Split Thread Was global collapse of WTC inevitable?

[ergo]

ergo

The mass of 15 intact floors and 15 destroyed floors are the same.

Mass doesn't disappear.

In our case, it does. Much of it--I would argue 30 to 50%--is ejected out of the "crush" zone. And a discussion of how rubble can crush 80 to 90 storeys of an intact building anyway is too silly to waste time on.

 

[ergo]

Well, actually, I wouldn't mind seeing a discussion of this by bedunkers. It would be very enlightening. But it deserves its own thread and concentrated focus.

 

[Grizzly Bear]

With all due respect to Heiwa, you don't need Heiwa to understand that a top-driven collapse (of a smaller something through its larger counterpart) won't work. However, I do credit him for bringing that point to public and popular understanding. It is not some kooky "Heiwa" theory. It is a description of Newton's Third Law in a gravitational collapse. It's elementary. It should be idiot-proof, but apparently it's not.

When presented with Ronan Point Heiwa suggested that the collapse initiated low in the building and that it was impossible that the collapse of a single floor was capable of progressing all the way down to the ground level for even one corner of the building. Is this something you agree with?

 

[Carlos]

In our case, it does. Much of it--I would argue 30 to 50%--is ejected out of the "crush" zone.

Can you prove the bold part?

And a discussion of how rubble can crush 80 to 90 storeys of an intact building anyway is too silly to waste time on.

The building was destroyed floor by floor.

 

[triforcharity]

Yes, Zhou? Bazant's lackey? What does he say here? What "energy absorbing device" does he talk about? Where are all these other papers about how Newton's Third Law fails us when planes crash into buildings? Or even when planes don't crash into buildings?

In the paper he discusses if there was a way to engineer a building so that it would arrest collapse. IIRC, in his conclusion, he states that there might be some way of designing something to arrest a collapse.

Now, why would he write a paper on this, if the building couldn't have collapsed completly in the first place?

 

[Carlos]

Third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and −F the "reaction". The action and the reaction are simultaneous.

So, where the WTC collapse violate the third Law?

 

[femr2]

It's shocking that femr and Major Tom support this utterly ridiculous notion.

I have repeatedly shown you step by step the simple thing you simply will not understand.


Last chance. I'll ask you a couple of very simple questions about a simple example. You answer them. By doing so, you'll understand...



1) 1 *floor* normally supports 100Kg
2) That floor WILL fail if you put 1000Kg on it.

Q) What will happen if you put 2000Kg on the floor ?

 

[ergo]

In the paper he discusses if there was a way to engineer a building so that it would arrest collapse. IIRC, in his conclusion, he states that there might be some way of designing something to arrest a collapse.

Now, why would he write a paper on this, if the building couldn't have collapsed completly in the first place?

Maybe because he was one of the two who originally found a supernatural abundance of kinetic energy from a simple collapse event in the first place. It's possible he doesn't understand what structural steel frameworks in buildings are for. It's possible he is describing local collapses, since there are no other examples outside of WTC of global collapse of a steel-framed building from fire alone. It's possible the article is simply being seeded into the scientific literature on it to validate this notion that steel-framed buildings routinely collapse from fire.

In short, we really don't know, do we? It might help if we could actually read the article.

 

[triforcharity]

Maybe because he was one of the two who originally found a supernatural abundance of kinetic energy from a simple collapse event in the first place. It's possible he doesn't understand what structural steel frameworks in buildings are for. It's possible he is describing local collapses, since there are no other examples outside of WTC of global collapse of a steel-framed building from fire alone. It's possible the article is simply being seeded into the scientific literature on it to validate this notion that steel-framed buildings routinely collapse from fire.

In short, we really don't know, do we? It might help if we could actually read the article.

No, no he is not describing local collapses.

I have read the paper (It's been a while) why don't you find the paper and read it? Are you too afraid that it will harm your delusions?

No other building outside of the WTC 1&2 were hit by an airliner traveling ~500 mph. In the case of 7WTC, no building has been allowed to burn for 7 hours without a single drop of water from a firefighter's hose.

 

[alienentity]

Absolutely false. You would have to suspend Newton's Third Law, whether it's an intact upper block, which it isn't, or a mass of rubble, which it also largely isn't.

