Was Column 79 the Achilles' Heel of WTC7?

[econ41]

@Thomas B I note with some sadness that once again you have persisted in forcing a discussion into a stalemate. How many times is this over several years? 4 or 5 previous occasions?

Thank you for at least responding with claims that are sufficiently clear to address.

You sometimes seem to just re-ask quesstions that I've explicitly disagreed with, without engaging with my objections.

I have responded to every claim that presents a reasoned relevant argument and is not a confused mess of ambiguities and irrelevancies. I note you say "seem". i.e. your perceptions. Those perceptions do not align with the reality of the preceding discussion.

I do not agree that the structural design of the building assumed that sprinklers would work.

You are wrong. When sprinklers are provided as part of the means of ensuring a "fire rating" they are assumed to work to a defined standard.

My understanding of the design principles is that the fire rating of the steel structure (including fire insulation) assumes that there are no functional sprinklers and no firefighting.

You are wrong on both of those "understandings".

Also, my understanding is not that the building is expected to collapse after the rated time.

Read your previous comments and my response.

Rather, the fuel is expected to be exhausted after that time, burned out.

That is wrong. AND I have now at least 5 times told you what the "fire rating" time provides for.

Also, it's not the whole building, but the local components that are fire rated.

The "fire rating" for the building is the fire rating for the building. It in part relies on component rating. More specifically the individual component ratings have to comply with and support the overall building rating.

That is, a building could burn for 24 hours without exceeding the design envelope as long as the fires are exhausting themselves and moving on from office to office, floor to floor.

That is total confusion. And another fact I have explained multiple times and you refuse to engage with the explanations I am trying to provide. The fundamental issues for your ill-defined question about "Achilles" are - for possibly the 6th or 7th time:
WTC7
(a) was a steel-framed building;
(b) vulnerable to fire;
(c) designed to a "fire rating"
(d) which by definition provides for active fire fighting << which was deliberately not undertaken
(e) plus sprinklers << which were ineffective.
Those factors and others of lesser significance are part of the "design envelope" (As I described it - NOT as a single factor issue as posted by Gamolon.
So your first assertion is nonsense and your pair of "as long as" qualifiers are irrelevant. With no active fire fighting and no sprinklers, the "design envelope" was already exceeded.

No active fire fighting and no effective sprinklers meant that WTC was subjected to gross trauma outside the range of parameters it was designed to resist. (And there are more that we need not define at this time)

Column 79 was a weak link exposed by gross trauma beyond design limits. It was NOT a faulty design. And I along with at least one other member disagree strongly with your attempt to impart blame.

The structure heating up and cooling locally within the fire-rated time.

Yes. The proximate trigger for the collapse was "walking" which is a consequence of heat<>cool cycling. AND totally irrelevant to what I am explaining and you are both ignoring and denying it.

These are all pre-9/11 understanding of structural response to fire,

False generalisation

of course. NIST explicitly said that the science had to "evolve"

Wow. As I have said previously both building design and the relevant fire science are evolving. Always have. Always will. 9/11 is a significant but not the only example. There is a world outside of USA.

on this in light of the events of 9/11, not least the collapse of WTC7.

Of course. But repeating the truism does not progress our discussion.

So once again @Thomas B I run out of patience with your evasive game playing.

 

[Thomas B]

You are wrong. When sprinklers are provided as part of the means of ensuring a "fire rating" they are assumed to work to a defined standard.

Can you provide some documentation for this? I'm thinking both of the general principle (e.g., the code or standard you're referring to) and its application to WTC7 (e.g., the part of the NIST report that makes this clear).

b) vulnerable to fire;

Can you provide documentation that fire engingeers and fire fighters were aware of the structural vulnerability of steel-framed buildings to fire-induced total-progressive collapse before 9/11? Can you show that NIST is simply wrong to say that they demonstrated this vulnerability "for the first time" in their 2008 report?

I note with some sadness...

I run out of patience with your evasive game playing.

I always regret making you feel this way. And, as always, I'm grateful for your patience as long at it lasts. I understand completely if you want to leave it there. Cheers.

 

[Miss VocalCord]

Since the FDNY did worry that the buildings would collapse, but couldn't have known that fire would be the reason (a "new phenomenon" that was discovered only afterwards), they must have had other reasons. The natural one to suppose they had in mind is the structural damage caused by the debris. (See also @Miss VocalCord's comment #79.)

That is not what my comments said; I clearly made two statements bold. The second one clearly states:

making loud noises as it burned indicated to them that it might be unstable.

So both the structural and the fires were causing worries about the stability of WTC7. It wouldn't matter if it partially collapse or fully; you simply don't want to risk any lives at that point.

Can you provide documentation that fire engingeers and fire fighters were aware of the structural vulnerability of steel-framed buildings to fire-induced total-progressive collapse before 9/11? Can you show that NIST is simply wrong to say that they demonstrated this vulnerability "for the first time" in their 2008 report?

The above statement does provide clear indication they were very well familiar with the fact it could (partially) collapse due to the fires.

