Moderated Continuation - Why a one-way Crush down is not possible

[aggle-rithm]

It seems everyone agrees that momentum is conserved in a 'closed' system. So what 'closed' system are we talking about? Upper part C alone? It is the allegedly moving assembly of elements, each with a mass, that, when displacing due to gravity, impacts lower part A, another assembly of elements with masses. Part C is evidently subject to external force - gravity - and its momentum is therefore increasing all the time during free fall until impact, BANG. So part C is not a 'closed' system.

At impact part A evidently applies new forces on part C - again modifying the momentum of part C.

Is part A a 'closed system'? Prior impact it was in static equilibrium and not moving at all. Its momentum was therefore zero. Why was part A not moving? Evidently becase it was attached to part E(arth)! Part E has almost infinite mass compared with parts A and C.

Are parts C and A together, after impact, a 'closed' system? Evidently not as part E applies an external force on it, i.e. on part A.

Are parts C, A and E a 'closed' system? Answer is no! Parts S(un) and M(oon) apply forces on it! A 'closed' system only exists to simplify, e.g. analysis of solid mechanics problems, where you just ignore external forces.

Anyone suggesting that part A is squeezed like a lemon between two bodies, parts C and E, due to gravity forces and conservation of momentum and pressed into a part B - rubble - has not understood basic physics.

You can obfuscate all you want, but the laws of physics will continue to operate as they always have, and not the way you wish them to.

 

[Dave Rogers]

I have done it several times, did you miss it? When a floor element in the WTC is overloaded for any reason, it - the element - or one of its connections to other elements fails. It is a local failure. It is step one in classical structural damage analysis. Step two is to find out what happens next.

So, since you've consistently refused to go as far as step two, how can you possibly conclude that collapse is arrested at any point? There's a fundamental contradiction in your claims; you claim that detailed damage analysis is necessary to determine whether or not a structure collapses, and at the same time you claim to know that the structure cannot collapse despite never having done detailed damage analysis.

Dave

 

[BasqueArch]

A floor is a secondary element of the tower structure. It (its trusses) carries load to the primary structure - the columns.
The floor is rated to carry 30 psf with a FoS 3.33, i.e. it can carry 100 psf.

If you overload the floor with say 300 psf lose items, e.g. scrap, you will locally damage it! The floor (truss) itself may break in the middle and the lose items flow down on the floor below through the opening in the floor. Or the floor may break its connection at an outside wall, floor drops down on next floor and lose items may flow out through the window there.

Evidently the columns are not damaged, when you overload a floor.

This is one reason why a one-way crush down of a structure with primary and secondary elements connected to one another cannot take place.

It doesn’t matter why you believe a “one-way crush down” is not possible. Your hypothesis is contradicted by the visual facts and is therefore wrong.

Visual Facts For What Happened: ONE. Perimeter columns gradually buckled and collapsed at the failed floors. TWO. Floor slabs subsequently collapsed inside the perimeter and core columns. THREE. Perimeter and core columns, not crushed nor exploded, subsequently toppled to the ground.

Audio/Visual Facts For What Didn’t Happen: ONE. No expected CD loud detonation sounds. TWO. No evidence for expected explosives/thermite damage to columns or spandrel plates. Evidence of large sections of connected, unexploded, unshattered toppled core and perimeter columns. THREE. CD explosives-ejected perimeter columns should have outdistanced the dust cloud behind them, they did not.
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You can't reason someone out of something he was never reasoned into. - Swift

 

[stateofgrace]

I have done it several times, did you miss it? When a floor element in the WTC is overloaded for any reason, it - the element - or one of its connections to other elements fails. It is a local failure. It is step one in classical structural damage analysis. Step two is to find out what happens next.

So when one floor is overloaded by weight in excess of six floors it fails and falls onto the next floor. So what happens to the next floor?

What happens to a floor that is now subject to a dynamic weight in excess of six floors plus the floor that as just failed?


Is the next floor also subject to "local failure" ?

 

[Justin39640]

Of course you didn't.

So what happens to a floor that cannot take more take the dynamic weight of six floors if more that six floors fall on it ?

i would love to hear that answer
its quite simple (even i understand it)

follow up question
what happens to the floor under that when the 7+ floors fall on it?
etc
etc
etc

 

[Heiwa]

Pure, unadulterated BS. The reaction force is matched by a downward force on A; that is Newton's Third. The force exerted on A by C matches the force exerted on C by A. All the arresting forces you've suggested are matched by compressive forces on A, and we know that they're enough to collapse A. Unless you can come up with a force that wasn't transmitted through A - and it's impossible that you could - then you're simply blowing smoke.

Dave

No, the impact force that C applies on A is matched by an impact reaction force that A applies on C. There is no arresting force!

This impact reaction force that A applies on C according Newton 3 can result in:

C bounces on A (it is kind of an arrest)

C is damaged in contact with A (is is also kind of an arrest)

C is simply stopped by A due to mutual damages, friction, etc. (yes, arrested and the force assisted).

