NIST doesnt release their computer models (now they've done it!)

[AZCat]

Tabouère, your English is unintelligible.

Could you write your last paragraph in French so I could try to translate?

Thanks for offering this, Pardalis - I was having great difficulty understanding his/her posts.

 

[tabouere]

People can't understand it because you continue to contradict yourself. It's difficult to take people seriously and follow their train of thought when they contradict themselves. I believe, therefore, that the lack of understanding is solely your fault.

Theory and speculation are two completely different things- and if you are trying to claim that the application of the laws of physics are not fact or proof, then you are miles away from having a valid point.

Powder and little rocks didn't bring down the building- that is a strawman. The "powder and little rocks" are a result of the building being brought down.

The speed of the fall is an aproximation done with a formula. To calculate the momentum of an impact, this data is required, when you add data that are not based on direct observation in an equation, the result is not a fact. And in their equation, they forgot many data like the lost of mass in powder, the fact that de concrete will be reduce to small rocks and the momentum of many rocks falling is really different with the momentum of a solid block falling.

My point is simple, their simulation of the collapsed is based on partial reconstruction and computer model, it's not truth, the result depend on the maths behind the computer model and the datas provided to the computer model.

 

[AZCat]

And in their equation, they forgot many data like the lost of mass in powder, the fact that de concrete will be reduce to small rocks and the momentum of many rocks falling is really different with the momentum of a solid block falling.

No, it isn't different. The relationship between mass and momentum is linear so any "system of masses" is going to have the equivalent momentum of a system containing a single mass of the same quantity if the two systems are travelling at the same speed.

 

[tabouere]

Tabouère, your English is unintelligible.

Could you write your last paragraph in French so I could try to translate?

Je suis désolé, je suis fatigué à soir, dure journée

je répète

And the energy that you talk about is for the first impact, it could be true because the upper part was in one piece, so it hit whit all his mass, but after many impact, only steel debris, powder and small concrete rock left no math or physic is required to notice, open your eyes. Nothing else is needed. Powder and debris don't bring down building completly.

L'énergie dont parle beachnut est l'énergie du premier impact, et c'est probablement vrai, car la partie supérieure était en un morceau, alors elle a frappé avec toute sa masse la partie inférieure. Mais après plusieurs impacts, cette partie supérieure n'est plus en un morceau, elle est composée de débris d'aciers, de morceaux de bétons et de béton en poudre. On a pas besoin de mathematic ou de physique pour se rendre compte de ça, on ouvre nos yeux et on regarde. De la poudre et des débris, ça fait pas tomber un building jusque dans ses fondations.

 

[tabouere]

No, it isn't different. The relationship between mass and momentum is linear so any "system of masses" is going to have the equivalent momentum of a system containing a single mass of the same quantity if the two systems are travelling at the same speed.

It will be true if all the debris hit at the very same moment.

 

[T.A.M.]

My point is simple, their simulation of the collapsed is based on partial reconstruction and computer model, it's not truth, the result depend on the maths behind the computer model and the datas provided to the computer model.

I think we get this point. I think others have tried to explain that computer models are what engineers and scientists use for this type of thing. You really cannot do any better. As others have said, a scale model is not only impractical, but not likely as accurate, due to the variability in so many aspects of the impact, that would make repeatability difficult.

TAM

 

[AZCat]

It will be true if all the debris hit at the very same moment.

If I understand you correctly then you're talking about impact dynamics (not the same thing and quite a bit more complicated) rather than just comparisons of the momentum of systems.

 

[Pardalis]

L'énergie dont parle beachnut est l'énergie du premier impact, c'est probablement vrai car la partie supérieure était en un morceau alors elle a frappé avec toute sa masse la partie inférieure. Mais après plusieurs impacts, cette partie supérieure n'est plus en un morceau, elle est composée de débris d'aciers, de morceaux de bétons et de béton en poudre. On a pas besoin de mathematic ou de physique pour se rendre compte de ça, on ouvre nos yeux et on regarde. De la poudre et des débris, ça fait pas tomber un building jusque dans ses fondations.

OK, so here's my attempt at a translation:

"The energy Beachnut is talking about is the energy from the first impact. The upper section was in one piece, and it hit with all its mass the lower section. But, after a couple of impacts, this upper section wasn't in one piece anymore, but composed of steel debris, chunks of concrete and also concrete powder. We don't need math or physics to see that, you just have to open your eyes and look. Powder and debris don't make buildings collapse down to the ground."

Still doesn't make any sense to me.

 

[T.A.M.]

I think he is trying to make the point that once the top section began to break up, and was nothing more that broken apart debris, it did not have the "consistency" the fortitude, to destroy the remainder of the building below it...

kind of like hitting a nail with a hammer. if half way through the strike, the hammerhead turns to powder, it will not continue to drive the nail into the wood.

TAM

 

[Slayhamlet]

OK, so here's my try at a translation:

"The energy Beachnut is talking about is the energy from the first impact. The upper section was in one piece, and it hit with all its mass the lower section. But, after a couple of impacts, this upper section wasn't in one piece anymore, but composed of steel debris, chunks of concrete and also concrete powder. We don't need math or physics to see that, you just have to open your eyes and look. Powder and debris don't make buildings collapse down to the ground."

Still doesn't make any sense to me.

I think you forgot to set your translator to "Woo-woo".

