How much research does a truther have to do to get any respect around here?

But probably more to the point why is full scale physical replication the ONLY method of confirmation you acknowledge?
Speaking of which, NIST commissioned an experiment where it had a full-scale section of the floor structure built (4 inch slab held up by fairly light truss "joists", with identical attachment methods to the vertical supports as used in the WTC). They had some difficulty replicating the exact same steel and concrete, and at least in the steel, had to substitute another type of steel that had as similar heat response/structural characteristics of the original, because the original steel simply wasn't manufactured/available any more.

It was put in the largest bake-test facility they could find, which turned out to be in Toronto Canada at the time. If I recall correctly, the test article was about 100' long and 30'+ wide.

With this they were able to demonstrate the test structure collapsing based on the temperature levels known to exist in the WTC. It matched.

Which ultimately proves that the floors would collapse in the conditions that were known to exist (even as promoted by AE911truth). Once one or more floors collapse, then some sort of ROOSD/progressive failure was inevitable. Pancake? Well, yes, but it got pretty pulverized falling that far. There's photographic evidence of pancake at the very bottom of the debris pile.

[The test is documented in one of the appendices of the NIST report.]
 
Pancake? Well, yes, but it got pretty pulverized falling that far.
This Austrian type of pancake is called "Kaiserschmarrn": :p
kaiserschmarrn-100__t-1496916933966_v-4to3__retina.jpg
The point here was that without *some* experience in material fabrication, or understanding loading, it's not obvious. If you weren't, and were of the right mindset, you'd be scavenging the broken bits looking for nano-thermite, israeli stealth cruise missiles, or holographic walkways.
Yeah. Like in my quote, first-year mechanical or structural engineering.
Which is a lot less than "engineering experience".

I've done it with metereology, had Amazon recommend me a first-year textbook, and learned a lot about the weather. That kind of knowledge is quite accessible to many people. Though for engineering, you'd want to not have sucked in physics or maths in school.


Simply, if ThomasB is a troll or a Poe-troll or a Truther or just a confused individual, your responses to him help me, and I think I speak for many here, understand things better and may some day help him understand.
That's one of my motivations to point out very clearly (some may say, impolitely) some of the aspects of his discussion style, e.g. where he is putting implicit assumptions and expectations in. If you are talking to other people like him, it helps to make yourself aware of these so you can think about them explicitly and regain some amount of control over the discussion; it's more difficult to spot oneself doing it.
 
Speaking of which, NIST commissioned an experiment where it had a full-scale section of the floor structure built (4 inch slab held up by fairly light truss "joists", with identical attachment methods to the vertical supports as used in the WTC). They had some difficulty replicating the exact same steel and concrete, and at least in the steel, had to substitute another type of steel that had as similar heat response/structural characteristics of the original, because the original steel simply wasn't manufactured/available any more.

It was put in the largest bake-test facility they could find, which turned out to be in Toronto Canada at the time. If I recall correctly, the test article was about 100' long and 30'+ wide.

With this they were able to demonstrate the test structure collapsing based on the temperature levels known to exist in the WTC. It matched.

[...]

[The test is documented in one of the appendices of the NIST report.]
Could I ask you to please dig up the precise reference - URL and page numbers? Because I think I remember that that structure exhibited NO collapse initiation, and this "failure to fail", if you will, is sometimes cited by Truthers as evidence that NIST's theory must be wrong. So, I want you to make sure you remember correctly.
 
So, I want you to make sure you remember correctly.
That is one issue of concern. I would also want to address the quantum leaps of presumption in this comment:
Which ultimately proves that the floors would collapse in the conditions that were known to exist (even as promoted by AE911truth). Once one or more floors collapse, then some sort of ROOSD/progressive failure was inevitable.
Yes the floors would collapse given those parameters BUT that argument falls a long way short of proving: "...some sort of ROOSD/progressive failure was inevitable."
Pancake? Well, yes, but it got pretty pulverized falling that far. There's photographic evidence of pancake at the very bottom of the debris pile.
Maybe but "pancake" has been subject of much controversy because either it was not defined or was not specifically located in the collapse sequence. Unless you define what you mean and where it fits in the collapse sequence "pancake" is not definitive of anything.
 
