RFC: NIST's Magic Bullet: Removal of Fireproofing in WTC1 Impact

Oops, NIST is right, there was massive fireproofing removed, I can see it in the photo.
wtc2impact.jpg

This is the 175 impacting the WTC, it was a KE (kinetic energy) event of 2093 pounds of TNT; more energy than 2,000,000 (2 million) shotgun blasts.

Looks like

However, NIST has not convincingly demonstrated that the fireproofing was indeed dislodged by the aircraft
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your thesis is WRONG.

Good job, your paper is more like the petition you signed. False claims and no real evidence. As you continue, I find your lack of knowledge on 9/11 topic to be poor, and expect someone who is trying to act like a scholar, to do much better. Good luck.


BTW, fuel can rip off insulation. I thought you said something that tries to say the fuel can't take off insulation, but gee, a finger can take off the insulation under the floors, and you are ignoring the fact fuel is mass. But that is my quick review as an engineer. Looks like your truth membership is showing on this paper, as you try to deceive instead of study and learn.

Looks like you need to study this more, not NIST, they actually were conservative. You are just being truthy.
 
GregoryUrich said:
Any on constructive and on topic comments or criticisms are welcome.

NIST's Magic Bullet

The file is fairly large so it might take a minute or two to download.
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What is the margin of error for NIST and fireproofing? Even if they estimated that too much was removed, was that amount necessary? Do you take into account vibration that would dislodge fireproofing?
 
You know the Magic Bullet theory was a straw man created by the CTers, right?
 
Disbelief said:
What is the margin of error for NIST and fireproofing? Even if they estimated that too much was removed, was that amount necessary? Do you take into account vibration that would dislodge fireproofing?
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In NSCSTAR 1-6A NIST used an order of magnitude which they expressed as 10**5 to 10**6 J/sq m. My very rough estimate puts the available energy closer to 2 x 10**4 MJ/sq m. I mention vibration only to point out that NIST has not attempted to show what the vibration might have been. NIST does demonstrate that accelerations of 20g and 55g would probaby dislodge SFRM from flat and round surfaces respectively.

The displacement caused by a 20g accelleration over 0.1 s would be .5 x 20 x 9.81 x (0.1)**2 = 0.98m, which I believe is more than NIST predicted. If we consider a 12 floor section of the building, the energy required would be roughly .5 x 33 x 10**6 x (9.81)**2 = 1,600 GJ, which is way more energy than would be available after other losses. A more detail analysis of vibration is very difficult which is why NIST hasn't done it.

ETA: I didn't really answer your question about the margin of error. NIST needed to tweak the impact input parameters to get what they considered to be the right amount of damage. As far as I can tell, the effects of the dislodged fireproofing are not available for scrutiny as they are deep inside the fire and collapse models. I don't think they identify a boundary value, but I have not spent alot of time in those reports. I'll take a look when I have time.
 
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Gregory Urich:

I believe your paper has an error on page 10 (the last page). It should be 10^5 J/m^2, not 10^5 MJ/m^2.
 
GregoryUrich said:
In NSCSTAR 1-6A NIST used an order of magnitude which they expressed as 10**5 to 10**6 J/sq m. My very rough estimate puts the available energy closer to 2 x 10**4 MJ/sq m. I mention vibration only to point out that NIST has not attempted to show what the vibration might have been. NIST does demonstrate that accelerations of 20g and 55g would probaby dislodge SFRM from flat and round surfaces respectively.

The displacement caused by a 20g accelleration over 0.1 s would be .5 x 20 x 9.81 x (0.1)**2 = 0.98m, which I believe is more than NIST predicted. If we consider a 12 floor section of the building, the energy required would be roughly .5 x 33 x 10**6 x (9.81)**2 = 1,600 GJ, which is way more energy than would be available after other losses. A more detail analysis of vibration is very difficult which is why NIST hasn't done it.

ETA: I didn't really answer your question about the margin of error. NIST needed to tweak the impact input parameters to get what they considered to be the right amount of damage. As far as I can tell, the effects of the dislodged fireproofing are not available for scrutiny as they are deep inside the fire and collapse models. I don't think they identify a boundary value, but I have not spent alot of time in those reports. I'll take a look when I have time.
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I guess what I am getting at, is that you are running into the same issue that NIST had with trying to determine what the actual amount of SFRM was dislodged. NIST made assumptions, like many scientific tests will, to try to determine the actual amount or be as close as possible. If you are saying that they were incorrect in their values, what then are you trying to prove? If you are saying that the fires could not have caused the collapse because not enough fireproofing was removed, would you not have to calculate the minimum amount needed to be removed to cause collapse?

