Was Column 79 the Achilles' Heel of WTC7?

econ41

Senior Member
I can't decide whether to praise the intrepid Metabunkers
who demonstrate nearly limitless patience to a poster who routinely agues in bad faith,
or damn them for feeding a worthless fire.
Then I'm probably a candidate for chastisement. In my defence, I claim that my posts have all been directed EITHER at directly returning the thread back onto the OP topic or attempting to explain some of the derails @Thomas B has used. (And that latter option has mostly failed.) So I'll plead guilty and claim, in mitigation of sentence, that I have left many off-topic posts to stand without attempting counterclaims.

Mea culpa,
 
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Gamolon

Active Member
I think they let the fires burn* because they were worried that the building would collapse because of the structural damage it had suffered from WTC1.
Does the following excerpt support your view that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?


savewtc7.jpg
 

econ41

Senior Member
Can you see it from my point of view at all, where I feel like I'm almost quoting NIST verbatim?
Yes.
"The collapse of WTC 7 is the first known instance of a tall building brought down primarily by uncontrolled fires."
Source: https://www.nist.gov/world-trade-center-investigation/study-faqs/wtc-7-investigation Question #15
Note: "uncontrolled" - and put that in context with my assertion that there were no effective sprinklers AND the deliberate decision to not undertake active fire fighting. It was possibly one of few burnings left unfought. And the only 47 storey "tall building".
When an occurrence is the "first known instance" of something, that means it has never happened before. So I don't think that's a "truther" talking point.
Get familiar with truther tactics. Truthers routinely argue that "cannot happen for the first time". All three WTC Tower collapses, allowing for commonality between WTC1 and WTC2, were "first times". And we more than sufficiently fully understand the collapse mechanisms and the primary role played by unfought fires in all three collapses.
"WTC 7 collapsed because of fires fuelled by office furnishings." -Shyam Sunder
Source: https://www.c-span.org/video/?280569-1/investigation-world-trade-center-building-7 @ 21:20

When there is a fire fuelled by office furnishings, that is an office fire.
Please don't ignore my explicit explanation. THEN be aware thatTRuthers use the expression "office fires" mendaciously. So if you use it you will risk misunderstanding.
So I also don't agree that is a "truther" talking point.
Rethink that opinion, please.
But I agree this is kinda off-topic.
Yes.
Drawing an equivalence between the damage from the plane impacts and debris hitting WTC7 seems like a stretch to me.
It is a false - invalid - argument. I haven't made it for that reason.
Correct me if I'm wrong, but I don't think any of the debris reached deep inside the building? The chunks of debris were falling mostly vertically and impacting the south face.
And starting fires. The structural damage was not significant in the collapse.
 

benthamitemetric

Senior Member
It's not a correct statement of my view, if that's what you mean. (I may of course be wrong.) I don't think the firefighters were worried that WTC7 would collapse because of the fires. I think they let the fires burn* because they were worried that the building would collapse because of the structural damage it had suffered from WTC1.

*Edit: yes, I know they didn't have adequate resources to fight the fires, so "let the fires burn" may not be the best way to put this. But we're here just talking about their reasons for thinking it might collapse.
Why would the firefighters think that WTC7 would suddenly collapse at a later time from impact damage it already survived? Can you name an instance where a high rise steel building that has been significantly damaged (but survived such damage) later spontaneously fell apart from that damage alone?
 

Thomas B

Active Member
Does the following excerpt support your view that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?
It is consistent with it.
 

Thomas B

Active Member
Why would the firefighters think that WTC7 would suddenly collapse at a later time from impact damage it already survived? Can you name an instance where a high rise steel building that has been significantly damaged (but survived such damage) later spontaneously fell apart from that damage alone?

Nearly 360 buildings, homes at risk of collapse following Mexico City earthquake​

MEXICO CITY – As many as 360 buildings and homes are in danger of collapse or with major damage in Mexico City nearly a week after a magnitude 7.1 earthquake completely collapsed 38 structures.

The risk of delayed collapse is real: The cupola of Our Lady of Angels Church, damaged and cracked by the Sept. 19 quake, split in half and crashed to the ground Sunday evening. There were no injuries.

Nervous neighbours continued calling in police on Monday as apparently new cracks appeared in their apartment blocks or existing ones worsened, even as the city struggled to get back to normality.

Officials said they had cleared only 103 of Mexico City’s nearly 9,000 schools to reopen Monday and said it could be two to three weeks before all were declared safe – leaving hundreds of thousands of children idle.

Mexico City Mayor Miguel Angel Mancera said at least seven schools were among the buildings thought to be at risk of tumbling.

At several points in the city, employees gathered on sidewalks in front of their workplaces Monday refusing to enter, because they feared their buildings could collapse.

“We are afraid for our own safety,” said Maribel Martinez Ramirez, an employee of a government development agency who, along with dozens of coworkers, refused to enter their workplace Monday. “The building is leaning, there are cracks.”

Mancera said 360 “red level” buildings would either have to be demolished or receive major structural reinforcement. Another 1,136 were reparable, and 8,030 of the buildings inspected so far were found to be habitable.
https://globalnews.ca/news/3767288/mexico-city-earthquake-building-collapse-risk/

PS: I'm not sure why you're suddenly invoking the precedent of "an instance where a high rise steel building" behaved in a particular way. After all, you didn't accept NIST's remark about how such buildings have never collapsed due to fire.

