Why a one-way Crush down is not possible

[alienentity]

And once again I think this exchange illustrates why guys who ACTUALLY build tall skyscrapers, notably the chief structural engineer of the WTC itself, Leslie Robertson, have signed off on the conventional understanding of the fire-driven collapses, and the guys who do NOT have these qualifications but have an emotional agenda think it was controlled demolition.

Thanks for playing, but I'll go with the chief SE on this one.

 

[Tony Szamboti]

Pot to kettle, pot to kettle (cough! nanothermite cough!controlled demolition! cough!)

What a hypocrite.

The rate of change of velocity is acceleration. There was loss of acceleration relative to freefall, because of the structural resistance. There's your lost velocity Tony. You can't see it because it's too obvious for you.

You can't even get your terms right.

Right here you say there was loss of acceleration relative to freefall because of structural resistance and want to say that is velocity loss. That isn't a velocity loss. You can't lose velocity you never had due to a restricted acceleration.

An example of velocity loss would be if something was accelerating at 0.7g and after 12 feet it was moving at 23 feet/second and then hit an obstacle and transferred some of it's kinetic energy and slowed to 10 feet/second.

What you are describing is that the thing could not accelerate at a rate beyond 0.7g because of resistance.

These two situations are not the same.

 

[bill smith]

There you have it folks. Tony has safely tucked away the engineering community from his sacred knowledge by these logical contortions:

1) Most engineers haven't looked into it, but presumably would eagerly endorse Mr. Szamboti's pet theories, if they only had the chance.
2) They wouldn't dare contradict a government report, so it's pointless for Mr. Szamboti to send leading firms or experts his work for evaluation.

Either way, Tony hopes to inoculate himself from the obvious problem that the greater scientific and engineering communities are ignoring his theories. I guess it makes him feel better, but it does make him look rather foolish.

Maybe you should listen to what this Top European demolition expert has to say on the sbject of why many firms and individuals do not speak out in America. Just as Tony said actually if you didn't have your head in your sand..
http://www.youtube.com/watch?v=QajDxF9uEf4 (loud volume)

 

[Tony Szamboti]

There you have it folks. Tony has safely tucked away the engineering community from his sacred knowledge by these logical contortions:

1) Most engineers haven't looked into it, but presumably would eagerly endorse Mr. Szamboti's pet theories, if they only had the chance.
2) They wouldn't dare contradict a government report, so it's pointless for Mr. Szamboti to send leading firms or experts his work for evaluation.

Either way, Tony hopes to inoculate himself from the obvious problem that the greater scientific and engineering communities are ignoring his theories. I guess it makes him feel better, but it does make him look rather foolish.

Not at all. A number of structural engineers have seen the paper. Dr. Bazant himself was sent a link to the paper as well as others. I obviously didn't write it to hide it, so your little silly taunt is proven to be just that.

 

[Tony Szamboti]

As has been explained to you before this applies only to a static condition in which the building is intact. How strong is a column once it's buckled? How strong is a column when you apply the same load outside of its vertical plane? Just why do you that accidental loads are so dangerous to built structures?

It isn't the strength of the column once it is buckling, it is the pre-buckling strength that accounts for a large part of the energy loss in deforming the columns.

The loads of the upper block weren't applied outside of it's vertical plane.

You seem fond of this assertion despite having having absolutely no basis for it. Since you seem to have your own practice of determining whether a load was present or not why don't you take a moment to explain it? What does one have to do to prove the existence of a dynamic load according the known architectural and engineering practices?

Deceleration of the impacting object beyond the rate of gravity and a velocity loss would prove a dynamic load took place. Otherwise the load can only be considered static.

 

[alienentity]

'What you are describing is that the thing could not accelerate at a rate beyond 0.7g because of resistance.

These two situations are not the same. '

Oh but they are. You just can't detect the small changes in velocity (due to limitations of video frame rates and resolution etc), so you pretend they didn't happen.

You employed a method in your missing jolt paper which failed to detect what you presumed was there. That's all.

Now if only you had proof positive of explosives, which you don't, you might be onto something. But even you admit that (in your own scenario) the explosions and their sounds would not be detectable, so can never be proven either.

I guess you'd be zero for two in that case.

Interesting how a lack of proof is interpreted so loosely by truthers - when they lack proof, they insist that it's irrelevant. But they argue the opposite when they view the conventional explanations. Small wonder the 9/11 'truth' community is floundering.

 

[alienentity]

Tony S wrote 'Dr. Bazant himself was sent a link to the paper as well as others'

Ah, so now you allow that the engineering community is not as ignorant of your theories as you implied. The problem is they haven't jumped on the truther bandwagon and endorsed you.

