Would the WTC Twin Towers have collapsed from fire alone, without plane impact?

Henkka

Active Member
even after it slipped past the initial columns that failed
How did they fail and "slip" in the first place... Here's my earlier interaction with econ41 on this question:

Me: But you need to get the columns disconnected and moving in the first place, so the missing can take place, no?
econ41: Yes, And, surprisingly, that is the key issue that few people have looked at or considered seriously.
Apparently, "few people" have even considered such a "key issue".

Maybe you can explain what you think happened to me... So when the plane impacted, sure, some core columns were cut or otherwise massively damaged. But I think it's fair to say that out of 47 core columns, the majority were still standing fine. The top block did not budge on impact, or start visibly sagging one way or another. Then you've got the jet fuel, but it burned off in a few minutes, which I sourced earlier with a quote from Sunder and from the NIST report. The jet fuel ignited office combustibles however, which were what was burning until the tower collapsed. But obviously, the office combustibles were in the office spaces, outside the core. I doubt there were much combustibles in the stairs and elevator shafts in the core. So while the air would certainly get very hot in the burning floors, the flames were not like pressed up against the core columns, especially the ones in the center. So how did they get hot enough to fail? Or are you still going to say they failed after losing lateral support from the floors, although FEMA observed the core failed first?
 

benthamitemetric

Senior Member
How did they fail and "slip" in the first place... Here's my earlier interaction with econ41 on this question:



Apparently, "few people" have even considered such a "key issue".

Maybe you can explain what you think happened to me... So when the plane impacted, sure, some core columns were cut or otherwise massively damaged. But I think it's fair to say that out of 47 core columns, the majority were still standing fine. The top block did not budge on impact, or start visibly sagging one way or another. Then you've got the jet fuel, but it burned off in a few minutes, which I sourced earlier with a quote from Sunder and from the NIST report. The jet fuel ignited office combustibles however, which were what was burning until the tower collapsed. But obviously, the office combustibles were in the office spaces, outside the core. I doubt there were much combustibles in the stairs and elevator shafts in the core. So while the air would certainly get very hot in the burning floors, the flames were not like pressed up against the core columns, especially the ones in the center. So how did they get hot enough to fail? Or are you still going to say they failed after losing lateral support from the floors, although FEMA observed the core failed first?
The columns got hot enough to fail because the planes blew gigantic holes into the core, stripped off much of their fire proofing, and started raging fires on multiple floors of the building all at once with a massive amount of additional heat generated by the jet fuel in a short period. All that heat jump started the heating process for the elements of the building, which the massive energy from the simultaneous burning of all of the office contents on multiple floors at once continued apace. The remaining columns were also already bearing more than their intended loads due to the impact reducing the ability of damaged columns to carry loads, so it didn't take as drastic a reduction in loads due to heat to cause them to fail as it would have been if the rest of the building had been pristine. You basically repeat this back as if it cannot explain the collapse, but NIST demonstrated very reasonably and in a very rigorous way that it would, which is very well documented and available for anyone, including you, to review.

Regarding the loss of lateral support, how many times do I have to explain to you that happened during the progression phase? How can you not understand that after it being told to you repeatedly? Two different phases. Initiation. Progression. Two different types of failure for the core columns. The core failed from a loss of lateral support in the progression phase, not the initiation phase. Holy smokes. Are you having a "Homer Thompson" moment here too?
 
Last edited:

Henkka

Active Member
The columns got hot enough to fail because the planes blew gigantic holes into the core, stripped off much of their fire proofing, and started raging fires on multiple floors of the building all at once with a massive amount of additional heat generated by the jet fuel in a short period. All that heat jump started the heating process for the elements of the building, which the massive energy from the simultaneous burning of all of the office contents on multiple floors at once continued apace. The remaining columns are also already bearing more than their intended loads due to the impact reducing the ability of damaged columns to carry loads, so it didn't take as drastic a reduction in loads due to heat to cause them to fail as it would have been if the rest of the building had been pristine. You basically repeat this back as if it cannot explain the collapse, but NIST demonstrated very reasonably and in a very rigorous way that it would, which is very well documented and available for anyone, including you, to review.
You're just peppering in big words like "gigantic holes", "raging fires", "massive amount of additional heat", "massive energy", in the hopes that if you describe it dramatically enough, that makes the story more convincing. Good grief. As I told you a few pages back, a massive steel column in the vicinity of a fire is not going to become as hot as the fire just like that. The fires will move around, they'll start going out in places where they've exhausted the combustibles, the steel will start to cool and so on... I'm sure you've seen the iconic image of a woman standing in the hole carved by the plane. If the core columns were cooking at that point, why wasn't she?
 

benthamitemetric

Senior Member
You're just peppering in big words like "gigantic holes", "raging fires", "massive amount of additional heat", "massive energy", in the hopes that if you describe it dramatically enough, that makes the story more convincing. Good grief. As I told you a few pages back, a massive steel column in the vicinity of a fire is not going to become as hot as the fire just like that. The fires will move around, they'll start going out in places where they've exhausted the combustibles, the steel will start to cool and so on...
NIST built a rigorous fire model based on multiple real world fire tests that gave a range of potential temperatures the core columns could reach. In that model, the columns failed under the prevailing conditions. Go check out it. You saying, without any analysis whatsoever, that, in your uninformed opinion the columns were too big to fail in that way isn't an argument.

I'm sure you've seen the iconic image of a woman standing in the hole carved by the plane. If the core columns were cooking at that point, why wasn't she?
"I can't understand how the food on my stove cooks when I can stand nearby and not similarly cook."
 
