Merged Freefall is not evidence for Controlled Demolition

[Dave Rogers]

That is not globally true Dave.

It is true for any specific outcome if we do not know the facts needed to support that outcome.

The need is not for "complete knowledge" - rather knowledge of all the necessary facts needed to support each relevant outcome.

We may know the facts needed for some outcomes whilst not knowing the facts needed to support other outcomes.

The most common error we see (IMO) are claims that "We cannot know "A" because we do not know ALL the facts" Not so. The true situations are:
1) 'We cannot know "A" because we do not know ALL the facts needed to establish "A" '; OR
2) 'We can know "A" because we do know ALL the facts needed to establish "A" ' (provided the known facts do in logic establish "A")

To "prove" "A" we don't need to know the facts which are not relevant to proof of "A".

I'm not saying we don't know enough, in this instance, to deduce the nature of the collapse initiation sequence in general. What we don't know, and can't know, is a level of detail sufficient to say, for example, "The initial failure was caused by floor truss X detaching / pulling in / column Y failing in buckling / compression," or something like that. There will always be enough uncertainty in the minutiae that an appeal to perfection can be made, and for the purpose of maintaining the illusion of uncertainty over the general cause, it seems any degree of uncertainty over specific cause is enough for those who simply want to keep the argument alive.

Dave

 

[ozeco41]

I'm not saying we don't know enough, in this instance, to deduce the nature of the collapse initiation sequence in general. What we don't know, and can't know, is a level of detail sufficient to say, for example, "The initial failure was caused by floor truss X detaching / pulling in / column Y failing in buckling / compression," or something like that. There will always be enough uncertainty in the minutiae that an appeal to perfection can be made, and for the purpose of maintaining the illusion of uncertainty over the general cause, it seems any degree of uncertainty over specific cause is enough for those who simply want to keep the argument alive.

Dave

Agreed naturally. And the "[illusion of|appeal to] perfection" flaws of logic well stated. Possibly "...keep the argument circling"

An example of what I was referring to is in recent comments by jay howard.

He was looking for specific answers to:
A) Which was the first column to fail; AND
B) What precise temperature in degrees were the columns heated to;
...and claiming that we cannot explain/"prove" the mechanism of the relevant stage of collapse mechanism without those specific bits of evidence.

I called foul. On the basis that we will never know those details BUT we don't need to know to explain/"prove" the mechanism.

I had anticipated that my answers which are both specific and sufficient were guaranteed to send a truther (probably a lot of left brained debunkers) off in a mad spin.

I said (words to the effect of):
The first column to fail in the cascade sequence was the first column to fail. AND SIMILARLY
The columns that failed through heating were hot enough to fail.

Both of those sufficient to prove the relevant conclusions that I drew.

(And I clarified the heating effect one by saying "In combination with (a) the actual load applied at the time of failure which could be increased over normal due to load redistribution from other failing members (b) any weakening due to increased unsupported length caused by loss of bracing and (c) any applied eccentricities/misalignments.")

BUT the answers "The first one was the first whichever it was" AND "The failed columns were hot enough to fail" are valid answers which do not require complete global knowledge of details - to support the claims I was making.

When presented by a cascade failure that runs to completion we know:
A) That it completed irrespective of which member was first to fail; AND
B) Every single column that failed was hot enough to fail...


...including those that were so overloaded that they would fail at ambient temperature.

 

[Crazy Chainsaw]

Agreed naturally. And the "[illusion of|appeal to] perfection" flaws of logic well stated. Possibly "...keep the argument circling"

An example of what I was referring to is in recent comments by jay howard.

He was looking for specific answers to:
A) Which was the first column to fail; AND
B) What precise temperature in degrees were the columns heated to;
...and claiming that we cannot explain/"prove" the mechanism of the relevant stage of collapse mechanism without those specific bits of evidence.

I called foul. On the basis that we will never know those details BUT we don't need to know to explain/"prove" the mechanism.

I had anticipated that my answers which are both specific and sufficient were guaranteed to send a truther (probably a lot of left brained debunkers) off in a mad spin.

I said (words to the effect of):
The first column to fail in the cascade sequence was the first column to fail. AND SIMILARLY
The columns that failed through heating were hot enough to fail.

