of a woman standing near this area where supposedly there are 1000C fires raging. With all the video and photos out there of the towers, wouldn't there be a bit of it showing raging fires inside? I guess I'm not understanding how these fires were so conveniently contained to such small areas that no direct evidence of them exists.

Only the conspiracy theorists who lack expertise and training seem surprised that the buildings collapsed entirely.

I'm surprised about how confident everyone is in these simulations as undeniable proof of that claim.

If you take the most powerful explosives available at the time and use those for the energy computations, it would still take a very conspicuous amount of them. If you tell me there's an elephant hidden in my house, it doesn't matter that you didn't give me hints whether he was in the kitchen or in the hall closet -- he's going to be noticeable no matter where he is.

Little if no evidence was ever taken from the basement levels, and they weren't included in any simulations. How can you claim something isn't there if you havn't looked for it? It appears that it was decided how the collapse occurred, and the investigators set out to prove that scenario.

[akirabakabaka]

Nobody has even answered dinAlt's basic question about the symmetry of collapse from an asymmetric fire. You apparently know quite a bit about these things, could you enlighten us?

Sure; it's easy. First, the WTC 7 collapse was not "symmetric". Second, there's no presumption in structural mechanics that assymmetric loading or localized failure must produce an "asymmetric" response in the structure.

WTC1 and WTC2 were arguably 'symmetric' collapses.

The hard evidence taken from the site remains the most credible...

No. Engineering has not thought this way for at least a decade. Computer models have evolved generally to the point where they are more predictive and useful than physical models. This is not to say that we ignore physical evidence or eschew empiricisim. But it is to say that we do not require extensive empiricism in order to draw defensible conclusions.

What good is a simulation if there is virtually no physical evidence to verify it? And why was the editor of the Fire Engineers so irate about the destruction of evidence?

I appreciate the lessons in structural dynamics, but I'm still not convinced that miraculously the entire core section was heated up for 40-some minutes in such a way that collapse of all of the core supports was near-simultaneous and that it left no physical evidence before or after.

[JayUtah]

Where was this recent 2005 NIST sample taken from if all of the steel was destroyed years ago?

I'm not aware of any "recent 2005 NIST samples." The steel used in the report published in 2005 was obtained years ago by NIST while the steel was in U.S. reclamation yards.

I was however able to make a case that much of it was likely taken from the upper levels of the towers, where the extreme temperatures supposedly existed.

Please re-read the discussion that deals with localized temperatures. You seem to believe that there were vast portions of one or more floors that were consistently at very high temperatures. That is not the claim, and that is not what is necessary to fail the structure.

Read the WPI report.

I have.

The no-melted-steel group has largely ignored this report, which found evidence of liquified steel.

Hardly. The conspiracy crowd staunchly argued that no evidence whatsoever of melted steel in any form had been found, thus the structure couldn't have softened and deformed as believed. Then one of my colleagues -- not the conspiracists -- came up with this citation. Now all the conspiracists use it to try to prove there was additional explosives or fuel other than what had been accounted for in the accident. No matter what the evidence, the conspiracists argue for some deliberate conspiracy in all cases!

The "no-melted-steel" group, so-called, disputes the claim that significant amounts of melted or molten steel were discovered in the WTC 1 and 2 basements, evidence they say of large-scale use of something like thermite. This has little to do with eutectic mixtures.

...since most of the evidence was destroyed, they have to verify their models using visual evidence.

Why is this improper? Why is "visual evidence" not empirical?

How many investigations have you personally directed?

"In some cases, assessment of enhanced photographic and video images of the towers enabled distinguishing between damage that occurred prior to the collapse and damage that occurred as a result of the collapse." (p.87) -- how reliable is that?

Extremely.

they appear to conclude that the wind load data is no good and so they don't use it?

Yes. Inconsistent data are properly rejected. It is not possible to determine why the various measurements diverge, so it is not possible to determine which, if either, were appropriate.