Last edited:

Henkka

Active Member
NIST built a rigorous fire model based on multiple real world fire tests that gave a range of potential temperatures the core columns could reach. In that model, the columns failed under the prevailing conditions. Go check out it. You saying, without any analysis whatsoever, that, in your uninformed opinion the columns were too big to fail in that way isn't an argument.

http://www.journalof911studies.com/volume/2007/NISTresponseToRequestForCorrectionGourleyEtal2.pdf

So the physical evidence they recovered at the site didn't support this idea of extremely high temperatures, but their computer model did. Really illuminating stuff. Reminds me of the WTC 7 investigation, where the entire thing was done in a computer.

"I can't understand how the food on my stove cooks when I can stand nearby and not similarly cook."
Hey genius, the core columns were also not on the "stove", which would be the burning office combustibles.
 

benthamitemetric

Senior Member

http://www.journalof911studies.com/volume/2007/NISTresponseToRequestForCorrectionGourleyEtal2.pdf

So the physical evidence they recovered at the site didn't support this idea of extremely high temperatures, but their computer model did. Really illuminating stuff. Reminds me of the WTC 7 investigation, where the entire thing was done in a computer.
The very small sample that they note was inconclusive was inconclusive. Whoopity-doo. That same sample showed no evidence of a controlled demolition. Are you ready to rule that out? And doing the investigation rigorously by computer via the application of known principles that are verified through extensive real world testing is better than just saying nonsense.

Hey genius, the core columns were also not on the "stove", which would be the burning office combustibles.
How far was she (both horizontally and vertically) from the point at which the collapse initiated? I'll wait.
 

econ41

Senior Member
@Henkka - one minor issue before I address your main points in a second post:

even after it slipped past the initial columns that failed
How did they fail and "slip" in the first place... Here's my earlier interaction with econ41 on this question:
Me: But you need to get the columns disconnected and moving in the first place, so the missing can take place, no?
econ41: Yes, And, surprisingly, that is the key issue that few people have looked at or considered seriously.
Apparently, "few people" have even considered such a "key issue".
And I offered to explain it in more detail for you - but it is an issue of 'Professional Group Dynamics' - of little relevance to the technical discussions of this thread. Just accept it as a fact that much of the early 8 years of WTC collapse discussion did not correctly understand some stages of the Twin Towers collapse mechanism. And that is one 'key issue' that was not - probably still has not been adequately - addressed.

Bottom line - there is little professional interest in the level of nit-pick detail that truthers like to indulge in. Both Twin Towers 'initiated' and, once started, global collapse was inevitable. Professionals understand that. Many lay persons probably don't. Dedicated Conspiracy Theorists don't want to.
 

econ41

Senior Member
Maybe you can explain what you think happened to me...
I can as I have offered many times on various aspects of Twin Towers collapses.
So when the plane impacted, sure, some core columns were cut or otherwise massively damaged. But I think it's fair to say that out of 47 core columns, the majority were still standing fine.
AGREED - both assertions.
The top block did not budge on impact, or start visibly sagging one way or another.
CORRECT.
Then you've got the jet fuel, but it burned off in a few minutes,
AFTER the plane had "Boeing Dozed" office contents and fit-out material into a concentrated fuel heap, that comprised the bulk of fuel that triggered the collapse initiation. The role of the jet fuel was as an accelerant >> as you correctly identify in a following sentence.
which I sourced earlier with a quote from Sunder and from the NIST report.
That fact is supported by visual evidence independent of whether or not NIST got it right. (I never rely on NIST when the evidence stands in its own right. Reasons not currently relevant.)
The jet fuel ignited office combustibles however, which were what was burning until the tower collapsed.
YES.
But obviously, the office combustibles were in the office spaces, outside the core. I doubt there were much combustibles in the stairs and elevator shafts in the core.
That could very well be true but it is not relevant. Once again you come up against the barrier resulting from not understanding the mechanism. The driving feature of the 'initiation' stage was a 'cascading failure of columns in axial compression driven by load redistribution' - a lot of words to describe a process where as one column failed its load moved to another column which then also overloaded and failed. The WTC scenario was very complicated but the principle can be explained using a simple model such as this one:

7colsA2-400-withfirenotated.jpg
Failure of A and B would apply far more load on to C that was previously carried by A and B. Possibly enough to start the failure of C. And columns further from the fire would probably fail without needing any heating. The exact figures are situation specific. But it should suffice for the current discussion if you understand the principles. Again - more explanation in a separate thread if you are interested.
So while the air would certainly get very hot in the burning floors, the flames were not like pressed up against the core columns,
CORRECT. And core columns may not have been heated sufficiently to cause failure from heat alone. It would be a complex mix of existing loads, re-distributed load from the initial impact, more redistributed loads imposed as fire leads to the 'cascading failure'. It is essential to understand the principles. We will never know the specific details.
especially the ones in the center. So how did they get hot enough to fail?
Read my previous comment. The core columns did not, necessarily, have to get hot enough to fail from heat alone. It is way off-topic here - so, once again, if you want detailed discussion, OP a thread.
Or are you still going to say they failed after losing lateral support from the floors,
Not so - and you have once again switched, confused and probably conflated stages. Heat weakening was relevant to the 'initiation' stage only. 'losing lateral support from the floors' was an issue for the 'progression' stage and there was no heating needed in the 'progression' stage'.
although FEMA observed the core failed first?
Yes. A contentious issue again not relevant to the current topic once you get the scenario correct.
 
