WTC collapses - Layman's terms again

[DC]

"Linsen-dictung" - elliptical seal ring? Or is it a brand name? What kind of compressor was it?

Linsendichtung
it is a type of seal, not a brand.

and it was a K8 Hyper Compressor like this one.

btw this is not this compressor, there was no damage to the compressor, the damage you see in the articel i link to is not from a wrong installed seal

 

[SpitfireIX]

hi

you are correct

its indeed Cosmos, and deformation is not displayed corectly, i should have writen that under the picture, but i didnt want to show the deformation.
just wanted to illustrate that not only the most upper floor will be affected.
which i understood that some seem to belive

Frankly, your model doesn't illustrate any such thing. First, as has been noted, it's so grossly oversimplified as to be virtually worthless.

Second, it doesn't show any significant stress in any of the other floors, except at the floor "connections" of the one immediately below the top. And because you haven't actually modeled the connections, or used the proper materials, we can't draw any conclusions about that.

Third, as has been mentioned numerous times, and Minadin reiterated, the weak link in the entire structure is the floor-truss connections to the support columns. We know that these will fail first, but your model assumes that they won't fail, and grossly misrepresents the geometry of the contact area between the floors and the columns. Therefore the stresses shown in the other floors may or may not (most likely not) be accurate.

Finally, I'm not certain what you believe your model is supposed to prove. It seems as though you might think that if you've loaded the top floor with, say, 1,000,000 kgf, that not all of that force will affect the floor. But it will. Assuming the truss connections don't fail, there will be a a total of 1,000,000 kgf in the connections pushing against the support columns. However, by Newton's Third Law, there is also a total of 1,000,000 kgf in the support columns pushing back against the connections. Further, again assuming the connections don't fail, for the structure to be in static equilibrium, there will be 1,000,000 kgf at the bottom of the support columns pushing against the bedrock, and 1,000,000 kgf in the bedrock pushing back against the bottoms of the support columns. So the fact that additional stresses are shown in other parts of the model in no way proves that not all of the force of falling debris would affect the top floor.

Btw how is that job called in English?

My two-year degree from Indiana Vocation Technical College is in "mechanical design," and my job title is "mechanical designer."

 

[DC]

Frankly, your model doesn't illustrate any such thing. First, as has been noted, it's so grossly oversimplified as to be virtually worthless.

Second, it doesn't show any significant stress in any of the other floors, except at the floor "connections" of the one immediately below the top. And because you haven't actually modeled the connections, or used the proper materials, we can't draw any conclusions about that.

Third, as has been mentioned numerous times, and Minadin reiterated, the weak link in the entire structure is the floor-truss connections to the support columns. We know that these will fail first, but your model assumes that they won't fail, and grossly misrepresents the geometry of the contact area between the floors and the columns. Therefore the stresses shown in the other floors may or may not (most likely not) be accurate.

Finally, I'm not certain what you believe your model is supposed to prove. It seems as though you might think that if you've loaded the top floor with, say, 1,000,000 kgf, that not all of that force will affect the floor. But it will. Assuming the truss connections don't fail, there will be a a total of 1,000,000 kgf in the connections pushing against the support columns. However, by Newton's Third Law, there is also a total of 1,000,000 kgf in the support columns pushing back against the connections. Further, again assuming the connections don't fail, for the structure to be in static equilibrium, there will be 1,000,000 kgf at the bottom of the support columns pushing against the bedrock, and 1,000,000 kgf in the bedrock pushing back against the bottoms of the support columns. So the fact that additional stresses are shown in other parts of the model in no way proves that not all of the force of falling debris would affect the top floor.




My two-year degree from Indiana Vocation Technical College is in "mechanical design," and my job title is "mechanical designer."

when bazant do oversimpliefy its ok, but others are not allowed to, even when they only want to show that not ONLY the most upper stoery will be affected.

and again, my point was just to show that not ONLY the most upper floor is affected.
and the model nicely shows that, i didnt want to show to which degree other floors are affected, not did i want to show where the first connections will brake etc.

oc the most upper storey will be affected most. which is also shown in the model.

and when all the floortrusses failed first, what brought down the inner tube aka the core?

 

[SpitfireIX]

My two-year degree from Indiana Vocation Technical College is in "mechanical design," and my job title is "mechanical designer."

I just noticed a typo in this sentence, and I wanted to correct it, as I was responding to DC's question about the English equivalent of my job title, and I don't want to confuse any non-native English speakers.

The school where I got my degree is called Indiana Vocational Technical College (or rather it was; the school has recently re-styled itself a "Community College"). Most people still just call it by its semi-official nickname, though, "Ivy Tech," which is a play on "I. V. Tech."