Could I ask you to please dig up the precise reference - URL and page numbers? Because I think I remember that that structure exhibited NO collapse initiation, and this "failure to fail", if you will, is sometimes cited by Truthers as evidence that NIST's theory must be wrong. So, I want you to make sure you remember correctly.
My memory is somewhat defective - eg: my sizes were off, but the tests were done on half-scale (18') and full scale (35') sections.

Here's a couple of references with more detail - they''re not something I can usefully cut-and-paste segments:

https://www.nist.gov/document/publicbriefingultestsrevc0825041pdf
https://info.publicintelligence.net/wtcfiretesting.pdf

I'll draw your attention to pages in the second reference - the photos on slide 16 and the table on slide 18, and the "test terminated" column - two were "imminent collapse" and two were "vertical deflection exceeded measurability". Note that they didn't attempt to simulate aircraft impact damage, nor wall flex, and we know that the outboard ends of some of the sections were severed at the perimeter. So it was clear that they would have collapsed under the real conditions. The tests were performed to determine fire rating under "normal" (no airplanes) conditions, which means testing to the point of unacceptable deflection OR collapse, once either was achieved, they stopped it.

I consider this proof of the heat-induced floor collapse scenario.
 
That is one issue of concern. I would also want to address the quantum leaps of presumption in this comment:

Yes the floors would collapse given those parameters BUT that argument falls a long way short of proving: "...some sort of ROOSD/progressive failure was inevitable."

Maybe but "pancake" has been subject of much controversy because either it was not defined or was not specifically located in the collapse sequence. Unless you define what you mean and where it fits in the collapse sequence "pancake" is not definitive of anything.
Someone here will remember the weight of each floor assembly and their rated load, because I'm no longer sure I remember exactly what the numbers were. However, the takeaway that I *do* remember is that, as designed, each floor was just strong enough to hold up itself, and a maximum loading roughly equivalent to it's own weight plus max contents. Which means that a floor would collapse outright under the weight of another floor or two and their contents. This is not even factoring in:

- the ceiling to floor drop kinetic impact
- point failures snapping the floor-wall connector bracket assemblies (eg: when the aircraft severed a large percentage of the perimeter structure on the aircraft impact side).

Once you have enough weight on one floor to cause it to collapse, it's going to collapse all the way down because no floor below it could withstand the progressively heavier mass of debris. Aka: inevitable. You can see that in the Plaxo collapse, and in another collapse ("Oxford" partial collapse?) where the building was a narrower tower on top of a rather broader base, and the collapse mostly stopped at the roof of the lower section because the strength profile changed.

As for pancaking, the common conception is seeing floor slabs stacked on top of each other as in a stack of pancakes. Whole articles are written about how 9/11 is not pancake collapse.

Yet, I distinctly recall (though I don't have it at the moment) of a photograph from inside the rubble field while it was being excavated out, a stack of at least 5 floors near the bottom of the pile. It's not a wide angle, and may only be a small segment of the complete floors, but it does show that *some* of it pancaked.

If I had to moderate a big discussion when the various adherents of pancake, ROOSD, progressive collapse etc. etc. were screaming at each other, and if I were asked afterwards "what do you think brought the towers down, ROOSD, pancake, or progressive collapse?" My response? One word: "yes". Because aspects of all occurred in the chaos, and I don't count angels on pinheads.

The condo collapse in Florida also showed aspects of at at least two.
 
NIST modeled a 1/20 model of the 96th floor of WTC1 and tested it under fire conditions. There was a peer reviewed article published about that modeling effort back in 2007:

Wang, Ming et al. “Scale Modeling of the 96th Floor of World Trade Center Tower 1.” Journal of Performance of Constructed Facilities 21 (2007): 414-421.