It is absolutely false that you would have to suspend Newton's Third Law. I agree. You are not arguing against the actual engineering arguments, you're simply creating an irrelevant strawman.

 

[alienentity]

In our case, it does. Much of it--I would argue 30 to 50%--is ejected out of the "crush" zone. And a discussion of how rubble can crush 80 to 90 storeys of an intact building anyway is too silly to waste time on.

You need to provide evidence to back up your assertions before they constitute anything serious.

You have not yet quantified 'rubble', so no intelligent point can be made either way.

I suggest you present your mathematics and evidence before further handwaving away all opposing viewpoints.

 

[Architect]

You know, I seem to recall that some clown - possibly Heiwa - tried to raise this very point some years ago (before his "block A/ block B" nonsense. IIRC Newton and myself spent some time explaining in technical terms that this was wholly impossible.

Ergo, can I suggest that you do some research before returning to this same old - and very tired - arena? Really, personally incredulity is no substitute for analysis and understanding. Or, dare I say it, professional expertise in relevant topics like structural engineering.

 

[Furcifer]

With all due respect to Heiwa, you don't need Heiwa to understand that a top-driven collapse (of a smaller something through its larger counterpart) won't work. However, I do credit him for bringing that point to public and popular understanding. It is not some kooky "Heiwa" theory. It is a description of Newton's Third Law in a gravitational collapse. It's elementary. It should be idiot-proof, but apparently it's not.

Oh you're absolutely correct, it's idiot proof.

This isn't some simple inelastic collision, where the rigid smaller upper section collides with the much larger lower section. You have the entire mass of the upper section available to overload each intact lower floor it comes in contact with.

It's perhaps best if you think of the upper section A as a block and the bottom section B broken up into it's individual floors, call them B₁, B₂....B_n where n is the lower most floor.

Only an idiot would consider the entire lower section as an intact block. Heiwa did and that's why he had so much trouble trying to figure things out.

 

[ergo]

Oh you're absolutely correct, it's idiot proof.

This isn't some simple inelastic collision, where the rigid smaller upper section collides with the much larger lower section. You have the entire mass of the upper section available to overload each intact lower floor it comes in contact with.

It's perhaps best if you think of the upper section A as a block and the bottom section B broken up into it's individual floors, call them B₁, B₂....B_n where n is the lower most floor.

Only an idiot would consider the entire lower section as an intact block. Heiwa did and that's why he had so much trouble trying to figure things out.

Both upper and lower sections of the building were built the same way -- except that the upper would be built of progressively lighter material, and also suffered all the fires. Point being that one is not a "block" while the other is merely "floors". They are both one or the other. Take your pick.

If one portion cannot handle the impact, then neither can the other. We see the upper block largely disintegrating. The impact it experiences (if we follow the Bazant/NIST scenario, and suspend our observation that in fact the upper block gets destroyed in mid air) is not just 15 floors on 90, but 90 floors on 15. The rubble supposedly created (and the volume that isn't ejected laterally) does not have the power to crush down the rest of the building because it is disassociated material. Sure, you could have floor failure, perhaps over several floors, but this wouldn't be able to tear down the entire building symmetrically, pulverizing all material, and at the rate of six floors per second. You would have a more organic, asymmetrical collapse where you could pretty easily see or at least tell what was happening.* You'd probably end up having floors caving in like they did in other buildings; floor assemblies hanging from the core, and you would have a much more significant core remnant that actually stayed standing and didn't disintegrate in mid-air 20 seconds after the rest.

I'm sure the rubble principle would be pretty easy to model, using a scale metal structure with a comparable height and framework with "floors" attached at both core and periphery, and dropping some debris of similar composition, or perhaps a bunch of rocks, onto the floors. See what happens to the structure.

 

[ergo]

* and by this I mean there wouldn't be nine-year-long debates going on about it. Just like there aren't nine-year-long debates about buildings that collapse from earthquakes or bombs or controlled demolition or other natural disasters. Collapses from those events follow expected modes of failure and nobody is surprised that the building behaves according to accepted principles of physics. These buildings do not and two government investigations contradicted each other about how they collapsed, and those with the technical qualifications to analyze it also disagree about the mode of collapse, with those who suggest that the government explanation is incorrect outnumbering the others.