 

[Jeffrey Orling]

My recollection is that the FDNY had reports from FF that the building was creaking and making sounds that were interpreted and warping/distortion ascribed to fire/heat. They also determined it was out of plumb at some point with a transit survey. I think these and the fact that the fires were not "burning out" informed their decision to remove all personal from inside the building and set up a zone around it forbidding people to enter. Obviously their concerns of a collapse turned out to be true. These concerns may have been conveyed to the press and (of course) misinterpreted by truthers to indicate that there was a plan to demolish the building with explosives.. the so called "fore knowledge" of collapse.
I am guessing there was not a database of outcomes for steel frames high rises burning for +/- 8 hrs without fire suppression from sprinklers or firemen with hoses. As noted above the fire ratings were established from empirical tests and enabled occupants to escape. FDNY is always concerned about adjacent properties/buildings to a structurally comprised building or one that is undergoing massive fire... and evacuate nearby properties.

 

[Thomas B]

So both the structural and the fires were causing worries about the stability of WTC7.

I read that differently. "As it burned" does not imply "because it was burning". I don't see any indication that the firefighters thought that if they could put out the fires the building would not collapse. They thought the building would (or at least might well) collapse in any case because of the structural damage it had already sustained.

 

[econ41]

My recollection is that the FDNY had reports from FF that the building was creaking and making sounds that were interpreted and warping/distortion ascribed to fire/heat. They also determined it was out of plumb at some point with a transit survey. I think these and the fact that the fires were not "burning out" informed their decision to remove all personal from inside the building and set up a zone around it forbidding people to enter. Obviously their concerns of a collapse turned out to be true.

Actually, it is irrelevant that it "turned out to be true". The likelihood of probable collapse was the basis for the correct decision to "pull out" or "pull; back". From that point of decision, the actual outcome has no part to play. Even if the building had not collapsed it would not make the decision wrong.

 

[Thomas B]

My recollection is that the FDNY had reports from FF that the building was creaking and making sounds that were interpreted and warping/distortion ascribed to fire/heat. They also determined it was out of plumb at some point with a transit survey.

If you can find the documentation for this it would be great. I don't think they were worried about thermal explansion, but the "out of plumb" thing (because of the structural damage) was definitely thought to be an issue. It's like worrying about the collapse of a building that has been heavily damaged in an earthquake but is not on fire. It could "go at any moment" as the structure settles into its new (out of plumb) configuration and the loads gradually shift. This is a mechanical, not a thermal, process.

But I'm happy to look at any documents that say otherwise.

 

[Mendel]

And it's not my sense that all the shear-connections between columns and floors in the building were such that, if any one of them fails, then the whole building comes down.

Right. So what happens if the fires burn longer, and two or three connections fail?

The idea that it might be immoral to question a fire department's actions from a layperson's perspective is very strange to me. Like any government agency (and like any organization whatsoever) it is capable of everything from well-intentioned mistake to outright corruption.

Yep. Accusing people of corruption when you have zero evidence is also immoral in my world.

It isn't complete speculation if you look at the reasons why they decided to give up any efforts on WTC7:

That's a good quote. Let us compare it to what Thomas B wrote: "it doesn't seem likely that they knew that it was the fires that would cause it[1]. They appear to have thought that the building was fatally wounded by the debris from the previous collapses[2]." Statement [2] is covered partially by your quote, except for word "fatally", and [1] is speculation, especially if the "loud noises" (Jeffrey: "groan and creak") only started as the fire progressed.
Thomas's assertion that the FDNY didn't think of the fire as a causal factor in a potential collapse is speculation. Since fire is often the cause when burning buildings collapse, they'd have to have a strong reason reason to think the opposite, especially when the building had burned longer (was projected to burn longer) than the time it was rated for.

The above statement does provide clear indication they were very well familiar with the fact it could (partially) collapse due to the fires.

Exactly. They needn't be concerned about structural damage if they believed nothing would collapse (even partially) as a result; and the precautions for partial and total collapse are the same, unless you can predict with certainty which parts won't collapse.

I don't see any indication that the firefighters thought that if they could put out the fires the building would not collapse. They thought the building would (or at least might well) collapse in any case because of the structural damage it had already sustained.

Speculation.

You have the burden of proof. You have not shown that the fire fighters were able to prevent the collapse (no use thinking about the impossible). And you can't argue from "no indications" unless you make a clear argument from similar cases what indications you would expect to see. If you can't, you need positive evidence.

 

[Thomas B]

Accusing people of corruption when you have zero evidence is also immoral in my world.

I think I see the issue. I'm of course not accusing anyone of corruption (if you think I have, please show me what post you mean, so that I can delete/correct it). But it is true that I am asking questions that should have answers and, therefore, if those answers aren't forthcoming, might indicate either incompetence or corruption. My view is that there was neither gross incompetence nor corruption on 9/11, and that there are good answers to my questions. Many of them of are ones that people in this forum have helped me to find and/or understand already.

 

[Thomas B]

You have the burden of proof.

I suppose I would if I were accusing anyone of anything. But I'm just trying to understand why the building collapsed and why the FDNY behaved as it did. I'm making good progress.

