29 Structural & Civil Engineers Cite Evidence for Controlled Explosive Demolition

[H'ethetheth]

I posted the data.

NIST said that WTC 7 fell at free fall acceleration and yet you deny it.

You are in denial. You have just proven this.

No fact, no mater how well documented, will penetrate your OCT filter.

You are saying that David and NIST are wrong and you know better.

Please

No, everybody is saying that NIST and Chandler are right about this with a degree of uncertainty that easily allows for the buckling of massively unsupported columns. The difference between NIST and Chandler is that Chandler doesn't see that this is the case.

 

[FineWine]

I posted the data.

NIST said that WTC 7 fell at free fall acceleration and yet you deny it.

You are in denial. You have just proven this.

No fact, no mater how well documented, will penetrate your OCT filter.

You are saying that David and NIST are wrong and you know better.

Please

Ultima1 was mentally ill. He repeated over and over assertions that had been proven false.
NIST did not say that WTC 7 fell at free fall acceleration. Your claim will NEVER be true. It is time to stop repeating it and attempt to learn what real engineers are trying to tell you.

As a suggestion, why not acknowledge that you are simply incapable of following the explanations provided by tfk and Newton's Bit? I'm not trying to be unkind, but maybe they can dumb it down for you.

 

[Christopher7]

No, everybody is saying that NIST and Chandler are right about this with a degree of uncertainty that easily allows for the buckling of massively unsupported columns. The difference between NIST and Chandler is that Chandler doesn't see that this is the case.

NIST counted pixels on each frame. Both graphs accurate to within a couple tenths of a second. They are nearly identical. There is a slight pause when the building is not moving down in both and then sudden free fall acceleration.

NCSTAR 1-9 Vol.2 pg 612 [pdf 274]
"The results of this scenario were consistent with the observations except that the screenwall on the roof fell downward before the west penthouse."

In other words, the results of this scenario were NOT consistent with the observations.

 

[tfk]

It's from a show called "the fast show".


I had the impression he wanted to approximate only the freefall phase, which (unlike Chistopher now claims) doesn't have these initial conditions. But what I like most about it is that it illustrates how easily an error of over ±6% arises in an analysis like this.

And this is the way that approximations SHOULD be used. Knowing the limitations of built into your approximations.

If you use it ONLY within that regime, then it's use is fine. And I have no problem with it. You can use it to interpolate. Not extrapolate.

And with equations like this, you have to be VERY careful when you differentiate or integrate these functions. (Differentiation being more twitchy.)

tom

 

[Newtons Bit]

Ultima1 was mentally ill. He repeated over and over assertions that had been proven false.
NIST did not say that WTC 7 fell at free fall acceleration. Your claim will NEVER be true. It is time to stop repeating it and attempt to learn what real engineers are trying to tell you.

As a suggestion, why not acknowledge that you are simply incapable of following the explanations provided by tfk and Newton's Bit? I'm not trying to be unkind, but maybe they can dumb it down for you.

Well, it did fall at roughly g for a portion of the collapse.




It makes complete sense, I don't know why Christopher7 is having problems understanding it. Objects with nothing supporting them fall at g. Isaac Newton figured that out over 300 years ago. Truthers still struggle with this fact.

 

[tfk]

I posted the data.

NIST said that WTC 7 fell at free fall acceleration and yet you deny it.

You are in denial. You have just proven this.

No fact, no mater how well documented, will penetrate your OCT filter.

You are saying that David and NIST are wrong and you know better.

Please

I am saying that Chandler is wrong.

This is not surprising. Chandler is a high school physics teacher. Regardless of whether or not you believe it, I am an experienced mechanical engineer.

This analysis is NOT a physics exercise. It is an ENGINEERING exercise.

The KEY difference? "Error analysis".

With regard to NIST, I am certainly better than some and worse than others. And they certainly did make a couple of MINOR errors here.

But this is the difference between you & I, Chris. You can NOT do your own analysis. I can.

I'll take your lack of response to my challenge as your concession that you cannot do the math or engineering to address these issues. Agreed? Or do you want to give it a shot. I am NOT interested in your "cutting & pasting" Chandler's stuff again. I am interested in you doing the math (calculus is required) and providing the concise commentary that proves that you understand the concepts. Thus far, you've provided zero math and LESS-than-zero commentary.

You depend on others to spoon feed you your "story". And you possess little understanding of the foundations of the story. You only know that you like the outcome. ("THEY" dunnit.)

I don't have to depend on either NIST or Chandler. Neither does anyone who possesses a relatively modest level of competence in physics, math & engineering.

