# WTC: Rate of Fall (rate of crush)

#### Jazzy

##### Closed Account
As I have said before, this is merely a modern version of Zeno's Paradox, or how causality may be misinterpreted.

In the paradox of Achilles and the Tortoise, Achilles is in a footrace with the tortoise. Achilles allows the tortoise a head start of 100 metres, for example. If we suppose that each racer starts running at some constant speed (one very fast and one very slow), then after some finite time, Achilles will have run 100 metres, bringing him to the tortoise's starting point. During this time, the tortoise has run a much shorter distance, say, 10 metres. It will then take Achilles some further time to run that distance, by which time the tortoise will have advanced farther; and then more time still to reach this third point, while the tortoise moves ahead. Thus, whenever Achilles reaches somewhere the tortoise has been, he still has farther to go. Therefore, because there are an infinite number of points Achilles must reach where the tortoise has already been, he can never overtake the tortoise.
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The above demonstrates the difference between semantics and physics. Jomper ignores it...
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#### Jazzy

##### Closed Account
this was not a four column this was MULTIPLE COLUMNS this is nonsense and you are ignoring what the issue is, I have already agreed to the basic point you have made but again you have dodged what the problem with your argument is. you will now respond with more nonsense and jargon that will not apply and try to make it seem like I don't understand. unfortunately I am just being realistic.
The four-column demonstrator was "multiple columns". They all gave up apparently simultaneously.

The face of a collapsing tower that began to buckle did indeed have a single point of failure. But the consequence of that was to transfer that load to its neighbors. IT HAD TO. That is what "being loaded" is all about. The load could not vanish when that column gave up resistance to it. It HAD TO transfer itself to the next column, and the next. This transference took place at the speed of sound in steel, about five miles per second.

Once the tower lost its symmetry it also lost any chance of stability. ALL the crush examples shown assume symmetry, so they are ALL bunk.

Despite claims of "understanding buckling failure" it is quite apparent that some people don't understand it at all.

A test for this is the following:

A column may fail completely to support a load by collapsing by buckling, yet be completely undamaged by this failure. True or false?

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#### MikeC

##### Closed Account
the transfer of energy to the columns would happen in succession since we all can agree it wouldn't happen instantly to all columns for no reason,

but there is a reason - the collapse/damage of some columns instantly loads up some other columns, and AS SOON AS THEY START TO SHED LOAD other columns have to start taking it - and failing.

There is no reason why this cannot be instantaneous to all intents and purposes - ie it might take fractions of seconds or longer - but such time is not going to be noticeable without accurate instrumentation.

#### Rod Martin Jr.

##### New Member
The upwards force only happens DURING CONTACT. When the upper block fall onto the lower block, there's a collision, the floor fails, and the block continues to accelerate.

So the upwards force will only affect the acceleration WHILE THE FLOOR IS BEING DETACHED. i.e., only while the joints are failing. That failure only takes a fraction of a second. But to calculate the amount of upwards force under his assumptions, you'd need to know how long it takes the floor to fail when 38,000 tonnes are dropped on it.

Interesting points, but one that I found even more interesting is that there does not seem to be the necessary deceleration at each floor in order to perform the necessary "breaking" or "detaching." Breaking the bonds at each floor requires work. That would take from the KE to perform that work. This isn't what we see in the slow motion analysis of the videos.

Has anyone seen a detailed energy assessment of the collapse? So much work was done while the building collapsed, but the roughly 1/3 of g that was lost may not adequately account for that required work done.
• Bending or breaking the steel beams at each floor.
• Pulverizing the concrete, mostly into a fine, powdery dust (which covered most of Lower Manhattan like snow).
• Laterally ejecting tons of iron and aluminum cladding, in some cases up to 600 feet away.
• Heating up the concrete dust as felt by many witnesses, some of whom thought they were going to be burned alive. Thankfully, they weren't, but from their descriptions, the material must've been heated up by more than a few degrees to be so uncomfortable.
• Blowing the pulverized concrete dust for many miles in nearly every direction.
Each one of these takes a massive amount of energy. What was the original PE budget? Was that budget exceeded by the amount of work done?