I understand. You're not getting any traction where it counts.(outside the truthersphere, that is)

 

[Tony Szamboti]

'What you are describing is that the thing could not accelerate at a rate beyond 0.7g because of resistance.

These two situations are not the same. '

Oh but they are. You just can't detect the small changes in velocity (due to limitations of video frame rates and resolution etc), so you pretend they didn't happen.

You employed a method in your missing jolt paper which failed to detect what you presumed was there. That's all.

Now if only you had proof positive of explosives, which you don't, you might be onto something. But even you admit that (in your own scenario) the explosions and their sounds would not be detectable, so can never be proven either.

I guess you'd be zero for two in that case.

Interesting how a lack of proof is interpreted so loosely by truthers - when they lack proof, they insist that it's irrelevant. But they argue the opposite when they view the conventional explanations. Small wonder the 9/11 'truth' community is floundering.

You are proving here, beyond any doubt, that you don't understand dynamic loads or kinetic energy transfer whatsoever.

If the collapse had been a natural event, the amount of energy loss which would have been incurred by the upper block, to just deform and buckle the columns on just the first floors on either side of the first collision, would have been about 87% of it's kinetic energy just prior to impact. That translates to a 75% velocity loss, so it wouldn't have been some undiscernable velocity loss we were looking for. If an impact capable of delivering the required energy had occurred, at a minimum, the upper block would have slowed from about 23 feet/second to about 5.5 feet/second and the video resolution and frame rate of 30 frames per second was more than up to that task.

You really should stop making a fool of yourself by trying to do that to me.

 

[Grizzly Bear]

It isn't the strength of the column once it is buckling, it is the pre-buckling strength that accounts for a large part of the energy loss in deforming the columns.

The loads of the upper block weren't applied outside of it's vertical plane.

I'll respond to this shortly. I'm working on a diagram for this. I'll comment on the other at the same time

 

[GlennB]

The amount of energy loss which would have been incurred by the upper block, to just deform and buckle the columns on just the first floors on either side of the first collision, was about 87% of it's kinetic energy just prior to impact. That translates to a 75% velocity loss, so it wouldn't have been some undiscernable velocity loss we were looking for.

Would this be based on simultaneous axial impact, column-on-column?

 

[alienentity]

You are proving here, beyond any doubt, that you don't understand dynamic loads or kinetic energy transfer whatsoever.

If the collapse had been a natural event, the amount of energy loss which would have been incurred by the upper block, to just deform and buckle the columns on just the first floors on either side of the first collision, would have been about 87% of it's kinetic energy just prior to impact. That translates to a 75% velocity loss, so it wouldn't have been some undiscernable velocity loss we were looking for. If an impact capable of delivering the required energy had occurred, at a minimum, the upper block would have slowed from about 23 feet/second to about 5.5 feet/second and the video resolution and frame rate of 30 frames per second was more than up to that task.

You really should stop making a fool of yourself by trying to do that to me.

You're (still) missing the point that your expectations are based on assumptions which can be argued are not the only valid set to apply, and in fact may be incorrect

and

that your sampling methods may have smoothed out the velocity changes you were looking for.

Either way, it fails to prove controlled demolition of any kind. It merely shows that you cannot find what you were looking for. That's not a big deal in science, it's just not proof of anything at this point.

If you guys didn't have a fixed conclusion (controlled demolition) you'd be far better off.

 

[Tony Szamboti]

Would this be based on simultaneous axial impact, column-on-column?

No, the amount of energy to deform and buckle the columns is what it is whenever it is done.

 

[alienentity]

Bazant created a simplified model of the collapse, which implied a deceleration 'jolt'. But from the outset the model was understood to be an approximation, not a literal depiction.

Mr. Szamboti has made the assumption that such a theoretical jolt would actually occur, and he set about to try to detect it. Having failed to detect it, he incorrectly assumes that the tower collapses weren't just simple gravity-driven events.

 

[Bluesky]

Sure....the perimeter column section appears to have been blown away from the building. The core was a mere remnant that lasted only seconds. So a crush down is an absolutely appropriate description..

The picture is of core columns. They lasted about a further month after the initial collapse... You are only a million liles away again

 

[GlennB]

No, the amount of energy to deform and buckle the columns is what it is whenever it is done.

Perhaps I didn't make it clear - I meant the 'velocity loss' (jolt) you expect to observe, not the total energy sink.
While you're here - higher up the thread I posted some photos regarding CD. One of them seems to easily disprove the claim that the 'spires' only consisted of central core columns as far as WTC1 is concerned. I'll next look at the photos/calculations for WTC2.