 

[Jeffrey Orling]

My recollection is that the FDNY had reports from FF that the building was creaking and making sounds that were interpreted and warping/distortion ascribed to fire/heat. They also determined it was out of plumb at some point with a transit survey. I think these and the fact that the fires were not "burning out" informed their decision to remove all personal from inside the building and set up a zone around it forbidding people to enter. Obviously their concerns of a collapse turned out to be true. These concerns may have been conveyed to the press and (of course) misinterpreted by truthers to indicate that there was a plan to demolish the building with explosives.. the so called "fore knowledge" of collapse.
I am guessing there was not a database of outcomes for steel frames high rises burning for +/- 8 hrs without fire suppression from sprinklers or firemen with hoses. As noted above the fire ratings were established from empirical tests and enabled occupants to escape. FDNY is always concerned about adjacent properties/buildings to a structurally comprised building or one that is undergoing massive fire... and evacuate nearby properties.

I suppose I would if I were accusing anyone of anything. But I'm just trying to understand why the building collapsed and why the FDNY behaved as it did. I'm making good progress.

There are many explanations and versions of them about why the building collapsed.... the sequence / progression of failures.... which has phases with characteristics which morphed one into another. Anything that collapses has lost support... the mechanism(s) to resist gravity.

 

[Thomas B]

Thomas's assertion that the FDNY didn't think of the fire as a causal factor in a potential collapse is speculation. Since fire is often the cause when burning buildings collapse, they'd have to have a strong reason reason to think the opposite, especially when the building had burned longer (was projected to burn longer) than the time it was rated for.

This is in the NIST report's summary of its findings:

The collapse of WTC 7 represents the first known instance of the total collapse of a tall building primarily due to fires. The collapse could not have been prevented without controlling the fires before most of the combustible building contents were consumed.

The fires in WTC 7 were similar to those that have occurred previously in several tall buildings (One New York Plaza, 1970, First Interstate Bank, 1988, and One Meridian Plaza, 1991) where the automatic sprinklers did not function or were not present. However, because of differences between their structural designs and that of WTC 7, these three buildings did not collapse. (p. 47)

https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf

At this point, the question will be whether we should assume that firefighters knew about these "differences between their structural designs". I doubt it, but I guess you'd say I'm "speculating". Even if they did know, however, they couldn't have known the implications (proneness to progressive collapse) since it was NIST who discovered this in hindsight by a careful analysis of the structural system that was not (and still isn't) required according to building codes.

The design of WTC 7 did not include any specific analysis of how the structural system might perform in a real fire. There is a critical gap in knowledge about how structures perform in real fires, particularly considering: the effects of the fire on the entire structural system; the interactions between the subsystems, elements, and connections; and scaling of fire test results to full-scale structures (especially for structures with long span floor systems). (p. 50)

So it's just unclear where the FDNY wouldn't have gotten the idea that this building was going to collapse from fire. (Not even its designers would have known.) So, though you'll say I'm speculating, I conclude that they thought it was going to collapse from the structural damage that it had obviously sustained and that certainly is known to bring down buildings. It turned out that this was not the cause, but it's the best reason they would have had at the time.

Let me also emphasize this:

The collapse could not have been prevented without controlling the fires before most of the combustible building contents were consumed. (p. 47)

Again, while it's not a strictly logical implication, I read this to be saying that if the fires had been controlled the collapse could have been prevented.

The apparently "insulting" idea that I have been proposing is that if the firefighters had known that the collapse could have been averted by putting out the fires (something, again, which I claim they did not know and could not have known) then they would have proceeded with somewhat greater urgency to get those fires under control, rather than abandoning the building to the mechanical (not thermal) forces they (reasonably, but mistakenly) thought would destroy it no matter what they did about the fires.

I look forward to hearing your thoughts.

 

[Henkka]

If column 79 was like Achilles' heel, it seems like a remarkable coincidence that a failure from thermal expansion happened right there. Unless I'm mistaken, this was the first time such a failure was identified in any building. At least Shyam Sunder said thermal expansion was a "phenomenon not considered in current building design practice" at the press briefing. (Source: Around 21:40 in https://www.c-span.org/video/?280569-1/investigation-world-trade-center-building-7 ) So what I take from that is that a failure from thermal expansion is an exceedingly rare event, since it wasn't even considered a problem before. That such a failure would happen to the one column that could bring the whole building down, because of randomly scattered office fires... I wouldn't know how to calculate the probability of that, but it seems it would be astronomically small.

If column 79 wasn't like Achilles' heel, and all or many other singular column failures could have caused the total destruction of the building, then it would mean WTC 7 was incredibly poorly designed and unsafe.

I wonder if before 9/11, you gave someone like CDI the task of demolishing WTC 7, could they have identified column 79 as the only one they needed to take out? That would have been very economical, save a lot of money.

 

[benthamitemetric]

Why so much speculation about what the firefighters thought? There is an entire chapter in NIST NCSTAR 1-9 (Chapter 6) that painstakingly details the emergency response on 9-11 as it related to WTC7. It is all there, packaged in a nice narrative form with references made to the direct source documents. In short, the various relevant firefighters on the ground assessed that that WTC7 had the potential to collapse due to a combination of the damage it had sustained and the observable fires. (See, e.g., subsection 6.6 of NIST NCSTAR 1-9.) This was their best professional judgment in the moment, assimilating what they knew about buildings and fire and the limited information they had about the actual condition of WTC7.

