WTC 1 & 2. What happened after collapse initiation?

[Mancman]

Show me video of the floors pancaking? Shyam Sunder stated, "When you did it previously, you showed that the floors actually pancaked, and we did not see any evidence of pancaking in the videos or photographs we have. Suddenly the columns snapped, and, as a result, the entire top of the building came down, pretty much in freefall, because kinetic energy that was unleashed was just huge."

You might want to show these videos to Shyam Sunder as well.

Oh my god. Are you serious? Sunder is clearly talking about pancaking during collapse initiation, not progression.

Really, that's what you have to offer?

 

[Cl1mh4224rd]

Oh my god. Are you serious? Sunder is clearly talking about pancaking during collapse initiation, not progression.

Really, that's what you have to offer?

tanabear has consistently been unable to differentiate between collapse initiation and collapse progression. He claims to know the difference, but then he keeps doing stuff like what you just quoted.

 

[X]

Okay, so if explosive charges are destroying a building top down, this looks the same as if the building was collapsing? So what is your explanation for what happened after initiation? Did the upper block crush the lower block in a pile-driver like effect? Did this upper block remain largely undamaged during this crush down, only to be destroyed when it hit the rubble pile? Or was this upper block being destroyed while it was crushing the lower block? Should all of this look the same regardless?

This is what I was afraid of. Now you are going to take my statement as tacit admission that explosives were a possible cause. I want to say, again, and in bold: Explosives were not used in the destruction of WTC 1 and 2 (and 7).[/i] But yes, ignoring everything else (including flashes, windows being blown out, unmistakeable persussive noises, seismic registers, etc etc etc), it might look the same.

The exact physiscs of what happened during collapse are complicated.
Many very competent people (far smarter than I) have performed studies of the collapse. The conclusion, agreed upon (in general, some people are still debating specifics) is that once the collapse began, the building could not stop it.

There is a lot of mass, and it is moving earthward. The movement is an important thing. The building was designed to support the mass when the mass was not moving downwards. Adding motion increases the strain the lower section of the building must withstand (momentum = mass * velocity; kinetic energy = 0.5 * mass * velocity²).
Not to mention that the building has been weakened by the collapse initiation (all of it;, each tower weas one structure, not stacked units).

This may come as a shock to some members of the truth movement, but Engineers approximate things. We make assumptions all over the place.

One of the things we assume is that an airliner will not come slamming into our bulding at 600 mph (Engineers had no reason to even concieve of this prior to 9/11). Another thing we assume is that the upper section of a skyscraper will not (due to impact damage and fire) begin to fall.

Accordingly, we don't design for it.

Yes, you read that right. This is the awful, terrible truth of engineering. We don't design structures to survive having their top third come crashing down. It is, I suppose, our failure as a profession, that we did not plan for calamities and that our lack of forsight prevented lives from being saved. The NIST report's aim was to correct this oversight, and modify building codes so that in the future, skyscrapers will be safer.

In short, the twin towers were not strung enough to survive such an event.

The top part comes down, and destroys the section below it. THis, obviously, results in destruction to the upper section, as well. Perhaps some of the debris is ejected of spills over the side. But not enough to make a difference, and you now have even more mass coming down to the next floor, and it keeps building. The tower was incapable of providing enough resistance to slow the collapse, so the big mass of debris kept accelerating downwards, destroying the tower and gaining the mass as it went.

I strongly suggest you read some of the papers written on this.
Mackey, Bazant, Greening, and others have all done very good research on this, beyond anything I am capable of.

Bear in mind, I am still an engineering student, not a Professional Engineer. Next year, I will graduate and become an Engineer in Training. After four years of that, a performance review, and a professional practice test, I will be a P. Eng. And even then, I will not be at the level of some members of this forum. We have members with Masters degrees and PhD's.

 

[tanabear]

Oh my god. Are you serious? Sunder is clearly talking about pancaking during collapse initiation, not progression.

Really, that's what you have to offer?

What type of failure is "pancake initiation," and how is it different from truss failure?

NIST says in their FAQ: "Thus, the floors did not fail progressively to cause a pancaking phenomenon." Note that the sentence mentions "floors" (that's plural) and a "pancaking phenomenon," not initiation.