6.6.3 explains how these global reference models weren't even used for the impact simulations. "the model had to “fit” on a state-of-the-art computer cluster and to run within weeks rather than months." (p.92) -- why such a limited time restraint after spending years on this investigation?

Because the computers themselves don't stay running for more than two weeks or so without something going wrong. If the computer breaks down during the run, most of the data are lost and the model must be re-run from the beginning. I design, build, and sell supercomputers for a living, which are then used by my customers, with my assistance, to solve these certain kinds of engineering problems. You're talking about my bread and butter here.

A computer does not exist in the unclassified world that can contain an ANSYS model of the entire WTC structure at the resolution necessary to provide as detailed a model for the entire building as was done for the affected floors. And my consultation with the ANSYS people -- with whom I do business -- has suggested that there are additional software limitations.

Wasn't it decided that the impact and fires caused the collapse, end of story?

Yes, but not before the study. The study was to determine whether there was anything falsifiable about the straightforward explanation. There wasn't, so parsimony demands we not introduce any non-falsifiable options. To be sure, there are many people claiming that something is "wrong" with the "official story," but I have yet to see anyone say so who is actually qualified to make that determination and can back it up with appropriate arguments. I wonder why these people hide, falsify, or exaggerate their actual qualifications in order to make their points. Dr. Jones has not, but many of the people upon whom he has uncritically relied, do.

but I would argue it had a high uncertainty and was open for significant tweaking of inputs.

Fine; I do this for a living. Convince me of your conclusion.

From what I can tell they only ran the impact simulation a single time.

Read again.

"The combined tower and aircraft model of more than two million elements, at time steps of just under a microsecond, took approximately two weeks of computer time" (p.92)

Why do you believe that run did not include multiple parameter sets?

The fires all took place in the same area near the point of impact.

No, they didn't.

Because there's pictures of a woman standing near this area where supposedly there are 1000C fires raging.

No. Those occurred at a different time and place. The report is fairly clear.

I guess I'm not understanding how these fires were so conveniently contained to such small areas that no direct evidence of them exists.

What's so "convenient" about it? Fires raging inside a structure are far more dangerous than fires that burn at the periphery. And since the fuel load was inside the building and not at the periphery, we can say with confidence that the fire follows the fuel. Keep in mind that the jet fuel was not the fuel load that created the high temperatures.

I'm surprised about how confident everyone is in these simulations as undeniable proof of that claim.

I'm surprised at your continued willingness to cast aspersion on something you clearly know little about. You ride in cars and airplanes whose designs were validated as safe using nothing but these computer models. You already trust your life to these algorithms, which have been tested and refined over 25 years; you just don't realize it.

You are simply desperate to disbelieve the models. Why?

How can you claim something isn't there if you havn't looked for it?

There was no anomalous observation in the record that led anyone to believe there was something amiss in the basement that should be investigated further. The collapses clearly started at the impact points, not in the basement. That is completely indisputable. Why look elsewhere?

It appears that it was decided how the collapse occurred, and the investigators set out to prove that scenario.

No, they set out to disprove it. That's basic scientific method. My job frequently involves forensic and failure-analysis engineering. I do this for a living. What investigations have you personally directed? Why is your intuition on how to study something to be considered more authoritative and correct than those, including me, who have been trained to do this?

This is what irritates me about conspiracy theorists. They ignorantly presume that what little they happen to know about some subject is as much as anyone knows, even qualified experts.

[turbonium]

Welcome to the board, turbonium.

Thanks, Alan.

[JayUtah]

WTC1 and WTC2 were arguably 'symmetric' collapses.

What do you mean by "symmetric" in the context of a structural collapse, and what is your evidence that the WTC collapses -- or any collapse -- is either "symmetric" or "asymmetric"?

What good is a simulation if there is virtually no physical evidence to verify it?

I explained it at length. You cannot rely on homespun expectations here.

And why was the editor of the Fire Engineers so irate about the destruction of evidence?

I've read several articles written by him, and he strikes me as the kind of person who is constantly irate. He seems to express irritation as a virtue. That's fine; his trade is journalism and striking a chord is a good talent to have in that profession. But simply because an outspoken editor blusters doesn't make it objectively salient.