And so what? Obviously none of those firefighters knew of the specific vulnerability inherent in the long span floors in the northeast corner of the building that NIST later identified as the probable locus of the initiation of the ultimate progressive collapse; however, the firefighters also had just watched thousands of people, including hundreds of their close friends and colleagues, be buried in the collapse of the towers (and, by the way, it should be a given that watching two damaged buildings collapse due to fires in such a spectacular fashion would of course prime them to think another damaged building might collapse due to fire) and the focus of their limited resources was rightly put on saving as many lives as they still could while avoiding further loss of life. The firefighters' decision was also informed by the fact that there was no water in the downtown hydrant system, which made fighting the fires difficult as a practical matter. Thus leaving the empty WTC7 alone given that attempting to fight its fires would divert scarce resources from the rescue efforts and could only lead to, and would not prevent, any further loss of life was such an obviously correct choice that there isn't much else left to say. The myopic and unnecessarily-speculative (i.e., uninformed) focus on how and why they made such an obvious call is truly missing the forest for the trees.

@Thomas B I suggest you actually read the NIST report from start to finish at some point as this isn't the first time you've spun up several pages on questions that could be readily answered thereby. When you're done, you would also likely benefit from reading the Aegis insurance litigation materials, as they may help you better understand why, even in retrospect, the vulnerability NIST identified was not likely the result of negligent design or any malfeasance.

 

[benthamitemetric]

If column 79 was like Achilles' heel, it seems like a remarkable coincidence that a failure from thermal expansion happened right there. Unless I'm mistaken, this was the first time such a failure was identified in any building. At least Shyam Sunder said thermal expansion was a "phenomenon not considered in current building design practice" at the press briefing. (Source: Around 21:40 in https://www.c-span.org/video/?280569-1/investigation-world-trade-center-building-7 ) So what I take from that is that a failure from thermal expansion is an exceedingly rare event, since it wasn't even considered a problem before. That such a failure would happen to the one column that could bring the whole building down, because of randomly scattered office fires... I wouldn't know how to calculate the probability of that, but it seems it would be astronomically small.

If column 79 wasn't like Achilles' heel, and all or many other singular column failures could have caused the total destruction of the building, then it would mean WTC 7 was incredibly poorly designed and unsafe.

I wonder if before 9/11, you gave someone like CDI the task of demolishing WTC 7, could they have identified column 79 as the only one they needed to take out? That would have been very economical, save a lot of money.

Thermal expansion undoubtedly happened all over the building, on different floors and in different areas, as the fires spread throughout over several hours, and NIST's models reflect this. Via such models, NIST determined that column 79 (or 80 or 81) likely proved to be the "Achilles' heel" of the building because, when it modeled that thermal expansion, it saw significant thermal expansion-induced failures of the girders and floor systems around those columns in particular, which it determined were sufficient to cause those columns to then buckle (which is consistent with the failure mode observed in reality).

Had the fires not traveled in the particular way they were observed to have traveled, it is conceivable that another column could have failed first and lead to a partial collapse or a different total progressive collapse. NIST did not test such counterfactuals, however, as there was no reason to. As I noted in another recent thread that veered onto this same topic, however:

NIST found that WTC7 was generally prone to classic progressive collapse due to the removal of column 79 between the floors of 11 and 13. As a result, one of NIST's recommendations was that structural systems be expressly designed to prevent such progressive collapses, and NIST even presented a model building code to address that point (see Section 5.1 of NIST NCSTAR 1). NIST's recommendations to that end have been adopted into the International Building Code, as well as many local codes, including the NYC Building Code, Chapter 16 of which was amended in 2008 to specifically to include, via the Key Element Analysis process, design requirements intended to prevent progressive collapses of tall buildings.

... NIST's findings were taken very seriously by the professionals who deal with these issues every day. It was not lost on any of the relevant professional bodies that NIST concluded that WTC7 was prone to progressive collapse. .... [T]aking those findings seriously involved a cost/benefit analysis, which was undertaken by multiple building code councils and other professionals over many years. Perhaps those specialists erred in their ultimate changes and there are still overly risky designs being built in certain places in the world. ...

As a side note, NIST's finding re WTC7's progressive collapse vulnerability likely formed the basis for the denial by the NTSB's legal counsel of the public release of NIST's entire model, which denial was widely met by truthers with much gnashing of teeth. If you put yourself in the shoes of someone who takes this seriously, however, you can understand why the government would not want to release to the public a full, ready-made suite of analytical models that could potentially be used by bad actors to identify similar progressive collapse vulnerabilities in other tall buildings (and hence would withhold such models on national safety grounds). The truthers who requested such models never exercised their right to appeal the denial into federal court, however, so we will never know for sure the exact rationale for the denial.