In favor of controlled demolition is the fact that much of the mass of the falling structure was ejected to the sides as the building collapsed. In other words, all that structural steel, aluminum cladding and pulverized concrete dust was not available to do any crushing as the building fell. This complicates the calculations considerably, and places far more burden on a much reduced PE.

If Mayor Giuliani had not committed felony destruction of crime scene evidence, then we may have been able to have pieced together a more accurate energy budget of the collapse. Like the crash of an airplane, the pieces are secured and saved in order to do a more perfect analysis. Mayor Giuliani's "incompetence(?)" did not allow for this. Since he was a former federal prosecutor, I don't think he could claim ignorance of the law (as if ignorance of the law is ever an excuse for crimes).

Here's a fun look at the physics of the North Tower collapse:

WTC7 Comparison

By comparison, WTC7 (the 3rd building to collapse on 9/11) fell at perfect free fall for 8 floors. In other words, for 8 floors, 100% of PE was being converted to KE! Only in cartoons and government reports does solid steel ever offer zero resistance to collapse.

There have been millions of conspiracies in the history of humanity. The government even offered their own "conspiracy theory" about 9/11 and this has become the official theory. Some even treating it as "fact." That's sad. Even Newton's "laws" of motion fell to relativistic concerns. As researchers we should never be too attached to any idea as "absolute."

Even if the official "conspiracy theory" turns out to be valid (and that would surprise me beyond belief), there is something definitely fishy about a building that offers as much resistance to collapse as air. Solid steel never does this.

#### Rod Martin Jr.

##### New Member
Once the tower lost its symmetry it also lost any chance of stability. ALL the crush examples shown assume symmetry, so they are ALL bunk....

A column may fail completely to support a load by collapsing by buckling, yet be completely undamaged by this failure. True or false?

Answer to your last question: false. Definitely. The idea of buckling is, in itself, an indication of damage. But I disagree with your supposition that loss of symmetry eliminates any chance at stability. I would wager that controlled demolition professionals could take out one or two columns and the building would continue to stand because of the support of the remaining columns. Perfect symmetry is gone, but the building would remain stable enough to stand for decades or even centuries, if not acted upon by some strong, outside force (earthquake, volcano or hurricane). Stability is not reduced to zero because symmetry is suddenly gone. Or am I misunderstanding your statement? Please clarify.

#### Rod Martin Jr.

##### New Member
OK . . . High Rise steel reinforced buildings are fragile . . . until 911 no one had seen such a demonstration of fragility in the collapse of three monsters by two different mechanisms . . . in almost free fall speeds . . . so show me some similar occurrences and I might start to change my mind . . .

My change of mind from "believer in the 'official conspiracy theory'" to "Truther" only took a few, clear facts. I might consider changing my mind back, but only with an equally startling set of facts. Evidence of another steel frame, high-rise building collapsing at perfect free fall (like WTC7, first 8 floors) or smoothly accelerating 2/3 of free fall (Towers) would raise questions, certainly, but that in itself would not be proof, to me, of the fragility of such buildings. It might suggest that, but with the restraint of a scientist, I would be open to all manner of possible explanations. I would not condone science by ridicule, as is so prevalent in today's society (Clovis First dogma and ridicule, for example). Such tactics only come from ego; not scientific method. And, ideally, ego has no place in science, despite the protestations of those who have the most ego at risk.

Even if someone showed me videos of 20 steel-frame, high-rise buildings collapsing like those on 9/11, I would still find it hard not to be someone who hungers for truth about those events, wherever that truth leads -- even to conspiracies. And for those who believe that conspiracies never existed, heaven help you!

For me, I seriously doubt if anyone could convince me that solid steel ever offers zero resistance as NIST implies happened in WTC7. That's too tall a mountain for even this humble scientist to climb.

#### jomper

##### Inactive Member
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#### Jazzy

##### Closed Account
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Yes. Zeno's Paradox is neatly debunked using a graph.

