CD = Free Fall?

[Oystein]

Please note that I said nearly simultaneously.
...

I nearly kissed Jana two weeks ago.




You get my drift.

 

[Zeuzzz]

But as you probably know, collapse of the building core was already ongoing for for several (on the order 5-6) seconds before the north wall roof started to decent.

Any evidence for the 5-6 second internal collapse?

Once columns start to fail, load distribution happens at the speed of sound in steel, and it isn't really all that surprising if collapse propagates quite rapidly.

Load distribution at the speed of sound would make a difference to the speed the collapse progresses at, but does little to effect the fact of if the building should have collapsed at all from the damage/fires alone.

Hm I suggest you find and show that graph here, so we can all see what we are talking about. Okay?

No need I just made a stupid mistake of reading it from the a=g section as this was the main part highlighted and the rest of the curve did not stand out. I presumed that the first a=g point was t=0.

 

[Oystein]

Any evidence for the 5-6 second internal collapse?

Yes. Video of the east penthouse falling into the core of WTC7 several seconds before north wall starts to descend.

Load distribution at the speed of sound would make a difference to the speed the collapse progresses at, but does little to effect the fact of if the building should have collapsed at all from the damage/fires alone.

I think you just moved goal posts. We were debating the speed of collapse propagation, and you seemed to argue that natural collapse would have been slower; you now switched to whether or not natural collapse could occur at all. Do you claim now that fires cannot destroy buildings at all (make them collapse)?

No need I just made a stupid mistake of reading it from the a=g section as this was the main part highlighted and the rest of the curve did not stand out. I presumed that the first a=g point was t=0.

So you retract your earlier premises? If so, will you also retract the conclusions you drew from them?

 

[Zeuzzz]

Yes. Video of the east penthouse falling into the core of WTC7 several seconds before north wall starts to descend.

Never noticed that before. How was that penthouse directly connected to the core column(s) in the designs? It is a lot further up than where the fires are.

I think you just moved goal posts. We were debating the speed of collapse propagation, and you seemed to argue that natural collapse would have been slower; you now switched to whether or not natural collapse could occur at all. Do you claim now that fires cannot destroy buildings at all (make them collapse)?

A natural collapse should have been slower. In a CD the main supports are specifically targeted so as to take out every main structural support that would resist the collapse. In a natural collapse the time it takes for the columns and other steel supports to fail will factor in and make it the slower collapse.

What damage are you assuming had happened to the main supporting column(s)?

In addition to that I'm still not even convinced a total collapse is possible from a natural collapse scenario. But I wont be sure of that till I've heard your explanation for the above.

So you retract your earlier premises? If so, will you also retract the conclusions you drew from them?

I'll answer this next few days ..

 

[Oystein]

Never noticed that before. How was that penthouse directly connected to the core column(s) in the designs? It is a lot further up than where the fires are.

The penthouse was sitting on top of the core columns.
The core columns were not hovering high up in the air - they reached all the way to the ground. It doesn't matter where you break them - 45th floor, 13th floor, 2nd floor - once you break (enough of) them, they can't hold up whatever weight they are carrying.
According to the NIST theory, fires around the 12th floor destroyed lateral support for column 79, a particularly massive column on the east side of the core, straight beneath the eastern penthouse. The load formerly carried by column 79 got redistributed to neighboring columns which in due turn also failed (the suffered to some extent from the same removal of lateral bracing), till too few columns were left to support the east penthouse and all the floors below it - they fell, and with them the east penthouse.

Destruction then progressed westward through the core, till the west penthouse also failed, marking the near-completion of the destruction of the building core. Only immediately after the west penthouse fell did the north face start its descent. As you can now imagine, with the core falling, the floors spanning between core and perimeter could no longer provide lateral support to the north wall (or any other wall), hence perimeter columns were free to rapidly buckle inward (more likely) or outward (less likely). At any rate, they buckled.

A natural collapse should have been slower.

How much slower?

What you are sayinstating there is, formally, an inequality: You say that observed collapse speed (v_observed) was greater than an upper bound for the speed of natural collapse derived from theory (v_natural).
Both speeds could be expressed as an average vertical velocity, having a positive value for downward movement, having the SI unit m/s.

v_observed) > v_natural​

But have you evaluated this equality? You only know it's true if you have in fact estimated a lower numerical bound for v_observed and an upper numerical bound for v_natural. (Alternatively you could compare collapse time: t_observed) < t_natural; in this case you'd need to know an upper numerical bound for t_observed and a lower numerical bound for t_natural)

But have you really evaluated any of those numbers?

