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David Chandler jumps the shark

Dave Rogers said:
And yet it's the founding assumption of your Missing Jolt hypothesis. Why is it a fatal flaw for Bazant and not for you?

Dave
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One cannot have a free fall while columns are buckling through the first story as they would have to have been in a natural collapse, as Bazant claims.

This is not an issue with the Missing Jolt point as it is simply predicated on the upper section moving and accelerating, not whether it is in free fall or not. The point is only that a moving upper section has to show relative deceleration to show there would have been a mechanism to overcome the reserve strength below in a natural collapse.
 
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WilliamSeger said:
Yes, I want to say that energy is the driver, but then, David Chandler wasn't my high school physics teacher. Do you understand Bazant's energy argument?
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Bazant embellishes the kinetic energy by using free fall through the first story with 8.52 m/s vs. the actual 6.13 m/s. This alone doubles the kinetic energy due to it being squared. He then nearly doubles the mass by using maximum design load vs. actual service load. In essence, he quadrupled the actual kinetic energy.

Bazant also underestimated the energy absorption capacity of the columns below by more than half. These facts show Bazant's analysis is bogus.

When the actual energy of the moving upper section is calculated and the actual energy absorption capacity of the columns below is calculated it shows a fall through one or two stories would have arrested in fairly short order. We calculated two stories after the first impact. Even if the energy absorption was not fully efficient there should have been a very serious deceleration.
 
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Tony Szamboti said:
Bazant embellishes the kinetic energy by using free fall through the first story with 8.52 m/s vs. the actual 6.31 m/s. This alone doubles the kinetic energy due to it being squared. He then nearly doubles the mass by using maximum design load vs. actual service load. In essence, he quadrupled the actual kinetic energy.

Bazant also underestimated the energy absorption capacity of the columns below by more than half. These facts show Bazant's analysis is bogus.

When the actual energy of the moving upper section is calculated and the actual energy absorption capacity of the columns below is calculated it shows a fall through one or two stories would have arrested in fairly short order. We calculated two stories after the first impact. Even if the energy absorption was not fully efficient there should have been a very serious deceleration.
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Sorry, your imitation Jedi mind tricks don't work on me.
 
deleted; questions already answered in TSz's next post. Hang on...
 
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Tony Szamboti said:
Bazant embellishes the kinetic energy by using free fall through the first story with 8.52 m/s vs. the actual 6.31 m/s. This alone doubles the kinetic energy due to it being squared. He then nearly doubles the mass by using maximum design load vs. actual service load. In essence, he quadrupled the actual kinetic energy.

Bazant also underestimated the energy absorption capacity of the columns below by more than half. These facts show Bazant's analysis is bogus.

When the actual energy of the moving upper section is calculated and the actual energy absorption capacity of the columns below is calculated it shows a fall through one or two stories would have arrested in fairly short order. We calculated two stories after the first impact. Even if the energy absorption was not fully efficient there should have been a very serious deceleration.
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So, Tony: When the top block descended through the vanished missing floor, did all of its mass impact nothning but pristine columns?

If not, please explain why you are not grossly overstating the energy absorption capacity of the lower block.


Also, even if we accept your claim that kinetic energy was 1/4 that of Bazant and columns' capacity to absorb energy was 2x that of Bazant ... that's a factor of 8. Didn't Bazant find a somewhat higher factor of "overwhelmingly"?
This all being premised of course on the 1D fantasy that all the mass crashes directly and squarely in nothing but vertical and pristine columns. A crazy, deluded fantasy if one were to mistake this for reality instead of a theoretical limiting case.
But that has been preached to you for soooooooooo many years...
 
Oystein said:
So, Tony: When the top block descended through the vanished missing floor, did all of its mass impact nothning but pristine columns?

If not, please explain why you are not grossly overstating the energy absorption capacity of the lower block.


Also, even if we accept your claim that kinetic energy was 1/4 that of Bazant and columns' capacity to absorb energy was 2x that of Bazant ... that's a factor of 8. Didn't Bazant find a somewhat higher factor of "overwhelmingly"?
This all being premised of course on the 1D fantasy that all the mass crashes directly and squarely in nothing but vertical and pristine columns. A crazy, deluded fantasy if one were to mistake this for reality instead of a theoretical limiting case.
But that has been preached to you for soooooooooo many years...
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In the Bazant & Zhou paper they claimed the kinetic energy to energy absorption capacity ratio to be 8 to 1, that it was "overwhelming" and that one could then see why the collapse had to propagate. Of course, this involved a huge amount of exaggeration.