 

[bill smith]

The picture is of core columns. They lasted about a further month after the initial collapse... You are only a million liles away again

Is that so ? Do you have some pictures ?

 

[Grizzly Bear]

First part...

It isn't the strength of the column once it is buckling, it is the pre-buckling strength that accounts for a large part of the energy loss in deforming the columns.

But to begin with this assumes that we're working off a scenario in which none of the columns weren't weakened by any mechanisms. This isn't true for the impact and fire region where columns would have been been more susceptible due to a combination of the redistributed loads after impact and then the heat induced loss in strength resulting in even tighter reserve strength.

The loads of the upper block weren't applied outside of it's vertical plane.

At the point of collapse initiation they were, that's the point. Beyond initiation the remainder of the collapse can be blamed on this sort of mechanism.
I did a quick and dirty diagram to show it...

2nd part

Deceleration of the impacting object beyond the rate of gravity and a velocity loss would prove a dynamic load took place. Otherwise the load can only be considered static.

Which refers only to the pre-collapse initiation conditions. The fire regions failed under the structure's static load from a combination of uneven load redistribution and loss of integrity from the fire. Everything beyond that point was dynamic because not only was the mass of the upper block moving, the impacts were not column to column. And nearly every column examined after the fact shows this clearly, that shear failure at the connections from -- in many cases -- angular load applications was responsible for them coming apart. The case you make about the deceleration being greater than gravity is correct but the net loss in velocity is entirely dependent upon the strength of the column along the axis it receives the load. This contact is taking place over such a small interval that the net loss in velocity is indistinguishable at the individual level.

 

[Bluesky]

In the marine structural field you have to consider dynamic loads from the beginning! The structure is located in the interface water/air and the water is moving - waves - which impose dynamic loads ... all the time. And they are of two types - the regular dynamic loads with frequency of the waves and the sudden impact ones - a rare freak wave impacting the structure. There is a third case - when two marine structures collide.

The latter is of interest for 911 research and with my 40+ years experience of marine structural design and damage analysis I would say that the top part of WTC 1 cannot possibly one way crush down the bottom part by imposing a dynamic load from the top. If the top part really tried to do it, the top part would first have been subject to a violent jolt and second to serious local failures to itself and then the destruction would have been arrested. No jolt is seen on any video and one reason is that the top part never imposes a dynamic load on the bottom part! The top part is actually destroyed locally so its roof is dropping, while the bottom part is still intact. A little later the bottom part is destroyed from top down by CD. No doubt about it.

I completely agree: the top part cannot crush the bottom part, but the top part can cause the bottom part to fail, as it did.

If the top part cuts connections that are critical, and causes the outer walls to blow out, and causes the internal core columns to be displaced sllightly leading to a failure of the stack joints, then a failure of the lower part occurs without crushing.

As one of the ae911truth's so called experts it is a pity that you only think of solid body action rather than local impacts. I suggest you keep to ships and leave buildings alone.

Try to remember the Titanic. A small mass of frozen water ( a material with small compression and tension capacity) impacts a large mass with an outer surface of thick steel. The frozen water impacting the steel causes enough damage to the ship to cause it to fail. Or try to remember the bullet analogy.

But then you like to keep spouting this nonsense, since you have heard sensible answers many times before...

 

[FineWine]

If you have something to debate by all means please bring it up with what you think supports your argument.

But just making inane pronouncements like the above is ridiculous.

I just can't understand why anyone would write something like this on a debating forum.

Yes, I understand your embarrassment at having been exposed. The nonsense you peddle is certainly foolish. I'll repeat: no one who works in demolition--no, not Bachmann, Schneider, nor Jowenko--thinks the collapses of the towers resembles controlled demolitions. The evidence for demolition is nonexistent, as you know.

Most of us can't understand why someone who claims to be an engineer is incapable of learning anything from other engineers. Heiwa clearly has serious problems. You, by contrast, appear sane.

What's your excuse?

 

[Tony Szamboti]

Bazant created a simplified model of the collapse, which implied a deceleration 'jolt'. But from the outset the model was understood to be an approximation, not a literal depiction.

Mr. Szamboti has made the assumption that such a theoretical jolt would actually occur, and he set about to try to detect it. Having failed to detect it, he incorrectly assumes that the tower collapses weren't just simple gravity-driven events.

What a ridiculous comment to make that I incorrectly assumed the tower collapses weren't just simple gravity-driven events.

Dr. Bazant said there would have been a jolt because he knew that was the only way the lower columns could be overloaded.

It is only psuedoscientists like you appear to be who would contemplate otherwise and now try to say he was only talking about an idealized situation that didn't happen.

Why don't you tell us how it could happen without a load amplification?