Trussbolt failiures and flame cutters

[twinstead]

I'm still trying to figure out how anybody wants the collapses to be CD SO much that they will automatically assume that the reason why there is no physical evidence of CD is because they were masked, instead of there is no physical evidence of CD because, well, there wasn't any CD.

 

[RedIbis]

And that is an assumption that only you make.

NIST used a very conservative approach in estimating fire protection loss. They only assumed such loss where photos showed such loss (on exterior columns), and where their models showed that steel would have been directly impacted by high-speed debris.

[swiki]Argument from Incredulity[/swiki]: the 9/11 denier's offense and defense. It was 56 minutes, by the way.

Good call. I don't like making even small mistakes on the details. Since they were assuming that the loss of fireproofing on photographed columns was due to the plane's impact, rather than some other possibility, and they based their conclusions on computer modeling comparing the impact to a shotgun blast, we might agree that their theory is far from conclusive and definitive, requiring further investigation.

In fact, NIST admits that only its most severe values of influential variables produced the collapse. It must be helpful to be able to tweak models until the desired result is met.

Why would you call me a 9/11 denier? I don't doubt 9/11 occured. And you're also suggesting that time is not a factor in heat weakening steel, which of course it is.

The heating and collapse initiation must occur in a very short period of time.

 

[R.Mackey]

Correct. But the fires never got hot enough to weaken the steel. So now we have analysis which states the towers could withstand significant column damage, even greater than experienced on 9/11, even against massive shear force.

Of course the fires did.

You've misunderstood the purpose of recovering the steel. You're also not the first -- virtually everyone from your camp, including David Ray Griffin, has made this error.

Steel was only recovered if it showed evidence of being involved in the impact and if its origin could be identified, plus a few others showing "weird" behavior.

Quite a lot of the steel could not be identified, as identifying marks were broken or burned off.

The purpose of recovering steel had nothing to do with estimating temperature. Such tests were conducted anyway, but not for the reason you think.

The reason NIST recovered this steel was to establish the failure modes of the steel. Did columns break at the welds or snap in between? Did they show necking or brittle failure? Did they tear out their bolt holes or shear the bolts off?

Steel was tested for temperature to verify that these failure modes were caused by impact/collapse only, and not exacerbated after the fact by heating. A broken column that was heated, annealed, and then crunched up during the collapse would be inconclusive and thus kept out of this study.

The fact that the NIST inventory steel never reached 250^oC is the desired result! And also note that only four pieces of core columns are in that inventory, only two of which were in the impact/fire zone, and those two were at the edge of the hole, below most of the fires, and cooled by inrushing air. It all makes perfect sense.

What I find most amusing is that -- while I realize you personally haven't made this claim, others such as DRG have -- the "Truth Movement," in one breath, talks about how the steel never got hot enough to weaken, yet cites "melted steel" as evidence for its own conclusions. Well, is there evidence for heated steel or not? You may only pick one.

In any case, I hope you now understand the significance of the recovered steel and its maximum temperature testing. It does not support your allegations. Quite the contrary.

 

[R.Mackey]

I'm simply addressing the contention that any failure to the perimeter or core would result in a global collapse.

Glanz and Lipton summarize the findings of the white paper:

The Vierendeel trusses would be so effective, according to the engineers' calculations, that all the columns on one side of a tower could be cut, as well as the two corners and several columns on the adjacent sides, and the tower would still be strong enough to withstand a 100-mile-per-hour wind.
--City in the Sky, p 133

And I didn't even have to go to the library to find this.

Oh, by the way, even though this is totally anecdotal, supported by no evidence, and is a gross simplification compared to the complexity of aircraft impact and fire...

... it's still wrong. You've quoted incompletely.

The original quote says the above is true if the perimeter columns were cut at ground level. At ground level, the core has its own diagonal bracing, and for that reason would withstand the wind load. Recall that there were only 1/3 as many columns on the ground floor? They're just not as important down low. The core is far stronger there to compensate.

Cut those columns at, oh, say the 80th floor, and you'd get a totally different result.

 

[uk_dave]

Since they were assuming that the loss of fireproofing on photographed columns was due to the plane's impact, rather than some other possibility....

Actually this is a good point. Why don't 'truthers' consider the possibility that the fireproofing was intentionally removed just prior to the planes crashing into the towers?

It would explain everything!!

No need for the mythical CD, just some fairly lightweight charges strategically placed to dislodge the fireproofing material and then let fire and gravity do the rest. I can't believe no 'truther' has managed to dream up this scenario before.

Maybe I should copyright it?