 

[tabouere]

If I understand you correctly then you're talking about impact dynamics (not the same thing and quite a bit more complicated) rather than just comparisons of the momentum of systems.

It's possible.

Ok let's make a drawing(it's word to word translation)

If I throw rocks one by one on top of a building, nothing will happen.

If I take all the rock that I've thrown, I fuse them in one giant rock and let it fall on the building, the result will be different.

It's magic

 

[Slayhamlet]

I think he is trying to make the point that once the top section began to break up, and was nothing more that broken apart debris, it did not have the "consistency" the fortitude, to destroy the remainder of the building below it...

kind of like hitting a nail with a hammer. if half way through the strike, the hammerhead turns to powder, it will not continue to drive the nail into the wood.

TAM

Well, if that is what he's trying to say, he's wrong. Spectacularly wrong.

 

[T.A.M.]

It's possible.

Ok let's make a drawing(it's word to word translation)

If I throw rocks one by one on top of a building, nothing will happen.

If take all the rock that I've thrown, I fuse them in one giant rock and let it fall of the building, the result will be different.

Even if this were true (which I doubt) , you still have no proof that the top section desintigrated anywhere close to the top of the collapse...after 1-2 seconds, the entire area is blocked out by dust and smoke...

TAM

 

[Pardalis]

Essaye donc ça en français voir?

 

[AZCat]

I think we get this point. I think others have tried to explain that computer models are what engineers and scientists use for this type of thing. You really cannot do any better. As others have said, a scale model is not only impractical, but not likely as accurate, due to the variability in so many aspects of the impact, that would make repeatability difficult.

TAM

A scale model in this case is not only impractical or inaccurate, it would not be representative of the physical behavior of the towers during collapse.

The problem is a common one. With respect to the collapse of the towers and the behavior of the structure, we care about (among other things) a particular engineering metric known as "stress", with units of force per unit area (such as pounds per square inch). Force is mass times acceleration, and mass is volume times density, so Force is volume times density times acceleration. Volume is a quantity that, if our model is scaled by some factor "x", would be modified by "x" to the third power (because the scaling factor affects three dimensions). This means that forces in our model are modified by x-cubed. The unit area used in determining stress would be modified by x to the second power (because the scaling factor affects two dimensions), so our stress calculation will be modified by x-cubed (for the force) divided by x-squared (for the unit area). This means that stresses in the model will be modified by a factor of "x". In other words, if we produce a 200:1 scale model of the towers, the stresses in the structure of the model would be 1/200th of their real-world equivalents. Severing the connections at a particular point in the model tower (the 85th floor, for example) and studying the response of the structure will grant no insight to the behavior of the actual towers, because the stresses are not at all the same. In order to recreate the structural response, the density of the materials used in the model would have to be increased by a factor of 200 without changing the material responses to stress - a feat I seriously doubt is possible.

This is why engineers like "virtual" models - they can build things to scale.

 

[tabouere]

Essaye donc ça en français voir?

Si je laisse tomber des roches une par une(peu importe le temps écoulé entre chaque lancer) sur le dessus d'un batiment, rien ne va se passer, le batiment va rester en place intact.

Si je reprend toutes les roches que j'ai lancer, que je fais une grosse roche avec le tas, puis je le laisse tomber sur le dessus du building, le résultat va être différent. L'endroit toucher pourrait ceder. Pourtant il a été touché par la même masse en chute libre, la seule différence, c'est que dans un cas, c'était des impacts multiples de petites envergures et dans l'autre, un seul impact.

 

[AZCat]

It's possible.

Ok let's make a drawing(it's word to word translation)

If I throw rocks one by one on top of a building, nothing will happen.

If I take all the rock that I've thrown, I fuse them in one giant rock and let it fall on the building, the result will be different.

It's magic

As I said - you're talking about impact dynamics, not momentum comparisons.

 

[Pardalis]

Tabouère, the top section didn't disintegrate on impact.

 

[T.A.M.]

The top section did eventually "disintigrate" or fair near did, leaving steel beams and smaller pieces of concrete etc, but I doubt it did so until well near the end of the collapse, at the very least, I suspect it made it, in some form, at least half way down...but I have no proof either, so it is speculation.

TAM

 

[Totovader]

The speed of the fall is an aproximation done with a formula.

Huh? Says who?

To calculate the momentum of an impact, this data is required, when you add data that are not based on direct observation in an equation, the result is not a fact.

What data? What are you talking about? Are you trying to say that equations are not facts? That's utterly ridiculous.

And in their equation, they forgot many data like the lost of mass in powder, the fact that de concrete will be reduce to small rocks and the momentum of many rocks falling is really different with the momentum of a solid block falling.

You lost me, here. If their equation is wrong, then it would not be a fact- but you cannot claim that all equations are not facts and then turn around and claim that this equation (whatever you're referencing) is double-wrong because it's also missing pieces.

I have no idea what equation you're referencing, however- and I have no idea what you're talking about.

We were talking about models...

My point is simple, their simulation of the collapsed is based on partial reconstruction and computer model, it's not truth, the result depend on the maths behind the computer model and the datas provided to the computer model.

I'm not even sure what you're saying- but you need to provide evidence for your claims, instead of just attempting to toss out science altogether. Baby with the bathwater, here...

This would be no different than me saying it's impossible for you to understand the NIST because our language is just so fundamentally flawed that the ideas cannot be understood by anyone. It's sophistry- and utterly ridiculous.