Bazant actually exaggerated this ratio by about 11 to 1, since he embellished the kinetic energy by about 3.6X and claimed the energy absorption capacity of the columns below was about 500 MN-m (or 0.5 GN-m) when in reality it was a minimum of 1,600 MN-m (or 1.6 GN-m).

Your claims that a 1D analysis here is fantasy shows your amateurism and that you are simply groping at straws. The upper section had enormous inertia and there were no lateral loads sufficient to move it out of alignment until it fell a few stories and started tilting due to eccentric loading. If you actually think the upper section could move out of alignment immediately before any impacts would have occurred in a natural collapse please show some calculations.
 
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Tony Szamboti said:
This is not an issue with the Missing Jolt point as it is simply predicated on the upper section moving and accelerating, not whether it is in free fall or not. The point is only that a moving upper section has to show relative deceleration to show there would have been a mechanism to overcome the reserve strength below in a natural collapse.
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In a natural collapse, the "reserve strength below" matters not if the columns are not impacted axially and are instead left unbraced due to the girders and joists being impacted.

Few were impacted axially, if at all. In WTC1, only 8 or 16 had a chance. From them, the impacts may have been distributed in time due to different buckling lengths, or the impacts may have been too soft to be measurable with your methods.

Your premise is basically speculative and exaggerated. You can't know for sure that the impacts happened all at a time producing a big jolt, and even if they did, they would definitely not cause the jolt that your paper expects.

(I want to thank the posters of this thread who helped me gain enough understanding as to be able to reply this)
 
Tony Szamboti said:
Your claims that a 1D analysis here is fantasy shows your amateurism and that you are simply groping at straws. The upper section had enormous inertia and there were no lateral loads sufficient to move it out of alignment until it fell a few stories and started tilting due to eccentric loading.
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Wait - the top fell a few stories and only then tilted?
Or does tilt somehow, magically, does not imply lateral motion of much of what'ls tilting?

Tony Szamboti said:
If you actually think the upper section could move out of alignment immediately before any impacts would have occurred in a natural collapse please show some calculations.
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If you think the top could have fallen without most columns being misaligned you must be out of your mind.

Tilt is rotation. All points in a 3D body that is rotating about a horizontal axis have a lateral motion component, except for those currently in the horizontal plane through the pivot. I don't need calculations to known that, and neither do you.

But even before any tilt even occurs, it is obvious that there are lateral forces when columns buckle. I need no calculations to know that, and neither do you.

Why do you ask for calculations to know things you already know without calculations? Strikes me as dishonest tactics.
 
Dishonest? Surely not? His claim he saw a video where Silverstein admitted blowing up WTC7 is as truthful as they come..
 
Tony Szamboti said:
This is not an issue with the Missing Jolt point as it is simply predicated on the upper section moving and accelerating, not whether it is in free fall or not. The point is only that a moving upper section has to show relative deceleration to show there would have been a mechanism to overcome the reserve strength below in a natural collapse.
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Yes, it is an issue. The Missing Jolt hypothesis is based on the assumption that there is a point at which a downward accelerating body suddenly comes into contact with a separate body below, indicating that it was not previously in contact with it. This is the assumption that you have described as a fatal flaw.

Dave
 
Dave Rogers said:
Yes, it is an issue. The Missing Jolt hypothesis is based on the assumption that there is a point at which a downward accelerating body suddenly comes into contact with a separate body below, indicating that it was not previously in contact with it. This is the assumption that you have described as a fatal flaw.

Dave
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And this is precisely what happened to those towers... they came apart from parts of them being "freed" from the structural matrix and falling and colliding with another part which was still part of the structural matrix or "in the path" of its motion....

The missing jolt is a reductionist argument that presents a reductio ad absurdum which does not explain the event at all. Just another silly useless cartoon conception... like the blocks of Gage and the limit case of Dr B.

The destruction involved billions or maybe trillions of collisions and they were spread out over a span of 10-14 seconds. Missing jolt? not missing... try billions of them blending into smooth movement on a macro level... the only one we can actually observe.
 