Chandler has enough competence in the physics. In the math, he has shown suprising "recklessness". He should know better. In the engineering, he's shown no interest, no effort. Which together, equals no competence.

To be precisely clear, until Chandler does a competent error analysis of EVERY STEP in his analysis, then he gets a failing grade. His error analysis WILL tell him exactly where his math was reckless. And, if he is clever, provide him with an alternative, and vastly superior, approach to the problem.

The single most important source of error is transcribing pixels to fall distance. This being his raw data, THAT error will ripple thru the rest of his work. I predict that the end result will be that the acceleration that his work can defend will be between .9G and 1.3G.

And with whatever range his data can REALLY support, the "fell at gravitational acceleration" claim evaporates.

tom

PS. BTW, you probably don't realize that it IS, in fact, possible for the wall to have fallen FASTER than G, without violating Newton or conservation of energy.

It is just highly, HIGHLY unlikely.

And, being an engineer - the very paragon of pragmatism (and let's not forget "good looks", "gratiousness" and "modesty"), that would cause me to reduce Chandler's error band to 0.9G to 0.99G.

 

[Newtons Bit]

With an angular rotation and a vertical acceleration, a single point can be seen accelerating faster than gravity. Likewise, the reverse is true, a point may actually be falling at g, but from the reference plane of a camera is seen moving less.

 

[tfk]

Hm, I think I should read what you said again, because I'm not sure I follow.

.

Check out the original post in this thread.

The "29 Structural & Civil Engineers" are members of ae911T. They have released one of their "engineering by press release" papers. ZERO engineering. ZERO analysis.

Just another tedious "we're a bunch of engineers, and while doing zero work, we'll say "nyah, nyah, nyah" to NIST".

Chandler is not on this list. But our amusing friend (& local poster) Heiwa (Anders Bjorkmann) is. There might be others who post here, but I'm not aware of them.

I guessed that Chandler was not one of those mentioned, because he is neither a civil nor a structural engineer.

I got lucky.

tom

 

[tfk]

C7,

And here is the EXACT problem, Chris...

NIST counted pixels on each frame.

.
Correct.
But... BUT... BUTT... (big hint here!!) gravity is NOT measured in PIXELS/second^2.
One of Chandler's biggest mistakes is not assessing the errors associated with this transformation (pixels -> distance)

Both graphs accurate to within a couple tenths of a second.

.
Wrong.
They are accurate to a much finer resolution than this. As long as you know how pixels are built & compressed.

They are nearly identical.

.
Yes. Nearly identical.

And neither should have been used.

There is a slight pause when the building is not moving down in both and then sudden free fall acceleration.

.
WRONG. Again wrong & I just explained to you EXACTLY why this statement is wrong.

That is NOT a height vs. time graph. It is a VELOCITY vs. time graph.

Is this too subtle for you to understand, Chris? If so, you have no hope of following the rest of the discussion. And I'll just stop swatting you about.

NCSTAR 1-9 Vol.2 pg 612 [pdf 274]
"The results of this scenario were consistent with the observations except that the screenwall on the roof fell downward before the west penthouse."

In other words, the results of this scenario were NOT consistent with the observations.

.
Chris, here's a strong suggestion. DON'T try to be "clever".

NCSTAR1A: 130 pages.
NCSTAR1-9 Vol 1: 404 pages.
NCSTAR1-9 Vol 2: 392 pages.

My SWAG at the pages of raw data & preliminary analysis that did NOT make the summaries: 10,000 pages.

ALL of this info generated, reviewed and cross-checked by a small army of the most competent structural, mechanical, comp sci, FEA, forensic engineers on the planet.

And the GLOBAL, considered assessment of that army is "we've got a handle on a never-before recognized, but explicable, failure mode that resulted in the collapse of that building." As clearly stated in their ~1000 page report.

In just the Summary Section that you are quoting here, there are 7 Pages of conclusions, broken into 3 Sections, 17 major headlines, 35 sub-headings, and 3 sub-sub-headings. All of which reinforces that army's assessment.

ONE of the sub-sub-headings reads, in toto:

"For the debris impact damage scenario, some of the interior columns on the west began buckling as the horizontal progression of interior column failures approached the middle of the core. For example, the middle line of interior columns directly behind the initially severed exterior columns buckled before the two north-south lines of columns immediately to their east. The middle line of interior columns lost lateral support in the north-south direction over 11 floors in response to the structural damage that was imposed. The results of this scenario were consistent with observations except that the screening wall on the roof fell downward before the west penthouse."

The next sub-sub-heading reads, in toto:

"For the no debris impact damage scenario, the horizontal progression of column failures occurred in order from east to west after collapse initiation (i.e., buckling of Column 79) and the vertical progression of failures on the east side. This scenario matched the observations where the screening wall on the roof fell downward before the west penthouse."