If not, you committed what Dave Rogers calls the Unevaluated Inequality Logical Fallacy.

In a CD the main supports are specifically targeted so as to take out every main structural support that would resist the collapse. In a natural collapse the time it takes for the columns and other steel supports to fail will factor in and make it the slower collapse.

As I described above, there was a slow phase of the collapse between (and possibly even starting before) the descent of the east penthouse and the start of the fall of the north wall. I think that counts.

What damage are you assuming had happened to the main supporting column(s)?

See above: Fire destroyed lateral support for column 79 along a height of several floors.

Much later, as the core was already tumbling and pulling floors attacjed to it down, falling floors pulled perimeter columns inward (first apparently about 8 floors above ground), making them buckle in rapid succession.

In addition to that I'm still not even convinced a total collapse is possible from a natural collapse scenario. But I wont be sure of that till I've heard your explanation for the above.

Argument from personal incredulity.
I notice that you weren't aware of some of the basics of the WTC7 collapse. I presume you have not yet read and understood the executive summary description of the NIST report's description thereof.

I'll answer this next few days ..

Maybe you find the time to read at least the summary of the NIST report on WTC7.

 

[beachnut]

Never noticed that before. How was that penthouse directly connected to the core column(s) in the designs? It is a lot further up than where the fires are.
...

You never studied WTC 7 collapse? The interior failed before the facade collapsed. The entire collapse tool over 16 seconds. Not near the free fall lies of 911 truth. Not one structural engineer has published a paper showing the collapse was not caused by fire. You would think Gage's 1600+ nuts would try to publish something other than delusional videos on the WTC 7 collapse. Bazant was able to publish a paper in days after 911 about collapsing buildings, and he included math. Gage's fools can't publish because not one is qualified to do more than fall for lies and spread nonsense.

http://www.youtube.com/watch?v=WieKk2o5GS8&feature=related

 

[alienentity]

Never noticed that before.

Bingo. That's why you don't understand what happened. Suggest you read NCSTAR 1-A and 1-9 and get back to us.

btw, 'nearly simultaneous' is not a measure of anything either. It's two words which can mean anything you want them to. If you're arguing that the failures were not simultaneous, all of us agree.
If you argue that they were 'too fast' for a natural collapse you'd have to proffer a well-researched, engineering based argument towards that. I've seen nothing yet, so there's nothing to rebut.

In addition to that I'm still not even convinced a total collapse is possible from a natural collapse scenario. But I wont be sure of that till I've heard your explanation for the above.

That's too bad, because partial and total natural collapses have happened to tall buildings many times for a number of reasons. You seem very out of touch with the reality of building collapses. Look at a few case histories and I think your perspective will improve a lot.

Don't rely on us to convince you - convince yourself by studying the matter. I've already suggested two NIST reports on WTC 7, but you can also look at various engineering studies done on other building collapses, such as the Kader toy factory, Delft University, and even WTC 5 (study published in Structure Magazine).

The more you learn, the less you need phantom controlled demolition to answer your questions. It just works that way.

 

[alienentity]

Zeuzzz, here's another interesting point - you could watch every single AE911Truth video, every Loose Change video, and you'll never see them discuss the progressive collapse of WTC 7, and the internal collapse which allowed the E and W mechanical penthouses to fall into the collapsing cores.
You just won't find it, and, believe me, they don't want you to. They avoid it like the plague, because it so devastatingly undermines and invalidates most of their specious claims.

 

[sylvan8798]

Well that makes perfect sense doesn't it, presumably in standard controlled demolition the top section of the building still has some resistance to collapse from the building below? There will be non structural vertical supports and the fact that (depending on the particular CD) not every column is taken out, and not generally taken out 100% instantaneously (depending on the type of CD performed).

What is a non-structural vertical support? An oxymoron?

Since GPE is simply being converted to E_k in the collapse then basic Newtonian mechanics shows that any resistance will be shown as a reactionary deceleration of the ~9.8 value.