 

[Thomas B]

There is an entire chapter in NIST NCSTAR 1-9 (Chapter 6) that painstakingly details the emergency response on 9-11 as it related to WTC7. It is all there, packaged in a nice narrative form with references made to the direct source documents. In short, the various relevant firefighters on the ground assessed that that WTC7 had the potential to collapse due to a combination of the damage it had sustained and the observable fires. (See, e.g., subsection 6.6 of NIST NCSTAR 1-9.)

https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf

I have read that section (in fact also section 6.5.2, 6.7 and 6.8, i.e., pp. 298-305) and I would not summarize it as you do. (Neither does NIST in the main report, 1A, which I have been quoting from in this thread.) As far as I can tell, at no point are the fires mentioned as reasons the building might collapse. If you can point me to the passage that gave you this impression, we can discuss it, of course. There is talk of the fires, but there is, in my opinion, nothing to suggest that they thought they were weakening the building. The danger of collapse was indicated to them by the structural damage.

by the way, it should be a given that watching two damaged buildings collapse due to fires in such a spectacular fashion would of course prime them to think another damaged building might collapse due to fire

I think you're forgetting that on the face of it they watched two buildings collapse due to planes having flown into them. The details of the collapse mechanism were not yet known. In their careers (and their education) they had, by contrast, never seen a building like this collapse due to fire. Like I say above (comment #92) with reference to the NIST report, it's unlikely that they would have immediately blamed the fires. The science simply hadn't evolved to the point of suggesting that as a likely reason for global collapse.

I think you (and others) are projecting knowledge that we have about the collapses into the situation. The firefighters simply didn't know these things. It was learned by NIST in the investigation.

 

[Mendel]

My recollection is that the FDNY had reports from FF that the building was creaking and making sounds that were interpreted and warping/distortion ascribed to fire/heat. They also determined it was out of plumb at some point with a transit survey. I think these and the fact that the fires were not "burning out" informed their decision to remove all personal from inside the building and set up a zone around it forbidding people to enter.

Your recollection concurs with NCSTAR 9-1 chapter 6.

p300 ff.:

So we can now correct some of the speculations: Thomas's "3 floors" are actually large fires on 6 floors. The decision to abandon the building was not based on any theory or past experience of collapse, but on clear and present indicators that WTC7 was no longer structurally sound (structural damage, buckling, noises). At the same time, there were no means to fight the fires successfully.

The exact mechanics of the potential collapse were not relevant to the decision to abandon the building.

 

[benthamitemetric]

https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf

I have read that section (in fact also section 6.5.2, 6.7 and 6.8, i.e., pp. 298-305) and I would not summarize it as you do. (Neither does NIST in the main report, 1A, which I have been quoting from in this thread.) As far as I can tell, at no point are the fires mentioned as reasons the building might collapse. If you can point me to the passage that gave you this impression, we can discuss it, of course. There is talk of the fires, but there is, in my opinion, nothing to suggest that they thought they were weakening the building. The danger of collapse was indicated to them by the structural damage.



I think you're forgetting that on the face of it they watched two buildings collapse due to planes having flown into them. The details of the collapse mechanism were not yet known. In their careers (and their education) they had, by contrast, never seen a building like this collapse due to fire. Like I say above (comment #92) with reference to the NIST report, it's unlikely that they would have immediately blamed the fires. The science simply hadn't evolved to the point of suggesting that as a likely reason for global collapse.

I think you (and others) are projecting knowledge that we have about the collapses into the situation. The firefighters simply didn't know these things. It was learned by NIST in the investigation.

The structural damage sustained by WTC7 from the collapse of WTC1 had already occurred and wasn't going to magically get worse on its own. So what could make it worse and thus create the potential for collapse? The large raging fires that the FDNY was monitoring throughout the afternoon and that represented one of the key reasons they decided to foregoing evacuate the area around the building. As for connecting the fires to the potential for collapse, just see the last bullet below, where that is expressly done in the NIST report:

(NIST NCSTAR 1-9 at pg. 302.)

And when you say in this context that the twin towers collapsed because they were hit by planes, I can only assume that you are being deliberately dense and have returned to your trolling ways. WTC7 incurred enormous structural damage from the impacts of massive pieces of WTC1. Similarly, both WTC1 and WTC2 incurred enormous structural damage from the impacts of the planes. All three survived their initial structural damage. Unfortunately, however, both the planes and the debris also started fires that lead to *additional structural damage* that wound up being the proximate cause of all three collapses.

So the fire fighters had just watched the exact same phenomenon they were witnessing in WTC7 play out before their eyes in both WTC1 and WTC2. I don't think we need to project any of our hindsight on them to assume they could make that obvious connection, given that they were also trained on, and have doubtlessly experience in other contexts, the fact that fire can and will cause massive structural damage and destroy buildings, and given that the NIST report expressly notes, based on their actual firsthand accounts, that they were making that connection in real time on 9/11.

 

[Mendel]

I've downvoted 3 posts of yours because you're simply repeating yourself while ignoring the responses to your earlier posts; in one post, you're even re-quoting my own source at me. I suggest re-reading both threads.

Again, while it's not a strictly logical implication, I read this to be saying that if the fires had been controlled the collapse could have been prevented.

The biggest problem I have is your continued assertion that the fires could have been controlled, which remains completely unsupported, and runs counter to the evidence in NCSTAR 9-1 6.6.

 

[Mendel]

given that they were also trained on, and have doubtlessly experience in other contexts, the fact that fire can and will cause massive structural damage and destroy buildings,

... and that they have been trained to watch out for and recognize signs of structural damage. Their own lives depend on it.

 

[econ41]

@Thomas B - your truther bias is becoming more obvious.