Anyway, it seems pretty common to worry about "delayed collapse" after buildings have been structurally damaged but have no ongoing fires in them. They lean, cracks develop, sometimes they "tumble". Etc.
 

benthamitemetric

Senior Member
https://globalnews.ca/news/3767288/mexico-city-earthquake-building-collapse-risk/

PS: I'm not sure why you're suddenly invoking the precedent of "an instance where a high rise steel building" behaved in a particular way. After all, you didn't accept NIST's remark about how such buildings have never collapsed due to fire.

Anyway, it seems pretty common to worry about "delayed collapse" after buildings have been structurally damaged but have no ongoing fires in them. They lean, cracks develop, sometimes they "tumble". Etc.
Which of the damaged structures that actually later collapsed was a high rise steel building?
 
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benthamitemetric

Senior Member
I don't know.
Of course you don't. So as far as you know, a high rise steel building spontaneously collapsing solely from damage it sustained but survived hours earlier would be just as new a "phenomenon" to the firefighters at Ground Zero as would a high rise steel building collapsing entirely from a combination of damage and fires. And yet you insist that the firefighters had to have concluded that the former was possible while ruling out the latter, even though the relevant testimony mentions their concerns about both the damage and fires. (And this of course ignores the fact, which you also ignore, that those fighters had actually seen two buildings collapse due to a combination of damage and fires that very morning, so, in reality, unlike the idea of a steel high rise that bided its time and waited patiently for hours before collapsing from damage alone, a steel high rise collapsing from fire and damage was not a new concept to them.)
 

benthamitemetric

Senior Member
And if there was any doubt that @Thomas B's theory of what the FDNY thought was incorrect, here's a press release that FDNY Chief Daniel Nigro issued on September 23, 2007 ahead of the release of the NIST report:

Release date: September 23, 2007

Regarding WTC 7: The long-awaited US Government NIST (National Institute of Standards and Technology) report on the collapse of WTC 7 is due to be published at the end of this year (although it has been delayed already a few times [ adding fuel to the conspiracy theorists fires!]). That report should explain the cause and mechanics of the collapse in great detail. Early on the afternoon of September 11th 2001, following the collapse of WTC 1 & 2, I feared a collapse of WTC 7 (as did many on my staff).

The reasons are as follows:

1 - Although prior to that day high-rise structures had never collapsed, The collapse of WTC 1 & 2 showed that certain high-rise structures subjected to damage from impact and from fire will collapse.
2. The collapse of WTC 1 damaged portions of the lower floors of WTC 7.
3. WTC 7, we knew, was built on a small number of large columns providing an open Atrium on the lower levels.
4. numerous fires on many floors of WTC 7 burned without sufficient water supply to attack them.

For these reasons I made the decision (without consulting the owner, the mayor or anyone else - as ranking fire officer, that decision was my responsibility) to clear a collapse zone surrounding the building and to stop all activity within that zone. Approximately three hours after that order was given, WTC 7 collapsed.

Conspiracy theories abound and I believe firmly that all of them are without merit.

Regards, Dan Nigro
Chief of Department FDNY (retired)

(Emphases added.)
(Statement preserved here.)

It's almost as if I've been directly channeling the man who actually made the fateful decision this entire time.
 

Gamolon

Active Member
It is consistent with it.
Oh really?
So when they said "The reports that WTC7 was making loud noises as it burned indicated to them that it might be unstable.", you think that statement supports your insinuation that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?

So when they said "There was no water immediately available for fighting fires.", you think that statement supports your insinuation that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?

So when they said "They didn't have equipment, standpipe kits, tools, and enough handie talkies for conducting operations inside the building.", you think that statement supports your insinuation that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?

So when they said "The building had large fires burning on at least six floors. Any one of those six fires would have been considered a large incident during normal FDNY operations.", you think that statement supports your insinuation that the FDNY Chief Officer made the decision to let the fires burn solely on the premise that WTC7 suffered structural damage from the collapse of WTC1 and WTC7 would collapse regardless of fires burning?

Are you kidding me?

:rolleyes:
 

deirdre

Senior Member.
Of course you don't. So as far as you know, a high rise steel building spontaneously collapsing solely from damage it sustained but survived hours earlier would be just as new a "phenomenon" to the firefighters at Ground Zero as would a high rise steel building collapsing entirely from a combination of damage and fires. And yet you insist that the firefighters had to have concluded that the former was possible while ruling out the latter, even though the relevant testimony mentions their concerns about both the damage and fires. (And this of course ignores the fact, which you also ignore, that those fighters had actually seen two buildings collapse due to a combination of damage and fires that very morning, so, in reality, unlike the idea of a steel high rise that bided its time and waited patiently for hours before collapsing from damage alone, a steel high rise collapsing from fire and damage was not a new concept to them.)
maybe Thomas thinks all firefighters in cities are expert high rise engineers, who are updated weekly on all the high rises world wide. (not that that would matter i bet...as the investigation concluded, that the Chief took way too long to evacuate the area around wtc7 and not let men into the building)
 

econ41

Senior Member
Let's see if we can we resolve the OP question:

"Was Column 79 the Achilles' Heel of WTC7?"

I claim it wasn't an "Achilles' Heel" and it wasn't even a "weak link" by any of the standards of design that were relevant.

This is the status of the debate as I see it:

"Achilles' Heel" is a poor metaphor for at least two reasons. I will explain one later in this post. Let's call it the "weak link that fails first leading to collapse" >> "weak link" for brevity. Here are what should be the agreed starting premises:

Postulate #1 - Every building will fail if pushed hard enough. It is not possible to design a building that can never fail. >> Should be a truism.
Postulate #2 - The first item which triggers the start of collapse will be the weak link. >> Should be a truism.
Postulate #3 - WTC 7 was designed to standards that were relevant at the time.
Postulate #4 - The events of 9/11 subjected WTC 7 to trauma in excess of what it was designed to survive and it collapsed.