Now apply some similar lateral thinking to the load handover problem, and the stability of slender columns under their own load, and you're with me. How high was that "spire"?

#### Mick West

Staff member
For me, I seriously doubt if anyone could convince me that solid steel ever offers zero resistance as NIST implies happened in WTC7. That's too tall a mountain for even this humble scientist to climb.

Rod, please stay on the topic of the rate of fall of the wtc towers. See:

If you feel you can debunk individual claims of evidence from the NIST report, then please do so in a separate thread.

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#### gerrycan

##### Banned
Banned
And while the core columns are increasingly strong, the floor connections are not. Hence you get the "spire" effect as the floors are stripped from the stronger lower core columns.
When you look at the 'spire effect', the cores that are remaining at that point are actually among the weakest of the 47 columns, and also they least accessible from the elevator shafts. Given the mode of momentum transfer that is quoted earlier in this thread, this makes no sense in terms of a gravitational event.

#### Jazzy

##### Closed Account
Answer to your last question: false. Definitely. The idea of buckling is, in itself, an indication of damage.
No. A perfectly-undamaged column may buckle without being subjected to material failure. Watch Mick's buckling demo video. It is reusable because no damage was incurred during the demonstration.

Yet the columns failed by buckling.

But I disagree with your supposition that loss of symmetry eliminates any chance at stability.
Bravo. If you can prove that true then nearly three hundred years of civil engineering science are proved wrong, and your mind is greater than that of Leonhard Euler. Unless, of course you are talking about some symmetry not including gravity for its vertical axis.

I would wager that controlled demolition professionals could take out one or two columns and the building would continue to stand because of the support of the remaining columns. Perfect symmetry is gone, but the building would remain stable enough to stand for decades or even centuries, if not acted upon by some strong, outside force (earthquake, volcano or hurricane). Stability is not reduced to zero because symmetry is suddenly gone. Or am I misunderstanding your statement? Please clarify.
You were.

A leaning tower or sprawling floor (anything pushing a column off its own vertical axis) rewrites all those equations so carefully-gathered centuries ago. Safety factors (usually of ten times) rapidly disappear.

Loss of lateral support (just one of them) threatens a column at half-strength due to fire. Loss of a second support next to the first takes this column past its safety factor. This will work regardless of position*, because safety factors and consistency are both features of good civil engineering design.

* Fire has to be there, of course. Once motion, momentum, and misalignment increase, the party (of load resistance) is over.

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#### Mick West

Staff member
When you look at the 'spire effect', the cores that are remaining at that point are actually among the weakest of the 47 columns, and also they least accessible from the elevator shafts. Given the mode of momentum transfer that is quoted earlier in this thread, this makes no sense in terms of a gravitational event.

A massive wave of fast moving dense rubble stripping away the horizontal members and pushing and pressing on the vertical members in a chaotic and unpredictable manner?

#### MikeC

##### Closed Account
Interesting points, but one that I found even more interesting is that there does not seem to be the necessary deceleration at each floor in order to perform the necessary "breaking" or "detaching." Breaking the bonds at each floor requires work. That would take from the KE to perform that work. This isn't what we see in the slow motion analysis of the videos.

Yes it requires work - but the work need not take any more than a fraction of a second, is invisible anyway in the clouds of dust, and the work is only being done by the falling elements that actualy strike something - the ones that do not - eg they are a foot above when the failure happens - do not decelerate.

The only way you would see it happening is if the segments failing were instrumented or under direct observation.

#### Jazzy

##### Closed Account
Yes it requires work - but the work need not take any more than a fraction of a second, is invisible anyway in the clouds of dust, and the work is only being done by the falling elements that actualy strike something - the ones that do not - eg they are a foot above when the failure happens - do not decelerate. The only way you would see it happening is if the segments failing were instrumented or under direct observation.
Adding to that a little - Steel is elastic enough to "smooth" its downward progress, in the manner of an automobile spring, if you like, with a bit of friction damping to boot.