And yet you, with your stunning background in stacking amplifiers on busses, selling home remodeling services and producing interesting guitar licks, you wade into that study & pull out this one part of one sentence.

And hold it up as tho ...? WHAT, Chris...?

What IDIOTIC conclusion do you derive from this one phrase? Do you think that you have found some golden nugget that eluded that army of world class engineers? The nugget that overturns EVERYTHING that they thought they knew about the collapse of that building??

Rein in your ego, Chris.

As I said, you AIN'T that clever.

tom

 

[tfk]

With an angular rotation and a vertical acceleration, a single point can be seen accelerating faster than gravity. Likewise, the reverse is true, a point may actually be falling at g, but from the reference plane of a camera is seen moving less.

I always like this demo:
http://www.youtube.com/watch?v=NFJPQLhWPvA

And until recently, I'd never seen this one:
http://www.youtube.com/watch?v=SfZk6o88nSU&feature=related

We need more "Mr. Science" type shows for kids...


tom

 

[H'ethetheth]

NIST counted pixels on each frame. Both graphs accurate to within a couple tenths of a second. They are nearly identical. There is a slight pause when the building is not moving down in both and then sudden free fall acceleration.

First of all, seconds is not the relevant measure of accuaracy. Furthermore, all distances in Chandler's video are calibrated to a distance that has an error of up to half a floor in 240 feet. That alone can create an error of up to +/- 2%

Now, you tell me how accurate the extrapolated accelerations are, and I'll tell you how likely it is that columns were crushed.

Secondly, as people have pointed out, there is not a pause in moving down in the graphs. There is a period of constant velocity, i.e. a period of not accelerating downward.

I can't answer the second part of your post, because I haven't read that part of the report yet.

 

[Christopher7]

And this is the way that approximations SHOULD be used. Knowing the limitations of built into your approximations.

If you use it ONLY within that regime, then it's use is fine. And I have no problem with it. You can use it to interpolate. Not extrapolate.

And with equations like this, you have to be VERY careful when you differentiate or integrate these functions. (Differentiation being more twitchy.)

tom

NIST said:
"In Stage 2, the north face descended at gravitational acceleration, . . . This free fall drop continued for approximately 8 stories or 32.0 m (105 ft),

If you can't understand that they said free fall acceleration, your reading comprehension is zero.

Site a credible source that says the graphs NIST produced are not accurate or stop making that claim.

 

[Christopher7]

C7,
"For the debris impact damage scenario, some of the interior columns on the west began buckling as the horizontal progression of interior column failures approached the middle of the core. For example, the middle line of interior columns directly behind the initially severed exterior columns buckled before the two north-south lines of columns immediately to their east. The middle line of interior columns lost lateral support in the north-south direction over 11 floors in response to the structural damage that was imposed. The results of this scenario were consistent with observations except that the screening wall on the roof fell downward before the west penthouse."

Can you not comprehend that that statement says?
Their scenario does NOT match the observed collapse. In the scientific method, if the results of a scenario don't match the actual event, the scenario is scrapped and a new scenario is formulated.

What IDIOTIC conclusion do you derive from this one phrase? Do you think that you have found some golden nugget that eluded that army of world class engineers? The nugget that overturns EVERYTHING that they thought they knew about the collapse of that building??

That is one of many 'nuggets' that unravel the NIST scenario.

The army of world class engineers had no say in the final report.

 

[Newtons Bit]

Christopher 7: do you know what a screening wall is?

 

[H'ethetheth]

NCSTAR 1-9 Vol.2 pg 612 [pdf 274]
"The results of this scenario were consistent with the observations except that the screenwall on the roof fell downward before the west penthouse."

In other words, the results of this scenario were NOT consistent with the observations.

Yes, that is correct. The reason for this is stated right in the higher level of the bulleted list that quote is from. The details of the progression of failure were apparently fairly sensitive to the initial damage put into the model. So the detailed sequence of events differed with differing damage input parameters, and since the damage estimates are not that accurate, their mileage may vary.

Also, that quote is from page 604 (pdf 266), not page 612.

 

[Christopher7]

Well, it did fall at roughly g for a portion of the collapse.

Sophistry!

The fall was "indistinguishable" from free fall acceleration.

NIST confirmed David Chandler's findings. This is basic physics. He is qualified to say it was indistinguishable from free fall acceleration. Post the name of someone more qualified who has stated publicly that he is wrong and why or stop making that absurd claim.

It makes complete sense, I don't know why Christopher7 is having problems understanding it. Objects with nothing supporting them fall at g. Isaac Newton figured that out over 300 years ago. Truthers still struggle with this fact.