Last edited:

econ41

Senior Member
So the physical evidence they recovered at the site didn't support this idea of extremely high temperatures, but their computer model did.
Yes. I also reject that logic. Sadly it sets up a 'false dichotomy' that has led to many 'both sides got it wrong' scenarios in these debates over many years. Computer simulation is, at best, supporting evidence. The key thing needed before you attempt to use computer data is to understand the mechanisms. (Yes - it is my hobby horse because so many discussions derail from not understanding the mechanism)

Here are the key issues for this matter - and again they are not often recognised:
1) Not all columns need heating;
PROVIDED
2) A sufficient small group of columns is heated - 'sufficient' to form a trigger. (Theoretically, that could be one column BUT not in the WTC scenario).
3) Sufficient additional columns are heated enough to continue the cascading failure. (And they may not need heating to the temperature where heat alone would cause failure - remember we have loads redistributing.)

And the overall picture is 4D complicated (3D plus TWO lots of time factors -viz load redistribution dynamics in combination with fire movement dynamics.)

It should be no surprise that most people need simplifying assumptions.
Really illuminating stuff. Reminds me of the WTC 7 investigation, where the entire thing was done in a computer.
Partial truth - the simulation was by computer. The failure of Col 79 was obvious from the video record. The possible cause of Col 79 failure can be identified from basic principles. (a) Application of gross overload >> no evidence for the needed logistic effort of importing and placing the extra load. (b) CD of Col 79 - to-one has ever proved it and there was no 'big banging noise'. OR (c) something removed horizontal bracing resulting in failure due to excessive critical length. None of that depends on computer simulation..
Hey genius, the core columns were also not on the "stove", which would be the burning office combustibles.
Mmmm.. I'll leave you to battle analogies.
 
Last edited:

Abdullah

Active Member
If the core columns were cooking at that point, why wasn't she?
Because Mrs. Cintron was nowhere near the core.

So while the air would certainly get very hot in the burning floors, the flames were not like pressed up against the core columns, especially the ones in the center.

The ones in the center were the least important ones. The outermost ring carried about ⅔ of the total load.
Screenshot_2022-08-01-08-26-37-133_com.microsoft.office.word.jpg
 

econ41

Senior Member
I think we should boycott all discussion of things related to collapse progression in this thread.

I am going to start responding to @Henkka in the relevant thread https://www.metabunk.org/threads/how-high-could-the-plane-have-hit-and-still-caused-a-total-collapse.12423/page-6#post-2
That is a good idea - let's have a bit of thread "on-topic" discipline.

Recalling that the OP question was:

"Would the WTC Twin Towers have collapsed from fire alone, without plane impact?"​

..and that is specific to both WTC and to the initiation stage. NOT "progression" and certainly NOT other towers which were CDed.

In fact, most of the off-topic meanderings have been false analogies and references to other buildings which have no demonstrated relevance to WTC. So boycotting irrelevant analogies and references to other buildings would probably assist focus more than simply ceasing discussion of WTC "progression".

Maybe those persons who want to discuss other topics could OP a thread and state a claim which is suitable for discussion or explanation???
 

benthamitemetric

Senior Member
That is a good idea - let's have a bit of thread "on-topic" discipline.
I plead guilty and await my sentencing to metabunk jail. It felt like we blew right past the question of whether fires alone could bring the building down, likely because the answer was an obvious and unexciting "theoretically yes, but practically not likely." When Henkaa and Thomas B then retreated down "but would a total collapse then ensue?" hole, I gave chase. Hard to let lies and nonsense lay dormant on this forum and the moderators are (rightly) not very focused on cleaning up these never ending 9-11 threads, given that there are actually timelier topics to address. In my defense, whether the global collapse would ensue is a question raised in the context of a fire-only induced collapse, but of course in the context of this thread it amounts to rehashing the obvious (yet again) as it would just follow the same principles as in the witnessed collapse, which is something every should now understand (though some won't).
 

econ41

Senior Member
I plead guilty and await my sentencing to metabunk jail.
mea culpa aussi Aussie. We could share a cell?
It felt like we blew right past the question of whether fires alone could bring the building down, likely because the answer was an obvious and unexciting "theoretically yes, but practically not likely."
Because it is 99.9% certain that no one could manage the logistics of starting the same scale and location of fire that resulted on 9/11. And "not getting caught" makes it 99.999...% But one aspect of my pedantry - I prefer to stay with the protocols of the scientific method. And "impossible" isn't in that dictionary.
When Henkaa and Thomas B then retreated down "but would a total collapse then ensue?" hole, I gave chase.
So did I but my SOP is different. (We have contributions from 3 or 4 serious debunkers who have differing but complementary styles.) And I lost count of how many times I offered a "Strategic Outline" of the relevant explanation and suggested discussion in another thread.
Hard to let lies and nonsense lay dormant on this forum and the moderators are (rightly) not very focused on cleaning up these never ending 9-11 threads, given that there are actually timelier topics to address.
That is how I read it - tho Landru has dropped a couple of hints and on both occasions IIRC I offered to take the discussion in another thread. Nobody seems to want to take me up on those offers; :(
In my defense, whether the global collapse would ensue is a question raised in the context of a fire-only induced collapse,
It is the real world big issue of strategy. The topic which Torero identifies but in limited scope which led a couple of our members astray. Maybe I should OP the topic "Was the fire design of WTC good enough?" My professional opinion is "It was as good as we could expect". (And "It is an evolutionary game where the whole profession is learning as we push the boundaries!") But it is hard to get members past the barrier that the 9/11 fires were orders of magnitude outside the design envelop. And the presumption that the designs were faulty. The towers were never tested against the design scenarios. And never can be.
but of course in the context of this thread it amounts to rehashing the obvious (yet again) as it would just follow the same principles as in the witnessed collapse, which is something every should now understand (though some won't).
There is still a lot of confusion. The two main stages seem to be accepted - at least by four (??) of us here. But a lot of the truther arguments touch on issues of the other two stages. Which are not yet even recognised in general discussion. And, specific for Twin Towers, the reality that initiation started the bypassing of column ends missing column ends. Then "transition" guaranteed it continues. THEREFORE >> progression. But there is still a lot of 'Bazantophile' rejection of how ROOSD started because the explanation falsifies Bazant and Verdure's "crush down/crush up" hypothesis... and most debunkers are not interested in explanations being more exact than is needed to once again tell the truthers they are wrong. (Except for a lone pedant :rolleyes: ;) )