As others have pointed out, the core fell first and then pulled in the exterior walls. The problem with attempting to use Newtonian mechanics is that while you might be able to calculate the "before" energy based on everything being at known elevations, you don't know the state during the collapse because you can't see all the parts. If parts of the interior have fallen further than the exterior, you have to take that into account. If the entire top fell exactly as it had stood, you would not see any effects of the collapse until it hit (broken windows, spalling facade, etc.). You can't simply take some time t and calculate the total energy remaining + the total kinetic energy. Not enough data.

 

[Zeuzzz]

Zeuzzz, here's another interesting point - you could watch every single AE911Truth video, every Loose Change video, and you'll never see them discuss the progressive collapse of WTC 7, and the internal collapse which allowed the E and W mechanical penthouses to fall into the collapsing cores.

I guess the reason being they have no remaining evidence for the progressive collapse other than the word of an organization they convinced themselves are not being honest (NIST) well before the WTC7 report was published. All the steel was destroyed.

The only real data and evidence they can use seems to be in fact the videos, the WTC7 plans and previous case studies of similar steel framed skyscraper 'progressive' collapses involving fire or structural damage.

If they never mention the penthouse (I was aware of the kink indicative of controlled demolition but not the penthouse) that would suggest they have overlooked a rather key aspect for sure ...

I notice that you weren't aware of some of the basics of the WTC7 collapse. I presume you have not yet read and understood the executive summary description of the NIST report's description thereof.

Scanned it when it came out originally, going to have to read it again now I guess. I just remember not being convinced of the idea that a failed column could destabilize the other columns enough to cause total collapse, and how such a column could apparently fail so completely in the first place for the building to be able to sustain free fall for so long.

Maybe you find the time to read at least the summary of the NIST report on WTC7.

I'll hopefully read the lot, and thanks for your explanation in #45

 

[RedIbis]

I just remember not being convinced of the idea that a failed column could destabilize the other columns enough to cause total collapse, and how such a column could apparently fail so completely in the first place for the building to be able to sustain free fall for so long.

As far as not being convincing, personally, I would add the idea that the fire got hot enough to compromise the steel floor system, so that when its connection to Column 79 was lost, it causes the column to collapse which eventually leads to the collapse of the entire building.

 

[alienentity]

I guess the reason being they have no remaining evidence for the progressive collapse other than the word of an organization they convinced themselves are not being honest (NIST) well before the WTC7 report was published. All the steel was destroyed.

I cannot agree with this statement. It is not NIST who creates any evidence; the evidence is there to be examined and understood by anybody who wants to.
The fact of progressive collapse is there for anybody who wishes to understand - seismic records, for example, corroborate this fact by demonstrating that significant events were going on internally before the remaining facade fell.

And since the steel was examined, but could not be identified as positively coming from WTC 7, no attempt was made to do that. However, in no case was there any evidence of cutter charges or any other incendiary devices on the steel from any of the buildings. It just isn't there.

AE911Truth's insistence that 'Freefall = CD' is not going to lead to any kind of 'truth', because it is fundamentally wrong as a principle. It is not 'evidence' of CD, anymore than the complete lack of artifacts of cutter charges is 'evidence' of CD. Neither are, in fact. Truthers make the mistake of shifting the burden of proof to those who are skeptics, but this is a reversal of what is required!

 

[Grizzly Bear]

Scanned it when it came out originally, going to have to read it again now I guess. I just remember not being convinced of the idea that a failed column could destabilize the other columns enough to cause total collapse, and how such a column could apparently fail so completely in the first place for the building to be able to sustain free fall for so long.

Considering you've got a handfull with other responses I'll comment only with a suggestion; locate the drawings and read the models of the NIST in detail. It would help for you to understand basic engineering principals related to load path, axial, and eccentric loading as well as others. If you have a basic understanding of those concepts and a basic understanding of how the building was constructed (via any publicly available floor plans or structure details) it would probably answer most of your concerns regarding progressive collapse. Unless you read the reports and study a little of the engineering, + precedents you'll likely remain in your so-called "limbo"

Since you're not likely to agree with peer comments you're best option is to self-study it yourself independent of the 9/11truth/debunker bias which means digging into a bit of academia

 

[ozeco41]

I guess the reason being they have no remaining evidence for the progressive collapse other than the word of an organization they convinced themselves are not being honest (NIST) well before the WTC7 report was published. All the steel was destroyed....