In no case can the impact reaction force that A applies on C damage A.

What really happens depends on the structures and masses of C and A. Are the structures same and the mass of C less than that of A, C may bounce, be damaged or stopped by A.

In no case C can one-way crush A. It is really embarrassing that you have still not understood this simple FACT.

 

[Heiwa]

So, since you've consistently refused to go as far as step two, how can you possibly conclude that collapse is arrested at any point? There's a fundamental contradiction in your claims; you claim that detailed damage analysis is necessary to determine whether or not a structure collapses, and at the same time you claim to know that the structure cannot collapse despite never having done detailed damage analysis.

Dave

??? I have explained steps 2, 3, etc., several times but you can read my paper at http://heiwaco.tripod.com/nist3.htm to refresh your mind.

There is no fundamental contradiction there!

OTOH, NIST's and Bazant's reports are full of fundamental contradictions! You'll find them in my paper.

 

[Tony Szamboti]

Tony and Heiwa,

I have asked a quite civil question, which as been ignored maybe it was because it was not grammatically correct, so I will ask it again.

NIST as stated that the WTC’s floors could only support six floors when this weight is applied suddenly.

Can you please explain what will happen to a floor in the WTC when this dynamic weight is exceeded?

Thank you.

Of course, if six floors in unison did pounce on one floor it would collapse as a unit.

Is that what you think happened?

 

[tfk]

The momentum of the bicyclist was reduced to zero, when friction force was applied to the bicyclist.

.
Let the "Heiwa games" begin.

Are you saying that the bicyclist's momentum is NOT transferred to the earth during the time interval in which he is skidding to a stop?

If F₁(t) is the arbitrary force applied to the bicyclist over the interval, and F₂(t) is the force that the bicyclist applies to the earth over that same interval, do you deny that:

F₂(t) = -F₁(t)

If F₂(t) = -F₁(t), do you deny that the impulse that the earth applies to the bicyclist is exactly equal & opposite to the impulse that the bicyclist applies to the earth?

If the bicyclist applies exact the same impulse to the earth that the earth applies to the bicyclist, do you deny that the momentum change of the earth is exactly equal & opposite to the momentum change of the bicyclist that happens during, and as a result of, this collision?

Do you deny that the TOTAL momentum of the bicyclist/earth system is conserved during this collision?

Tom

 

[tfk]

The momentum of the bicyclist was reduced to zero, when friction force was applied to the bicyclist.

.
Simple question, simple answer.

Are you saying that the bicyclist's momentum was NOT transferred to the earth?

___

For the record, Newton's 3rd law REQUIRES that momentum be ALWAYS conserved for any and all interactions. From subatomic particles to galaxies.

As long as you consider the momentum of ALL the interacting components.

Your song & dance makes you look foolish.

tk

 

[Heiwa]

.
Simple question, simple answer.

Are you saying that the bicyclist's momentum was NOT transferred to the earth?

___

For the record, Newton's 3rd law REQUIRES that momentum be ALWAYS conserved for any and all interactions. From subatomic particles to galaxies.

As long as you consider the momentum of ALL the interacting components.

Your song & dance makes you look foolish.

tk

I am happy that you acknowledge Newton 3!

Thus, when the bicyclist (or WTC upper part C) contacts ground (lower part A) friction force stops the bicyclist. An outer force is applied on the bicyclist system, which affects its momentum.

It means that the momentum of the bicyclist is reduced and becomes zero - due to friction. Same should happen to WTC upper part C if impacting lower part A.

The bicyclist furthermore cannot one-way crush the ground, when the bicyclist drops for obvious reasons, e.g. too little energy and momentum involved, the bicyclist cannot apply the energy without damaging itself, etc, etc. Same rules apply to WTC 1 parts C and A.

According tfk/NWO physics it seems the bycyclist shall start to produce rubble in contact with ground (a new system is created), that this rubble is compacted and that then the rubble (!) produces a one-way crush down of the ground below. It does not happen in the real world as everyon knows! Just go cycling and drop off your bike and you'll find it out the hard way.

 

[Dave Rogers]

In no case can the impact reaction force that A applies on C damage A.

That's obvious. However, there is no reason whatsoever that the impact force that C applies on A, which is equal and opposite to the reaction force that A applies on C, cannot damage A. If you doubt that, drop a marble on an egg some time. If the impact force exceeds the ultimate strength of A, then damage will result.

Dave

 

[Dave Rogers]

??? I have explained steps 2, 3, etc., several times but you can read my paper at http://heiwaco.tripod.com/nist3.htm to refresh your mind.

This is deliberate obfuscation. At no point have you carried out detailed damage analysis. Your claims are therefore contradictory.

Dave

 

[stateofgrace]

Of course, if six floors in unison did pounce on one floor it would collapse as a unit.

Is that what you think happened?

So when one floor is overloaded by weight in excess of six floors it fails and falls onto the next floor. So what happens to the next floor?