Tony Szamboti said:
In the Bazant & Zhou paper they claimed the kinetic energy to energy absorption capacity ratio to be 8 to 1, that it was "overwhelming" and that one could then see why the collapse had to propagate. Of course, this involved a huge amount of exaggeration.

Bazant actually exaggerated this ratio by about 11 to 1, since he embellished the kinetic energy by about 3.6X and claimed the energy absorption capacity of the columns below was about 500 MN-m (or 0.5 GN-m) when in reality it was a minimum of 1,600 MN-m (or 1.6 GN-m).

Your claims that a 1D analysis here is fantasy shows your amateurism and that you are simply groping at straws. The upper section had enormous inertia and there were no lateral loads sufficient to move it out of alignment until it fell a few stories and started tilting due to eccentric loading. If you actually think the upper section could move out of alignment immediately before any impacts would have occurred in a natural collapse please show some calculations.
Click to expand...

You are claiming there was no tilt until after fall initiation?
 
tsig said:
You are claiming there was no tilt until after fall initiation?
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There was little to no tilt until about three stories into the collapse of the North Tower. So the tilt has nothing to do with why we don't observe a deceleration when the columns should have been impacting. The columns were not involved and it cannot be because they missed each other as some amateur commenters on this website want to insist without a basis.

The inertia of the upper section was enormous and it would fall straight down until eccentric axial loading started to have an effect and cause a tilt. That did not happen right away.
 
JSanderO said:
And this is precisely what happened to those towers... they came apart from parts of them being "freed" from the structural matrix and falling and colliding with another part which was still part of the structural matrix or "in the path" of its motion....

The missing jolt is a reductionist argument that presents a reductio ad absurdum which does not explain the event at all. Just another silly useless cartoon conception... like the blocks of Gage and the limit case of Dr B.

The destruction involved billions or maybe trillions of collisions and they were spread out over a span of 10-14 seconds. Missing jolt? not missing... try billions of them blending into smooth movement on a macro level... the only one we can actually observe.
Click to expand...

Quite the contrary, it is what you are saying that is not reflective of reality and does not answer the question as to why there was no deceleration observed in the fall of the North Tower's upper section.
 
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Tony Szamboti said:
Quite the contrary, it is what you are saying that is not reflective of reality and does not answer the question as to why there was no deceleration observed in the fall of the North Tower's upper section.
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Yes, it's a mystery, given that we know that the perimeter columns were not severed by explosives and therefore must have caused exactly such a deceleration. It can't be because their resistance was negligible, because we know that it reduced the acceleration from 1G to about 0.64G, yet there was no jolt despite the fact that Szamboti et al insisted that there must be. It's almost as if the entire Missing Jolt model is completely wrong.

Dave
 
Dave Rogers said:
Yes, it's a mystery, given that we know that the perimeter columns were not severed by explosives and therefore must have caused exactly such a deceleration. It can't be because their resistance was negligible, because we know that it reduced the acceleration from 1G to about 0.64G, yet there was no jolt despite the fact that Szamboti et al insisted that there must be. It's almost as if the entire Missing Jolt model is completely wrong.

Dave
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The corner connections of the perimeter walls were indeed severed with charges. The video clearly shows very rapid focused ejections on both sides of the corner where the spandrel plates were bolted to the corner.

It has also then been explained to you that after losing their orthogonal support the perimeter walls would behave as a slender sheet and provide some resistance but less than that required to support the static load above them. Thus the upper section would bend them down and outward while accelerating at 1G - resistance from the slender sheet.
 
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Tony Szamboti said:
The corner connections of the perimeter walls were indeed severed with charges. The video clearly shows very rapid focused ejections on both sides of the corner where the spandrel plates were bolted to the corner.
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Very rapid? I think Chandler says around 100 MPH, kind of slow for explosives don't you think? :rolleyes:
 
Tony Szamboti said:
There was little to no tilt until about three stories into the collapse of the North Tower.
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Really??
Ok, I must say I am surprised to read this. I admit at this point that I have never myself studied the motion of the NT's top carefully frame by frame and assumed that both towers had tilt from the start. Got to look into this... Anyone else going to comment?

Do you agree that the South Tower started to tilt from the first moment on? I believe ozeco's oft-posted animated gif with the pivot overlayed is ST.
 
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