Here's the abstract:

This paper presents an experimental investigation of the World Trade Center Tower 1 (WTC1) collapse using a 1∕201∕20-scale model. The WTC1 fire on the 96th floor is reconstructed on a small scale, and structural members including the floor trusses and the exterior wall subsystem are built and tested under scaled fire load. Scaling rules are used to determine the values of the insulating material on the structural systems. This experimental study demonstrates the use of scaled models to investigate a real-world fire disaster. Results from the experimental investigation are compared to analytical results and visual evidence compiled in the National Institute of Standards and Technology report on the investigation of the collapse of WTC towers. This study helps engineers and researchers better understand the fire behavior and the associated structural response in WTC1, and a more solidly grounded collapse hypothesis can therefore pursued.
I know I have a copy of the full article saved to another computer and could excerpt from it later if there is any question on exactly what was done.

EDIT: There appears to be a full text version of the Wang article for free here, though it lacks to the pictures of the tables of the original.
 
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If I had to moderate a big discussion when the various adherents of pancake, ROOSD, progressive collapse etc. etc. were screaming at each other, and if I were asked afterwards "what do you think brought the towers down, ROOSD, pancake, or progressive collapse?" My response? One word: "yes". Because aspects of all occurred in the chaos, and I don't count angels on pinheads.
You missed out "gravity". But, humour aside, conflating all the elements and agreeing they all apply does not address the point I made.

You made an unwarranted assertion. You said: "Once one or more floors collapse, then some sort of ROOSD/progressive failure was inevitable." Stand alone as you presented it that assertion is not valid proof. Or as I said 'that argument falls a long way short of proving: "...some sort of ROOSD/progressive failure was inevitable."'

I don't mind if you dont want to address the issues but this is now the fourth time you have quoted a point I raised then totally ignored that point to present an unrelated claim of your own or - in this case - to trivialise the serious point I made.

If you don't want to engage with points I raise in discussion please simply either disregard my post or, preferably, state that you don't want to engage on the issue.
 
I am not a truther, but I have some sympathy for them. It is hard to understand how the World Trade Center buildings collapsed, and it would be much easier if demolition were involved. I personally can't believe that the buildings were demolished, but I also don't really understand the mechanics of their progressive collapse.

Perhaps it's some kind of intellectual arrogance, but I feel I should be able to understand this. I think that my grasp of physics is strong enough that I should be able to study the topic and arrive at an understanding within a reasonable amount of time. I started wondering about it in earnest in 2005 and I don't think 15 years is a "reasonable" time frame. It should be possible for someone of my intelligence and discipline to satisfy their curiosity.
It is a lost cause. The fact that the lower portion of a skyscraper must support more weight does not mean we should know the distribution of steel down the structure.

The ability to model the Tacoma Narrows bridge in a wind tunnel in only 4 months in 1940 does not mean we should have been able to make physical or virtual models of the North Tower in TWENTY YEARS.

Believe what you are told! How dare you expect to think for yourself and expect even people claiming to be EXPERTS to not leave obvious gaps?

Who DO you think you are?
 
It is a lost cause. The fact that the lower portion of a skyscraper must support more weight does not mean we should know the distribution of steel down the structure.

The ability to model the Tacoma Narrows bridge in a wind tunnel in only 4 months in 1940 does not mean we should have been able to make physical or virtual models of the North Tower in TWENTY YEARS.

Believe what you are told! How dare you expect to think for yourself and expect even people claiming to be EXPERTS to not leave obvious gaps?

Who DO you think you are?
Not true. The lower portion of the WTC towers, aka the floors, did not support the upper floors. The floor fail when over loaded, this is a fact, and there is no need to model the WTC to know that once started, the collapse will not stop when floors are overloaded.

The core and shell supported all the floors, as if they were hanging on the core and shell, which they were. The great strength of the WTC was also why it fell as it did. Anyone who studies and understands the WTC tower structure understand how the WTC tower collapse after the upper floor fell on the lower floors, even NIST knows.

https://www.nist.gov/world-trade-center-investigation/study-faqs/wtc-towers-investigation#:~:text=vertical connection capacity-,(29,000,000 pounds,-) of a floor

See, even NIST was able to add up the connections of a floor and see when it fails, and NIST was able to say, "Once the upper building section began to move downwards, the weakened structure in the impact and fire zone was not able to absorb the tremendous energy of the falling building section and global collapse ensued." It is math, so "global collapse ensued" is due to the fact floors failed when overloaded past ~29,000,000 pounds - a fact even NIST knows, but 9/11 truth refuses to understand.