And, sadly from my perspective, @Henkka has had a few insights that have been lost in the"glossing over the details".
 
Last edited:

Henkka

Active Member
Because Mrs. Cintron was nowhere near the core.
Were the fires in the core, though? As I've said, I don't think there were many combustibles in the core... They were in the office space. So I could understand the combustibles nearest to the core heating up the outermost core columns as they burned, but combustibles that were further away would be limited in their ability to heat the core columns. Also, none of this could be happening evenly... The combustibles probably weren't evenly placed, the fires moved around, and the fire proofing would be unevenly dislodged. I think I've posted this video before, but it's a good one:

Source: https://www.youtube.com/watch?v=Y-buceElLVY

No-click: Video on the Cardington fire test, demonstrating what generally happens to steel buildings in fires.

Now in this test, it's more of a traditional steel building where the vertical columns were in the office space, and thus directly exposed to the flames. So they were in the "stove" if we use the earlier analogy. And "there was no chance of a sudden collapse". But there's differences too of course, like that they still had intact fire proofing.

I guess my issue is that in my mind, the damage being done to the building by the fires must have been:

1) Gradual

and

2) Asymmetrical

But then when we see the collapse, it is strikingly immediate and symmetrical. We can confirm this impression by looking at David Chandler's measurement of the fall:



One moment the building is holding just fine, it's not even leaning some way or gradually sagging, but in the blink of an eye it lets go and goes into 64% of g downward acceleration. And as you can see from the end of the Cardington video, all three visible corners start moving simultaneously. So what happened in that fraction of a second where the building let go? Also, would the collapse look any different in your opinion if there were demolition charges cutting the core at this moment? Or are we to believe the fires just coincidentally caused a collapse that is indistinguishable from a demolition?
 

econ41

Senior Member
I guess my issue is that in my mind, the damage being done to the building by the fires must have been:

1) Gradual
We know it was.
and

2) Asymmetrical
Also known fact. The effect was also asymmetric - easiest seen on WTC2 with the greater 'tilt' of the Top Block. But WTC 1 also tilted.
But then when we see the collapse, it is strikingly immediate and symmetrical. We can confirm this impression by looking at David Chandler's measurement of the fall:
Remember that Chandler is limited by two aspects - (1) he, like T Szamboti, was still thinking "Top Block dropping to impact" AND he does not distinguish the stages of collapse.
One moment the building is holding just fine, it's not even leaning some way or gradually sagging, but in the blink of an eye it lets go and goes into 64% of g downward acceleration.
Yes it was fast but overall part of the 'cascading failure of columns' which was the observed driving process. The "blink of an eye" the result of a process that went exponential. And was very fast in that final second or so.
And as you can see from the end of the Cardington video, all three visible corners start moving simultaneously. So what happened in that fraction of a second where the building let go?
Cardington wont help explain WTC. You know my advice - understand what happened at WTC and don't be distracted by flawed analogies. HINT: How does a single column fail in compressive overload with heat weakening? Here is a clue (It is NOT Twin Towers for reasons which should be obvious:
buckle300A.jpg
That is one way of a mostly heat drivwen failure. If heat had been less and load more the failure more likely by bending/buckling over a greater length.
Also, would the collapse look any different in your opinion if there were demolition charges cutting the core at this moment? Or are we to believe the fires just coincidentally caused a collapse that is indistinguishable from a demolition?
Unless the demolition charges mimicked the actual initiation stages. Including perimeter column inwards bowing -- of course the demoliton by explosives would look different.
 
Last edited:

Mendel

Senior Member.
They got their lateral bracing at each floor (every 12' or so) from the spandrel plates and, ultimately, the corner connections to the perpendicular facade.
"lateral" still means 2 dimensions, only 1 if which the spandrel plates really provide for
the corners are strong because the corner angle provides the missing dimension, but it gets worse the further away from the corner you go (consider leverage)