 

[tanabear]

tanabear has consistently been unable to differentiate between collapse initiation and collapse progression. He claims to know the difference, but then he keeps doing stuff like what you just quoted.

I'll defer to you since you are an expert. Explain the difference between "pancake initiation," and "pancake collapse." I'll look for your answer in the morning.

 

[Jonnyclueless]

One being a cause and the other being a result. No one needs to be an expert in anything to understand that.

 

[tanabear]

One being a cause and the other being a result. No one needs to be an expert in anything to understand that.

Not an acceptable answer. Is "pancake initiation," something different from truss failure? If it is, I want to know exactly what "pancake initiation" refers to.

 

[Confuseling]

...Yes, you read that right. This is the awful, terrible truth of engineering. We don't design structures to survive having their top third come crashing down. It is, I suppose, our failure as a profession, that we did not plan for calamities and that our lack of forsight prevented lives from being saved. The NIST report's aim was to correct this oversight, and modify building codes so that in the future, skyscrapers will be safer....

Engineering is the art of modelling materials we do not wholly understand, into shapes we cannot precisely analyse so as to withstand forces we cannot properly assess, in such a way that the public has no reason to suspect the extent of our ignorance.
- Dr AR Dykes
British Institution of Structural Engineers, 1976.



As a budding political economist, let me seek to reassure you. The world is constructed out of compromise. If you don't have any train crashes, you're spending too much on train safety - plain and simple. Keep spending less, and less, and less, until they start crashing (but not very often). Spend the money you saved on medicine, and suddenly it's become an ethical decision - economics is a bit like triage, in that you can't save everyone.

In a world with limited resources, we expect buildings to fall down.

 

[Jonnyclueless]

Not an acceptable answer. Is "pancake initiation," something different from truss failure? If it is, I want to know exactly what "pancake initiation" refers to.

Yes an acceptable answer, just requires a usable brain.

 

[funk de fino]

I'll defer to you since you are an expert. Explain the difference between "pancake initiation," and "pancake collapse." I'll look for your answer in the morning.

You are joking right?

 

[R.Mackey]

Not an acceptable answer. Is "pancake initiation," something different from truss failure? If it is, I want to know exactly what "pancake initiation" refers to.

This has been explained numerous times, but it bears repeating yet again. It is a reasonable question, and I like to encourage those.

"Pancake initiation" is the notion that floors would fall independently of the frame, and set off a chain reaction. The initial failure is the floor truss connections at the perimeter and core columns. The floor itself then falls on the floor below, which (in this model) cannot handle the added weight and shock of impact, and that floor's connections fail too.

After a few floors fail in this mechanism, the columns -- until now, still standing -- buckle not because of increased weight, but because they've lost their cross-bracing and thus the unsupported column length, and hence their effective slenderness ratio, increases due to the floors going away. Thus they do not require additional weight or impact to buckle, just loss of stabilization. Once the columns fail, the upper structure comes down as a whole, destroying whatever is left.

This differs strongly from NIST's hypothesis and does not match what we saw. In this model, it is highly unlikely for inward bowing to appear at the perimeter columns ahead of collapse -- this is indicative of very strong truss connections, and makes it unlikely that floors even could fall as single units. Also, the video clearly shows the perimeter walls buckling inward at the moment of instability.

These and other effects lead us to NIST's "progressive collapse" mechanism, which is that the floors remained intact, but bowed, creating inward stress on the perimeter columns, reducing their strength not through loss of bracing, but by creating eccentric loading that causes them to buckle. This is added to other factors, including weakening due to impact and heat, and creep particularly in the core accelerated by heating and redistributing the load to the perimeter. There are other factors NIST does not consider significant but others do, primarily thermal expansion and contraction, though this does not conflict with NIST's hypothesis, only adding to it.

NIST treated the "pancake initiation" hypothesis explicitly in Appendix B to NCSTAR1-6D. In this experiment, using simulation they demonstrate that a single floor failure is not expected to cause a cascading failure, even with damage taken into account. The impact from a single floor is nowhere near as huge as the entire upper block of floors and frame. This result makes the "pancake initiation" hypothesis very difficult to support, even had the video not led us away from it in the first place.