Thus - "How much research does a truther have to do to get any respect around here?" - First a truther has to accept and understand facts and evidence, like why the floors failed after overloaded, to get respect. Stop ignoring facts.

 
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The problem with scale models is that different properties of materials scale differently: some scale with length, some scale with area (e.g. a cross-section), some scale with volume (e.g. weight). If you make a 1:10 scale model, area scales 1:100, and volume scales 1:1000. If you want to mimic a full collapse sequence and not just find a resonant frequency, that may simply be impossible to scale.

The strength of the steel is only of secondary importance. If you almost fall out of a window on the 10th floor, but manage to grab onto the window frame, and are now hanging outside thee building, you will not eventually fall down because the wall collapses, but because your fingers can't hold your weight any longer. (Or if the villain dislodges your fingers.)
Each floor falls because its connections to the vertical steel fail; this happens because the floors are not supported by a narrow grid of columns as in a traditional high-rise building, but because they'fe held up by the outer shell and the inner core alone. The shell and the core lose their strength as soon as they get deformed. You can experience the latter with an empty soda can: it's hard to crush vertically when intact, but if you bend it, it crushes more easily.
So what happened was approxinately:
1) something fails from the heat (sprinkler system damaged, fires too big)
2) top block starts moving down
3) the floors below fail one by one from the immense weight hammering down because their connections to the vertical steel fail (the fingers on the window frame)
4) outer shell and inner columns are no longer braced laterally (sideways) and topple in parts as they become damaged by the avalanche of the floors (soda can instability)

The steel columns can only hold the floors up if they're all properly attached. Once a few of them start moving, it's over, because the connections shear off.
 
So what happened was approxinately:
1) something fails from the heat (sprinkler system damaged, fires too big)
2) top block starts moving down
3) the floors below fail one by one from the immense weight hammering down because their connections to the vertical steel fail (the fingers on the window frame)
4) outer shell and inner columns are no longer braced laterally (sideways) and topple in parts as they become damaged by the avalanche of the floors (soda can instability)

The steel columns can only hold the floors up if they're all properly attached. Once a few of them start moving, it's over, because the connections shear off.
And that explanation could be the "Abstract" to the formal paper OR the "Executive Summary" to the report OR the "Preface" to the layman's "Dummies Guide to Twin Towers Collapses" which @Thomas B keeps asking for.

Then we add as many layers of deeper detail as needed by the "audience". Because:
"1) Something fails..." was a cascading sequenced failure of columns. Columns losing their capacity to support vertical loads until there were not enough left to support the "Top Block". Which can be explained to an interested layperson by discussing this simplified abstract model.

7colsA2-400-withfirenotated.jpg or this easier to explain version> 7colsA2-400-withcutsnotated.jpg


It was something like "Toppling Dominoes". Sure a couple of grades more complicated but most people can relate to "Toppling Dominoes".

Call that the "initiation stage"; THEN
"2) top block starts moving down.." Call that ""Transition stage". No need to discuss further at this level of detail. FOLLOWED BY:

"3) the floors below fail one by one..." AKA "progression stage" which is probably best split into two sub stages:
..."3a) Early progression">>>> When Top Block broke concurrently with dismantling of top of "Lower Tower" AND
..."3b) Established progression". Often contentiously described as "ROOSD" (Runaway Open Office Space Destruction). Contentious because truther researchers got it right. And "debunkers" didn't like it. This graphic possibly the first time the significance of "ROOSD" had been posted on line.
003c350.jpg The author never realised that at the time (Nov 2007) it opposed the "prevailing wisdom". THEN

..."4) outer shell and inner columns are no longer braced laterally (sideways) and topple in parts..." >>> And they "toppled in parts" - no need for truther claims for "Explosive Projection" >> which is not possible BUT leave that derail for another time.

THEN - for whatever paper OR "Dummies Guide" >> several more chapters or optional "off line" explanations for those who want to understand basic elements of the physics or who need "proof".
 