Those 4 should sufficiently define the context and should be agreed facts.

Then my opinions are:

(A) We know that WTC 7 was "pushed beyond its design limits" and collapsed. Also that Column 79 was - for purposes of this discussion - the "weak link"

(B) We cannot know whether or not WTC7 would have survived the type of fire scenario it was designed for BECAUSE it was never tested with such a fire scenario.

(C) THEREFORE we cannot know what "weak link" may have been revealed in an "as designed" scenario. INCLUDING we cannot know if Column 79 would have been a weak link in such a scenario.

(D) We cannot know whether there was any other "weak link" that could have been identified in a different fire scenario.

(Side issue - THEREFORE we cannot know if Column 79 was an Achilles' Heel because a true Achilles' Heel would be the sole** - only - point of vulnerability.) And, tho' I normally do not accept NIST as any form of ultimate authority, for moot purposes of this discussion I agree with NIST's proof that failure of Col 79 would result in total collapse.

So >> Column 79 was NOT an Achilles' Heel.

BUT there is a lot more to discuss in two related aspects which are:
(i) Whether or not regulations should seek to limit "single item failure" vulnerabilities for future buildings; AND
(ii) To what extent building designs should seek to prevent or minimise the extent of progressive collapses.
Discussion of those topics is a natural outcome of this topic BUT goes beyond its current scope.
.
.
** Ouch. The "sole<>heel" pun" was not intended but I'll leave it there.
 
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benthamitemetric

Senior Member
Let's see if we can we resolve the OP question:
...

So >> Column 79 was NOT an Achilles' Heel.

BUT there is a lot more to discuss in two related aspects which are:
(i) Whether or not regulations should seek to limit "single item failure" vulnerabilities for future buildings; AND
(ii) To what extent building designs should seek to prevent or minimise the extent of progressive collapses.
Discussion of those topics is a natural outcome of this topic BUT goes beyond its current scope.
.
.
** Ouch. The "sole<>heel" pun" was not intended but I'll leave it there.
I actually disagree. I think NIST presented strong evidence that columns 79, 80 and 81 did form an Achilles Heel for the building. I base this on the fact that NIST ultimately recommended significant building code changes to reduce the chance that such a vulnerability would be included in future designs, and such recommendations were widely adopted, including in NYC, which I take to be a serious acknowledgement by the structural engineers who deal with these design issues for a living that those columns were a significant design issue.

Of course, that is with hindsight and such new codes were arguably only practically implementable with the immense computer modeling capabilities that NIST played a significant role in pioneering with the WTC7 report in particular, so the presence of such a weakness in an older construction does not necessarily evidence any incompetence, negligence, or malfeasance by any of the building's designers. Notably, the Aegis Insurance litigation was dismissed because the judge did not accept the plaintiffs claims that WTC7 was negligently designed or constructed, and none of those claims focused on column 79 itself (which is a tacit acknowledgement that even the plaintiffs believed it was built within code following prevailing design principles, inherent lurking vulnerability notwithstanding). The judge's reasoning in dismissing those claims was very similar to your reasoning in not accepting that column 79 was an Achilles Heel.

Ultimately, reasonable minds can readily disagree on this question, however, as it is merely one of opinion and not objective fact.
 

econ41

Senior Member
I actually disagree.
Actually, I don't think you do. My comment may still be too brief. I suspect we may still not be understanding each other.
I think NIST presented strong evidence that columns 79, 80 and 81 did form an Achilles Heel for the building.
I have no doubt that the 79, 80, 81 column cluster was the weakness revealed by the actual event.

For the reason I stated and the emotive implications that @Thomas B has ambiguously "loaded" on the term I prefer to NOT use "Achilles' Heel"

I think that you are aware that I do not accept NIST as a final or ultimate authority for reasons I have explained many times - I can repeat if there is interest. BUT I do not know if NIST "presented strong evidence that columns 79, 80 and 81 did form an Achilles Heel for the building" under the "as designed" range of fire scenarios. << That is the key point I have been trying to see discussion recognise. IF NIST did so identify that risk could you provide me with the reference you rely on so I can review it? BUT my focus is on the facts of the real event as relevant to the OP topic. Not whether or not NIST identified it. i.e. was C79 a weak link sufficient to trigger a collapse in an as-designed scenario THEN possibly to discuss the philosophy of regulating to minimise single item failure weaknesses as I said in my post?
I base this on the fact that NIST ultimately recommended significant building code changes to reduce the chance that such a vulnerability would be included in future designs, and such recommendations were widely adopted, including in NYC, which I take to be a serious acknowledgement by the structural engineers who deal with these design issues for a living that those columns were a significant design issue.
I have zero doubt about either of those two critical points, (a) Reduce the vulnerability of future designs AND (b) both the issues I identified are contemporary issues for serious consideration viz minimisation of runaway progression and reducing vulnerability to collapse from single point weaknesses
Of course, that is with hindsight and such new codes were arguably only practically implementable with the immense computer modeling capabilities that NIST played a significant role in pioneering with the WTC7 report in particular, so the presence of such a weakness in an older construction does not necessarily evidence any incompetence, negligence, or malfeasance by any of the building's designers. Notably, the Aegis Insurance litigation was dismissed because the judge did not accept the plaintiffs claims that WTC7 was negligently designed or constructed, and none of those claims focused on column 79 itself
I comprehend that background information:
(which is a tacit acknowledgement that even the plaintiffs believed it was built within code following prevailing design principles, inherent lurking vulnerability notwithstanding). The judge's reasoning in dismissing those claims was very similar to your reasoning in not accepting that column 79 was an Achilles Heel.
I'll resist the temptation to commend the judge, ;) I've been trying to get this thread's discussion to resolve the OP Achilles' Heel issue without all the meandering around the topic and the personality tensions. The real issues of engineering and regulatory significance are those future benefits including the lessons already (and variably) learned worldwide. I am NOT conversant with the current status of progress.
Ultimately, reasonable minds can readily disagree on this question, however, as it is merely one of opinion and not objective fact.
I don't think you and I are as far apart as it may seem.
 