And it should be noted that his article was written before NIST's harvesting got underway.

You have to realize that Ground Zero was not a typical collapse. You had pieces of different buildings all mixed up together, and a fairly unprecedented scale of destruction in a sensitive place. The normal forensic disassembly and recovery process was not practical in that context, and not likely to produce the kind of in situ data that normally warrants such a process.

I appreciate the lessons in structural dynamics, but I'm still not convinced that miraculously the entire core section was heated up for 40-some minutes in such a way that collapse of all of the core supports was near-simultaneous and that it left no physical evidence before or after.

The "entire core section" did not have to be heated up. This was explained at length in the draft summary report.

The heating profiles varied during the interval between collision and collapse, and included both heating and cooling cycles. The effects of these cycles has been empirically demonstrated at scale.

The collapse of the core columns is "near simultaneous" because that is what is expected, and I explained at length why.

It is not a case of there having been "no physical evidence." The physical evidence that, in your lay opinion, is crucial is simply not among the small amount of material recovered from the site. I do not agree that your assessment of cruciality in the empirical evidence is accurate, and I have explained at length why.

Apparently we have little left to discuss. The facts have been explained to you by someone qualified to understand and explain them, and you simply choose to believe otherwise. That's your perogative, but it's not rational. Your disbelief does not make the facts go away.

[turbonium]

You say that "...a relatively small amount of explosives placed in strategic points would be sufficient to cause their collapse..." So what?

Because it is relevant in reply to your earlier post, which was...

Even for the most powerful conventional explosives, theories require such a large amount of explosives that they would have been noticed around the building.

Your points mentioned below, as I said earlier, are not relevant to my point....

There are several ways of knocking over the building - plane impact followed by fire, or explosives in strategic locations. Romero considers the buildings collapsed due to plane impact followed by fire.

However.....

I suspect a lot of people would agree that strategically placed explosives could knock the building down. I suppose I agree with the idea too.

....this is the relevant point - that theories do not "require such a large amount of explosives that they would have been noticed around the building."

[turbonium]

I wrote..

Only ones that had fire / impact damage were to be sought out.

To which the reply was..

No, I don't think so. I think the laundry list of criteria is an or-connected list, not an and-connected list. So if you found one with fire damage but no impact damage, that was okay; and if you found one with impact damage but no fire damage, that was okay too. And if you found fractured bolts with no heat damage, that was okay. I've done this sort of thing before; you typically only need to match one criteria, not all of them, in order to make a good specimen

Sorry, I erred in my statement above. It should have read, and which was also my intent, as "only ones that had fire and / or impact damage." So yes, you are correct in your reply.

[Peter B]

G’day Turbonium

What exactly is the point you’re trying to make here?

As I said earlier, Romero said on 21 September that explosives weren’t needed to collapse the towers. He also said that he had concluded that explosives weren’t used to collapse the towers.

You’ve said he never retracted his original statement that a relatively small amount of explosives placed in strategic points would be sufficient to cause the collapse of the towers.

But in saying that he thought explosives weren’t necessary or used, that indicates that even though a relatively small amount of strategically placed explosives *could have* collapsed the towers, he doesn’t think that happened.

Fair dinkum, Turbonium, how is your argument not sophistry?

[turbonium]

I don't see any evidence whatsoever that this is what happened. Are you speaking hypothetically, or are you actually claiming that heat-damaged steel from WTC 1 and 2 were rejected because the criteria were too artificially limiting?

I constructed a theoretical possibility for how the steel being sourced could have been rejected because it did not meet the requirements for acceptable inclusion in NIST's sample analysis collection.

You do yourself and the industry a great disservice by ignorantly labeling these models "fictional". These are state of the art models, and the modeling techniques have been used for more than 25 years in nearly every branch of engineering with great success. This is not just something that was made up in order to study the WTC collapse. These are standard industry techniques that all engineers learn.