 

[The Almond]

Good call. I don't like making even small mistakes on the details. Since they were assuming that the loss of fireproofing on photographed columns was due to the plane's impact, rather than some other possibility, and they based their conclusions on computer modeling comparing the impact to a shotgun blast, we might agree that their theory is far from conclusive and definitive, requiring further investigation.

If we are to assume that computer modeling is a completely invalid method for arriving at a solution to a multivariable problem, that a shotgun blast did not produce the same kinetic energy as airplane debris, and that magical pink unicorns are capable of dislodging fireproofing, then you would be correct.

First, let's ask a rhetorical question: If 100,000 pounds of metal were to slam into a building structure at 500 miles per hour, fracture into shrapnel and enter the building, what would it destroy? Would it destroy the steel columns? Would it destroy the office furniture? Would it destroy the gypsum boards?

If it would destroy all of those things, why wouldn't it destroy the fireproofing? If fireproofing exists in the path of the shrapnel, destroying everything behind it, why would the shrapnel not destroy the fireproofing as well?

Had you read page 129 of NCSTAR 1-6, you would realize that NIST's criteria for determining whether the fireproofing was dislodged was to determine if the gypsum wallboards were broken, or if the office furnishings around the structural component were destroyed. Specifically, the first bullet point on pg 129 explains that gypsum wallboard has an impact strength of 500 psi, while the spray on fireproofing had an adhesive strength of about 12 psi. Can you see how this is an approximate, yet highly conservative method?

As for computer modeling, if you have a method for simultaneously calculating thermal, gravity, strain and lateral loads, all of which are dependent on each other, and whose variables number in the hundreds, I'm all ears. The modeling you refer to is a method for solving hundreds of differential equations within a series of time increments, and since none of these equations have deterministic solutions, a stochastic method is the only available option.

In fact, NIST admits that only its most severe values of influential variables produced the collapse.

Perhaps a more careful reading of the NCSTAR will correct this misconception. NIST chose the most severe case because it was the only one that most closely matched the photographic evidence. It was the only case that matched the observed deflections of the steel and produced the noticeable tilt for the top section of the towers. See page 144 of NCSTAR 1 for a summary of why NIST chose the most severe case.

It must be helpful to be able to tweak models until the desired result is met.

Especially when the desired result is closest to reality.

Why would you call me a 9/11 denier? I don't doubt 9/11 occured.

Your posts indicate a strong denial of relevant data a further global denial of reality.

And you're also suggesting that time is not a factor in heat weakening steel, which of course it is.

Straw man.

The heating and collapse initiation must occur in a very short period of time.

According to whom?

 

[RedIbis]

According to whom?

I apologize if I didn't clarify my point, as you seem to have misread the irony in my statement,

"The heating and collapse initiation must occur in a very short period of time. "

The official story relies on the sequence that the plane crashed into the building the resulting shredding plane parts stripped beams of their fireproofing, allowing them heat sufficiently in the ensuing fires.

At best this is a hypothesis, which even if proven, does not explain how core column temperatures could heat so rapidly, especially in a diffuse flame environment.

Certainly photographs of the towers burning do not suggest superhot, inferno like conditions.

 

[BigAl]

NIST reports that in the 1975 WTC fire where the sprinklers worked, firemen had water to fight the fire and if there was asbestos, it wasn't knocked off by a collision, steel did buckle.
I have this via 102 Minutes but it may be from NIST Interim Report May 2003

 

[The Almond]

I apologize if I didn't clarify my point, as you seem to have misread the irony in my statement,

I apologize if I misread the statement, but it's my experience that sarcasm and irony do not transmit well across the internet.

"The heating and collapse initiation must occur in a very short period of time. "

The official story relies on the sequence that the plane crashed into the building the resulting shredding plane parts stripped beams of their fireproofing, allowing them heat sufficiently in the ensuing fires.

This sequence is well established by witnesses and photographic evidence. It is further supported by mathematical calculations and forensic investigations of the steel itself. That being said, this statement:

At best this is a hypothesis,

Is demonstrably false.

which even if proven, does not explain how core column temperatures could heat so rapidly, especially in a diffuse flame environment.

Indeed, the stripping of fireproofing does not, by itself, explain how the core temperatures rose. Rather, a comprehensive analysis of the combustible material combined with the input of airflow into the system, as well as a heat balance analysis, does provide said explanation. Fortunately, NIST made said calculations and combined them with the structural data to provide a global analysis.

Certainly photographs of the towers burning do not suggest superhot, inferno like conditions.

NIST is very clear on the temperatures achieved in the fires.

 

[NYCEMT86]

Certainly photographs of the towers burning do not suggest superhot, inferno like conditions.