Both of those sufficient to prove the relevant conclusions that I drew.

(And I clarified the heating effect one by saying "In combination with (a) the actual load applied at the time of failure which could be increased over normal due to load redistribution from other failing members (b) any weakening due to increased unsupported length caused by loss of bracing and (c) any applied eccentricities/misalignments.")

BUT the answers "The first one was the first whichever it was" AND "The failed columns were hot enough to fail" are valid answers which do not require complete global knowledge of details - to support the claims I was making.

When presented by a cascade failure that runs to completion we know:
A) That it completed irrespective of which member was first to fail; AND
B) Every single column that failed was hot enough to fail...


...including those that were so overloaded that they would fail at ambient temperature.

Ambient temperature failure of welds actually should speed the collapses.
Welds are more susceptible to shear, at room temperature.

 

[ozeco41]

Ambient temperature failure of welds actually should speed the collapses.

Only if weld failure is the "critical path". For the Twin Towers initiation Column failures in axial loading the main factor. Possibly weld failure could be a contributory factor but I don't see how. Or how it could change the overall explanation - everything I have said so far is sequence dependent but not speed dependent.

Welds are more susceptible to shear, at room temperature.

Sure ....BUT:
More susceptible than what?
In what scenario relevant to Twin Towers "initiation"?

 

[JSanderO]

The "precise" outcome of a very complex and chaotic event is not predictable.. nothing to do evidence set.

There is ample evidence to predict "global collapse" but clearly never to show where all the steel will end up.

 

[Grizzly Bear]

You are one of I think 6 members here who could decode my comments. On recount it is 8 so far - edit at 1559 local so 1hr21 after the original post - do your own time zone translations.

(Nice edit window time on this forum )

Eastern time zone here... I spent some time dabbling with the trio myself, had my brief run over there, then a snag hit and I stopped going.

The freefall seems to be a sticking point, if you do as done here and point out it's an irrelevancy to "CD" then you're insinuated to have not known the significance, or as one such "B" put it, you don't know what free fall is a all. Since the sampling size of TM members is so small here these days though it's rare to get any real reasoning out of the group, such that it seem unlikely we'll see a response from the CT camp in this thread or on this matter any time soon

 

[beachnut]

The problem for me with the collapses is that the investigative team for the Twin Towers have came to the conclusion for the cause but not entirely the effects. They have indicated what was happening to the building like the changes of the exterior columns, but in neither of the Twin Towers did they pinpoint what specific failure caused floors the size of an acre to start falling down. It boils down to a 'first cause' issue. They came to that sort of conclusion with WTC #7, but not for the Twin Towers. Whether they can't or they don't want to is irrelevant to me, what is relevant to me is knowing what caused what I saw and can see in any video I watch of it.

Yes, they did account for the entire collapse.

A floor in the WTC can hold 29,000,000 pounds; top section failed, the first lower floor instantly failed when overloaded. The floors hold the core to the shell. The shell an core share the load. Then the next floor fails when the mass hits the next floor; the floor fail to the ground.

After the floors fail, the core can't stand without being connected to the shell for lateral support. The shell was ripped up in sections as overwhelming mass fails the floors and rips into the shell, and core.

After initiation, the floors below can not hold the mass coming down. Which part of floors can't hold the mass coming down needs explaining.


I guess people have a hard time grasping the floor, a floor only holds 29,000,000 pounds. The core and the shell hold up the all the floors, but a floor only holds a certain load.

If you place over 29,000,000 pounds on a floor carefully, it would be possible to destroy the WTC towers. It is due to the structure. What we saw on 911 was each floor failing, and the falling mass was smashing the entire building.

 

[ozeco41]

The freefall seems to be a sticking point, if you do as done here and point out it's an irrelevancy to "CD" then you're insinuated to have not known the significance, or as one such "B" put it, you don't know what free fall is a all.

It is the easiest of the false memes to address technically. Clear cut and simple. Other memes like "falling in footprint" are harder to pin down.

Since the sampling size of TM members is so small here these days though it's rare to get any real reasoning out of the group, such that it seem unlikely we'll see a response from the CT camp in this thread or on this matter any time soon

And the level of reasoning by debunkers has fallen. Hard to not drop to the truthers level since the claims all come from their side.