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Henkka

Banned
Banned
Postulate #4 - The events of 9/11 subjected WTC 7 to trauma in excess of what it was designed to survive and it collapsed.

I think I would disagree with this... Or at least question it. So on 9/11, WTC 7 was subjected to two types of trauma:

1) Debris damage from chunks of WTC 1 falling and impacting the southern face
2) Fire damage from office fires burning uncontrollably for about 7 hours, without any firefighting efforts or sprinklers

But according to NIST, the debris damage did not really play a role in the collapse. They go so far as to say the building would have collapsed solely from the fires, just in a different way:

"A separate analysis showed that even without the structural damage due to debris impact, WTC 7 would have collapsed in fires similar to those that occurred on Sept. 11, 2001. None of the large pieces of debris from WTC 2 hit WTC 7 because of the large distance between the two buildings." Question #16 in the FAQ

So we mostly just need to consider the fire damage, and we can all agree that WTC 7 was built in accordance with the building codes at the time. It also had intact fire proofing, unlike WTC 1 and 2.

With all that in mind, I don't understand the statement that WTC 7's design could not be expected to survive 7 hours of uncontrolled fires without total collapse, when we have examples like One Meridian and First Interstate suffering similar or worse fires without even a partial collapse.
 

FatPhil

Senior Member.
solely
solely
solely
solely

This is the word you should have been putting in bold, as it seems that's the - vitally important to your point - word that's been either overlooked or ignored. Remove that word from your question, and his answers make more sense, but that means he's not answering the question actually asked.

@Thomas B - please make sure you understand how important that word is in the question.
 

econ41

Senior Member
I think I would disagree with this...
Read the next part of your own post. You have already agreed the fire was left: "without any firefighting efforts or sprinklers"
Or at least question it. So on 9/11, WTC 7 was subjected to two types of trauma:

1) Debris damage from chunks of WTC 1 falling and impacting the southern face
2) Fire damage from office fires burning uncontrollably for about 7 hours, without any firefighting efforts or sprinklers
Please read my posts. The building was not designed for fire intitiaion on multiple floors or surviving such a fire without any firefighting efforts or sprinklers
But according to NIST, the debris damage did not really play a role in the collapse.
Yes, I accept that the assessment is true. Why are you disagreeing with it?
They go so far as to say the building would have collapsed solely from the fires, just in a different way:
Which is - or should be - the STARTING premise. The debate in THIS thread should not be about fire causing the collapse. It should be a "given".
So we mostly just need to consider the fire damage, and we can all agree that WTC 7 was built in accordance with the building codes at the time. It also had intact fire proofing, unlike WTC 1 and 2.
Sorry YES those are agreed facts for purposes of THIS discussion - why raise them? They are irrelevant to the current discussion. The key point is that the fire was not fought in accordance with what the building was designed for. i.e. there was no active fire fighting supplemented by sprinklers.
With all that in mind, I don't understand the statement that WTC 7's design could not be expected to survive 7 hours of uncontrolled fires without total collapse,
Who made that statement. I certainly didn't. If some person did make that statement they are wrong. I've made my position explicitly clear.
when we have examples like One Meridian and First Interstate suffering similar or worse fires without even a partial collapse.
Please stop playing truther games posting invalid comparisons and false analogies. I comprehend that you say: "I don't understand ..." You are going far off-topic - the topic of this thread is: "Was Column 79 the Achilles' Heel of WTC7?" I and at least one other have said it wasn't. Nobody so far has proved it was. And I've already offered to explain or respond to your concerns. Why not OP a thread OR return to the discussion of the topic of this thread.
 
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Thomas B

Active Member
Are you kidding me?
I'm absolutely and completely serious.

Like I say, I don't claim those statements support my views, only that they are consistent with them. I understand why you think they contradict me. But I don't read them that way. I think that's probably as far as we're going to get this time around.

My view remains that if they had believed that putting out the fires would have significantly reduced the probability of total progressive collapse (i.e., reduced the odds of the worst case scenario for the building) then they would have devoted more of their energies (with "greater urgency") to the task of getting water on them. I don't think they believed this, and, on my reading of the NIST report, they had no way of knowing this, so they let the fires burn, and left the building to its fate.

I have no expertise to judge the wisdom of this decision, neither in the moment or in hindsight. Those who do seem to agree that it was wise. I accept their judgment. But I'd be surprised if this experience hasn't changed how firefighters approach fires in skyscrapers. Their sense of the possible, and the necessary, has been expanded, and abandoning a skyscraper to the fires raging inside it (and even delaying a little in engaging with them) is now a somewhat different decision than it perhaps once was.

I'm out of this thread now. Thanks, everyone. I may have something for a new thread in a few weeks.
 

benthamitemetric

Senior Member
...