Yes, "fictional" is too harsh a label, I agree and apologize for that. I meant to emphasize that FEA is at best a method of analysis for which even at it's optimal employment still can only achieve approximate, not definitive, results and conclusions.

You don't really need a mathematical model if you can recover all the empirical evidence.

I agree, and that is exactly where my point of contention lies. Collecting relevant evidence does not preclude collecting steel samples which were undamaged and / or unexposed to fires - if the steel was from the affected floors (where the collapses initiated).

You yourself admitted that it wasn't practical to recover all the steel that might have been affected by impact or fire. So you already accept that some degree of guesswork is necessary and appropriate. So given that a model is necessary and acceptable practice, why not use the techniques that have been used for this sort of thing for many years? You can't credibly trash those methods just because you're unfamiliar with them.

But the steel from the floors where the collapses initiated could, and should, have been recovered for analysis. The NIST steel collection procedures were not only puzzling, but also counterproductive to their concluding theory of collapse. For example, in the NIST report "shopping list", one category of samples they are looking for is any steel directly above the fire and / or impact damaged floors. But, the NIST report proposes that the fire exposed floors were where the collapses initiated, specifically that several of the core columns from these floors weakened sufficiently from fire exposure to initiate the collapses. The primary, most relevant steel to look for and recover is not from the floors above the initial point of collapse, but rather from the floors within the initial point of collapse. That includes all the steel from these floors, whatever condition they are in. But as I said, NIST excluded any steel from these floors unless they had impact damage and / or exposure to fire.

I again say....WHY? You agree that "You don't really need a mathematical model if you can recover all the empirical evidence" The empirical evidence is the steel from the floors where the collapses initiated - ALL of the steel, not only the impact damaged and / or fire exposed steel.

You can't try to make professional engineers and investigators submit to your homespun methods of analysis.

That is not what I am attempting to do. The primary goal in this or any investigation is to procure and analyse as much relevant physical evidence as possible - to eliminate, as much as possible, any guesswork that would be needed to fill that void.

[turbonium]

But in saying that he thought explosives weren’t necessary or used, that indicates that even though a relatively small amount of strategically placed explosives *could have* collapsed the towers, he doesn’t think that happened.

Fair dinkum, Turbonium, how is your argument not sophistry?

Hi peter. Let's see if I can make my point clear so you will understand it is not sophistry....it does not matter whether Romero believes that fire, or explosives, or little aliens from Planet X caused the collapses. I am trying only to point out that he has stated that the amount of explosives needed to cause the collapses is not "enormous", but rather "relatively small". Period.

If he now believes explosives were not used, or not needed, to cause the collapses, is absolutely irrelevant to my point. He's not saying that because he now believes explosives were not used or needed, also means he now believes only a large amount of explosives would have been needed to cause the collapses (hypothetically)...

[Gillianren]

How large an amount is meant by "relatively small"? Do you know? Does he specify? See, that word "relatively" is important, here. Is it "relative to how much the layperson might think"? Is it "relative to the atomic bomb"? Unless you know to what the amount is relative, you have no information that's actually useful. Heck, I'll say a relatively small amount would be needed--and that's relative to the size of the building.

[Tolls]

How large an amount is meant by "relatively small"? Do you know? Does he specify? See, that word "relatively" is important, here. Is it "relative to how much the layperson might think"? Is it "relative to the atomic bomb"? Unless you know to what the amount is relative, you have no information that's actually useful. Heck, I'll say a relatively small amount would be needed--and that's relative to the size of the building.

Not only that, but it also doesn't give us any idea of how much time it would have taken to plant these explosives and whether this could have been done without people suspecting something. All in all it doesn't really get us anywhere.

[JayUtah]

I constructed a theoretical possibility for how the steel being sourced could have been rejected...

Yes. You made up a fanciful story that speaks to a supposed motive that you already believe for other reasons. You have no evidence that this actually happened. There are innumerable posssibilities, including the one that an army of invisible elves toppled the towers. Why haven't you considered that "possible" scenario too?