My related frustration is that there is no interest in discussing those few remaining areas of technical complexity which are still not understood by either side.

The 3D process of Twin Towers cascade failure initiation sage the main one. Thinking (mmm...) is still dominated by 1D heresies derived from Bazant. And three dependent sub issues flow from that lack of understanding:
1) "Missing Jolt" and the Chandler version. All that looking for Jolts when the scenario never existed. And both sides falling for the trap;
2) All the time wasted arguing if tilt would stop column ends impacting. Utter crap - and again both sides fell for it. By the time you have tilt the column ends have already missed. That is WTF caused tilt. One side getting lower because the columns had got shorter through buckling. (And "Missing Jolt" is merely a specific sub set of that same failure to comprehend what happened.)
3) Toppling - or "Why didn't the Top Block Fall over the Side". Same underlying misunderstanding - comprehend the cascade failure and you have the ground for why it didn't topple. The specific being that toppling needed a pivot and once Top Block starts falling the support which provided the pivot is gone. Falling wins the race against remnant rotational or toppling momentum.

All bleedingly obvious. Or should be but......

"how did ROOSD get started?" also related - it wasn't accumulation of floor debris.

...no interest left in serious stuff - every one in comfort zone playing "Whack-a-Mole".


Time for a new hobby - problem is this one fitted my civil/military engineer skill suite AND so one sided favouring the good guys made it easy to focus on technical explanation and in reality ignore the CT aspects other than as a source of material to rebut technically.

 

[ozeco41]

If you place over 29,000,000 pounds on a floor carefully, it would be possible to destroy the WTC towers...

It would be a good test of nerves. As you carry the umpteenth minus one lead block onto the target floor - and don't quite know if this one will be the one that tips the scale.

Would need a good supply of fresh underwear I suspect.

 

[000063]

You're thinking like an engineer. If you think like a detective, it's obvious that freefall implies controlled demolition.

Dave

Well, as long as you have motive, and have means which you had to make up and whose existense isn't proen, and spend over a decade with no opportunity, then that's all you need, innit? Case closed, book him, Danno.

 

[Jango]

Twin Towers Collapse mechanisms - Re-explained

Some preliminary comments:
1) First this is strictly Off Topic however it is a related issue since it sets one context in which Free Fall is often raised as an issue. So I will respond with an outline explanation.

(If anyone wants to request a separate thread the heading above will serve as OP title with this post as the new OP);

2) There are two conflated issues (or sets of issues) which are:
(a) Understanding how the collapse occurred as a structural mechanism; AND
(b) Whether or not the official explanations went far enough and/or were accurate. I will focus on the explanation of what actually happened - once we have some shared understanding we can, if we wish, discuss the sufficiency of official findings; AND

3) The issue of CD is often treated as if the collapse options were the dichotomy of "Natural" or "CD" mechanisms. That is not true. The two options are "Natural" alone OR "Natural plus CD assistance". With my usual comments about somewhat inappropriate use of the word "natural".

THEREFORE In explaining there are two choices to legitimately address the CD element - EITHER:
a) Include CD in the discussion from the outset; OR
b) Set it aside until the mechanisms are clear THEN address CD in that context.

I will try this by method "a)" - CD on the table from the start.

THEN 4) I intend to start from the big picture AND known facts - "drilling down" to such details as we need. So in direct contrast with the usual truth movement "argument" which starts from a detail which the proponent cannot explain and some false leaps to the conclusion "I cannot explain it >> THEREFORE CD >> THEREFORE you have to disprove it."

So the aim is "Explain the collapses which actually occurred allowing that CD assistance could be one of the factors."

The collapses of WTC1 and WTC2 were similar so I will treat them as the same until we reach a stage where differentiation is necessary (probably on the issue of "tilt".)

These are the "big picture" facts which we should agree on - let me know if you don't.

The collapse sequence was:
1) Aircraft impact caused some initial damage and started fires;
2) Fires were essentially unfought;
3) A period of increasing damage followed;
4) The "Top Blocks" were seen to move and tilt UNTIL
5) The impact and fire damaged zone(s) could no longer support the Top Block(s);
6) Which dropped/fell
7) In a sequence which progressed to ground level (allowing for the debris heap.