My view remains that if they had believed that putting out the fires would have significantly reduced the probability of total progressive collapse (i.e., reduced the odds of the worst case scenario for the building) then they would have devoted more of their energies (with "greater urgency") to the task of getting water on them. I don't think they believed this, and, on my reading of the NIST report, they had no way of knowing this, so they let the fires burn, and left the building to its fate
Well, you are completely wrong and you have no basis to continue to insist that the firefighters did not understand the risk posed by the fires. I provided you with a direct statement from the man who made the decision to not fight the fires that clearly attests to the fact that he understood the ongoing fires were creating the risk of collapse. He thus clearly understood that the building could have potentially been saved if the fires were effectively fought. He simply chose not to fight those fires because he wasn't sure they could be effectively fought given the circumstances and, more importantly, he didn't want to risk further deaths to save an empty building and was dedicating as much of his scarce resources as he could to the search and rescue operations.
 
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Gamolon

Active Member
Please read my posts. The building was not designed for fire intitiaion on multiple floors or surviving such a fire without any firefighting efforts or sprinklers

Sorry YES those are agreed facts for purposes of THIS discussion - why raise them? They are irrelevant to the current discussion. The key point is that the fire was not fought in accordance with what the building was designed for. i.e. there was no active fire fighting supplemented by sprinklers.
Agree 100% with both of these above statements.


Edit: sorry, I keep changing my mind about this. I think it would have to be a known weakness if it is part the design envelope.
Per the above quote, Thomas B is saying that the above mentioned scenarios should have been accounted for during the design phase and the column 79 Achilles' Heel/weakness should have been corrected. He is also implying that the engineers missed it (whether deliberately missed or not, he didn't answer when I asked him previously). As you and I have been saying, the scenario that occurred on 9/11 was not within the design scope/parameters.
 

deirdre

Senior Member.
My view remains that if they had believed that putting out the fires would have significantly reduced the probability of total progressive collapse (i.e., reduced the odds of the worst case scenario for the building) then they would have devoted more of their energies (with "greater urgency") to the task of getting water on them.
My view is that you do not at all comprehend the situation in lower Manhattan that day.
 

Henkka

Banned
Banned

It's hard to say, since it was an Iranian building built in the 60s. So I have no idea how the building codes would compare... Or if any corners were cut during its construction. WTC 7, One Meridian and First Interstate were all modern, American skyscrapers. So I assume the codes were quite similar.

It becomes even more confusing if you argue that One Meridian was saved by the firefighting efforts, since obviously the fires in the Plasco building were being extensively fought when it suddenly collapsed, killing many firefighters. So will firefighting efforts save steel buildings from collapse, or not?
The key point is that the fire was not fought in accordance with what the building was designed for. i.e. there was no active fire fighting supplemented by sprinklers.

One Meridian also lacked sprinklers in the burning floors, though. So the key difference between One Meridian and WTC 7 is that the fires in One Meridian were fought by firefighters, whereas with WTC 7 the building was left to its own devices.

This is not straightforward either, however. As you can see from any video documenting the fire in One Meridian, the firefighting efforts were severely limited by the fact that they thought the building was too dangerous to enter. So they had to fight the fire from adjacent buildings:

meridianplaza_fire_3.jpeg
bc1c0f72e288ef108d3747ca48bc1291.jpeg

As you can see, the firefighters had a hard time reaching deep inside the building after the evacuation order. So in effect, the fires burned out of control until they were stopped on the 30th floor by sprinklers. According to the Wikipedia page, the fires continues until they literally started running out of fuel:

The fire's spread only stopped when it reached the 30th floor, which was the first fire-affected floor to have automatic sprinklers. Ten sprinklers extinguished the fire on the 30th floor and prevented continued spread. Contained by the sprinklers and running out of fuel, the fire was declared under control at 3:01 p.m.. The fire lasted over nineteen hours, destroyed eight floors, and killed three firefighters and injured twenty-four.
https://en.wikipedia.org/wiki/One_Meridian_Plaza

The evacuation order came at 7:30AM, with the fire declared under control at 3PM. So that would be seven and half hours of burning with the only firefighting efforts being from adjacent buildings. And before that, it burned through the night with some firefighting taking place inside.

As for this being "off-topic", it relates directly to one of your points on whether or not column 79 was "Achilles' heel". That being that WTC 7 was not designed to withstand 7 hours of fires without sprinklers or firefighting efforts. If it was built in accordance with the same (or similar) code as One Meridian, it's hard for me to see how that could possibly be the case.
 

Gamolon

Active Member
I'm absolutely and completely serious.

Like I say, I don't claim those statements support my views, only that they are consistent with them. I understand why you think they contradict me. But I don't read them that way. I think that's probably as far as we're going to get this time around.

My view remains that if they had believed that putting out the fires would have significantly reduced the probability of total progressive collapse (i.e., reduced the odds of the worst case scenario for the building) then they would have devoted more of their energies (with "greater urgency") to the task of getting water on them. I don't think they believed this, and, on my reading of the NIST report, they had no way of knowing this, so they let the fires burn, and left the building to its fate.

I have no expertise to judge the wisdom of this decision, neither in the moment or in hindsight. Those who do seem to agree that it was wise. I accept their judgment. But I'd be surprised if this experience hasn't changed how firefighters approach fires in skyscrapers. Their sense of the possible, and the necessary, has been expanded, and abandoning a skyscraper to the fires raging inside it (and even delaying a little in engaging with them) is now a somewhat different decision than it perhaps once was.

I'm out of this thread now. Thanks, everyone. I may have something for a new thread in a few weeks.
Tell you what Thomas B.

Why I didn't think of this before, I'll never know. I know a Lieutenant Fire Marshal. I'm actually going to see him this weekend. I will discuss your views with him and see what he says. I'll ask if 9/11 change the way firefighters approach fires in skyscrapers. If they worry about the possibility of total collapse. If they increased their "urgency" of fighting fires in skyscrapers based on what happened on 9/11 to avoid the potential of total collapse.

I'll keep you posted.
 