An empiricist looks at the collapses, the observables, as Major Tom calls them, compares them to what is known about building collapses, and if there are anomalies, starts investigating those anomalies. Two government investigations have occurred about these anomalies. If there were no anomalies, why would there be investigations? The fact that there were two investigations commissioned is the recognition that the collapses did not follow expected failure patterns.

 

[femr2]

Ergo,

I have repeatedly shown you step by step the simple thing you simply will not understand.


I'll ask you a couple of very simple questions about a simple example. You answer them. By doing so, you'll understand...



1) 1 *floor* normally supports 100Kg
2) That floor WILL fail if you put 1000Kg on it.

Q) What will happen if you put 2000Kg on the floor ?

 

[Grizzly Bear]

* and by this I mean there wouldn't be nine-year-long debates going on about it. Just like there aren't nine-year-long debates about buildings that collapse from earthquakes or bombs or controlled demolition or other natural disasters.

Ergo, meet the flat earth society
Debating earth's 'flatness' since 1541

 

[excaza]

Is this going to be another thread where ergo says a rubble pile the size of the moon couldn't crush a building?

 

[Furcifer]

Both upper and lower sections of the building were built the same way -- except that the upper would be built of progressively lighter material, and also suffered all the fires. Point being that one is not a "block" while the other is merely "floors". They are both one or the other. Take your pick.

No. If you don't understand then try it this way, what was in motion and what wasn't? The entire upper block was in motion, the lower section wasn't.

If one portion cannot handle the impact, then neither can the other.

No,again this is just the wrong way to think about it. Ignore the Bazant model and the destruction of the upper block for a minute and simply consider what was moving. It's the upper block that has kinetic energy, it's this energy that destroys the lower, one floor at a time. The lower section was stationary and only designed to hold the upper block when it was stationary.

We see the upper block largely disintegrating. The impact it experiences (if we follow the Bazant/NIST scenario, and suspend our observation that in fact the upper block gets destroyed in mid air) is not just 15 floors on 90, but 90 floors on 15.

No, we have 15 floors falling on 1 floor at a time, over and over again. 15 floors moving meeting with 1 stationary floor. Floors below the impact zone can't lend any strength to the ones being pummeled by the 15 floors in motion.

For simplification purposes you could essentially lay out each of the lower floors and drop a 15 story section onto the first one, a 16 story onto the next and so on. That's the nature of a "cascade" failure.

The rubble supposedly created (and the volume that isn't ejected laterally) does not have the power to crush down the rest of the building because it is disassociated material. Sure, you could have floor failure, perhaps over several floors, but this wouldn't be able to tear down the entire building symmetrically, pulverizing all material, and at the rate of six floors per second.

No this is incorrect. I'm not sure where you learned this but it's wrong. "Disassociated" material as you call it still has MASS. Do you know any physics? Where does shape or rigidity come into the equations of motion? How does it affect kinetic energy or work? It doesn't, physics unlike the human mind doesn't distinguish between shape or consistency, a pound of feathers and a pound of lead, doesn't matter.

You would have a more organic, asymmetrical collapse where you could pretty easily see or at least tell what was happening.* You'd probably end up having floors caving in like they did in other buildings; floor assemblies hanging from the core, and you would have a much more significant core remnant that actually stayed standing and didn't disintegrate in mid-air 20 seconds after the rest.

Again this is just an artifact of the human mind. You believe because you want to the WTC was some solid monlithic entity. It wasn't, it was made up of millions of tiny pieces that all failed one after the other.

I'm sure the rubble principle would be pretty easy to model, using a scale metal structure with a comparable height and framework with "floors" attached at both core and periphery, and dropping some debris of similar composition, or perhaps a bunch of rocks, onto the floors. See what happens to the structure.

Some rocks? lol, these are boulders, hills and mountains, not rocks.

I can see you suffer from a common failing, that of scale. You should take a look into the effects and limitations of scaling. I think it would benefit you greatly.

 

[Furcifer]

Is this going to be another thread where ergo says a rubble pile the size of the moon couldn't crush a building?

"Another"? Oh man if I had known that I wouldn't have bothered.