"There does not seem to be the necessary deceleration at each floor" - unless that deceleration is represented by the reduction in the downward acceleration of the towers by a third of a G. And that third of a G coupled to hundreds of thousands of tons of mass made for a tremendous amount of destructive energy.

A rough calculation suggests that the reduction in downward acceleration with respect to G was equivalent to an explosive release of more than thirty tons of TNT.

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#### gerrycan

##### Banned
Banned
A rough calculation suggests that the reduction in downward acceleration with respect to G was equivalent to an explosive release of more than thirty tons of TNT.
You need to show your work for this, I don't think you can. Keep in mind that NIST say that the tower accelerated at a CONSTANT rate throughout the 'collapse'.

#### Jazzy

##### Closed Account
You need to show your work for this, I don't think you can. Keep in mind that NIST say that the tower accelerated at a CONSTANT rate throughout the 'collapse'.
Using:

Weight of tower = 450,000 tons* - http://hypertextbook.com/facts/2004/EricChen.shtml
Height of tower = 416 m
G = 9.81 m/sec/sec
Downward acceleration of Tower 2 = 0.71 G
Downward acceleration of Tower 1 = 0.64 G
Equivalence value for 1 ton of TNT = 4.184*10^9 Joules

Calculating:

PE of tower = 0.5*m*h*G = 0.5*450,000*1000*416*9.81 = 9.18*10^11 Joules

Destructive energy left in Tower 2 (not reaching ground zero) = 9.18*10^11*0.29 = 2.66*10^11 Joules = 2.66*10^11/4.18*10^9 = 63.6 tons TNT equivalent.

Destructive energy left in Tower 1 (not reaching ground zero) = 9.18*10^11*0.36 = 3.30*10^11 Joules = 3.30*10^11/4.18*10^9 = 78.9 tons TNT equivalent.

Reasoning:

The reasoning is that the potential energy of the towers* is the energy available, and that any slowing of the towers' descent involves, and is commensurate with, a redistribution of that energy to the disintegrating material structures.

The remaining energy becomes the kinetic energy available for impact with ground zero, intervening steelwork wreckage on the ground transferring that energy, to some degree, also to ground zero.

There is no need to "keep in mind" what you suggest. There never is.

* Just in case Harvey is off the banned list, the mass of a tower is that of the steelwork PLUS everything the towers were holding up, namely the cladding, the plumbing and services, equipment and support machinery. The TOTAL LOAD raised above ground zero.
.

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#### dunbar

##### Active Member
Using:

The reasoning is that the potential energy of the towers* is the energy available, and that any slowing of the towers' descent involves, and is commensurate with, a redistribution of that energy to the disintegrating material structures.

The remaining energy becomes the kinetic energy available for impact with ground zero, intervening steelwork wreckage on the ground transferring that energy, to some degree, also to ground zero.

I'll see your potential energy and raise you tremendous support reactions and resistance through structural efficiency, structural robustness, and over all structural integrity that should have easily compensated for the accidental loading that occurred had the structure not been deliberately sabotaged. This is the rub, get it? So you can't just say "95.000 tons of tnt" like it has some meaning without context or justification, you have to actually address the actual issues and not rely on Discovery Channel factoid sound bites.

#### Jazzy

##### Closed Account
I'll see your potential energy and raise you tremendous support reactions and resistance through structural efficiency, structural robustness, and over all structural integrity that should have easily compensated for the accidental loading that occurred had the structure not been deliberately sabotaged. This is the rub, get it?
The structure immediately sagged over the impact hole. Loads were immediately transferred elsewhere. Fire started its work of expansion, sagging and creep. Creep is time-dependant and increasingly allows more loads to be transferred to weaker members, so arriving at a point of collapse was simply a matter of time. The towers failed in the region of the worst fires in both cases.

Your "tremendous support reactions and resistance through structural efficiency, structural robustness, and over all structural integrity" winked out one-by-one as the towers sagged, leaned, bulged, and crept. All of this has been well-documented, and isn't something you can hide your head in the sand about.