Miss VocalCord

Senior Member.
My view remains that if they had believed that putting out the fires would have significantly reduced the probability of total progressive collapse (i.e., reduced the odds of the worst case scenario for the building) then they would have devoted more of their energies (with "greater urgency") to the task of getting water on them. I don't think they believed this, and, on my reading of the NIST report, they had no way of knowing this, so they let the fires burn, and left the building to its fate.
Where did you get that idea from? To me it is quite obvious the reason to evacuate and not fire fight any fires is because of the loud noises the building was making; This together with the structural damage and the ongoing fires they had observed.

The building was empty, why would they risk any more life for an empty building; they already lost enough that day.
 

Miss VocalCord

Senior Member.
One Meridian also lacked sprinklers in the burning floors, though. So the key difference between One Meridian and WTC 7 is that the fires in One Meridian were fought by firefighters, whereas with WTC 7 the building was left to its own devices.
No the key difference between the Meridian and WTC7 is how the building was constructed. If two buildings are build according the same building code it doesn't mean they have to be constructed exactly the same. This is also discussed in the Q&A on WTC7

Why did WTC 7 collapse, while no other known building in history has collapsed due to fires alone?​


The collapse of WTC 7 is the first known instance of a tall building brought down primarily by uncontrolled fires. The fires in WTC 7 were similar to those that have occurred in several tall buildings where the automatic sprinklers did not function or were not present. These other buildings, including Philadelphia's One Meridian Plaza, a 38-story skyscraper that burned for 18 hours in 1991, did not collapse due to differences in the design of the structural system.

Factors contributing to WTC 7's collapse included: the thermal expansion of building elements such as floor beams and girders, which occurred at temperatures hundreds of degrees below those typically considered in current practice for fire-resistance ratings; significant magnification of thermal expansion effects due to the long-span floors in the building; connections between structural elements that were designed to resist the vertical forces of gravity, not the thermally induced horizontal or lateral loads; and an overall structural system not designed to prevent fire-induced progressive collapse.
https://www.nist.gov/pao/questions-and-answers-about-nist-wtc-7-investigation
 

Henkka

Banned
Banned
No the key difference between the Meridian and WTC7 is how the building was constructed. If two buildings are build according the same building code it doesn't mean they have to be constructed exactly the same. This is also discussed in the Q&A on WTC7

https://www.nist.gov/pao/questions-and-answers-about-nist-wtc-7-investigation

Yeah, I've seen that FAQ answer before. They don't go very deeply into specifics, though. If WTC 7 was built in a way that made it remarkably less capable of surviving fires than a much older skyscraper, I feel like someone should have been held liable for that.
 

deirdre

Senior Member.
Where did you get that idea from? To me it is quite obvious the reason to evacuate and not fire fight any fires is because of the loud noises the building was making; This together with the structural damage and the ongoing fires they had observed.
that happened in the afternoon though. Thomas seems to think early on they should have moved all the evacuees out of the way and the debris out of the way and asked 30-40 firefighters to slog through all the dust debris to somehow rig hoses and pumps and generators (that they took from other burning areas) to the Hudson River, in the hopes the pumps would be strong enough to get sufficient water pressure from the Hudson to WTC7.
 

Miss VocalCord

Senior Member.
Yeah, I've seen that FAQ answer before. They don't go very deeply into specifics, though. If WTC 7 was built in a way that made it remarkably less capable of surviving fires than a much older skyscraper, I feel like someone should have been held liable for that.
I think people would have been held liable if it wasn't build according the at the time valid building code/standards.
If you think it wasn't can you point to what rules they have broken with the construction of WTC7?
 

Gamolon

Active Member
Yeah, I've seen that FAQ answer before. They don't go very deeply into specifics, though. If WTC 7 was built in a way that made it remarkably less capable of surviving fires than a much older skyscraper, I feel like someone should have been held liable for that.
Bolding mine.

Back when WTC7 was designed, do you think the engineers who designed it analyzed fire scenarios where the sprinkler system would not function or if the firefighters would abandon fighting said fire?

What is your perception of how fire protection mechanics were applied to buildings when being designed back then? What is taken into consideration when they came up with a buildings fire protection mechanics?
 

Henkka

Banned
Banned
I think people would have been held liable if it wasn't build according the at the time valid building code/standards.
If you think it wasn't can you point to what rules they have broken with the construction of WTC7?

Well actually from a legal standpoint, yeah you are right. I doubt you could successfully sue anyone if it really was built to code.

But why would two buildings built according to the same (or similar) code behave so differently in an extremely bad fire? One collapsing totally after 7 hours of burning, other one not even partially collapsing after 19 hours.
 

Gamolon

Active Member
But why would two buildings built according to the same (or similar) code behave so differently in an extremely bad fire? One collapsing totally after 7 hours of burning, other one not even partially collapsing after 19 hours.
Different design/construction. You are assuming all buildings being built to the same code, will react to fire scenarios in the same fashion.

Also, WTC7 was subjected to a fire scenario OUTSIDE of the design codes/parameters.
 

econ41

Senior Member
My view is that you do not at all comprehend the situation in lower Manhattan that day.
Spot on!! One of the biggest emergency incidents seen in a dense urban setting. Two of the world's tallest buildings collapsed due to fire. A third large building was already evacuated and fully involved with fire. The correct decision which any competent emergency manager would have taken - pull back, create a safety zone and let it take its chances.

That is the exact same decision scenario that bush fire fighters make routinely when they decide which houses they can save and which they can't. Provided all the people have escaped let the buildings take their chance. Only the scale differed.

And - SOP for @Thomas B - after keeping the discussion going round in offtopic circles he departs the scene. For the 4th or 5th time? I've lost count.