I won't comment on this first paragraph. Whether NIST is right or wrong is of no significance to the discussion of the OP.

https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf

I have read that section (in fact also section 6.5.2, 6.7 and 6.8, i.e., pp. 298-305) and I would not summarize it as you do. (Neither does NIST in the main report, 1A, which I have been quoting from in this thread.) As far as I can tell, at no point are the fires mentioned as reasons the building might collapse. If you can point me to the passage that gave you this impression, we can discuss it, of course. There is talk of the fires, but there is, in my opinion, nothing to suggest that they thought they were weakening the building. The danger of collapse was indicated to them by the structural damage.

Let's look at this collection of outlandish claims:

I think you're forgetting that on the face of it they watched two buildings collapse due to planes having flown into them.

Utter nonsense. They saw or knew about the plane impacts and the fact that the Twin Towers both survived the impacts but were subject to very large fires. And, at the time relevant to this WTC7 discussion, they had seen towers collapse as a result of fires. Again you persist in denigrating the intelligence, training and professionalism of the fire fighters of all ranks.

The details of the collapse mechanism were not yet known.

They had all the details they needed at that time. Planes impacted WTC1 & 2 - towers stood. Large fires occurred - couldn't be fought - towers collapsed. WTC7 is "fully involved in fire". They "pulled back" from active fire fighting for reasons including resource limitations. They established a collapse zone. << So they recognised the possibility of collapse and chose the "play safe"option. It is ludicrous to suggest that: (a) "They" were unaware of either the site and event-specific risks or the general risk in such a scenario; and (b) that the worldwide profession of firefighting did not see collapse as possible until AFTER NIST wrote a report. And why the collapse zone if there was no risk?

In their careers (and their education) they had, by contrast, never seen a building like this collapse due to fire.

Your persistent insulting of their training and professionalism becomes boring. The vulnerability of steel framed high rises is core accepted fact in the industry. It is a main reason for fire rating

Like I say above (comment #92) with reference to the NIST report, it's unlikely that they would have immediately blamed the fires.

Repeating the same derogatory insults. And, again, NIST is not the final authority nor the source of reasoning needed to respond to the topic of this thread.

The science simply hadn't evolved to the point of suggesting that as a likely reason for global collapse.

That statement must rank as a deliberate untruth.

I think you (and others) are projecting knowledge that we have about the collapses into the situation.

I need not refer to the kitchen utensils and reflectivity aphorism.

The firefighters simply didn't know these things. It was learned by NIST in the investigation.

Again the insult. And NIST only added some details which may be correct, and may support the reasoned argument. But are strictly redundant. We could still address the OP topic if NIST's explanations were all wrong.

 

[Mendel]

@Thomas B , it appears you are promulgating two claims here:

1) The FDNY had the means to extinguish the fires in WTC7 and thereby prevent its subsequent collapse, but chose not to do so.

2) If the FDNY had known that buildings like WTC7 have an "Achilles heel" that can cause them to collapse, it would have chosen to extinguish the fires in WTC7.

Am I summarizing you correctly?

 

[Thomas B]

The decision to abandon the building was ... [based] on clear and present indicators that WTC7 was no longer structurally sound (structural damage, buckling, noises). At the same time, there were no means to fight the fires successfully.

We agree about this. I've removed the idea that experience and theory didn't enter into it. I'm pretty sure that both science and experience informs firefighting decisions all the time. These are well-trained and well-educated people. Maybe you meant something different, but the important thing here is that we agree that they believed the building was no longer structurally sound.

The exact mechanics of the potential collapse were not relevant to the decision to abandon the building.

We disagree about this. It turns out that they were wrong about what was killing the building. So it was very relevant that they didn't think the fires would cause total progressive collapse but did think that the debris damage would. If they had gotten this right (though there was no science or experience to prevent their mistake) they may not have abandoned the firefighting efforts. After all, they did not know how much time they had, but they would have known that time was of the essence. (Again, these are things they didn't know and couldn't have known. So please don't tell me I'm blaming them.)

 

[Thomas B]

@Thomas B , it appears you are promulgating two claims here:

1) The FDNY had the means to extinguish the fires in WTC7 and thereby prevent its subsequent collapse, but chose not to do so.

2) If the FDNY had known that buildings like WTC7 have an "Achilles heel" that can cause them to collapse, it would have chosen to extinguish the fires in WTC7.

Am I summarizing you correctly?

No.

1) They did not have the means immediately available. There was of course water in the Hudson. They would have to work with great urgency to get that water to the building. They may have done so if they thought it would prevent the collapse of WTC7. But they didn't think this, because no one had ever previously prevented a steel-framed building from collapsing by pouring water on it. NIST found that, in this case, that would in (counter)fact have done the trick.

2) Actually, I think this is a different issue (but much closer to the theme of this thread). If they had known that WTC7 had an Achilles Column (let's call it that) but didn't know which one, they might have stayed away from it altogether (especially since the structure was so damaged already). It seems like a very precarious situation to get into. So I think this part of the NIST findings actually pulls in the opposite direction. It would be really interesting to read some recent fire-fighting manuals that address this directly. What do firefighters expect of 50-story steel-framed skyscrapers that are on fire.