CD is plausible at three points:
A) Anywhere before "3" with pre cutting to weaken the core;
B) Anywhere in the impact and fire zone during 1-2-3 & 4 either by pre-positioned devices OR by devices installed during the event. Both having some difficulties BUT the possibility remains on the table; AND
C) During "7)" - the progression. ( Whether or not CD was applied in "7" it had to be in addition to either of the two previous options - reasons should be or should become obvious.)

Now the two critical collapse mechanisms are:
X) The "initiation" mechanisms of stages 3 and 4; AND
Y) The "progression" mechanisms of stage 7.

The "initiation" mechanism was a cascade failure process. (Despite recent assertions against that on another thread.)

A "cascade failure" involves progressive and sequenced failures where each failure is partially or wholly caused by the preceding failure. Similar to but several orders more complicated than the toppling of a row of dominoes.

The big picture truth is that what held up the Top Block was a collection of columns. Two simple must be true facts follow:
1) The Top Block fell; THEREFORE
2) All the columns had failed.

So the key to understanding the overall mechanism of the initiation stage is understanding why and how columns failed - both singly and in combination.

Whether they failed by "natural" process caused by impact damage and unfought fires OR there was assistance from CD doesn’t change the fact that all columns failed.

And it must have been a "cascade" - whether or not there was any CD in there to help - because:
j) It occurred over time - progressively - not all at once instantaneous; AND
k) With columns failing in sequence (whether by natural or CD processes) the processes of "load redistribution" must happen (also whether natural or CD) AND
..those two are the defining characteristics of a cascade failure - sequenced over time with each step triggering the next.

I'll leave it there for now - having set the groundwork for a more detailed explanation AND having legitimately left the CD option in the discussion.

The main issues we need to address in the next stage of explanation are:
p) How does any single column fail - what are the consequences;
q) How does any column fail given the interactions which must occur with nearby columns (and that is the really complicated bit ) THEN
r)How do these sequenced column failures progress to involve all of the columns;
s) Initially to the stage where there is not sufficient residual strength in the remaining columns to support the "Top Block at which point;
r) The Top Block falls causing all the remaining "surviving" columns to fail instantly.

Watch for a follow on post.

Do you feel certain about your beliefs about the collapses or are you still fighting through uncertainties? Given all that you know, all of the videos you've watched and all of the pictures you've seen and books/documents/articles you've read, where do you place the CD hypothesis (any of them) in terms of possibility and probability?

Perhaps combining what data we have about the impacts with the architecture data of the Twin Towers, we could narrow down what happened. As it stands now, there is a ? in the formula NIST used to come to their conclusion. We have impacts, fires, instability & then collapse. We're missing _____ failed initiating collapse sequence.

Looking at it in a purely objective manner highlights the incomplete information chain. I understand that it is a highly complex event with many literally moving parts, but isn't a tenet of skepticism questioning accepted truths, especially that of which isn't airtight thus open for cross examination? The missing ____ failure initiating collapse sequence is a part of their equation, they don't know what failed but they know something failed. That isn't conclusive science, not by any practical or legitimate standard.

 

[NoahFence]

No jango.
Skeptics stop being skeptical when the irrefutable facts are known. The twin towers fell due to their impact damage and subsequent fires.

Period. Full stop.

 

[ProBonoShill]

Do you feel certain about your beliefs about the collapses or are you still fighting through uncertainties? Given all that you know, all of the videos you've watched and all of the pictures you've seen and books/documents/articles you've read, where do you place the CD hypothesis (any of them) in terms of possibility and probability?

Perhaps combining what data we have about the impacts with the architecture data of the Twin Towers, we could narrow down what happened. As it stands now, there is a ? in the formula NIST used to come to their conclusion. We have impacts, fires, instability & then collapse. We're missing _____ failed initiating collapse sequence.

Looking at it in a purely objective manner highlights the incomplete information chain. I understand that it is a highly complex event with many literally moving parts, but isn't a tenet of skepticism questioning accepted truths, especially that of which isn't airtight thus open for cross examination? The missing ____ failure initiating collapse sequence is a part of their equation, they don't know what failed but they know something failed. That isn't conclusive science, not by any practical or legitimate standard.