 

[pomeroo]

Nothing could impede it? There was tens of thousands of tons of steel and concrete beneath the area of impact. It sounds like you are promoting the "no building theory" when it comes to the destruction of WTC1 and 2, at least no structure beneath the area of impact.

There is, as you know, no such animal as the "no building theory."

Show me video of the floors pancaking? Shyam Sunder stated, "When you did it previously, you showed that the floors actually pancaked, and we did not see any evidence of pancaking in the videos or photographs we have. Suddenly the columns snapped, and, as a result, the entire top of the building came down, pretty much in freefall, because kinetic energy that was unleashed was just huge."

You might want to show these videos to Shyam Sunder as well.

No need. He has a functioning brain. As has been pointed out countless times on this forum, when a boxer takes a hard punch to the jaw and is knocked unconscious, he doesn't lose because he falls down. He loses because he got hit. BUT--he does fall down. And, no, you don't get it.

The pancaking explanation and the pile-driver explanation are different. Pancaking supposedly occurs when the trusses break free from the perimeter columns and one floor falls on top of the other one. The pile-driver collapse is initiated by column failure. The upper block comes down as one piece onto the lower block crushing it.

Arguing with the debunkers is difficult because they seem to have their own meaning for words and phrases. Alice ran into the same problem while talking with Humpty Dumpty.

`And only one for birthday presents, you know. There's glory for you!'

`I don't know what you mean by "glory,"' Alice said.

Humpty Dumpty smiled contemptuously. `Of course you don't -- till I tell you. I meant "there's a nice knock-down argument for you!"'

`But "glory" doesn't mean "a nice knock-down argument,"' Alice objected.

`When I use a word,' Humpty Dumpty said in rather a scornful tone, `it means just what I choose it to mean -- neither more nor less.'

`The question is,' said Alice, `whether you can make words mean so many different things.'

`The question is,' said Humpty Dumpty, `which is to be master - - that's all.'

Alice in Wonderland/Through the Looking-Glass belong to a genre known as nonsense literature. The official explanation for the collapse of the towers belongs to a genre known as "nonsense science"

No adult should be permitted to quote Alice's exchange with Humpty Dumpty unless he understands it. Carroll's brilliant satire on logic could be recast in contemporary terms to mock the hopelessly irrational fools of the fantasy movement who equate "explosions" with "explosives." There is, as you know, no "official" explanation for the collapse of the Towers. The conclusions of all serious researchers were reached through the application of real science. Your uninformed, agenda-driven nonsense is bogus science.

How was the upper block dropped onto the lower block? The majority of the core and perimeter columns were still connected. Did a giant walk by and pick up the upper block and then drop it onto the lower block? You might want to explain how this happened.

Instead of continuing to make yourself appear ridiculous, you might try reading a few pages of the NIST Report.

Charles Thornton, one of the initial leaders of the ASCE team, stated to Karl Koch, "Karl, we all know what caused the collapse." How did he know this before he had examined any of the evidence? Why should someone who claims to already know what caused the collapse be placed on a team to investigate this collapse? So what does this have to do with NIST and other scientists investigations? Well, based on the fact that some scientists already claimed to know how the towers collapsed, the decision was made to recycle much of the steel from WTC1,2 and 7. Create a consensus and then destroy much of the evidence. Representative Joseph Crowley(D) called the destruction of evidence, "borderline criminal."

An ignorant pol seeking to score lunatic partisan points can't shed much light on a scientific subject. Yes, many engineers and physicists have stated that they were not surprised that the Towers collapsed. They are saying that their professional expertise gave them insight into the behavior of structures, enabling them to make educated guesses that proved correct. Serious researchers who study a problem are not blank slates. They bring with them certain preconceptions that (here's the point you are guaranteed to ignore) they will subject to critical scrutiny.

Okay, so if explosive charges are destroying a building top down, this looks the same as if the building was collapsing? So what is your explanation for what happened after initiation? Did the upper block crush the lower block in a pile-driver like effect? Did this upper block remain largely undamaged during this crush down, only to be destroyed when it hit the rubble pile? Or was this upper block being destroyed while it was crushing the lower block? Should all of this look the same regardless?