it would have helped your quest for "load path diagrams" if you had played some bridge building games since I suggested it to you over a year ago
It would be great (and entirely on topic) if you could quantify this for us
search for "MW" (megawatts) in NIST NCSTAR 1-5 to get power, multiply with time
So do you think the collapse of a building can be considered "controlled" only if it lands 100% in its own footprint? 90% won't do?
you asked why demolitions are controlled collapses
controlling doesn't always achieve its purpose (cf. "controlled flight into terrain")
but that doesn't make it uncontrolled
the purpose of controlling a demolition is to fulfil a civil liability to comply with a contract while not causing damage or injury not contracted to be caused
I could grant you all that for the sake of the argument, but I still think you're describing an entirely different event than what we saw happen. To me, it sounds like you're describing the floors being sort of stripped off of the core. You've implied that after the core columns lost lateral support of the floors, they would fail also, but I don't think you cited anything to back that up.
remember these pictures of core remnants standing that @Gamolon and I showed you? yes? why are you asking for backup, then?
The core columns were laterally braced between themselves. So chronologically, you seem to be saying the floors failed first, and then the core. But according to FEMA, this did not happen, and the collapse began in the core:
I explained this to you weeks ago:
1. The weight was held by columns.
2. Some columns were damaged/destroyed by the impact.
3. Some columns and trusses were weakened from heat.
4. NIST showed that this reduced the load capacity of the structure so much that it failed.
5. The structure became unable to support the top block, because of 4.
6. The top block fell on a floor below, increasing its load.
7. The floor became overloaded, detached from the columns, and fell.
8. The debris fell onto the floor below that.
9. The floor became overloaded, detached from the columns, and fell.
10. The debris fell onto the floor below that.
11. The floor became overloaded, detached from the columns, and fell.
12. The debris fell onto the floor below that.
13. The floor became overloaded, detached from the columns, and fell.
14. The debris fell onto the floor below that.
15. Repeat all the way to the bottom.

This left the facade and much of the core standing, but unbraced, and the pertubations of the debris avalanche caused those columns to fall as well in short order.

tl;dr the impact & the fires destabilised the top block, the weight of the top block then overloaded the floors in turn.
Note that "the core" is involved in steps 2 and 3, and then again after step 15.
Do not conflate the initiation and the late progression.

but NIST demonstrated very reasonably and in a very rigorous way that it would, which is very well documented and available for anyone, including you, to review.
as did Arup, and I think others?
But then when we see the collapse, it is strikingly immediate and symmetrical.
the top block tilted in a quite asymmetrical fashion (we have been over this)
Article:
Maps of dust and debris show asymmetric distribution of materials.


P.S. the uncertainty regarding your motives could be reduced if you did not avoid the questions aimed at them; I've asked several times about your aims, what you think a good discussion is, and how the discussions here meet or fail your goals; I don't remember seeing an answer.
 
Last edited:

Mendel

Senior Member.
HINT: How does a single column fail in compressive overload with heat weakening? Here is a clue (It is NOT Twin Towers for reasons which should be obvious:
buckle300A.jpg
That is one way of a mostly heat driven failure. If heat had been less and load more the failure more likely by bending/buckling over a greater length.
sweet example of damage explosives could never do!
 

Henkka

Active Member
Cardington wont help explain WTC. You know my advice - understand what happened at WTC and don't be distracted by flawed analogies. HINT: How does a single column fail in compressive overload with heat weakening? Here is a clue (It is NOT Twin Towers for reasons whiuchshould be obvious:
buckle300A.jpg
That is one way of a mostly heat drivwen failure. If heat had been less and load more the failure more likely by bending/buckling over a greater length.
That's an interesting image, but I'm not sure it helps my understanding... That column is messed up, but it's still there. The top also hasn't become totally detached from the bottom, which would required for the columns to "miss". So I can totally imagine some columns in the core slowly bending, sagging, buckling etc, as they are gradually heated up by the fire. But I can't imagine a scenario where they are seemingly holding just fine one moment, and then totally let go the next.

By the way, this is kind of secondary, but part of what frustrates and mystifies me so much about the WTC collapses is that to even get some detailed discussion of what might've happened to the core, I have to come on obscure (no offense) internet forums like Metabunk in the first place. Wikipedia tells me the Bazant story, which seems inaccurate. The NIST FAQ barely mentions the core (And they admit they didn't investigate what happened after initiation). And if I look up this topic on Youtube, the algorithm really, really wants me to watch videos like this one:
Source: https://www.youtube.com/watch?v=4LFZA0Rx1gg

The core columns are briefly mentioned in the beginning of the video, but never again. As with NIST, the focus seems squarely on the floor trusses and perimeter columns. They do a ridiculous demonstration of a blowtorch being directly applied to a steel beam, as if anything like that was going on in the towers. At 7 minutes in, the guy shows a drawing of the WTC structure, but he neglected to draw the core columns in the middle (Although he has a second drawing with the core, but makes no comment about it). He then compares the WTC towers to soda cans, neglecting to mention they were not by any means hollow, but had vertical support in the middle. Then when they illustrate the collapse with motion graphics, it again only shows the floors "pancaking", as if we're still in 2002. It's incredibly frustrating. But never fear, Youtube will also serve you up videos such as "This Computer Simulation How The Twin Towers Fell" (It's a spreadsheet), and "How Aluminum May Have Collapsed The Twin Towers"... (???)
 

Mendel

Senior Member.

econ41

Senior Member
That's an interesting image, but I'm not sure it helps my understanding... That column is messed up, but it's still there.
Do try thinking it through. Yes that example stopped at that partial failure point. How else would we get a photo? That single column is buckling because it is getting shorter. IF it had kept getting shorter where would those two "knees" have gone?

Take it one step at a time.
 