No we're not. Unfought fires weakened steel and the structure could no longer support the load it was bearing. This is simple 4th grade physics.

The fire experts were standing outside the building and knew it was going to collapse well before it did, how do you think they knew that?

 

[ozeco41]

@Jango. Thanks for the response. For reasons of practical length of post my reply will not be pedantically bulletproof - we can sort out any clarifications in future posts if we need them. OK - here goes:

Do you feel certain about your beliefs about understanding of the collapses or are you still fighting through uncertainties?

Forgive the edit but the word "belief" is tainted in forum discussion - it is associated with a faith based position such as in religion. My preference is for a reason and evidence based objective position as per either scientific method or para-legal style proof. With that disclaimer:

1) I am very confident of my understanding of the Twin Towers collapse mechanisms in all significant major aspects.
2) I am confident that I understand those mechanisms from a qualitative descriptive basis at least as well as or better than most internet forum posters and the main strands of academic publishing.
3) I am confident that there are no aspects where rigorous quantitative analysis would compromise my qualitative understanding.
4) I have zero doubt that there was no CD at the Twin towers:
(a) I can prove to my professional satisfaction based on my own technical assessments (would swear on oath if called as expert witness) that there was no need for CD in the "progression" stage.
(b) I cannot prove no need for CD in the "initiation" stage" on purely technical grounds - only that it was highly likely there was no need for CD. BUT I would assert on logistics and security grounds that CD was not plausible.
5) I am also convinced that there was no CD at WTC7 but cannot prove that aspect on technical grounds - the evidence concealed inside and mechanisms not as obvious. However the logistic and security improbability says "no CD at WTC7".
6) I do not rely on "official reports" reasoning in any way in forming my professional opinions about the collapses.

Given all that you know, all of the videos you've watched and all of the pictures you've seen and books/documents/articles you've read, where do you place the CD hypothesis (any of them) in terms of possibility and probability?

I have never seen a pro CD hypothesis that even meets prima facie standard - i.e. is worthy of professional consideration in any detail. All claims I have seen from the truth movement are obviously and fatally flawed at preliminary reading.

Perhaps combining what data we have about the impacts with the architecture data of the Twin Towers, we could narrow down what happened.

I'm confident that is true. In fact I'm immodestly confident that I have already formed my own adequate explanations for all the significant aspects of Twin Towers collapses. And have formed rebuttal arguments for truth movement WTC7 claims that are strong enough to rebut any claim made to date. Certainly no truth movement supporter in the setting of this and several other forums has ever falsified my claims or supported their own claims against my counter claims in rebuttal. (I'm not the only one - but I'm presenting my position...with no benefit of "False Modesty 302" - I never did the unit of study. )

As it stands now, there is a ? in the formula NIST used to come to their conclusion. We have impacts, fires, instability & then collapse. We're missing _____ failed initiating collapse sequence...

Two points:
1) Correct we are missing the initiating sequence explanation. There is very little interest by people good enough to comprehend and explain it. And most thinking has been derailed by some false concepts arising out of the works of Prof Z Bazant. My post which you quoted was the scene setter from which I would present my explanation. And I have never done it before as a comprehensive overview. Plenty of bits and pieces scattered over the years. BUT it is an area where the technical stuff has not been explained or even ventured on - recall most hold to caricature 1D simplifications arising from the Bazant based heresies.

2) I have no need for NIST explanations and do not rely on them. The need is to understand how the collapse mechanisms worked. NOT whether NIST was right or wrong in its explanations. Their data is often helpful but confusing the two objectives -"Explain the collapse" and "Was NIST right or wrong" has over the years derailed a lot of internet discussion. So I deliberately keep the two well separated. Try NOT to discuss both in the same post.

Looking at it in a purely objective manner highlights the incomplete information chain. I understand that it is a highly complex event with many literally moving parts, but isn't a tenet of skepticism questioning accepted truths, especially that of which isn't airtight thus open for cross examination?

Several issues there and I'm going to refocus each of them. They are all "shades of grey" issues and this first explanation will not close every hole - in interest of brevity. I want you to comprehend "where I am coming from" OR "What direction I'm heading in" - we can sort out details later. Here goes:
1) For the Twin Towers there is sufficient information to form valid conclusions on the main big picture elements and most of the mid level stuff that matters.
2) Correct on the tenet of scepticism;
3) I doubt that there are any major points which have big holes. BUT we need to look at specific issues - discussing generics will never converge a solution;
4) those three will do for now.