So you can't just say "95.000 tons of tnt" like it has some meaning without context or justification, you have to actually address the actual issues and not rely on Discovery Channel factoid sound bites.
Point out where I said "95.000 tons of tnt". I work to sig.figs, chummy, and engineering calculations do have meaning and do justify.

The potential energy doesn't feature in the progression to collapse, but afterwards, when it is being exchanged for kinetic energy as the structure falls. As such, the calculation inputs are all documented and given, the reasoning and equations are correct, and indicate exactly the direction of movement of energy according with good engineering practice.

Your response therefore suggests an inclination not to believe, rather than to obviously set about to learn, question, and appreciate facts.

Science disregards belief. It also disregards pseudoscience.

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#### gerrycan

##### Banned
Banned
500,000 tons was the MAXIMUM dead+live load of a tower. 450k is still way too high, you need to rethink that figure.
It kind of looks as if you are supposing that all of the mass is at max height, i may be wrong here, i will look at it later, worth revisiting this jazzer

#### Tony Szamboti

##### Active Member
500,000 tons was the MAXIMUM dead+live load of a tower. 450k is still way too high, you need to rethink that figure.
It kind of looks as if you are supposing that all of the mass is at max height, i may be wrong here, i will look at it later, worth revisiting this jazzer
The actual in-service load of the WTC Twin Towers was in the 300,000 metric ton range. The 500,000 metric ton figure was absolute maximum design load (as you are saying) and is not what was actually on the buildings. Zdenek Bazant himself determined this with a mass frequency analysis shown in the addendum to his 2001 paper (although he did not use that calculation and instead fraudulently used the maximum design load, as it made his argument for a naturally occurring collapse better). See the paragraph on the upper right side of page 7 of the attached. Where it says 141 x 10e6 kg was 44% of the tower mass. That equates to 320,000 metric tons for the entire building.

In 2008 electrical engineer Gregory Urich did a mass analysis available here http://www.journalof911studies.com/volume/200703/GUrich/MassAndPeWtc.pdf using actual contracts for material and other available information. He shows the actual in-service load mass to be in the 288,000 ton range. See page 25 where he shows that this puts the Twin Towers in sync with the mass per unit area of the Sears Tower and John Hancock buildings. Whereas the 500,000 ton figure puts the mass per unit area at nearly double what those buildings have.

Additionally, in their report NIST even admits that the 12 story upper section of the North Tower was about 73,000 kips or around 33 x 10e6 kg. Bazant fraudulently used 58 or 54.18 x 10e6 kg for the upper section mass in his papers, and this was derived from a 500,000 metric ton maximum design load total mass.

#### Attachments

• Bazant and Zhou (2001).pdf
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#### Jazzy

##### Closed Account
500,000 tons was the MAXIMUM dead+live load of a tower. 450k is still way too high, you need to rethink that figure.
It kind of looks as if you are supposing that all of the mass is at max height, i may be wrong here, i will look at it later, worth revisiting this jazzer
Well, I never mentioned 500,000 tons at all, and 450,000 was an average sort of figure from the various estimates I found.

I know it's really difficult to calculate the PE unless you do it floor-by-floor. But I also know a few tricks, and the one I used here was to place the whole mass at half height. I knew that it was a fair approximation to the correct figure, which later I validated. So take the whip away - the horse will never rise.

The actual in-service load of the WTC Twin Towers was in the 300,000 metric ton range. The 500,000 metric ton figure was absolute maximum design load (as you are saying) and is not what was actually on the buildings. Zdenek Bazant himself determined this with a mass frequency analysis shown in the addendum to his 2001 paper (although he did not use that calculation and instead fraudulently used the maximum design load, as it made his argument for a naturally occurring collapse better). See the paragraph on the upper right side of page 7 of the attached. Where it says 141 x 10e6 kg was 44% of the tower mass. That equates to 320,000 metric tons for the entire building.