Quite the opposite. People in the Truth movement accept the fact that WTC 7 fell at free fall acceleration. JERFers are the ones having a problem with free fall acceleration.

 

[Christopher7]

First of all, seconds is not the relevant measure of accuaracy. Furthermore, all distances in Chandler's video are calibrated to a distance that has an error of up to half a floor in 240 feet. That alone can create an error of up to +/- 2%

You keep ignoring the fact that NIST confirmed David Chandler's findings.
They stated unequivocally that the north wall fell at gravitational [free fall] acceleration.

Secondly, as people have pointed out, there is not a pause in moving down in the graphs. There is a period of constant velocity, i.e. a period of not accelerating downward.

The graphs clearly show a momentary pause. When the line is flat [horizontal] between two or more spots, that wall is NOT moving downward.

 

[alexi_drago]

You keep ignoring the fact that NIST confirmed David Chandler's findings.
They stated unequivocally that the north wall fell at gravitational [free fall] acceleration.

The graphs clearly show a momentary pause. When the line is flat [horizontal] between two or more spots, that wall is NOT moving downward.
http://img34.imageshack.us/img34/5822/graphcompare.jpg

I've not been following this but did I really read that right?

EDIT:: C7 actually capitalised his own error.

 

[H'ethetheth]

You keep ignoring the fact that NIST confirmed David Chandler's findings.
They stated unequivocally that the north wall fell at gravitational [free fall] acceleration.

No, I keep telling you that I agree that they both find that there is a phase of acceleration indistinguishable from freefall. The devil is in the details, namely in the accuracy of this measurement. You don't seem to want to understand that this is not an accurate measurement, meaning that we cannot confidently say that there was no energy to bend columns.

The graphs clearly show a momentary pause. When the line is flat [horizontal] between two or more spots, that wall is NOT moving downward.
[qimg]http://img34.imageshack.us/img34/5822/graphcompare.jpg[/qimg]

No, sorry, you're simply wrong. A horizontal line in a velocity graph indicates a constant velocity (i.e. no acceleration, i.e. maintaining its current velocity), not a constant position, unless it is a horizontal line on the level of zero velocity, which it isn't.

 

[Christopher7]

1-9 Vol.2 pg 612 [pdf 274]
"The results of this scenario were consistent with the observations except that the screenwall on the roof fell downward before the west penthouse."

In other words, the results of this scenario were NOT consistent with the observations.

Yes, that is correct. The reason for this is stated right in the higher level of the bulleted list that quote is from. The details of the progression of failure were apparently fairly sensitive to the initial damage put into the model. So the detailed sequence of events differed with differing damage input parameters, and since the damage estimates are not that accurate, their mileage may vary.

A progressive collapse, spreading accross the core would result in the screenwall and west penthouse collapsing in a similar manner. According to NIST, it took 1 to 2 seconds for the collapse of each north south column row to cause the collapse of the next row. There were 6 column rows in the core area under the screenwall and west penthouse.

Horizontal collapse time line:
Time line using data from NCSTAR 1-9 Vol.2 pages 579-585 [pdf 241-247]
-1.3s Column 79 failed [Group 1]
-0.5s Column 80 fails [Group 1]
-0.5s Column 66 fails [Group 8]
~0.0s Column 81 fails [Group 1]
0.0s Kink in penthouse visible
1.3s Columns 77 & 78 failing [Group 2]
2.5s Columns 77 & 78 fail [Group 2]
3.5s Column 76 fails [Group 2]
4.3s Columns 59, 62, 65 & 68 fail [Group 7] G6 & G8 loading
4.5s Columns 73 - 75 fail [Group 3]
5.3s Columns 60, 63 and 69 fail [Group 8]
5.3s Column 58 failed [Group 6]
5.5s Group 3 still failing
6.3s Columns 70 - 72 failing [Group 4]
6.3s Columns 61, 64 and 67 failed [Group 6]

BTW: There is no explanation for column 66 [Group 8] failing when it did. The debris damage occurred 7 hours earlier and the fires had burned out in that area long before 5:20 PM.

Furthermore, Group 7 was supported in the north south direction by the columns in Groups 6 and 8. It could not fail before Group 8 as the result of "loss of lateral support in the north south direction" as NIST states on pg 612.
1-9 Vol.2 pg 612 [pdf 274]
13. Horizontal Progression of Failure.
"The middle line of interior columns directly behind the initially severed exterior columns buckled before the two north-south lines of columns immediately to their east. The middle line of interior columns [Group 7] lost lateral support in the north-south direction over 11 floors in response to the structural damage that was imposed."