 

[Belz...]

but nobody can be knowledgeable in everything

very true indeed

Then you admit that people with expertise on a subject are more likely to be correct on said subject than a layman ?

my position is that i want new independent investigations.

I'm pretty sure you wouldn't even know what that'd be. Who would fund this investigation and how would it be "independent" ?

And what results would satisfy you that didn't satisfy you with the previous ones ?

 

[AZCat]

Linsendichtung
it is a type of seal, not a brand.

and it was a K8 Hyper Compressor like this one.

btw this is not this compressor, there was no damage to the compressor, the damage you see in the articel i link to is not from a wrong installed seal

Thanks. Unfortunately I can't read German. I can look at the pictures, though. These are reciprocating compressors, right?

 

[padragan]

and again, my point was just to show that not ONLY the most upper floor is affected.
and the model nicely shows that, i didnt want to show to which degree other floors are affected, not did i want to show where the first connections will brake etc.

But what's your point? Are you saying that the impact would be spread out over all the floors so that in effect they all do their part of withstanding the impact? If so an even higher theoretical tower with 1000 floors would hold up much better, and surely you do not suggets that, do you?

I look at it as a chain, if you pull a chain the energy you use to pull affects every single link at the same time, and with full force. Every link needs to withstand the full force or break.

If we once again think of a hypothetical tower with different sections made of different materials I wouldn't be surprised to see the floor made out of glass to be the first to break even if it were well below the impact zone. However, that does not mean that the collapse in any way shape or form would stop. The floors on top of that one would just get a few extra meters of acceleration adding more energy, and if something else breaks on the way and stuff keep going down you will have stuff fail until the remaining structure could take all the impact coming down or the building have collapsed completely.

Now, in this case the building were not made out of different materials, and the lower down you get the thicker steel, therefore the weakest point when the collapse started would be the impact zone with all the fires. So I find it pretty natural that the upper floor of the lower part and the lower floor of the upper part tear each other appart in the process, but since part of the lower block lose it's integrity it will ALSO start falling down, adding more weight and energy. In fact I think that is how the collapse look like.

Now, I must also point out that this is just my layman thinking, I don't have any professional knowledge about collapsing buildings, I just found your reasoning about affected floors were strange. So please feel free to correct me if I misinterpreted you or made any flawed conclusions.

 

[funk de fino]

when bazant do oversimpliefy its ok, but others are not allowed to, even when they only want to show that not ONLY the most upper stoery will be affected.

and again, my point was just to show that not ONLY the most upper floor is affected.
and the model nicely shows that, i didnt want to show to which degree other floors are affected, not did i want to show where the first connections will brake etc.

oc the most upper storey will be affected most. which is also shown in the model.

and when all the floortrusses failed first, what brought down the inner tube aka the core?

If you look at photos of both towers during collapse you can see a large part of the core stood longer than the rest of the building. It stayed up for a while but all its support from the perimeter columns was lost when the floors broke away and it collapsed because it cannot stand on its own.

This is one of Heiwas junk ideas, that the core or perimeter could stand independantly of each other.

 

[SpitfireIX]

when bazant do oversimpliefy its ok, but others are not allowed to, even when they only want to show that not ONLY the most upper stoery will be affected.

Bazant and Zhou did not oversimply. They merely simplified. From their paper:

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. Unlikely though such a distribution may be, it is nevertheless the most optimistic hypothesis to make because the resistance of the building to the impact is, for such a distribution, the highest. If the building is found to fail under a uniform distribution of the impact forces, it would fail under any other distribution.[bolding mine]

In other words, they're taking the best-case scenario in favor of collapse prevention (which is also the simplest to calculate), and they demonstrate that collapse will occur even under those assumptions. There is no need to demonstrate the results of any other cases at that point.

and again, my point was just to show that not ONLY the most upper floor is affected.

And, for the reasons I stated, your model does not show this.

and the model nicely shows that, i didnt want to show to which degree other floors are affected, not did i want to show where the first connections will brake etc.

To reiterate, you can't draw any conclusions about this, both due to the inaccuracies in your model, and the fact that the connections would fail.

oc the most upper storey will be affected most. which is also shown in the model.

This is a trivial point, and should be self-evident without reference to a model.

and when all the floortrusses failed first, what brought down the inner tube aka the core?

As funk de fino stated, the core could not stand on its own without the bracing provided by the floors. Basically, the core columns eventually buckled under their own weight, due to eccentric loading. Think about how much torque even a 5 mph wind will cause at the top of a thousand-foot tall column.