In 2008 electrical engineer Gregory Urich did a mass analysis available here http://www.journalof911studies.com/volume/200703/GUrich/MassAndPeWtc.pdf using actual contracts for material and other available information. He shows the actual in-service load mass to be in the 288,000 ton range. See page 25 where he shows that this puts the Twin Towers in sync with the mass per unit area of the Sears Tower and John Hancock buildings. Whereas the 500,000 ton figure puts the mass per unit area at nearly double what those buildings have.

Additionally, in their report NIST even admits that the 12 story upper section of the North Tower was about 73,000 kips or around 33 x 10e6 kg. Bazant fraudulently used 58 or 54.18 x 10e6 kg for the upper section mass in his papers, and this was derived from a 500,000 metric ton maximum design load total mass.
Unlike you, my concern is not to demote the work of others, or even to promote myself, but instead to demonstrate the general order of energies being wreaked at that moment, lest some opportunists come along with further misinformation, and pretend that the heat and damage of this disaster was the product of some other energetic process.

So, to the both of you: to me it is immaterial whether the towers weighed 500,000, 400,000, or 300,000 tons. Their potential energies would have been distributed as impact damage to their previously-intact structures at rates commensurate with their below-G decelerations, and certain opportunists are no longer able to pretend that the damage required additional energy from elsewhere.

These same opportunists are also no longer able to claim that the heat in ground zero was also the product of some other energetic process, when it was quite obviously the remnant of the towers' kinetic energy.

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#### Tony Szamboti

##### Active Member
Well, I never mentioned 500,000 tons at all, and 450,000 was an average sort of figure from the various estimates I found.

I know it's really difficult to calculate the PE unless you do it floor-by-floor. But I also know a few tricks, and the one I used here was to place the whole mass at half height. I knew that it was a fair approximation to the correct figure, which later I validated. So take the whip away - the horse will never rise.

Unlike you, my concern is not to demote the work of others, or even to promote myself, but instead to demonstrate the general order of energies being wreaked at that moment, lest some opportunists come along with further misinformation, and pretend that the heat found in the wreckage was the product of some other energetic process.

So, to the both of you: to me it is immaterial whether the towers weighed 500,000, 400,000, or 300,000 tons. Their potential energies would have been distributed as impact damage to their previously-intact structures at rates commensurate with their below-G decelerations, and opportunists are no longer able to pretend that the damage required additional energy from elsewhere.

These same opportunists are also no longer able to claim that the heat in ground zero was also the product of some other energetic process, when it is quite obviously the remnant of the towers' kinetic energy.

The measurements show the North Tower continuously accelerated and never decelerated at any time. Without deceleration there can't be a dynamic load.

Here is a short video explaining it if you don't understand

#### Jazzy

##### Closed Account
The measurements show the North Tower continuously accelerated and never decelerated at any time. Without deceleration there can't be a dynamic load.
Here is a short video explaining it if you don't understand
They didn't fall at G so they were being decelerated.

Don't waste my time. Waste your own time.

#### gerrycan

##### Banned
Banned
Well, I never mentioned 500,000 tons at all, and 450,000 was an average sort of figure from the various estimates I found.

I know it's really difficult to calculate the PE unless you do it floor-by-floor. But I also know a few tricks, and the one I used here was to place the whole mass at half height.
You are way off. And what you call a 'trick' is just a plain error. About half of the mass a tower is in the first 35 or so floors. Where does that leave your multiply by 0.5 trick ??

#### Jazzy

##### Closed Account
You are way off. And what you call a 'trick' is just a plain error. About half of the mass a tower is in the first 35 or so floors. Where does that leave your multiply by 0.5 trick ??
Not so far off as to make any difference to my point, as you are apparently well aware. The amount out was a matter of a couple of floors, because half the mass of the steelwork alone was where you say it was, but the installations that followed were absolutely evenly distributed, but with a preponderance of engineering floors further up, and must by most accounts have been of approximately equal mass.