 

[econ41]

We agree about this. I've removed the idea that experience and theory didn't enter into it. I'm pretty sure that both science and experience informs firefighting decisions all the time. These are well-trained and well-educated people. Maybe you meant something different, but the important thing here is that we agree that they believed the building was no longer structurally sound.

Thank you.

 

[Thomas B]

The vulnerability of steel framed high rises is core accepted fact in the industry. It is a main reason for fire rating

Can you source this? The portions of the NIST report (and the article from the Society of Fire Protection Engineers) I've cited seem to say the opposite. Your repeated assurances that this is wrong aren't persuading me.

 

[Miss VocalCord]

We disagree about this. It turns out that they were wrong about what was killing the building. So it was very relevant that they didn't think the fires would cause total progressive collapse but did think that the debris damage would. If they had gotten this right (though there was no science or experience to prevent their mistake) they may not have abandoned the firefighting efforts. After all, they did not know how time they had, but they would have known that time was of the essence.

That would mean that every possible scenario would have to be known and simulated. What if the fires were hotter as simulated? what if there was some structural damage to column 79?
Even then they have to rely on their experience. You're not going to send in people into a building you think is going to come down; they already lost many people that day.

 

[econ41]

What do firefighters expect of 50-story steel-framed skyscrapers that are on fire.

It depends on the scale of the fire compared with the "design envelope" - which potentially brings us back to the topic and the key issues identifies much earlier in the thread.

 

[Miss VocalCord]

No.

1) They did not have the means immediately available. There was of course water in the Hudson. They would have to work with great urgency to get that water to the building. They may have done so if they thought it would prevent the collapse of WTC7. But they didn't think this, because no one had ever previously prevented a steel-framed building from collapsing by pouring water on it. NIST found that, in this case, that would in (counter)fact have done the trick.

Water wasn't the only problem at that moment:

They didn't have equipment, hose, standpipe kits, tools, and enough handie talkies for conducting
operations inside the building

 

[Mendel]

They did not have the means immediately available.

"immediately" is not part of my summary. You seem to say they had the means required to use the Hudson water, and that they could have extinguished WTC7 with it.

NIST found that, in this case, that would in (counter)fact have done the trick.

I don't believe NIST found this. You derive this from them in a fashion you admit is "not strictly logical". NIST did not say the FDNY had the ability to extinguish the fires.

If they had known that WTC7 had an Achilles Column (let's call it that) but didn't know which one, they might have stayed away from it altogether

I feel this is a reversal of your previous position. Just another circle in the convo, eh?
Note that they did "stay away from it altogether".

For reference, this is your previous position:

If firefighters had known then (on 9/11) what they know now, they might have spent those three hours (from 2:30 onwards) working very deliberately (and with great urgency) to get water to the building (from the Hudson) in hopes of avoiding further thermal expansion.

"work with great urgency" vs. "stayed away from it". 180⁰.

 

[Thomas B]

"immediately" is not part of my summary. You seem to say they had the means.

I think I've now explained what I mean. You seem very interested in showing that I am (or have at some time earlier in the discussion been) wrong about something. I'm always happy to acknowledge my mistakes and if you think my views have evolved over the last couple of weeks I'm not embarrassed to grant that that is possible. But my real interest is in understanding what happened.

You derive this from them in a fashion you admit is "not strictly logical". NIST did not say the FDNY had the ability to extinguish the fires.

I'm glad to hear you see me as an authority on logic. I can assure you also that my conclusions are nonetheless reasonable. And it is also (logically) possible that something that you don't have the ability to do would, if you (counterfactually) could do it, achieve the result you seek. That implication is all I'm talking about.

 

[Thomas B]

180⁰.

=

this part of the NIST findings actually pulls in the opposite direction.

I think we're almost on the same page now. Making progress.

 

[Mendel]

I think I've now explained what I mean.

You haven't.

You seem very interested in showing that I am (or have at some time earlier in the discussion been) wrong about something.

I'm interested in nailing down your actual claims, but you're evasive. The observation that you don't actually care about nailing down a claim to be discussed calls your motives into question.

 

[Mendel]

You seem to say they had the means required to use the Hudson water, and that they could have extinguished WTC7 with it.

@Thomas B is this correct?

 

[benthamitemetric]

1) They did not have the means immediately available. There was of course water in the Hudson. They would have to work with great urgency to get that water to the building. They may have done so if they thought it would prevent the collapse of WTC7. But they didn't think this, because no one had ever previously prevented a steel-framed building from collapsing by pouring water on it. NIST found that, in this case, that would in (counter)fact have done the trick.

There is absolutely nothing in the record that indicates the FDNY thought the collapse of WTC7 was inevitable or even highly likely. They simply recognized it as a possibility and, for all of the reasons we've now listed multiple times in this thread (including the inherent risk posed by that possibility of collapse), decided that fighting its fires was not a priority. There's also no evidence that they believed they could get sufficient water from the hudson to meaningfully fight the fires, in any case. You keep bringing that up as if it were a real possibility, but nothing in the actual record supports that. And what you say about them not wanting to pour water on the fire because that had never done before to stop the collapse of a building is just a bunch of nonsense that had nothing to do with the firefighters known motivations, which, again, you are keen to ignore.