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...the layman's "Dummies Guide to Twin Towers Collapses" which @Thomas B keeps asking for.
This is instructive:
7colsA2-400-withfirenotated.jpg or this easier to explain version> 7colsA2-400-withcutsnotated.jpg
To get a sense of what I'm looking for, use the same level of simplification but make the model 3D and maybe 10 stories tall. Use 8 perimeter columns and 1 core column. Make sure the perimeter columns are connected by spandrel plates at every floor. Connect the floors to the spandrels. Then illustrate the total collapse of the model with 10-20 frames showing the state of the structure at each step.

This obviously won't be a model of the actual collapses (just as your drawings aren't). But it would be a good start.

PS. I know I said I'd leave the forum alone. But since you mentioned me directly, I thought this might help. Looking forward to seeing where you take it, if you do. Otherwise, have a nice day.
 
This is instructive:
The "end product" is a teaching aid. The purpose is "explanation" AKA "instruction. The post itself is not the instructional teaching aid - just an explanation of the scheme.
To get a sense of what I'm looking for, use the same level of simplification but make the model 3D and maybe 10 stories tall. Use 8 perimeter columns and 1 core column. Make sure the perimeter columns are connected by spandrel plates at every floor. Connect the floors to the spandrels. Then illustrate the total collapse of the model with 10-20 frames showing the state of the structure at each step.
It is not intended for you. You have made it very clear that I do not meet your standards of required competence to be author of a laypersons guide to Twin Towers collapses. PLUS, as an experienced teacher, I would NOT start with a more complicated model until I was confident that the "student" comprehended the principles shown by the simplified model. Which is why I said "or this easier to explain version" >> The cut columns model is an order less complicated to understand than the "heated to failing" columns model. In fact I would probably lead off explanation with an even simpler model. Such as this one:

3colsmodelaC.jpg
The GREEN 100 200 100 are the loads BEFORE the RH row of columns is cut. Assume the "Top Block" is rigid - no bending. What are the loads NOW after the RH row is cut? >> And that one is even simpler than the previous two "7 columns" models.

This obviously won't be a model of the actual collapses (just as your drawings aren't). But it would be a good start.
It would never be a "start". It is pointless starting with a complex model before the principles are understood/agreed. And it risks going down a derail path that I would avoid.
 
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Can you explain what you mean by "unnaturally"?
Any cause for the building to fall down, other than due to the plane. So if someone(s), prior to the plane hitting the towers, has done something to induce collapse: that would be what I mean with unnatural. Other than due to the impact, heat, explosion and weight etc. of the plane.
 
Any cause for the building to fall down, other than due to the plane. So if someone(s), prior to the plane hitting the towers, has done something to induce collapse: that would be what I mean with unnatural. Other than due to the impact, heat, explosion and weight etc. of the plane.
Thanks. To be pedantically correct the collapse was NOT started by the "...impact, heat, explosion and weight etc. of the plane" UNLESS "etc" incorporates the large scale fires started by the plane crash.

The Twin Towers both with stood all the DIRECT effects of the plane impacts.

The collapse was the result of large scale fires >> far bigger than the building was designed for >> which had no effective suppression from sprinklers and were unfought. Granted the scale of the fires - size; multi storey initiated; fuel concentrated by "BoeingDozing" impact; and start up near instantaneous due to aircraft fuel accelerant - was the direct consequence of the plane impact. But the fires caused the collapses - not the initial impact.

And, although the distincyion may be unnecessarily pedantic in the context of this thread, it can be critical to correct analysis of the collapses OR rebuttal of many truther false claims.
 
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The GREEN 100 200 100 are the loads BEFORE the RH row of columns is cut. Assume the "Top Block" is rigid - no bending. What are the loads NOW after the RH row is cut?
My guess is L=0, C=400. The left side of the top block will be pushed up as long as the L force is greater than zero
 
My guess is L=0, C=400. The left side of the top block will be pushed up as long as the L force is greater than zero
CORRECT. Provided "Top Block" is rigid. In a more realistic situation where "To Block" is flexible it will topple to the right.

HOWEVER the main reason an explanation needs to start at such a simplified example it that a lot of truther "arguments" are based on the concept that, if you remove (say) 25% of columns THEN all the remaining columns will increase load by 33.3% - uniformly. 'Taint so. And the real scenario is 99.9% certain to create a worse situation. Hence the next step model, This one:

7colsA2-400-withcutsnotated.jpg
Because - if "A" and "B" were carrying 100 before they were cut - the extra load which goes to "C" is more than 100+100=200. How much depends on how flexible the Top Beam is.... and it gets more complicated...