I quote myself:

"Unlike you, my concern is not to demote the work of others, or even to promote myself, but instead to demonstrate the general order of energies being wreaked at that moment, lest some opportunists come along with further misinformation, and pretend that the heat and damage of this disaster was the product of some other energetic process".

You are aware of the meaning of the words "general order"?

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#### Tony Szamboti

##### Active Member
They didn't fall at G so they were being decelerated.

Don't waste my time. Waste your own time.
I think you may mean they did not fall at G so they were being resisted in some way. It is true that the North Tower fell at about 64% of G. However, it was always accelerating and deceleration is needed to amplify the load.

You apparently do not understand the difference between acceleration and deceleration. One is positive and one is negative. Less than G acceleration is not deceleration in any universe.

In other words, the upper section needed to have a negative acceleration (deceleration) for an amplified (dynamic load) to occur and more force than the upper section weight to be applied to break a structure capable of handling several times the load above it.

The only one wasting anyone's time here is the one who does not understand.

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#### Mick West

Staff member
I think you may mean they did not fall at G so they were being resisted in some way. It is true that the North Tower fell at about 64% of G. However, it was always accelerating and deceleration is needed to amplify the load.

You apparently do not understand the difference between acceleration and deceleration. One is positive and one is negative. Less than G acceleration is not deceleration in any universe.

The only one wasting anyone's time here is the one who does not understand.

Or the one who cannot explain.

Let's try to reach a common understanding without resorting to insults. I think we are all familiar with the basic equations of motion, force, acceleration, etc.

Jazzy's says "They didn't fall at G so they were being decelerated."

This means that there was an upwards force that partially counteracted the downward force of gravity, a resistance, r. This resistance was a decelerating force. g is accelerating (and the signs here are pretty arbitrary). g > r, so there's the net downwards acceleration.

Tony says there was no deceleration. By which I take it he means that g > r, when he thinks that g < r? That the top of the building should slow down and stop?

Now g is constant. r varies. Perhaps Tony means that just sometimes g < r? During "jolts"?

What do you mean Tony?

#### Mick West

Staff member
And what does "amplify the load" mean?

#### Tony Szamboti

##### Active Member
And what does "amplify the load" mean?
It means the load felt by the impacted lower structure is greater than the static load.

Amplified load = mg + m(deceleration)

#### Mick West

Staff member
It means the load felt by the impacted lower structure is greater than the static load.

Amplified load = mg + m(deceleration)

What has the static load to do with anything? The falling bits are not static. There is no static load, it's a very dynamic load.

#### Tony Szamboti

##### Active Member
What has the static load to do with anything? The falling bits are not static. There is no static load, it's a very dynamic load.
Mick, the static load is there plus the dynamic component, which is a function of the deceleration (which is synonymous with negative acceleration).

How much does a 100 lb. item on earth weigh when it is falling through the air? It does not constitute a dynamic load at that point. So your thinking that because it is moving it is dynamic isn't germane here.

What is your definition of a dynamic or impulsive load due to impact? How do you define it mathematically?

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#### Mick West

Staff member
Mick, the static load is there plus the dynamic component, which is a function of the deceleration (which is synonymous with negative acceleration).

How much does a 100 lb. item on earth weigh when it is falling through the air? It does not constitute a dynamic load at that point. So your thinking that because it is moving it is dynamic isn't germane here.

What is your definition of a dynamic or impulsive load due to impact? How do you define it mathematically?

You define it as F = ma in a very loose sense, in a really simple model, if we were talking about billiard balls. The static load is negligible compared to the dynamic load in a collision of any semi-rigid bodies when dropped a few feet. Jazzy will give you the example of hitting a nail with a hammer vs. resting the hammer on the nail. I would give you the example of dropping a weight on a cardboard box.

Seems like you are arguing at a semantic level here Tony. Let's look at what actually happened.

Why don't you show a graph of what you think the velocity should look like, and one of what it does look like. Then explain what accounts for the difference.

Do the graph at continuous and 1/30th of a second intervals, for the first three floors. You don't need exact figures, just the general slopes and kinks that you would expect.