What happens to a floor that is now subject to a dynamic weight in excess of six floors plus the floor that as just failed?

Is the next floor also subject to "local failure" ?

So what happens after the first floor fails Tony ?

or are you suggesting it does not fail? Is that what you think happened ?

 

[Heiwa]

This is deliberate obfuscation. At no point have you carried out detailed damage analysis. Your claims are therefore contradictory.

Dave

See part V of http://heiwaco.tripod.com/nist3.htm what you and I would expect to happen when WTC 1 upper part C impacts WTC 1 lower part A due gravity. There are no contradictions there. Weaker part C is arrested/damaged by stronger part A. Happens in every gravity collision between similar structures and when C is smaller than A.

 

[Dave Rogers]

See part V of http://heiwaco.tripod.com/nist3.htm what you and I would expect to happen when WTC 1 upper part C impacts WTC 1 lower part A due gravity.

That paper contains no detailed damage analysis. In fact, it doesn't even contain a credible attempt to model the real structure of the towers, without which detailed damage analysis is impossible. Therefore, your claim that the towers would not collapse is based on no detailed damage analysis, which contradicts your insistence that the behaviour cannot be predicted without detailed damage analysis. Your sole basis for your conclusion that the towers should not collapse is your starting assumption that no such structural collapse can occur, an assumption that has been shown to contradict real-world collapses. Therefore your analysis is worthless.

Dave

 

[stateofgrace]

See part V of http://heiwaco.tripod.com/nist3.htm what you and I would expect to happen when WTC 1 upper part C impacts WTC 1 lower part A due gravity. There are no contradictions there. Weaker part C is arrested/damaged by stronger part A. Happens in every gravity collision between similar structures and when C is smaller than A.

The weaker part is the floor directly below the falling dynamic weight, which is in excess of six floors

So what happens to the next weaker part ? The floor directly below the floor that you class as being subject to " local failure" ?

Is the next floor also subject to "local failure"?

What is you mechanism that stops the floors from " local failures" ?

Please provide a detailed analysis of the precise events that leads to floors that an unable to support the dynamic weight of six times their own weight that shows how the floors can do this and arrest the collapse.

 

[Heiwa]

That paper contains no detailed damage analysis. In fact, it doesn't even contain a credible attempt to model the real structure of the towers, without which detailed damage analysis is impossible. Therefore, your claim that the towers would not collapse is based on no detailed damage analysis, which contradicts your insistence that the behaviour cannot be predicted without detailed damage analysis. Your sole basis for your conclusion that the towers should not collapse is your starting assumption that no such structural collapse can occur, an assumption that has been shown to contradict real-world collapses. Therefore your analysis is worthless.

Dave

Well, my 3-D structural analysis in part V is more detailed than the one-dimensional analysises reviewed in previous parts I to IV of my paper. And with present FEA tools it is quite easy to do a detailed analysis of any structure A with a part C on top and then disconnect part C and drop it on A to confirm that C cannot one-way crush down A.

As a lot of steel/composite structures of all kinds are designed in the USA using FEA of all sorts today, it is thus very easy to confirm what I have already concluded.

NIST even suggests that structures can be completely destroyed without dropping part C on A, i.e. just remove one element in A and - POUFF - A is destroyed by multiple, progressive failures in all directions even resulting in free fall of big sub-assemblies of part A!!! See http://heiwaco.tripod.com/nist7.htm for an example of such NIST nonsense!

 

[aggle-rithm]

... it is quite easy to do a detailed analysis of any structure A with a part C on top and then disconnect part C and drop it on A to confirm that C cannot one-way crush down A.

In your simplistic view of the universe, in which momentum vanishes into nothingness and all structures of all shapes and sizes behave exactly the same, I imagine it would be easy. Especially when you can redefine your terms at will to allow reality to fall into place with your ideals -- in your mind, at least.

Most people who deal professionally with momentum and structures, however, have to contend with the universe we've got, and the laws it imposes on us.

 

[Dave Rogers]

Well, my 3-D structural analysis in part V is more detailed than the one-dimensional analysises reviewed in previous parts I to IV of my paper. And with present FEA tools it is quite easy to do a detailed analysis of any structure A with a part C on top and then disconnect part C and drop it on A to confirm that C cannot one-way crush down A.

As a lot of steel/composite structures of all kinds are designed in the USA using FEA of all sorts today, it is thus very easy to confirm what I have already concluded.

Again, you're dodging the issue. You've said it's impossible to predict the behaviour of the structure correctly without carrying out detailed damage analysis. You haven't done any damage analysis. You've predicted the behaviour of the structure. By your own criteria, your prediction is worthless. That's all there is to it.

Your 3-D analysis may or may not be more detailed; lacking a realistic model of the structure, it can't possibly be accurate, or even relevant. Nor is it relevant to point out that damage analysis is possible; that doesn't change the fact that you haven't done it.

Dave