BUT remember the context - I am describing an explanation for lay persons. And once the lay-person understands the concept they shouldn't need to go into the post-grad engineering details. AND digging much more into complex engineering goes outside the scope of the "Dummies Guide to WTC Collapses" AKA "The Layman's Explanation".

So - in this "7 columns" model. If we cut columns "A" and "B" the load on "C" increases. What happens to the load on "D"?
 
Why exactly would the WTC have fallen down unnaturally? I mean, why would someone do that?
Article:
The ultimate goal of the 9/11 perpetrators, many believe, was to generate popular support for wars in various Muslim-dominated countries, with the aim of ensuring U.S. control of perhaps the most geopolitically important region in the world.

Then a lot of anti-semitic conspiracy theories can attach to that ("the Mossad was behind 9/11"), as happens with the "New World Order" CTs; although ae911truth.org are fairly careful to keep it off their site.
I remember seeing some of it in their court filings for the WTC7 collapse that they were asking to go to a grand jury, because that building was owned by an Israeli businessman at the time.
 
CORRECT. Provided "Top Block" is rigid. In a more realistic situation where "To Block" is flexible it will topple to the right.

HOWEVER the main reason an explanation needs to start at such a simplified example it that a lot of truther "arguments" are based on the concept that, if you remove (say) 25% of columns THEN all the remaining columns will increase load by 33.3% - uniformly. 'Taint so. And the real scenario is 99.9% certain to create a worse situation. Hence the next step model, This one:

7colsA2-400-withcutsnotated.jpg
Because - if "A" and "B" were carrying 100 before they were cut - the extra load which goes to "C" is more than 100+100=200. How much depends on how flexible the Top Beam is.... and it gets more complicated...

BUT remember the context - I am describing an explanation for lay persons. And once the lay-person understands the concept they shouldn't need to go into the post-grad engineering details. AND digging much more into complex engineering goes outside the scope of the "Dummies Guide to WTC Collapses" AKA "The Layman's Explanation".

So - in this "7 columns" model. If we cut columns "A" and "B" the load on "C" increases. What happens to the load on "D"?
Via google translate:
Can I compare it to laying a ruler on the edge of a table, where C corresponds to the table edge? When you press with one finger on each end of the ruler, it bends in an arc. The height of the arch above the table corresponds to the reduced load on D, E, F
 
Econ's cartoon is illustrative of some physics... vectors..
It does not directly relate to any of the buildings except 2WTC which has significant asymmetrical damage to the SE side of the "square foot print"... and tipped that a way as it dropped most likely when column ends translated laterally, misaligned and insufficient bearing followed... destruction of load paths. That means "drop" is a coming.
 
Via google translate:
Can I compare it to laying a ruler on the edge of a table, where C corresponds to the table edge? When you press with one finger on each end of the ruler, it bends in an arc. The height of the arch above the table corresponds to the reduced load on D, E, F
Yes. The graphic is one out of a series that I have used to present a step-by-step explanation of the key aspects of physics involved in the Twin Towers collapse intuition. And targetted at a layperson who has some natural aptitude for applied physics whether or not they have actually studied or practiced physics.
 
Don't be too sure. ;)
I am not too sure...
I understand that the intent was to explain...
that loads (from top block) did not disappear
that load paths were interrupted by fire and plane impacts
this left fewer columns supporting the load

Depending on the structural design's "efficiency" in load "redistribution" various "collapse" forms would manifest.

We know the the design of the facade... panels with integral sprandrels we very efficient in distributing loads laterally if there was a load path interruption..

The core however was less efficient and loads. It should be noted that the core columns being 3 stories would distribute loads via 3 beams/braces. It should also be noted that the office floor loads were carried by a belt girder surrounding the core and that belt girder was cantilevered on short beams from the 24 perimeter core columns. 23 interior core columns were not supporting outside the core loads... especially when a perimeter column or two failed.
 
It's a simplication to explain why the columns next to a failure take on more load than the now unsupported weight, via leverage.