Henkka

Active Member
this may be because people don't frequently ask about it,
and also because it is covered extensively in NCSTAR 1-6. From the index:
Article:
SmartSelect_20220801-092612_Samsung Notes.jpg


I wish you guys would spend a fraction of the time you write here on studying the sources.
I'm sure you'd find any support you'd need here to help you work past any obstacles that arise.
Okay, can you quote the part you think is most illuminating rather than just pointing me to a 470-page PDF? I checked out page 335 which is supposedly summarising the findings of the study, but it barely says anything at all. I think if they had a very solid and understandable explanation of what happened to the core, they would have just included that in the FAQ.
 

Mendel

Senior Member.
Okay, can you quote the part you think is most illuminating rather than just pointing me to a 470-page PDF? I checked out page 335 which is supposedly summarising the findings of the study, but it barely says anything at all. I think if they had a very solid and understandable explanation of what happened to the core, they would have just included that in the FAQ.
Summaries tend to brief. It's also worthwhile to read the rest of it, not just the one page.

Search for "core" in the PDF document, you will find the other places in the index (at the front of the document) that show you the relevant sections.

They didn't need to include it in the FAQ because it is already included in the report. The FAQ mostly addresses concerns that the report did not.
 

econ41

Senior Member
Okay, can you quote the part you think is most illuminating rather than just pointing me to a 470-page PDF? I checked out page 335 which is supposedly summarising the findings of the study, but it barely says anything at all. I think if they had a very solid and understandable explanation of what happened to the core, they would have just included that in the FAQ.
The NIST Reports are not suitable for relative novice learners. You are better served by discussing with someone who is a competent trainer, understands the engineering and is prepared to explain each aspect step by step in the language you can understand. That means you have to be willing to say "I don't understand that - can you explain in (more detail) (simpler language)"

"Arguing" is a poor setting for learning. Learning is best served by a teaching context.
 

Henkka

Active Member
The NIST Reports are not suitable for relative novice learners.
I agree... It doesn't make a whole lot of sense to me that if a layperson wants to understand something pretty fundamental about the WTC collapses, their only avenue to do so is reading the entire technical report, which will mostly go over my head anyway. You would think the entire purpose of the FAQ existing would be to explain it in layman's terms, but you just get this:

11. What caused the collapses of WTC 1 and WTC 2?
Based on its comprehensive investigation, NIST concluded that the WTC towers collapsed because:

  1. The impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; and
  2. The subsequent unusually large number of jet-fuel ignited multi-floor fires (which reached temperatures as high as 1,000 degrees Celsius, or 1,800 degrees Fahrenheit) significantly weakened the floors and columns with dislodged fireproofing to the point where floors sagged and pulled inward on the perimeter columns. This led to the inward bowing of the perimeter columns and failure of the south face of WTC 1 and the east face of WTC 2, initiating the collapse of each of the towers.
Both photographic and video evidence—as well as accounts from the New York City Police Department aviation unit during a half-hour period prior to collapse—support this sequence for each tower.
I would also think that searching on Youtube about such an important historical event would bring up many videos, from universities for example, that exhaustively explain the collapses in layman's terms. But instead, such a search brings up very few videos, and they are anything but exhaustive... My favourite is probably the one from the Smithsonian with nearly 5 million views, positing the theory that molten aluminum coming into contact with sprinkler water made the towers explode!
 

Thomas B

Active Member
"lateral" still means 2 dimensions, only 1 if which the spandrel plates really provide for
the corners are strong because the corner angle provides the missing dimension, but it gets worse the further away from the corner you go (consider leverage)
Or consider "shear lag":

Screenshot 2022-08-01 at 11.41.06.png
Source: Ali & Moon (2007). Structural Developments in Tall Buildings: Current Trends and Future Prospects, Architectural Science Review, 50(3).
https://www.researchgate.net/public...Buildings_Current_Trends_and_Future_Prospects

Anyway ... I have come to the reluctant conclusion that the expertise here is more apparent than real. Sorry. I think the consensus on this forum about how the outer shells of the WTC towers (to name just one component) worked is simply wrong. Here's how they are described by Feng Fu in Advanced Modelling Techniques in Structural Design (Wiley, 2015).

Screenshot 2022-08-01 at 11.35.25.png
Screenshot 2022-08-01 at 11.35.58.png
pp. 30-31

Ali and Moon (2007) is the same paper I quoted the shear lag passage from. This is what they say about perimeter tubes. (They go on to mention WTC as a specific example.)

Screenshot 2022-08-01 at 11.38.51.png
Source: Ali & Moon (2007). Structural Developments in Tall Buildings: Current Trends and Future Prospects, Architectural Science Review, 50(3).
https://www.researchgate.net/public...Buildings_Current_Trends_and_Future_Prospects

At this point there is no doubt in my mind that the perimeter shells could stand on their own in a hurricane (and an earthquake) even when hollow. They'd be like a giant empty box (or a cup). All experts who write and talk about this say the same thing. To imagine the perimeter shells crumpling under their own weight (or in a light breeze) if you remove the floors is to imagine a much, much weaker structure than they really were. It's no wonder you think it is a no-brainer how they completely collapsed from fire.

Unfortunately, only a building that had been pre-weakened for demolition would be as susceptible to collapse as you think the WTC was. Since that (i.e., the conspiracy to both execute a demolition and cover it up) is absurd, it's back to the drawing board for me to understand how the buildings really collapsed.

CC: @Mick West , @benthamitemetric , @econ41 , @Jeffrey Orling , @Abdullah, @Gamolon , @Oystein
 

Attachments

  • Screenshot 2022-08-01 at 11.35.58.png
    Screenshot 2022-08-01 at 11.35.58.png
    94.4 KB · Views: 27
Last edited:

benthamitemetric

Senior Member
....