Which goes to a fundamental flaw of truther argument - the constant confusion of objectives. Is the objective "understand WTC7 collapse" OR is it "prove NIST wrong". The engineering forensic understanding of plausible WTC7 collapse mechanisms stands independent of whether NIST was right or wrong. And, going the step further to "intent", whether NIST, if wrong, was wrong by accident or by deliberate mendacity. So my advice is forget NIST and focus on seeking plausible mechanisms for collapse.

Then comes the next barrier. Do you have sufficient engineering forensic skills to take the evidence and work it out for yourself. I'm fortunate, I do have the expertise. For those who do not have the expertise it then comes down to "which experts explanation do I accept?" Ultimately you have to internalise that acceptance so it becomes your own decision.

Sadly in some ways those in the truth movement who are committed to the pre-determined duo of "NIST lies" AND "The collapse was CD" choose to keep the two objectives mixed together - which serves as a debating trick to make rebuttal more difficult. Some of them who employ the trick probably don't recognise it - merely parroting Gage or some other archetypal hero.

...If they never mention the penthouse (I was aware of the kink indicative of controlled demolition but not the penthouse) that would suggest they have overlooked a rather key aspect for sure ...

It is not proof by a long shot BUT the fact that when the truth movement publishes videos of WTC7 collapse they almost inevitable crop the first few seconds showing the penthouse falling. A fact which goes against the "credibility of the witness" - if hey believe what they are preaching why dishonestly remove the counter evidence?

 

[Animal]

Never noticed that before. How was that penthouse directly connected to the core column(s) in the designs? It is a lot further up than where the fires are.

It was supported by those column......that is how buildings are designed.

A natural collapse should have been slower.

Your proof of such a claim?

In a CD the main supports are specifically targeted so as to take out every main structural support that would resist the collapse.

Wrong In a CD various structures are targeted to be taken out at a specifice timing in order to cause the structure to fall in a planned path.

In a natural collapse the time it takes for the columns and other steel supports to fail will factor in and make it the slower collapse.

What damage are you assuming had happened to the main supporting column(s)?

Not much if any damage......the columns lost their lateral support and buckled due to their slenderness ratio vs loading.

In addition to that I'm still not even convinced a total collapse is possible from a natural collapse scenario. But I wont be sure of that till I've heard your explanation for the above.




I'll answer this next few days ..

 

[Oystein]

I guess the reason being they have no remaining evidence for the progressive collapse other than the word of an organization they convinced themselves are not being honest (NIST) well before the WTC7 report was published. All the steel was destroyed.

This sounds as if you already realize that these AE911T types judge everything with precomnceived conclusions and prejudices. Right?

The only real data and evidence they can use seems to be in fact the videos, the WTC7 plans and previous case studies of similar steel framed skyscraper 'progressive' collapses involving fire or structural damage.

Which isn't ideal, but not too bad either.

If they never mention the penthouse (I was aware of the kink indicative of controlled demolition but not the penthouse) ...

What makes you think the kink is indicative of controlled demolition? Years of experience with explosive demos? Your sound degree in structural engineering? Your detailed studies of the WTC7 structure and all its internal connections? You gut feeling coupled with things AE911T whispered to you? Which is it? Seriously, I want you to answer this! I have asked similiar questions of you before, which I really would like you to answer; I think if you write often enough that you are guided solely by truther, and use nothing but your layman's intuition, unbothered by any relevant education, expertise or math, then it should dawn on you that your arguments and even your questions are built on quicksand.

...that would suggest they have overlooked a rather key aspect for sure ...

No. They did not overlook it. They (Chandler etc.) cut it out deliberately in a conscios attempt at keeping you away from the truth.

Scanned it when it came out originally, going to have to read it again now I guess. I just remember not being convinced of the idea that a failed column could destabilize the other columns enough to cause total collapse, and how such a column could apparently fail so completely in the first place for the building to be able to sustain free fall for so long.

I'll hopefully read the lot, and thanks for your explanation in #45

So basically you are arguing from incredulity while being almost entirely ignorant of nearly everything. Right? You did not even know the collapse sequence in its crudest, simplest form when you hand waved the results of any man-years of work by top structural and forensic engineers, is that not so? Is that not a fair description of what you did?