The "simplification" should not have included the words "pivot" or "fulcrum" unless the labelled parts actually behaved as a pivot or a fulcrum. We were attempting to explain a collapse, hypothesising that the part which will next collapse won't collapse is an unnecessary complification.
 
In Econ's diagram... removing the left two columns means the mass above has a portion "cantilevered". So the loads that are above the two removed columns can move axially and therefore find a horizontal load path until they reach column C and perhaps D, and E where the load then goes axially down. If those columns can "handle" the extra load... there would be no collapse. If they can't the will; buckle... and the top will descend and likely tilt toward the left as it does.
 
In Econ's diagram... removing the left two columns means the mass above has a portion "cantilevered". So the loads that are above the two removed columns can move axially and therefore find a horizontal load path until they reach column C and perhaps D, and E where the load then goes axially down. If those columns can "handle" the extra load... there would be no collapse. If they can't the will; buckle... and the top will descend and likely tilt toward the left as it does.

Sure, if that point on the diagram had been labelled "point of highest load", or similar, then I'd not have felt the need to enter the thread. That would have covered 2 of the failure modes (next column collapses, supported floor buckles). I think I'd have also added an indicator at the top where the overhang starts "point of greatest tension" too, to include the "supported floor snaps" scenario that some parameterisations could result in.
 
I do think that there are at least two fuzzy areas which are not well explained.

1 - how loads were transferred before the towers collapsed.

If a load is transferred and does not overwhelm the remaining structure... the building can stand less the destroyed column(s). I think we want to hope that one failed column does not mean an entire skyscraper will completely collapse. Of course this IS kinda what happened to 7WTC...

2 - runaway progressive structural failures

This sort of a slightly more descriptive phrase than the NIST "global collapse ensued".. But the progression of failures was not detailed at all. We can see some distinct failure modes... such as the progression of floor collapses from top to bottom... with mass crushing the floor is fell upon... rinse, wash and repeat.

And there is consensus that heat was what did the twin towers in... But what were the sequence of failures? NIST shows some IB on one place of the South face of 1WTC... but they fail to explain how so many columns were compromised to cause a top drop. There are no... dots to connect...or rather we don't know what the dots were.

The same progression is missing for 7 WTC.... column 79 "fails" on floors 12-13... and then the building collapses.

So we have some good concepts which describe in a general way aspects of the collapses.. but we really have nothing like a complete coherent step by step description. And even if it is not THE series of steps... but a plausible series of steps would help.
 
It's a simplication to explain why the columns next to a failure take on more load than the now unsupported weight, via leverage.
EXACTLY. And it is one step out of a series of mini-steps designed to help a layperson comprehend what is - overall - a very complex process. The diagram was never intended as a stand-alone comprehensive explanation of the whole WTC collapse initiation mechanism. It was - still is - the diametric opposite. A simplified explanation to illustrate a couple of principles. And only one "mini-step" of the explanation.
The "simplification" should not have included the words "pivot" or "fulcrum" unless the labelled parts actually behaved as a pivot or a fulcrum.
Sure, if that point on the diagram had been labelled "point of highest load", or similar, then I'd not have felt the need to enter the thread.
Actually, both are true >> "pivot/fulcrum" AND "point of highest load", Because it acts as a fulcrum it causes that column to become a point of high load.

Remember we are discussing ONE step of a process to help laypersons comprehend a complex 4D mechanism. You correctly identify some of the next steps:-
That would have covered 2 of the failure modes (next column collapses, supported floor buckles). I think I'd have also added an indicator at the top where the overhang starts "point of greatest tension" too, to include the "supported floor snaps" scenario that some parameterisations could result in.
... which could possibly be going into more detail than a layperson would need or comprehend. If the setting was a "Face to Face" discussion the depth of detail needed is something I (or "we") would adjust on the fly. Interactively.
 
Forces are "invisible" and obviously hard for a layman to understand. A static structure has forces / resists forces... but one can't see them... but a collapse you get to see what they can do when they are not "contained" in the load paths of a structure - columns and beams... slabs.
And when you add the dimension of time almost no one can visualize / conceptualize the collapse in anything but gross movements.
 