Trying reading something not published by other conspiracy liars.

 

[Newtons Bit]

I'll defer to you since you are an expert. Explain the difference between "pancake initiation," and "pancake collapse." I'll look for your answer in the morning.

Pancake initiation is the theory put forth by the early FEMA report in which the mechanism of collapse initiation was overheated floor trusses that went into catenary action, slipped their bolts and an entire floor fell off all at once. NIST rejected this as the collapse initiation mechanism after they conducted a full scale FE model that showed the collapse initiation was rather due to an entire wall being pulled in from this catenary action.

Pancake collapse should be self-explanatory.

 

[bje]

Nothing could impede it? There was tens of thousands of tons of steel and concrete beneath the area of impact.

Tanabear, what do you think the designers of the WTC towers were trying to accomplish? Do you think they were trying to build structures that were efficient, cost-effective, able to withstand the commonly-occurring forces of wind and perhaps earthquakes?

Or do you think they were tring to build structures that would deal with any forces and damages that could ever conceivably come up or may never be conceived of to begin with? How would such a structure be built or overbuilt to account for forces that have an exremely low probability of occuring? Could such a structure be built and at what cost?

In fact, structures are built with a margin of safety that exceeds what would be expected in normal conditions of weather or earthquakes. Are any buildings built to withstand forces of an upper part of a structure falling onto a lower structure? If so, please cite the litertaure, architects, and structural engineers who do this.

Do you believe it is conceivable that the orginal designers of the WTC towers in the mid 1960s thought about the possibility, and therefore designed into the structures, allowance for a situation where the possibility of a section of tower would fall on to the lower structure and that the entire building should be designed to withstand those forces no matter on which floors the damage occurred?

If you say "yes, they were built to withstand the forces of a falling upper section, that's why they needed explosives", then can you demonstrate factually that the design and construction of the towers were overbuilt to accomplish that? And that the costs were reasonable? Not to speak of the failure of anyone to demonstrate explosives going off starting at the damaged area.

So, tell us your knowledge of the situation, Tanabear.

 

[pomeroo]

A re-bump to make the same point. Yoo-hoo, Heiwa--we're not going to let you refer to your imbecilic paper any longer.


(I wrote a couple of days ago)

A bump to make an obvious point.

Heiwa's idiotic contention that dropping the top third of a tall building onto the bottom two-thirds won't crush the whole structure has received the ridicule it deserves. BUT--please note that he hasn't abandoned the lunatic notion. He has merely vanished.

HE WILL ASSUREDLY RESURFACE SOONER OR LATER TO MAKE THE SAME INSANE CLAIMS. HE WILL CONTINUE TO CITE HIS WORTHLESS, INCOMPETENT "PAPER" AND LIE ABOUT THE SERIOUS RESEARCHERS WHO HAVE "PEER-REVIEWED" IT.

 

[Panoply_Prefect]

Maybe the idea that explosive charges can destroy buildings, even WTC1 and 2, will no longer be controversial one day as well.

Who claims that explosives cannot destroy buildings?

 

[tanabear]

The top part comes down, and destroys the section below it. THis, obviously, results in destruction to the upper section, as well. Perhaps some of the debris is ejected of spills over the side. But not enough to make a difference, and you now have even more mass coming down to the next floor, and it keeps building. The tower was incapable of providing enough resistance to slow the collapse, so the big mass of debris kept accelerating downwards, destroying the tower and gaining the mass as it went.

I strongly suggest you read some of the papers written on this.
Mackey, Bazant, Greening, and others have all done very good research on this, beyond anything I am capable of.

So when the upper block crushed the lower block, did it break apart while it was crushing, or did it remain intact while it was destroying the lower block, only to be destroyed itself when it came in contact with the rubble pile. Bazant et al suggest the latter. In other words, did the crush-down and crush-up occur simultaneously or at separate times?