 

[Zeuzzz]

This sounds as if you already realize that these AE911T types judge everything with precomnceived conclusions and prejudices. Right?

'everything' seems a bit too absolute a word to use there.

Is this NIST WTC7 report I'm reading now peer reviewed, if so what journal was it published in?

 

[Oystein]

'everything' seems a bit too absolute a word to use there.

Is this NIST WTC7 report I'm reading now peer reviewed, if so what journal was it published in?

Uhm... what difference does this make?
Nothing the truth movement or AE911T ever published has ever been honestly peer reviewed, they have conducted no peer review of the NIST reports.

The more important point is the actual impact the report has had on the actual world of engineering: It has been significant in that code changes are being implemented around the world as a result of NIST's findings.



The answer short is of course "no". I might add that the question is slightly moronic, because this is a report, not a journal article. Have you ever seen an article in any peer-reviewed journal that has over a thousand pages?
Who told you to aks that question?
Wouldn't it be more pertinent to ask if the report is consistant with all the known facts, and relies on nothing but the known facts?

The long answer would be "xes, sort of" - NIST published a draft, solicited comments, and worked many comments they got into the final version. One such comment came from David Chandler, and his comment has made it into to the final report. I think this should be enough to convince you that NIST did indeed ask peers for review, and listened to what they said.

 

[Dave Rogers]

Is this NIST WTC7 report I'm reading now peer reviewed, if so what journal was it published in?

That question suggests a lack of understanding of the term "peer review". One form of peer review is the anonymous peer review conducted by a journal on a paper for publication, in which the editor sends copies of the paper to a small number of neutral referees for comments and a recommendation as to whether the paper is suitable for publication in the journal. It is therefore a necessary condition for publication in a reputable scientific journal that a paper is peer reviewed in this specific way. However, it's affirming the consequent to say that a report that has been peer reviewed must therefore have been published in a journal, because there are other forms of peer review. One, for example, is that peer review effectively contiues after publication, in that papers are subject to comments by their readers, to which the authors may then reply; a good example is the response by Zdenek Bazant to various comments on his papers on the WTC collapses. Another form of peer review, practiced in the case of the NIST report, is to pre-release the report in draft form with a request for interested parties to comment, then to respond to these comments with revisions of the report where appropriate; a good example of this is David Chandler's observation that for a period in the collapse of WTC7 the facade was observed to accelerate at close to 1G, which was incorporated by NIST into the final version of the WTC7 report.

So the answer is that the NIST reports were peer reviewed; that the process for peer review employed was release of a draft, a general invitation to interested parties to comment, and revision of the report to respond to these comments; and that this is in no way related or relevant to publication in a journal.

Dave

 

[alienentity]

That question suggests a lack of understanding of the term "peer review". One form of peer review is the anonymous peer review conducted by a journal on a paper for publication, in which the editor sends copies of the paper to a small number of neutral referees for comments and a recommendation as to whether the paper is suitable for publication in the journal. It is therefore a necessary condition for publication in a reputable scientific journal that a paper is peer reviewed in this specific way. However, it's affirming the consequent to say that a report that has been peer reviewed must therefore have been published in a journal, because there are other forms of peer review. One, for example, is that peer review effectively contiues after publication, in that papers are subject to comments by their readers, to which the authors may then reply; a good example is the response by Zdenek Bazant to various comments on his papers on the WTC collapses. Another form of peer review, practiced in the case of the NIST report, is to pre-release the report in draft form with a request for interested parties to comment, then to respond to these comments with revisions of the report where appropriate; a good example of this is David Chandler's observation that for a period in the collapse of WTC7 the facade was observed to accelerate at close to 1G, which was incorporated by NIST into the final version of the WTC7 report.

So the answer is that the NIST reports were peer reviewed; that the process for peer review employed was release of a draft, a general invitation to interested parties to comment, and revision of the report to respond to these comments; and that this is in no way related or relevant to publication in a journal.

Dave

Here's some info on NIST's internal peer-review process

'To ensure high quality, accurate published information for all NIST authoredmanuscripts, NIST follows a stringent peer review process before releasing any technicalmaterial for publication. All official findings must be approved whether published by NIST, a professional society, or a commercial publisher.'
'Overview of the NIST Peer Review ProcessThe peer review system consists of an Editorial Review Board (ERB) at each NISTlocation.'