As for vibration analysis, I agree that would be difficult to determine, but it would cause the loss of some insulation. Also, I have a question about the performance of the SFRM. If some of it is removed, would an intense fire cause more of it to fail and ho quickly? This is important because while your initial calculations could be right, even small amounts of lost fireproofing could lead to something worse.
 
Quad4 72:

Well, let's get the numbers corrected first; then we can discuss Gregory's theory!
 
Disbelief said:
I guess what I am getting at, is that you are running into the same issue that NIST had with trying to determine what the actual amount of SFRM was dislodged. NIST made assumptions, like many scientific tests will, to try to determine the actual amount or be as close as possible. If you are saying that they were incorrect in their values, what then are you trying to prove? If you are saying that the fires could not have caused the collapse because not enough fireproofing was removed, would you not have to calculate the minimum amount needed to be removed to cause collapse?

As for vibration analysis, I agree that would be difficult to determine, but it would cause the loss of some insulation. Also, I have a question about the performance of the SFRM. If some of it is removed, would an intense fire cause more of it to fail and ho quickly? This is important because while your initial calculations could be right, even small amounts of lost fireproofing could lead to something worse.
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I'm saying that NIST didn't prove their case. They took a leap from the energy density to fire proofing removal without considering trajectory. Nonetheless, they did show that trajectory is important as anything more than 60 degrees from a perpendicular hit will not dislodge the fireproofing. The general path of debris was 90 degrees from perpendicular to the fireproofing on the floors.
 
GregoryUrich said:
IThe general path of debris was 90 degrees from perpendicular to the fireproofing on the floors.
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What do you mean by this? 90 degrees from perpendicular is parallel. Are you saying that the general path of the debris was parallel to the fireproofing on the floors? I have been just reading the discussion and am a bit confused.
 
GregoryUrich said:
I'm saying that NIST didn't prove their case. They took a leap from the energy density to fire proofing removal without considering trajectory. Nonetheless, they did show that trajectory is important as anything more than 60 degrees from a perpendicular hit will not dislodge the fireproofing. The general path of debris was 90 degrees from perpendicular to the fireproofing on the floors.
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Does this matter? Is the amount of SFRM that you determined was removed (even though you do not address that lost due to vibration or performance, or even how it reacts to the addition of jet fuel) still enough to cause collapse?

If so, what is your next step?

If not, was it just to nitpick?

I am not trying to be a jerk here, I am just trying to determine the relevance of your line of thinking.
 
van_dutch said:
What do you mean by this? 90 degrees from perpendicular is parallel. Are you saying that the general path of the debris was parallel to the fireproofing on the floors? I have been just reading the discussion and am a bit confused.
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He is saying that, and it isn't correct, as I've pointed out to him before. The dynamics of impact will be extremely turbulent. This is why, for instance, the basically horizontal impacts created enormous vertical loads on the floors near the impact. A similar thing will happen with the fireproofing.

Regarding NIST's "energy" estimate, we need to be very carefuly about what NIST is saying. Their energy estimate is not an estimate of total energy. Instead, it is an estimate of the random kinetic energy per surface area, at the blast front, and the value decays as a function of time and distance from impact. It's a strange convention and cannot be treated with the usual dimensional analysis, particularly because this energy would be conservative if all debris impacts were elastic.

To say that "NIST's estimate is high and it should have been 2x10^4 J/m^2" actually makes no sense at all. The contours NIST provided for fireproofing removal are the contours where the KE/area calculation has a value of 10^5 J/m^2. If, for instance, NIST's calculation was high by a factor of 5, this would mean the correct contour was closer to the point of impact, with a distance scaled by roughly 5^1/3 or about 1.7.

It is possible for NIST's value to be an overestimate. This energy/area calculation comes from LS-DYNA, a method radically different from Gregory's method, and thus the two probably cannot refute or validate each other in the first place. However, NIST also couldn't really find the lower bound of dislodgment energy in its "shotgun tests," so it may be an overestimate as well.

I also remind people that later investigations demonstrate there probably needed be no fireproofing removal at all for the collapses to occur. NIST's calculation is overly conservative, and no "magic bullet" is needed. Thus we should check Gregory's work on its own merit, rather than assuming the conclusion and working backwards, as always.
 
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OK, I've now read the paper in question. I'm sorry, Gregory, you are completely wrong.

The main reason is that we have no idea how much energy fireproofing dislodgment actually dissipates. On Page 10 you state the following:
Gregory Urich said:
In NIST NCSTAR1-6A it is established that energy levels on the order of at least 10^5 MJ/m^2 are necessary to dislodge fireproofing. Also, it is established that the area of the fireproofing removal should have been 800m^2.Thus, 80 MJ would be required to be evenly distributed remove the amount of fireproofing that NIST suggests was dislodged. Since the energy was
most likely not evenly distributed it would be reasonable to assume that twice that amount, or 160 MJ, would be necessary compared with 19.5 MJ available.
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The problem is that you make the assumption, incorrectly, that the KE was distributed over this entire area all at once. It doesn't work like that. Think of the KE as being contained in a wavefront, but this KE is not necessarily consumed. The wave will disspiate due to three factors -- (a) dispersion into larger space, (b) damage to the structure, i.e. inelastic collisions, and (c) turbulence becoming heating. But since the fireproofing is so fragile, it dissipates virtually nothing. The wave can pass over the fireproofing, dislodging it, and continue with negligible dissipation.