The missing ____ failure initiating collapse sequence is a part of their equation, they don't know what failed but they know something failed. That isn't conclusive science, not by any practical or legitimate standard.

You claim "That isn't conclusive science, not by any practical or legitimate standard" is not necessarily true. And I've explained why several times in recent days in a scenario identical with yours. You say "...they don't know what failed but they know something failed." In some situations that is both valid and sufficient logic. e.g. the "cascade failure" of the "initiation stage" for Twin Towers collapses was a cascade failure. A sequence where each item that fails triggers failure of the next one in line which fails in turn. The critical issue - at least for most purposes - is that it was a sequenced cascade, Not which was first to fail. We do not know and never will know which column failed first. BUT there is no legitimate need to know. The conclusion "the fire and impact zone" underwent a cascade failure which weakened it until it could no longer support the Top Block is valid. (There is at least one obvious "yes but" exception in that but I'm keeping it simple for brevity in this post.)

Your turn.

 

[Jango]

No we're not. Unfought fires weakened steel and the structure could no longer support the load it was bearing. This is simple 4th grade physics.

The fire experts were standing outside the building and knew it was going to collapse well before it did, how do you think they knew that?

What 'specifically' failed? That's what you were responding to. You didn't respond with what 'specifically' failed. So, yes,

We're missing _____ failed initiating collapse sequence.

 

[Jango]

No jango.
Skeptics stop being skeptical when the irrefutable facts are known. The twin towers fell due to their impact damage and subsequent fires.

Period. Full stop.

Irrefutable facts like the equation I laid out:

As it stands now, there is a ? in the formula NIST used to come to their conclusion. We have impacts, fires, instability & then collapse. We're missing _____ failed initiating collapse sequence.

What we have is like this: https://www.youtube.com/watch?v=tO5sxLapAts

 

[Dave Rogers]

My related frustration is that there is no interest in discussing those few remaining areas of technical complexity which are still not understood by either side.

While I can agree that's an interesting and important topic in structural and safety engineering, it's not really germane to this forum. Once you start from accepting that the collapses were consequential to the airliner impacts, then you're not talking about conspiracy theories any more. The upshot of that is that, practically speaking, you can't really have that conversation here; it's inevitably going to be derailed into arguments over that initial acceptance, and without agreeing the starting point how can the discussion proceed rationally? If it were held on a forum dedicated to fire safety engineering, then you could tell the conspiracists to come here and discuss it, but you can't really complain on this forum when someone insists 9/11 was an inside job in a thread even tangentially related to it.

Dave

 

[Dave Rogers]

What 'specifically' failed? That's what you were responding to. You didn't respond with what 'specifically' failed. So, yes,

See, that's precisely what I was getting at. There will never be, cannot ever be, a sufficiently detailed understanding of the collapse mechanism to exclude a Thermite of the Gaps argument, because the precise site of initial failure couldn't be observed. Hence, this argument can never be resolved.

Dave

 

[Crazy Chainsaw]

Only if weld failure is the "critical path". For the Twin Towers initiation Column failures in axial loading the main factor. Possibly weld failure could be a contributory factor but I don't see how. Or how it could change the overall explanation - everything I have said so far is sequence dependent but not speed dependent.

Sure ....BUT:
More susceptible than what?
In what scenario relevant to Twin Towers "initiation"?

In any scenario, shear lag was evident in almost all the picutres of world trade center steel,
Except that which was sufficiently softened by the fires.

Shear lag is an indication of very rapid weld failure.

 

[JSanderO]

Failed tends to be too vague for some and perhaps it's too general. I suppose the intended meaning is that something failed... means it no longer was performing structurally to minimum specification which was required to maintained structural integrity as well as keep the slabs, beams, girders, and columns plumb, true etc.

As the systems nodes and elements pass the minimum performance spec the loads they were "carrying" or conveying... do not disappear but find their way to other parts of the structure... which may push these nodes and elements closer to being out of spec or failing them as well.

Downward movement occurs when insufficient axial capacity attends.