 

[DC]

Thanks. Unfortunately I can't read German. I can look at the pictures, though. These are reciprocating compressors, right?

sorry

i cant find anything good in english thats for free :/

afaik in english it is a lens-seal.

a) Lens-seal
b) Pipes
c) Flange

it is a metal seal, mostly the same metal as the flanges(or pipe). the sealing area of the flange(or pipe) is konical and the sealing area on the seal has a radius.

indeed reciprocating compressors

but we are way OT now

 

[DC]

Bazant and Zhou did not oversimply. They merely simplified. From their paper:




In other words, they're taking the best-case scenario in favor of collapse prevention (which is also the simplest to calculate), and they demonstrate that collapse will occur even under those assumptions. There is no need to demonstrate the results of any other cases at that point.




And, for the reasons I stated, your model does not show this.




To reiterate, you can't draw any conclusions about this, both due to the inaccuracies in your model, and the fact that the connections would fail.




This is a trivial point, and should be self-evident without reference to a model.




As funk de fino stated, the core could not stand on its own without the bracing provided by the floors. Basically, the core columns eventually buckled under their own weight, due to eccentric loading. Think about how much torque even a 5 mph wind will cause at the top of a thousand-foot tall column.

Bazant and Zhou uses elementary calculations

to conclude that
the collapse of the majority of columns of one floor must have
caused the whole tower to collapse.

i used a simplified FE model to show something that i think some do not understand.
while it is also part of bazant's paper

For a short time after the vertical impact of the upper part, but
after the elastic wave generated by the vertical impact has propagated
to the ground, the lower part of the structure can be approximately
considered to act as an elastic spring @Fig. 2~a!#.
What is its stiffness C? It can vary greatly with the distribution of
the impact forces among the framed tube columns, between these
columns and those in the core, and between the columns and the
trusses supporting concrete floor slabs.

According to
this hypothesis, one may estimate that C 71 GN/m (due to unavailability
of precise data, an approximate design of column
cross sections had to be carried out for this purpose!.)

my very simplified model shows actually exactly this. and some jump on me like i lied or did "Fraudulent Modelling" or that i want to prove that the first floor would have arrested collapse, while i just showed one part of theyr paper in 3d.

i wonder how well some of you do understand the stuff you talk about in "non layman words"

and while i do not really want to agree with Heiwa about the outer "tube/cage" (the outher cage standalone theory seems a bit optimistic to me, i doubt the "stability" of the the "horizontal spandrel plates" that connected the perimeter columns horizontaly, for sure with wind and no glass)

i think (i dont claim,know nor can prove) the core would be able to stand on its own without the bracing provided by the floors.
the few remaining columns that did not collapse for a few seconds to not really count as "remain standing" for me.

 

[funk de fino]

i think (i dont claim,know nor can prove) the core would be able to stand on its own without the bracing provided by the floors.
the few remaining columns that did not collapse for a few seconds to not really count as "remain standing" for me.

It is a fact the core could not stand on its own. You do not have to think.

What you should think about is looking at the core that remained standing even after the rest of the collapse for a good while. It was not just a few columns and they were huge columns as the truther like to keep telling us.

The floors gave way, the perimeter columns peels from the building and then the core fell once it lost support. What do you think was the weakest part of the connections between the floor, perimter columns and core columns?

NIST has already explained the collapse in laymans terms. If you do not believe it then prove it wrong. Many have tried and failed.

Heiwas paper is junk, if your gonna back a longshot you should choose better next time.

 

[DC]

But what's your point? Are you saying that the impact would be spread out over all the floors so that in effect they all do their part of withstanding the impact? If so an even higher theoretical tower with 1000 floors would hold up much better, and surely you do not suggets that, do you?

the impact would indeed sort of beeing spread out(like in a spring), but i dont want to agree on the higher tower
because this does not mean the tower can resist, every "spring" has its limits.

I look at it as a chain, if you pull a chain the energy you use to pull affects every single link at the same time, and with full force. Every link needs to withstand the full force or break.

a chain, would be exactly the opposite,
in the tower example , that would be like after the failure of the remaining columns. the top part would go into the other direction.
would that have happened, we all would agree that law of physics was violated or have to be reconsidered.

If we once again think of a hypothetical tower with different sections made of different materials I wouldn't be surprised to see the floor made out of glass to be the first to break even if it were well below the impact zone. However, that does not mean that the collapse in any way shape or form would stop. The floors on top of that one would just get a few extra meters of acceleration adding more energy, and if something else breaks on the way and stuff keep going down you will have stuff fail until the remaining structure could take all the impact coming down or the building have collapsed completely.

Now, in this case the building were not made out of different materials, and the lower down you get the thicker steel, therefore the weakest point when the collapse started would be the impact zone with all the fires. So I find it pretty natural that the upper floor of the lower part and the lower floor of the upper part tear each other appart in the process, but since part of the lower block lose it's integrity it will ALSO start falling down, adding more weight and energy. In fact I think that is how the collapse look like.

in your example of the chain, its like a chain that starts with thick chain-segments and goes over to thinner chainsegments.
the thicker chainsegments would with great propability survive.
but in the case of a collapse they would give more resistance, but theyr surviving is nto so sure, some claims they would some claim the coudnt.
we saw they didnt survive, now we sit here an fight about why simplified spoken.