I may give it one more try to see if anyone wants to discuss the actual thread topic which is:
"Was Column 79 the Achilles' Heel of WTC7?"

;)
 
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benthamitemetric

Senior Member
....

I think that you are aware that I do not accept NIST as a final or ultimate authority for reasons I have explained many times - I can repeat if there is interest. BUT I do not know if NIST "presented strong evidence that columns 79, 80 and 81 did form an Achilles Heel for the building" under the "as designed" range of fire scenarios. << That is the key point I have been trying to see discussion recognise. IF NIST did so identify that risk could you provide me with the reference you rely on so I can review it? BUT my focus is on the facts of the real event as relevant to the OP topic. Not whether or not NIST identified it. i.e. was C79 a weak link sufficient to trigger a collapse in an as-designed scenario THEN possibly to discuss the philosophy of regulating to minimise single item failure weaknesses as I said in my post?
....
I believe the key issue is complexity. When you introduce complexity into a building design, you increase the chance that broadly applicable design standards, which were developed from first principles to try to set some minimum safety envelope for a broad and diverse range of structures, no longer actually achieve that goal when applied to your building (i.e., the "fire rating" given by the code becomes meaningless in practice). This is because complexity introduces second order, third order, fourth order, and beyond effects that are very difficult to anticipate with very simple models, and most standard building codes rely only on very simple models by necessity .

With WTC7, I think it is most likely that designers and builders followed the building codes, but the problem was that the complexity they added to their design (in particular with the long span floors), which was not really factored into those building codes, left the building with a fatal flaw at column 79, even though it was nominally in spec.

Now, in reality, the fireworthiness of the building was only ever tested on a day when there were scores of confounding variables (damage to the building, fire started on multiple floors at the same time, sprinklers not working on all floors, no active fire fighting), so we can't easily evaluate how much design itself factored into the collapse. But the analyses done by NIST, ARUP, and Weidlinger all converges on the same conclusion: regular office fires could, at least in some circumstances, cause a complete collapse of the building. And, under the right circumstances (e.g., if fires started closer to the NE corner of the building), I think that such a collapse could have happened even more quickly than it actually did on 9/11, even with the confounding variables removed, though that is just an untested high level hypothesis after steeping in the engineering reports for years. That's why I view that corner of the building as an Achilles Heel, at least.

I should note that the idea that complexity confounds simple safety standards is not my own. Prof. Jose Torero, one of the preeminent experts on fire engineering in the world and one of the contributors to the Aegis Insurance Litigation expert reports, gave a great lecture on the subject many years back, which I happened to stumble upon when researching those reports. The lecture is still available here. In it, Dr. Torero spends some time talking about the WTC buildings, but then talks more broadly about how minor or even seemingly superficial additional design complexities can confound our ability to assess the safety of a structure in a real world fire. Definitely worth watching.

(Note to any lurking truthers: this video is a great example of how actual experts on the subject of high rise engineering and fires discuss this topic. Watch enough of this type of material and you will be better able to see myopic charlatans like Hulsey and Gage for what they are.)
 
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deirdre

Senior Member.
Two of the world's tallest buildings collapsed due to fire. A third large building was already evacuated and fully involved with fire. The correct decision which any competent emergency manager would have taken - pull back, create a safety zone and let it take its chances.
see i would describe that day as a nationwide terrorist attack that had already killed thousands including many brother firemen, with more fireman perhaps buried alive in the rubble. screaming, crying people covered in thick layers of dust, crushed firetrucks, fires everywhere, little to no water....etc. (basically just painting the picture of "they had bigger fish to fry" than worrying about some ugly old building once people were pulled away from it).
 

econ41

Senior Member
see i would describe that day as a nationwide terrorist attack that had already killed thousands including many brother firemen, with more fireman perhaps buried alive in the rubble. screaming, crying people covered in thick layers of dust, crushed firetrucks, fires everywhere, little to no water....etc. (basically just painting the picture of "they had bigger fish to fry" than worrying about some ugly old building once people were pulled away from it).
Yes - and I have no difficulty putting it in full context. And "bigger fish to fry" is the setting that any emergency manager has to be able to maintain. I'm probably the only member here who is an experienced emergency manager. My frustration with this thread is that the OP cannot even focus on the topic of his own OP and put that essentially technical question in the technical context of WTC7. And zero indication that he has any idea about the real-time practicalities of side issues like relay pumping of water from the Hudson.
 

econ41

Senior Member
I believe the key issue is complexity. When you introduce complexity into a building design, you increase the chance that broadly applicable design standards, which were developed from first principles to try to set some minimum safety envelope for a broad and diverse range of structures, no longer actually achieve that goal when applied to your building (i.e., the "fire rating" given by the code becomes meaningless in practice). This is because complexity introduces second order, third order, fourth order, and beyond effects that are very difficult to anticipate with very simple models, and most standard building codes rely only on very simple models by necessity .
Understood and agreed. We could discuss this further but I'm already convinced that we would agree on the underlying principles.
With WTC7, I think it is most likely that designers and builders followed the building codes, but the problem was that the complexity they added to their design (in particular with the long span floors), which was not really factored into those building codes, left the building with a fatal flaw at column 79, even though it was nominally in spec.
Understood. I've been there many times in a wide range of real world situations. I'll suggest a discussion of the WTC7<>Col 79 issue in my response to next paragraph.
Now, in reality, the fireworthiness of the building was only ever tested on a day when there were scores of confounding variables (damage to the building, fire started on multiple floors at the same time, sprinklers not working on all floors, no active fire fighting), so we can't easily evaluate how much design itself factored into the collapse. But the analyses done by NIST, ARUP, and Weidlinger all converges on the same conclusion: regular office fires could, at least in some circumstances, cause a complete collapse of the building. And, under the right circumstances, I think that such a collapse could have happened even more quickly than it actually did on 9/11, even with the confounding variables removed (e.g., if fires started closer to the NE corner of the building), though that is just an untested high level hypothesis after steeping in the engineering reports for years. That's why I view that corner of the building as an Achilles Heel, at least.
The scope of the topic - strategic scope at the level of evolving regulation and not limited to USA - Is where I wanted (over optimistically) to see the discussion move in this thread. Probably no more than two members recognise the need. Guess which two. ;)

Let me try yet another summary:
1) The status near enough quo for WTC7 - it met - letter of the law style - the code requirements of its day. It was pushing the limits for reasons you identify as "complexity".