Remember we are discussing ONE step of a process to help laypersons comprehend a complex 4D mechanism. You correctly identify some of the next steps:-

... which could possibly be going into more detail than a layperson would need or comprehend. If the setting was a "Face to Face" discussion the depth of detail needed is something I (or "we") would adjust on the fly. Interactively.

Indeed, it's a difficult challenge.

Is there an online interactive "physics" website/app where you could build a simple model that others could play with to help understand the points being made? I know of some simple rigid body physics simulations, but that's not enough, it would need to understand stress/strain and general irrigidity.
 
Is there an online interactive "physics" website/app where you could build a simple model that others could play with to help understand the points being made? I know of some simple rigid body physics simulations, but that's not enough, it would need to understand stress/strain and general irrigidity.
Simple bridge building games have been available for 20 years now. They typically feature a design phase and a simulation phase, with the option to display stresses in that phase.

Here's a free example of the genre:
Article:

bdThe West Point Bridge Design software is a free-to-use simulation for basic bridge design. Students will be introduced to the basic theory of structural design (forces, materials, properties, etc.) and learn the various types of bridges that are used in the world. A video of the Tacoma Narrows Bridge collapse will be viewed and the engineering failures of this design will be discussed. Students will then be able to create the designs described in the introduction and then make their own bridges to compete for the cheapest, working bridge.

The objectives of this lesson are to introduce students to civil engineering and bridge design, construct a prototype that can be tested in the program, use the appropriate vocabulary in describing the construction of their bridge, and utilize technology to demonstrate prototyping and engineering practices.
Unfortunately, the bridge design competition which went along with this software is no longer happening, but the program is still available to use.
 
Thanks. To be pedantically correct the collapse was NOT started by the "...impact, heat, explosion and weight etc. of the plane" UNLESS "etc" incorporates the large scale fires started by the plane crash.
Sorry, I kinda forgot about Metabunk for a few days.

I know that the official story is that of the fuel. But the fuel is part of the plane and I thought I covered that by saying "heat".
Article:
The ultimate goal of the 9/11 perpetrators, many believe, was to generate popular support for wars in various Muslim-dominated countries, with the aim of ensuring U.S. control of perhaps the most geopolitically important region in the world.
I understand that if one were to prove that the buildings fel down unnaturally that it is an argument for the above to be true. But why not just fly in planes and leave out the collapse? That would've been much easier and wouldn't leave any evidence that it was a set up. It wouldn't have been a big enough statement/gesture/excuse to go to war? And even if the collapse was natural, then still the plane could've been sent by someone with the above agenda. Anyway, I didn't look into any of this, but wanted to approach it a little differently, by asking questions. I do know I don't trust Bush though.
 
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But why not just fly in planes and leave out the collapse? That would've been much easier and wouldn't leave any evidence that it was a set up. It wouldn't have been a big enough statement/gesture/excuse to go to war?
I'm pretty sure the truther's response to this would be that, no, that would not have provided a pretext for war. Without the shock of the buildings collapsing (killing thousands instead of hundreds), the main issues (other than finding OBL, of course) would have been about how it was possible to hijack the planes and fly them into something. (That is, there'd still be a pretext for what is sometimes called "security theatre," also among truthers.)

I mean the main political issue. It would have been a strange and terrible day, to be sure, but not, as the truthers would put it, a "day of infamy," a new Pearl Harbor. Bush needed a reason to bomb the hell out of two countries, the argument goes. He needed a crater in the middle of Manhattan.
 
I'm pretty sure the truther's response to this would be that, no, that would not have provided a pretext for war. Without the shock of the buildings collapsing (killing thousands instead of hundreds), the main issues (other than finding OBL, of course) would have been about how it was possible to hijack the planes and fly them into something. (That is, there'd still be a pretext for what is sometimes called "security theatre," also among truthers.)

I mean the main political issue. It would have been a strange and terrible day, to be sure, but not, as the truthers would put it, a "day of infamy," a new Pearl Harbor. Bush needed a reason to bomb the hell out of two countries, the argument goes. He needed a crater in the middle of Manhattan.
Right. "It wouldn't have been a big enough statement/gesture/excuse to go to war?"
 
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