I meant to emphasize that FEA is at best a method of analysis for which even at it's optimal employment still can only achieve approximate, not definitive, results and conclusions.

And you say this from your vast experience in finite-element analysis and engineering test and development?

You have no clue what you're talking about; you're trying to FUD your away around standard practice. Not only are these models able to achieve incredible levels of fidelity to the real world, they are supplanting empirical, physical models because they are better than physical models at producing definitive results and supporting conclusions. This doesn't mean that FEA is more real than real, but rather that the ability to instrument and query FEA models far exceeds the ability to query physical or conceptual models, and the epsilon for FEA results is generally negligible.

Boeing, for example, doesn't actually build wind-tunnel models anymore. All their design efforts stem from computational fluid dynamics, which is one incarnation of FEA. They learn far more, far more quickly, and with far less cost with CFD than with physical models. Yes, it is remotely possible that the CFD models will vary from the behavior of the actual article, but not to any appreciable degree. They are willing to commit billions of dollars of development to the fidelity of these models. The other guy here asked me how we can have so much faith in these models. That's one reason why -- they work, and people are willing to bet the farm that they work.

You don't really need a mathematical model if you can recover all the empirical evidence.
I agree, and that is exactly where my point of contention lies.

Let me finish the statement, then. It is usually not possible to recover all the physical evidence, and often less revealing in the long run. Let's say you find a bent girder in a pile of rubble. How do you know that girder was bent in the chain of events that led to the collapse, or was instead bent after the collapse had already begun and was thus unstoppable?

NIST, as with all such investigating agencies, knew it would not be possible or practical to recover and identify a significant percentage of WTC steel, nor necessarily possible to locate and recover the steel that had been at the hottest points in the structure. Therefore they knew going into the investigation that some sort of CSD model would be the primary investigative tool. With that in mind, you don't have to recover specific elements of steel, only sufficiently diverse pieces to validate the model. That is a broader set of criteria that have to be met, and therefore one more likely to be met from convenience samples.

You seem to argue that this is somehow a scientific foul, or that it introduced too many degrees of freedom for the model to be predictive. That is simply ignorant; that's not how FEA models work.

But the steel from the floors where the collapses initiated could, and should, have been recovered for analysis.

It was in part, unless your memory of the NIST samples is better than mine.

The NIST steel collection procedures were not only puzzling...

Again, what does it matter that someone's procedures puzzle people who have no experience in forensic engineering? Just because you don't understand why something is done doesn't mean it's automatically suspicious.

For example, in the NIST report "shopping list", one category of samples they are looking for is any steel directly above the fire and / or impact damaged floors. But, the NIST report proposes that the fire exposed floors were where the collapses initiated...

It looks like you're presuming all the specimen criteria were intended for all of NIST's objectives. You say that criterion A doesn't fit objective B, therefore it's improper. But consider that criterion A was intended to satisfy objective A instead. Part of NIST's mandate was to investigate the structural response of the building to the impacts alone, irrespective of the fire. After impact, the gravity loads of the building were redistributed around the impact zone, and that activity involves primarily the structure immediately above the impact. Since the coarse, global model was the likely tool to investigate that, it was likely to require separate validation from the detailed ANSYS model of the directly affected floors. There is interest in that region of the buildings whether or not there was impact or fire.

The primary, most relevant steel to look for and recover is not from the floors above the initial point of collapse, but rather from the floors within the initial point of collapse.

No. You're trying to paste your approach onto NIST.

That includes all the steel from these floors, whatever condition they are in. But as I said, NIST excluded any steel from these floors unless they had impact damage and / or exposure to fire.

Now you're trying to apply criterion B to objective A.

You can't try to make professional engineers and investigators submit to your homespun methods of analysis.
That is not what I am attempting to do.

LOL! That's exactly what you are attempting to do. You're saying the investigation was done wrong because it relied on modeling rather than inspection of recovered steel, and you're trying to say that NIST looked in the wrong place for the samples they did recover. But your objection is simply based on your personal notion of how to conduct a forensic engineering analysis and investigation.