2) It was foreshadowing the need for improved practices including evolutionary improvements to regulatory standards;

3) It was hit by a suite of circumstances more extreme than it was designed for.

My own belief is that the area for serious debate is in "2)" i.e. what evolutionary improvements should flow (proximately motivated by 9/11)

WTC7's design was not "wrong" for its day. It possibly fell short on the day. It wouldn't meet expectations today. And for it to meet expectations either today or tomorrow will require changes to rules and design practice.

I've several times hinted at or explicitly stated two areas where I see a need for change. And in the discussion in this thread, I was not prepared to risk identifying rules change whilst ever the discussion was circling, confused etc etc

Those two are: (a) Limiting - minimising exposure to single item failure vulnerability. AKA the WTC7 style of "Achilles' Heel" situation; AND (b) improving resistance to runaway progressive collapse as seen with WTC1 & WTC2. ( and I'm retired, not up to date with contemporary practice or emerging developments.) << THIS is an area for serious discussion but I doubt there is sufficient informed interest.
I should note that the idea that complexity confounds simple safety standards is not my own. Prof. Jose Torero, one of the preeminent experts on fire engineering in the world and one of the contributors to the Aegis Insurance Litigation expert reports, gave a great lecture on the subject many years back, which I happened to stumble upon many years when researching those reports. The lecture is still available here. In it, Dr. Torero spends some time talking about the WTC buildings, but then talks more broadly about how minor or even seemingly superficial additional design complexities can confound our ability to assess the safety of a structure in a real world fire. Definitely worth watching.
Thanks, I will follow that up as time permits.
(Note to any lurking truthers: this video is a great example of how actual experts on the subject of high rise engineering and fires discuss this topic. Watch enough of this type of material and you will be better able to see myopic charlatans like Hulsey and Gage for what they are.)
Agreed. Personally, I'm over 20 years out of contact and interactions at high levels both in the political and policy arenas and the technical regulatory fields. I've only seen the charlatans and have only interacted with the variable level of persons involved in these on-line discussions. It is about 8 years since I met any challenge in discussing the forensic engineering of WTC collapses. I'm "past my use by date" for contemporary knowledge and probably getting rusty. ;) :rolleyes:
 
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econ41

Senior Member
Thanks for the reference to this:
I should note that the idea that complexity confounds simple safety standards is not my own. Prof. Jose Torero, one of the preeminent experts on fire engineering in the world and one of the contributors to the Aegis Insurance Litigation expert reports, gave a great lecture on the subject many years back, which I happened to stumble upon when researching those reports. The lecture is still available here. In it, Dr. Torero spends some time talking about the WTC buildings, but then talks more broadly about how minor or even seemingly superficial additional design complexities can confound our ability to assess the safety of a structure in a real world fire. Definitely worth watching.
Definitely a man of like mind to a younger me. I think you are aware of some of my technical engineering history - essentially I came to WTC Twin Towers collapse debate in Nov 2007 with a personal challenge to explain the Towers collapses at a professional level. I studied it from an engineering and applied physics perspective. (And it doesn't need the fire science side to explain the collapses - in fact it has been a bit of a derail in some debates. It is lower-level detail - not the high-level strategic issues that Dr. Torero presents.)

And, online from Nov 2007, I had to work through the confusions of that early era when two sides were emerging and starting to polarise and both sides were down the same false trail in the collapse mechanisms. Whilst I recognised that the engineers and architects were acting like rival camps I had not looked at the impact because of the focus on understanding so that I could explain the operational level complexities of forensic physics.

Dr Torero lucidly explains the higher strategic level needs for what I would call a "paradigm shift" integrating all the professions and especially the disparity between the need for performance-based design and the old reliance on prescriptive regulation. It is both embarrassing and doubly ironic that I hadn't spotted the issue at that more a strategic level given my experience with paradigm shifts in other non-technical areas of management.

From now on I will need to be alert to the problems of prescriptive reliance on regulation among the other issues identified by Dr Torero. But I suspect that the issue will not help many in most of the discussions we see online.

Thanks again for bringing it to my attention.
 
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Thomas B

Active Member
Prof. Jose Torero, one of the preeminent experts on fire engineering in the world and one of the contributors to the Aegis Insurance Litigation expert reports, gave a great lecture on the subject many years back, which I happened to stumble upon when researching those reports. The lecture is still available here.
I just watched it and took some notes. Wow! I feel both enlightened and completely vindicated.

“In the past, no one would have ever thought that … the failure of a single connection could bring down a 47-story building. Today, we actually do believe that that might be possible. A very important technical lesson that we’ve learned through the World Trade Center.” (45:00)
Content from External Source
I've taken some notes, and I'll watch it again. I think this is worth a thread of its own and I'll leave my thoughts for then. But thank you, @benthamitemetric. Thank you very much. Great find!
 
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