Now, I must also point out that this is just my layman thinking, I don't have any professional knowledge about collapsing buildings, I just found your reasoning about affected floors were strange. So please feel free to correct me if I misinterpreted you or made any flawed conclusions.

therefor this layman terms topic seems a good place for us 2
i also have no professional knowledge about collapses
i didnt want to show that the lower floors would have halted the collapse, i just wanted to illustrate that the lower floors would be affected, because i think that some didnt know that, and some didnt know.
but this fact must not neceserely mean that a collapse have to be halted.

 

[DC]

It is a fact the core could not stand on its own. You do not have to think.

didnt expect to read that from a JREFer^^

What you should think about is looking at the core that remained standing even after the rest of the collapse for a good while. It was not just a few columns and they were huge columns as the truther like to keep telling us.

The floors gave way, the perimeter columns peels from the building and then the core fell once it lost support. What do you think was the weakest part of the connections between the floor, perimter columns and core columns?

NIST has already explained the collapse in laymans terms. If you do not believe it then prove it wrong. Many have tried and failed.

Heiwas paper is junk, if your gonna back a longshot you should choose better next time.

i have troubles with that lost support.
how much did the core support the building? didnt i read, 60%? not sure anymore.
but standing alone is not possible?

and thats a fact?

what exactly makes that a fact pls?

 

[DC]

Originally Posted by Dictator Cheney :
and again, my point was just to show that not ONLY the most upper floor is

affected.

Originally Posted by SpitfireIX :
And, for the reasons I stated, your model does not show this.

does it show that ONLY the most upper floor is affected?

 

[DGM]

Why is it the people that argue the strongest about how a building should perform know the least about the subject?

DC If you have kids grab their Lego's and build a single block width tower 20 feet tall. Hey one stands on top of the other. Why wouldn't 300 of them do the same thing? (Hint= Buckling) Core "blocks" do the same thing.

 

[DC]

It is a fact the core could not stand on its own. You do not have to think.

What you should think about is looking at the core that remained standing even after the rest of the collapse for a good while. It was not just a few columns and they were huge columns as the truther like to keep telling us.

The floors gave way, the perimeter columns peels from the building and then the core fell once it lost support. What do you think was the weakest part of the connections between the floor, perimter columns and core columns?

NIST has already explained the collapse in laymans terms. If you do not believe it then prove it wrong. Many have tried and failed.

Heiwas paper is junk, if your gonna back a longshot you should choose better next time.

what exactly is junk in his paper, beside that it is not "peer-reviewed" and that it is not agreeing with other "experts".

what exactly are his lies?

 

[funk de fino]

didnt expect to read that from a JREFer^^

People here quite often give truthers facts. The problem is the truthers ignore them.

i have troubles with that lost support.
how much did the core support the building? didnt i read, 60%? not sure anymore.
but standing alone is not possible?

and thats a fact?

what exactly makes that a fact pls?

In simple terms, what was the design of the towers? It will give you a clue.

The core could not stand on its own. If you disagree then show me how it could and back it up. Your thoughts or beliefs matter little as you have shown us you are no expert.

 

[funk de fino]

what exactly is junk in his paper, beside that it is not "peer-reviewed" and that it is not agreeing with other "experts".

what exactly are his lies?

nearly every claim, i will list them one by one tomorrow if you like

 

[Minadin]

didnt expect to read that from a JREFer^^


i have troubles with that lost support.
how much did the core support the building? didnt i read, 60%? not sure anymore.
but standing alone is not possible?

and thats a fact?

what exactly makes that a fact pls?

The core columns were not designed to withstand the overturning moment of wind loads on their own. They needed the floors and the exterior column wall to stand. Furthermore, without the floors there for bracing, the effective length, and thereby, slenderness ratio of the core columns is increased. (Layman's terms: bad thing)

Picture this, if you will. Let's say that you have a length of dowel rod about 8mm thick and 150mm long. It's a pretty sturdy little piece of wood, such as might be suitable for any number of hobby / craft type of projects, right? What happens if you increase the length to 50cm? 1 meter? 10 meters? Before long, it becomes so flimsy that you can't even hold it up straight without the top whipping all around. Eventually, it will break on its own just from the weight of the length.

If the case of the WTC core sections that stood for a few seconds after the rest of the building had collapsed, keep in mind that they had just suffered from severe jarring during the collapse, were no longer braced, and were now subject to new loads that they were not designed to handle.