What about the photographs that show the exterior columns being pulled in as the truss members began to sag? Which clearly shows that the trusses where heated to the point where the strength started to deteriorate.

http://www.debunking911.com/sag.htm

NIST doesn't say how long these 1000C fires were burning. And this is the air temp that would occur in only brief, flashover moments, not the steel temp.

a flash over is the point where unburned combustible materials reach their fire point and simultaneously ignite in a closed space. So before a flashover the fire must reach that point of 1000F.

Read my post on Basic Principles of Fire Behavior

 

[RedIbis]

NIST is very clear on the temperatures achieved in the fires.

True. In all seriousness, I recognize it can be exasperating to cover ground that has been previously discussed in other threads. This is a huge forum. I read a good deal of the analysis posted here. I don't know all of your explanations, but I do know the official ones.

I imagine I'll ask the same questions, make some of the same comments as others before me.

Still, that doesn't change the fact that NIST is quite clear that core columns never reached 250C.

If their core column steel samples are not representative, then why didn't they have access to what they needed? If there were columns that experienced the 450C+ temps that were necessary to weaken them, why didn't NIST study them?

 

[Gravy]

In fact, NIST admits that only its most severe values of influential variables produced the collapse.

I just gave you one example of why this statement is false. You said, "Good call."

You're referring to the most severe of NIST's global models, which most closely matched observed events.

In fact, there are many examples of NIST adjusting damage and fire estimates downwards, i.e. less favorable for collapse initiation. It's funny that 9/11 deniers never, ever mention that. Perhaps that's because one must read the report to find those examples. I suggest that you do.

Why would you call me a 9/11 denier? I don't doubt 9/11 occured. And you're also suggesting that time is not a factor in heat weakening steel, which of course it is.

Denialism.

The heating and collapse initiation must occur in a very short period of time.

We know that it did occur in 56 and 102 minutes in the case of the towers and about seven hours and twenty minutes in the case of building 7.

Perhaps the case of the Kader Toy Factory will be instructive to you. It was a large 4-story uninsulated steel building that began to collapse less than 40 minutes after a small fire began on a single floor. It was not hit by an airliner.

At my site, which is linked in my signature, you will find many months worth of reading in these subjects.

 

[Gravy]

Certainly photographs of the towers burning do not suggest superhot, inferno like conditions.

This is sheer madness. Denialism.

Five minutes before collapse:

Shortly after impact:

Later:

Seven minutes before collapse:

 

[Gravy]

Still, that doesn't change the fact that NIST is quite clear that core columns never reached 250C.

You are wrong. At no point does NIST say or suggest such a thing, much less state it "clearly."

If their core column steel samples are not representative, then why didn't they have access to what they needed? If there were columns that experienced the 450C+ temps that were necessary to weaken them, why didn't NIST study them?

Please read NIST NCSTAR 1-3C, which will tell you all about the difficulties in identifying the as-built locations of the recovered core columns.

Will you do that?

 

[RedIbis]

You are wrong. At no point does NIST say or suggest such a thing, much less state it "clearly."


Please read NIST NCSTAR 1-3C, which will tell you all about the difficulties in identifying the as-built locations of the recovered core columns.

Will you do that?

Really, so you have a NIST document that says that core column steel samples show evidence of having reached over 250C?

If you do, please post the quote and the link. Otherwise, I'll post the quote I have cued up, and hopefully, you'll have the integrity to admit that you are wrong.

 

[Gravy]

Really, so you have a NIST document that says that core column steel samples show evidence of having reached over 250C?

If you do, please post the quote and the link. Otherwise, I'll post the quote I have cued up, and hopefully, you'll have the integrity to admit that you are wrong.

You said,

"Still, that doesn't change the fact that NIST is quite clear that core columns never reached 250C."

I replied,

"You are wrong. At no point does NIST say or suggest such a thing, much less state it "clearly."

Please present your evidence that NIST states that no core columns reached 250C.

How about those fires, RedIbis? Care to reconsider them being infernos? Perhaps these quotes will help you along.

We were looking at two large bodies of fires that neither of us in our 33-year careers had ever seen anything that enormous. So it's pretty much, you know, I thought we would lose a company or two possibly. I didn't think we would come out of this unscathed at all. It was just too enormous. –FDNY Chief of Safety Albert Turi


"It was the most unbelievable sight I ever saw, up until that point.