NIST treated the "pancake initiation" hypothesis explicitly in Appendix B to NCSTAR1-6D. In this experiment, using simulation they demonstrate that a single floor failure is not expected to cause a cascading failure, even with damage taken into account. The impact from a single floor is nowhere near as huge as the entire upper block of floors and frame. This result makes the "pancake initiation" hypothesis very difficult to support, even had the video not led us away from it in the first place.

That was exactly my point. There is no pancaking going on, at least according to what can now be considered the official story. Brent Blanchard also made the same point as Shyam Sunder, "As many are aware - and as we go on to explain later in Assertion #2 - the buildings did not actually 'pancake'. Our use of the word is not intended to be taken literally, rather it is used to represent a general visual description that helps readers conceptualize the more advanced points that follow."

One of the goals of this thread was to attempt to clear up some confusion because many debunkers still insist that the official explanation is that the floors pancaked. As prominent 9/11 debunker Ronald Wieck has stated, "Once the global collapse ensued, the floors necessarily pancaked. What else could they be expected to do?"

Do you believe it is conceivable that the orginal designers of the WTC towers in the mid 1960s thought about the possibility, and therefore designed into the structures, allowance for a situation where the possibility of a section of tower would fall on to the lower structure and that the entire building should be designed to withstand those forces no matter on which floors the damage occurred.

So if only the top two floors fell onto the lower structure it would destroy the entire building? If that was the case then the World Trade Center towers were the worst designed buildings in history.

“The structural analysis carried out by the firm of Worthington, Skilling, Helle & Jackson is the most complete and detailed of any ever made for any building structure. The preliminary calculations alone cover 1, 200 pages and involve over 100 detailed drawings… The building as designed is sixteen times stiffer than a conventional structure. The design concept is so sound that the structural engineer has been able to be ultra-conservative in his design without adversely affecting the economics of the structure.”

Who claims that explosives cannot destroy buildings?

I'm saying that it isn't controversial to suggest that explosive charges can destroy buildings. It is only controversial in regards to WTC1,2 and 7. People can accept the fact that explosions can destroy buildings. They can't accept this when it comes to 9/11. Why not?

 

[Jonnyclueless]

"There is, as you know, no such animal as the "no building theory."

Hogwash. Mr Gage presented an undeniable demonstration using his cardboard boxes proving there were no buildings.

 

[applecorped]

So when the upper block crushed the lower block, did it break apart while it was crushing, or did it remain intact while it was destroying the lower block, only to be destroyed itself when it came in contact with the rubble pile. Bazant et al suggest the latter. In other words, did the crush-down and crush-up occur simultaneously or at separate times?



That was exactly my point. There is no pancaking going on, at least according to what can now be considered the official story. Brent Blanchard also made the same point as Shyam Sunder, "As many are aware - and as we go on to explain later in Assertion #2 - the buildings did not actually 'pancake'. Our use of the word is not intended to be taken literally, rather it is used to represent a general visual description that helps readers conceptualize the more advanced points that follow."

One of the goals of this thread was to attempt to clear up some confusion because many debunkers still insist that the official explanation is that the floors pancaked. As prominent 9/11 debunker Ronald Wieck has stated, "Once the global collapse ensued, the floors necessarily pancaked. What else could they be expected to do?"



So if only the top two floors fell onto the lower structure it would destroy the entire building? If that was the case then the World Trade Center towers were the worst designed buildings in history.

“The structural analysis carried out by the firm of Worthington, Skilling, Helle & Jackson is the most complete and detailed of any ever made for any building structure. The preliminary calculations alone cover 1, 200 pages and involve over 100 detailed drawings… The building as designed is sixteen times stiffer than a conventional structure. The design concept is so sound that the structural engineer has been able to be ultra-conservative in his design without adversely affecting the economics of the structure.”



I'm saying that it isn't controversial to suggest that explosive charges can destroy buildings. It is only controversial in regards to WTC1,2 and 7. People can accept the fact that explosions can destroy buildings. They can't accept this when it comes to 9/11. Why not?

Because it didn't happen.

 

[~enigma~]

People can accept the fact that explosions can destroy buildings. They can't accept this when it comes to 9/11. Why not?

They can't? You seem to be confusing the fact that people don't accept that the WTC were a CD with "explosives can't destroy buildings." Why is it that truthers always have trouble with logic?