#### Mick West

Staff member
To put this in other (still overly simple) terms. The static load is mass * gravity. m time g. When you stand on the ground, you are pulling one g.

When you drop from a height, you pull more than one gee when you hit the ground. The actual amount depends on how much you and the ground deform before you stop moving. Now during that time you are still pulling one g, that's true, the static load is still there. But you are pulling many many more g's while you stop. The dynamic load (assuming you stop) is mass times velocity divided by stopping time m*v/t, if you don't stop, then it's just m*(v2-v1)/t

There really should be a way of illustrating what the disagreement is here. It's not rocket science. Let's draw some diagrams.

#### Tony Szamboti

##### Active Member
The point is that you have to hit something and decelerate (that is have a negative acceleration and lose velocity) at a certain rate to have a dynamic load. Whatever that rate of deceleration is relative to the rate of gravity is what we call the G level. In other words, if something decelerates at 322 feet/s^2 it is decelerating at 10 G's.

If an object's weight (static load) suddenly cannot be withstood by whatever was supporting it and the object then accelerates at a rate less than gravity due to residual resistance, there is no deceleration and dynamic load.

Attached is a velocity graph calculated every 1/100th of a second interval for column energy dissipation in the North Tower. It adds kinetic energy at every step due to the amount of potential energy converted by the differential drop height and it burns up energy at each step based on the force and the distance the column bends down from the equation using plastic moment of the columns shown as Eq. 8 in the attached Bazant paper. It shows what the deceleration should have been in a natural collapse vs. the actual measurement by David Chandler, and Bazant's nonsense.

#### Attachments

• WTC 1 velocity curve with actual 1st story acceleration and upper section mass.pdf
35.2 KB · Views: 413
• Bazant and Zhou (2001).pdf
98 KB · Views: 383
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#### Tony Szamboti

##### Active Member
For anyone interested attached is a refutation of the last Zdenek Bazant paper on the WTC collapse published in the Journal of Engineering Mechanics (JEM) in January of 2011. We submitted a Discussion of it showing it contained severe errors in May 2011. The JEM tried to reject the Discussion a year later in May 2012. We showed the review was unjustified and they had to re-accept the Discussion paper with minor revisions in June 2012. After that yet another year passed with no action, in spite of inquiries from us concerning its status. We finally wrote to the chief editors about it in May 2013. They asked for some time to look into it and came back in August 2013 rejecting it again, with the comment that the Discussion was "out of scope" for the JEM. Just amazing! How could a Discussion correcting errors in a paper they published be "out of scope"? They never showed we were incorrect and were clearly acting in a dishonest way.

#### Attachments

• Le and Bazant (2011).pdf
72.8 KB · Views: 534
• Discussion of Le and Bazant 2011 paper, Rebuttal to reviewer, and second submission.pdf
272.7 KB · Views: 451
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#### Mick West

Staff member
So you think it would just drop two stories and then stop?

#### Tony Szamboti

##### Active Member
So you think it would just drop two stories and then stop?
That is what the calculations say. At the very least there should have been an enormous deceleration in a natural collapse.

You can see through what is said in his paper and our discussion of it that through various embellishments and underestimates Bazant was deceptively trying to say the deceleration wouldn't be observable.

What do you think about that Mick?

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#### Mick West

Staff member
Bazant's paper was never meant to model what happened. It was a worse case scenario.

#### Mick West

Staff member
Can you explain why the slope in section B is never greater than the slope in A?

Something more like this seems far more reasonable:

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#### Tony Szamboti

##### Active Member
Can you explain why the slope in section B is never greater than the slope in A?

Something more like this seems far more reasonable:

The slope in A is occurring during the first story drop and is an acceleration. The slope in B is occurring during the impact and column deformation and is a deceleration. They are separate and distinct. I am surprised you needed to ask this question.

You can't be serious with the miniscule jolts you tried to draw between Chandler's error bars. Did you even read our paper? Do you understand how much energy the columns were capable of absorbing?

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