At this point there is no doubt in my mind that the perimeter shells could stand on their own in a hurricane (and an earthquake) even when hollow. They'd be like a giant empty box (or a cup). All experts who write and talk about this say the same thing. To imagine the perimeter shells crumpling under their own weight (or in a light breeze) if you remove the floors is to imagine a much, much weaker structure than they really were. It's no wonder you think it is a no-brainer how they completely collapsed from fire.

Unfortunately, only a building that had been pre-weakened for demolition would be as susceptible to collapse as you think the WTC was. Since that (i.e., the conspiracy to both execute a demolition and cover it up) is absurd, it's back to the drawing board for me to understand how the buildings really collapsed.
Wow, I wonder how you plan to go back to pretending to not be a truther after this. Doesn't it feel silly that you spent two entire years here dishonestly representing yourself and your point of view now? Henkka and must other truthers didn't feel the need to do that.

Anyway, all of this can be dismissed because it does not follow from general statements that perimeter assemblies are generally designed to withstand known and expected forces that WTC towers' perimeter frameworks as actually designed and built were capable of withstanding any particular set of forces, whether anticipated (as from wind loads or earthquakes) or unanticipated and extreme, such the various impacts they suffered on 9/11. It further does not follow that the WTC perimeter would be capable of withstanding any such loads when disconnected from the rest of the building. You are so far off the mark that it's almost besides the point to note that no one here has even proposed that the perimeter columns buckled from windloads or self-buckling after the collapse of the floors. Rather, we can all see quite clearly that the the debris from the top block damaged them severely and pushed them out in sections as their connections to the floors were stripped away. The self-bucking that was witnessed was the core, not the perimeter.

That said if you could snap your fingers and remove the internal portion of the towers without damaging the perimeters, I think, based off the extensive documented difficulty the engineers faced in bracing the buildings for windloads, that the perimeters would almost certainly buckle and fail, if not just by themselves then in foreseeable windloads. But no one tested this because the building was designed as an interdependent system for a particular purpose given particular cost constraints, not as a cartoon.
 
Last edited:

Abdullah

Active Member
[
At this point there is no doubt in my mind that the perimeter shells could stand on their own in a hurricane (and an earthquake) even when hollow. They'd be like a giant empty box (or a cup). All experts who write and talk about this say the same thing.
No they don't. They just give (over)simplified analogies which you have taken out of context.
 

Gamolon

Active Member
At this point there is no doubt in my mind that the perimeter shells could stand on their own in a hurricane (and an earthquake) even when hollow. They'd be like a giant empty box (or a cup). All experts who write and talk about this say the same thing.
They "say"?!

This coming from the person who demands calculations to understand things?! Why do you demand calculations when someone explains to you how the buildings collapse due to plane impacts and/or fire, but when it comes to someone speaking against fire and/or plane impacts. you take them at your word?

I think we all know why at this point...
 

Mendel

Senior Member.
It doesn't make a whole lot of sense to me that if a layperson wants to understand something pretty fundamental about the WTC collapses, their only avenue to do so is reading the entire technical report, which will mostly go over my head anyway.
Yes, but you are asking for details that go over your head, and for these you will need to work through the report, instead of accusing NIST that they don't gave a firm grasp of them.

You can't get to knowledge by shortcut. There is no "quantum mechanics for people who skipped physics", and if there were, it would either not be very detailed, of would require you to learn much of the physics you skipped.

The NIST report contains this knowledge at different levels of detail. You already found the summary. There's also an executive summary at page xxxvii of NCSTAR 1-6.

To demand an education without putting the legwork of studying in is an unfulfillable demand.
 
Last edited:

Gamolon

Active Member
It's closer than you think. I'll try to find Starossek's textbook where tube-in-tube design is described basically like this.
Currently reading this PDF from Nikolay Lalkovski and Uwe Starossek:

The Total Collapse of the Twin Towers: What It Would Have Taken to Prevent It Once Collapse Was Initiated

https://tore.tuhh.de/bitstream/11420/11260/1/(ASCE)ST.1943-541X.0003244.pdf

Abstract: It is generally taken as a given that there is no reasonable design concept that could have prevented the collapse of the Twin Towers, once it was initiated, from progressing all the way down to the ground. This view is rooted in the idea that the force generated during the inevitable impact between what may be called the intact upper section (IUS) and the intact lower section (ILS)—meaning the building sections above and below the initially lost columns, respectively—will exceed by at least one order of magnitude the capacity of the latter. On closer inspection, this turns out to be only partially correct—it is correct with regard to the topmost floor plate of the ILS but not with regard to the columns below this floor plate. This paper shows that if the ILS in the Twin Towers had been topped by a stronger-than-ordinary floor plate allowing the columns below to respond properly, rather than be bypassed, these columns—and with them the ILS—would likely have survived. The paper subsequently proposes a building design concept consisting in the insertion of strengthened floor plates in intervals of 10–20 stories. DOI: 10.1061/(ASCE)ST.1943-541X.0003244. This work is made available under the terms of the Creative Commons Attribution 4.0 International license, https://creativecommons.org/licenses/by/4.0/.
 