2) Actually, I think this is a different issue (but much closer to the theme of this thread). If they had known that WTC7 had an Achilles Column (let's call it that) but didn't know which one, they might have stayed away from it altogether (especially since the structure was so damaged already). It seems like a very precarious situation to get into. So I think this part of the NIST findings actually pulls in the opposite direction. It would be really interesting to read some recent fire-fighting manuals that address this directly. What do firefighters expect of 50-story steel-framed skyscrapers that are on fire.

This is a pointless counterfactual. In the circumstances as they actually were, which are very well and clearly documented based on firsthand accounts from the firefighters, the decision to not fight fires in WTC7 was obviously the correct call that any reasonable firefighter would have made based on the factors that have already been spoon fed to you multiple times. You can wish all those circumstances away but there is no point in doing so other than to troll the board.

You are flailing to try to find some tension--any tension--between the decisions the fire fighters made on 9/11 and what NIST ultimately concluded, but there is none. The firefighters made highly prudent and rational choices given what they knew and NIST made a technical report that detailed aspects of the building about which the firefighters could not have known.

This thread is also veering off topic and what the firefighters did and what they thought is irrelevant to the OP, as others have pointed out.

 

[Thomas B]

@Thomas B is this correct?

I haven't looked closely at what happened later, but it's my sense that they did eventually get water to the site. (Wasn't water poured on it for weeks and weeks later?) It eventually extinguished all the fires.

So, yes, they did have the means to get water to the site. The question is whether they had the time to do it before the building collapsed. Since they didn't know it would collapse at exactly 5:20 PM (only conspiracy theorists believe they had this foreknowledge) the question reduces to their sense of urgency about extinguishing the fires. As I keep saying, they didn't feel it was urgent because they didn't know that putting out the fires would be the key to preventing the collapse.

They (reasonably) believed they had more important things to worry about. And that one of these things was making sure that if the building does collapse (because of the structural damage it had already sustained) the area was cleared.

 

[Thomas B]

The firefighters made highly prudent and rational choices given what they knew and NIST made a technical report that detailed aspects of the building about which the firefighters could not have known.

I don't disagree with this statement in the least. In fact, it's what I have been saying again and again when people have imputed the opposite idea to me in this thread.

 

[Oystein]

... They would have to work with great urgency to get that water to the building. ...

No. Utterly, criminally, inhumanly FALSE. Stop concocting such blatant nonsense!

There were potentially hundreds of lives to save, victims to find and rescue - but NOT in THAT building, which was empty of people.

It was prudent, smart, intelligent, socially adequate, and proof of human decency that the FDNY decided to abandon WTC7 and "pull" all (limited!!!) resources from it, as ZERO lives were at stake there.

Your entire posting record in this thread and elsewhere seems to be the opposite of all that.

 

[Henkka]

Thermal expansion undoubtedly happened all over the building, on different floors and in different areas, as the fires spread throughout over several hours, and NIST's models reflect this. Via such models, NIST determined that column 79 (or 80 or 81) likely proved to be the "Achilles' heel" of the building because, when it modeled that thermal expansion, it saw significant thermal expansion-induced failures of the girders and floor systems around those columns in particular, which it determined were sufficient to cause those columns to then buckle (which is consistent with the failure mode observed in reality).

Yeah clearly there would be thermal expansion wherever there was heat from fires, I was more thinking of failures caused by thermal expansion. Meaning, what is the probability of thermal expansion causing something like a girder being pushed off of a column. If it's very unlikely, it seems like an incredible coincidence that it just so happened on the one column that was the "Achilles' heel" of the building. If column 79 wasn't Achilles' heel, and total destruction could have ensued from a single girder being pushed off of any column, it seems the building was quite fragile.

 

[Oystein]

...
So, yes, they did have the means to get water to the site.

No. Crap.

The question is whether they had the time to do it before the building collapsed.

No. Nonsense.
There was ZERO priority to save that building when elsewhere there were HUMANS TO BE RESCUED.

Since they didn't know it would collapse at exactly 5:20 PM (only conspiracy theorists believe they had this foreknowledge) the question reduces to their sense of urgency about extinguishing the fires.

No. Wrong. You have read all the information you need to know that this is WRONG.
There was a conscious, informed, intelligent and highly credentialed decision to NOT EVER attempt to put out those fires. ALL resources were prudently pulled, the building was explicitly left to its own devices, to either burn out or collapse before burning out.

As I keep saying, they didn't feel it was urgent because they didn't know that putting out the fires would be the key to preventing the collapse.

Holy shmoly I have rarely read anything more brutally DUMB than this dreck!
These people are FIREfighters - you tell they don't know what firefighting is for???? Really?!?!?!?!?

They (reasonably) believed they had more important things to worry about. And that one of these things was making sure that if the building does collapse (because of the structural damage it had already sustained) the area was cleared.

Exactly. Except of course the silly, dishonest bit in parentheses: Pathetically WRONG that bit. OF COURSE fire fighters, particularly the professionals in NYC with its unique landscape of skyscrapers, understand a billion times better than you what the hazards of fire are and why buildings might collapse.

Why did you write all the stupid nonsense above if you now pretend to understand FDNY priorities after 11 a.m.?