I had been in some very busy units during my time in the fire department. I broke in, in Engine 46 and Ladder 27 in the South Bronx when the South Bronx was burning down. I was in Rescue 3, which was extremely busy; they covered the Bronx and Harlem. And then as a lieutenant, I was in the Lower East Side when that was burning down. As a captain, I was in Chinatown. I saw some unbelievable fires in Chinatown.

What I saw pales in comparison to anything else I had seen previously."
–FDNY Captain Jay Jonas

 

[RedIbis]

Gravy,
You're deflecting from the original point.

If you want to bring up quotations of raging fires, you're mistaking air temp for steel temp.

Secondly, you know as well as anyone how many quotes there are of firefighters and survivors talking about small fires. You even have the NIST temp charts showing you that the core temp was cooling before collapse.

What you have not presented is any evidence that NIST found core column temps above 250C.

Again, if you have NIST saying they found column samples with evidence exceeding 250C please post it.

If you respond and say that NIST only studied 3% of available samples, you're assuming that unstudied steel did exceed 250C, but such column temps are not reported.

I don't mean to be presumptious and contentious, and I do sincerely appreciate the dialogue. This is a complex subject and deserves reasonable debate. Thanks again for responding to my questions.

 

[T.A.M.]

"core columns" versus "core column samples that they tested" may be one issue here.

TAM

 

[The Almond]

True. In all seriousness, I recognize it can be exasperating to cover ground that has been previously discussed in other threads.

If I exasperate myself while performing a voluntary activity on the internet, I am an idiot. It is not a problem for me to look up the references and make concise arguments regarding the factuality of a position.

This is a huge forum. I read a good deal of the analysis posted here. I don't know all of your explanations, but I do know the official ones.

With all due respect, it is my opinion that you only think you know the official explanation. It occurs to me that you've only read annotated or commented copies of parts of the NCSTAR, and since you've gotten a number of details wrong and provided a number of demonstrably false summaries of the methods and processes used by NIST to arrive at their conclusion, I assume that you haven't read the entire report.

I imagine I'll ask the same questions, make some of the same comments as others before me.

Very specifically, David Ray Griffin and Kevin Ryan, whose claims and objections are very similar to yours.

Still, that doesn't change the fact that NIST is quite clear that core columns never reached 250C.

If you'll refer to page 180 and 181 of the NCSTAR 1, you will find that NIST states none of the steel recovered exceeded 600 degrees centigrade, and that of the recovered exterior columns, three reached over 250 degrees centigrade. They add a note that states that none of the samples were from an area where such heating was predicted. Furthermore, I would suggest reading the bottom of page 90 and the top of page 91, where NIST specifically states that the columns tested were not from an area that was predicted to have temperatures above 600 degrees centigrade.

NIST admits that their sampling wasn't representative, so you can't extrapolate that none of the columns reached over 250.

So NIST does not actually state that none of the columns ever reached 250 C, but rather that, of the columns tested none reached said temperature.

If their core column steel samples are not representative, then why didn't they have access to what they needed? If there were columns that experienced the 450C+ temps that were necessary to weaken them, why didn't NIST study them?

Because the primary reason for acquiring the columns and other structural steel was to determine their mode of failure, their compressive strength, yield strength and stress-strain relationship, not necessarily the temperature. Indeed, the paint and metallurgical analyses are far too coarse for any actual analysis. They are primarily qualitative in nature, looking for benchmarks for heat, rather than being used to determine the actual temperature experienced.

 

[The Almond]

Gravy,
You're deflecting from the original point.

If you want to bring up quotations of raging fires, you're mistaking air temp for steel temp.

Secondly, you know as well as anyone how many quotes there are of firefighters and survivors talking about small fires. You even have the NIST temp charts showing you that the core temp was cooling before collapse.

What you have not presented is any evidence that NIST found core column temps above 250C.

NIST found three samples whose temperature, based on paint analysis, exceeded 250 degrees centigrade. Of the core columns tested, only two had enough paint to make such an analysis. What does that tell you about the efficacy of making a paint analysis on all samples?

Again, if you have NIST saying they found column samples with evidence exceeding 250C please post it.

NIST did not acquire steel from an area of the core whose simulations showed that the steel would reach temperatures above 250 C.

If you respond and say that NIST only studied 3% of available samples, you're assuming that unstudied steel did exceed 250C, but such column temps are not reported.

NIST does indeed report column temperatures above 250 C, just not from the tested samples. See figures 6-47 and 6-48 on pages 139 and 140 for reference.

I don't mean to be presumptious and contentious, and I do sincerely appreciate the dialogue. This is a complex subject and deserves reasonable debate. Thanks again for responding to my questions.

And I don't wish to steal Gravy's thunder, but your questions appear to be in line with what we were talking about earlier.