This is the same mistake that Kevin Ryan and so many others have made. The fireproofing doesnt expend 10^5 J/m^2. That's the strength of the wave required to shake it loose. It's like saying I can stand in the ocean and stay on my feet if a wave no higher than 1m washes over me -- if I get knocked down, that doesn't mean I absorbed an entire 1m wave. The wave barely notices me whether I fall down or not.

The other problem, again, is in your assumptions regarding ricochets and lift. The flow inside the structure will be completely turbulent. Gravity will have virtually no effect, and "lift" -- actually drag -- can occur up or down with virtually no bias. Again, if you want to see this effect, estimate the Reynolds and Froude numbers of the flow and see what you get.

NIST's approach, again, was to use LS-DYNA. This predicts, to reasonable granularity, what the flow and momentum of individual particles of debris were throughout the structure. NIST also keeps track of dissipation due to heavy furnishings and transfer to the structure. NIST does not add additional dissipation caused by the fireproofing, but to first order, this is correct. Instead, NIST estimated a lower bound for energy per area (should really be impulse, shame on NIST) required to dislodge the fireproofing, and made a hard cutoff -- after the wave falls below this value, no more dislodgment.

It's coarse, but it is valid. NIST can be criticized for not really finding the lower bound, not attempting other types of dislodgment (e.g. hot jet without any debris, sand-blasting, shock, etc.), and so on, but their method is appropriate.
 
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R.Mackey said:
I also remind people that later investigations demonstrate there probably needed be no fireproofing removal at all for the collapses to occur. NIST's calculation is overly conservative, and no "magic bullet" is needed. Thus we should check Gregory's work on its own merit, rather than assuming the conclusion and working backwards, as always.
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What is 911 but assuming outsiders did it, and working backwards?
 
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Actually, we have no idea on the condition of fireproofing PRIOR to 9/11/2001.

1) What makes us so sure that the fireproofing in the areas the plane hit weren't already dislodged?

2) was their maintenance records that kept track of the fireproofing and its condition?

3) what if the fireproofing in the areas the plane were hit, thinner than the areas the planes did not hit?
 
NIST used many factors in their analysis:

1. Variation in the thickness of the SFRM (as seen in photographs of trusses well before the 2001 attacks)
2. Gaps where NO SFRM was found (as seen in photographs of trusses etc...well before 2001 attacks)
3. Effect of Impacts on removal of SFRM.

NISTNCSTAR1-6 Pages 24-31
NISTNCSTAR1-6 Pages 33 -

2.7 ESTIMATION OF SFRM DISLODGED BY AIRCRAFT IMPACT
To analyze the thermo-structural response of the WTC towers during the fires after the aircraft impacts, it
was necessary to estimate the extent of dislodged thermal insulation on structural members.
Dislodgement could occur as a result of direct impact by debris or due to inertial forces resulting from
aircraft impact. The dislodgement due to flying debris was estimated from results of the aircraft impact
analyses that predicted damage to the structure (columns, beams and floors), partitions, and furnishings.
In addition, a study was conducted to estimate dislodgement due to inertial forces. NIST established
conservative estimates for the extent of dislodged SFRM. However, since NIST was not able to establish
robust criteria to predict the extent of vibration-induced dislodgement, insulation dislodged by inertial
effects other than that dislodged by direct debris impact was ignored and not included in the analyses.
The methodology and criteria for estimating the extent of damage and dislodgement of SFRM from
results of the aircraft impact analysis are presented in Chapter 5.
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TAM:)
 
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Arus808 said:
Actually, we have no idea on the condition of fireproofing PRIOR to 9/11/2001.

1) What makes us so sure that the fireproofing in the areas the plane hit weren't already dislodged?

2) was their maintenance records that kept track of the fireproofing and its condition?

3) what if the fireproofing in the areas the plane were hit, thinner than the areas the planes did not hit?
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Well NIST did have access to photographs of the trusses and other structures within from 1993-1998. They used this, for among other things, to establish that "Gaps" in the SFRM did exist, and likely would have existed when the impacts occured. The photographs also confirmed, IIRC, that the thickness of the SFRM varied.

They also had documentation from 1994 measuring the thickness variation on trusses from floors 23 and 24 of WTC1.


See pages 10-31 in NISTNCSTAR1-6.

TAM:)
 
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