Mendel

Senior Member.
My favourite is probably the one from the Smithsonian with nearly 5 million views, positing the theory that molten aluminum coming into contact with sprinkler water made the towers explode!
By Christian Simensen:
Article:
A theory for the collapse of the World Trade Center
June 2014 Engineering Failure Analysis 41:39–47
DOI:10.1016/j.engfailanal.2013.07.032

Two airplanes of type Boeing 767 flew into the Twin Towers in the morning of September 11th 2001. The crashes caused fuel to ignite, and the airplanes to be cut to pieces and be buried under building fragments. They were subsequently heated to a high temperature. 30 tonnes of aluminium alloys in the airplanes were melted at 660 °C while the surrounding building was only heated to a much lower temperature due to insulation effects. When the temperature reached 750–800 °C, the huge amount of aluminium melt managed to stream down to the lower floors. There it came in contact with water from the automatic sprinkler devices and possibly other sources. This encounter resulted in a series of fierce explosions due to the generation of hydrogen gas and local heating to high temperatures well above 1200 °C. A complete floor of the buildings was blown apart, and the upper part fell onto the bottom part leading to a complete collapse.

Metabunk thread at https://www.metabunk.org/threads/al...s-theory-of-collapse-christian-simensen.3161/
 

Mendel

Senior Member.
Or consider "shear lag":
Yes. So why don't you?

Feng Fu, in Design and Analysis of Tall and Complex Structures, 2018
Article:
However, due to the flexibility of spandrel girders and columns, there is a shear lag effect, with a hyperbolic-type stress distribution in the plan cross section. Therefore, when the exterior framed tube is subjected to wind loading, columns situated near the corners of the tube experience the greatest axial forces and it spreads nonlinearly for the web frame and flange frame of the plan, whereas the middle columns experience a reduction in the axial load and hence stiffness. The stresses in the inner columns lag behind due to the bending of the spandrel beams.

The shear lag effect greatly reduces the effectiveness of the framed tube.

The more flexible the tube is, the more shear lag you'll have. Once the bracing goes away, shear lag stresses rise, overloading the structure.

(Not gonna happen in your round tube.)
 

Gamolon

Active Member
A quick update on this. One way to try to understand what @benthamitemetric calls @Henkka's and my (and truthers') "incredulity" is to imagine this two-foot thick, 64-foot wide pipe, surrounded by another one, one-foot thick and, say, 200 feet wide. Imagine them bolted directly to bedrock and standing 1000 feet high and then put in 100 evenly spaced round floors on trusses connecting the outer pipe to the inner pipe.

[Edit: feel free to have the thickness of the pipe tapering appropriately as you go up if you think that's better.]

Now, imagine it going through ROOSD. Of course, that structure isn't exactly like the WTC (and it is in many ways impossible to build), but the WTC (as I imagine it) was at least as strong.
Reread your last sentence and explain to me how this imaginary structure, which you claim is impossible to build, is similar to the WTC structure?
 
Last edited:

Mendel

Senior Member.
Currently reading this PDF from Nikolay Lalkovski and Uwe Starossek:

The Total Collapse of the Twin Towers: What It Would Have Taken to Prevent It Once Collapse Was Initiated
Paraphrased: if you can find a safe way to transfer the overload on the floors onto the vertical columns, your design may be safe against progressive total collapse.

I wonder how they plan to accomplish this without diagonal trusses through that office space.

Edit: the design devotes a whole storey to each "strong floor".
 
Last edited:

Thomas B

Active Member
Yes. So why don't you?

Feng Fu, in Design and Analysis of Tall and Complex Structures, 2018
Article:
However, due to the flexibility of spandrel girders and columns, there is a shear lag effect, with a hyperbolic-type stress distribution in the plan cross section. Therefore, when the exterior framed tube is subjected to wind loading, columns situated near the corners of the tube experience the greatest axial forces and it spreads nonlinearly for the web frame and flange frame of the plan, whereas the middle columns experience a reduction in the axial load and hence stiffness. The stresses in the inner columns lag behind due to the bending of the spandrel beams.

The shear lag effect greatly reduces the effectiveness of the framed tube.

The more flexible the tube is, the more shear lag you'll have. Once the bracing goes away, shear lag stresses rise, overloading the structure.

(Not gonna happen in your round tube.)
(Not your fault, but this disappearing images problem is a real pain.)

You're quoting the same book I was quoting, to the same effect. I'm not sure what you're taking issue with. Square tube frames are carefully designed to manage the shear lag, something Nordenson praised Robertson for doing with carefully selected grades of steel in the case of the WTC.

The point I was making is that shear lag initially causes the opposite problem that you seemed to be getting at with "leverage", so that the middle of the faces see much less action from wind than the corners, not more, but once dealt with you end with a close approximation of the strength of solid round tube.

I don't think we need to discuss it any longer. We simply don't respect each other's basic knowledge of the subject enough to let the other convince us we're misunderstanding a textbook. I'm going to have to go an struggle with this elsewhere.

I could be wrong. But I'm not going to discover my mistake here. Time to try something else.
 
Last edited:

Mendel

Senior Member.
once dealt with you end with a close approximation of the strength of solid round tube.
Yes.

Because if you do not deal with it, you get "The shear lag effect greatly reduces the effectiveness of the framed tube" (Fu).
And because shear lag is "due to the flexibility of spandrel girders and columns" (Fu), you deal with shear lag by bracing these, reducing their flex.

(i) braced tube = little shear lag = effective
(ii) unbraced tube = lots of shear lag = bad at countering wind

removing the floors transforms the WTC from (i) to (ii).

Something Nordenson praised Robertson for doing with carefully selected grades of steel in the case of the WTC.
praise applied to (i), not (ii)
 
Last edited:
Top