Understanding the claim of "The top of the north tower fell at 65% or 2/3 of g"

[Gamolon]

I see this statement from time to time, but most recently posted by Henkka:

The top of the North Tower accelerated down smoothly at about 65% of g as long as it was visible, it did not decelerate. Chandler will claim this is proof that the top is not crushing what's below, but is instead falling as its supports are being removed by something else.

I'm trying to understand how a falling object, with no resistance and being affected only by gravity, can only fall at 65% or 2/3 of g? Doesn't this mean that there is resistance of some kind that is keeping the object from falling at freefall?

Would someone kindly explain? What am I missing?

Thanks in advance.

 

[econ41]

@Gamolon @Henkka is referring to the measurements by either D Chandler or T Szamboti. They both produced similar results and made the same couple of fundamental errors. (As did most debunkers in those early days - in part due to the common misunderstanding of Bazant & Zhou's paper -- let's not get distracted ) Error 1 - they measure gross motions without differentiating between the two main stages of collapse viz "initiation" (what allowed the top block to start falling bodily down" and "progression" (the rapid descent of collapse to effectively ground level.

The approx 2/3rds "g" is recognised as the rate of motion for the "progression" stage. (acceleration not speed - but you and I won't be confused by the difference)

Recall that the key feature of that stage was what we can call ROOSD. The falling debris missed the columns and landed on floor spaces. (The same in both the "OOS" (open office space) and the core - but let's not derail there at present. So there was no significant column resistance to slow the falling acceleration. The two main resistances came from shearing the floor joist/beam connections to the columns. And the need to increase the momentum of the falling debris as each successive floor added to the total mass.

Multiple attempts at calculation suggest that the momentum change was the dominant factor causing the "loss" of that missing 1/3rd "g".

So the brief answer to your question: " Doesn't this mean that there is resistance of some kind that is keeping the object from falling at freefall?" is "YES!". Some of it came from shearing floor joist connections but most resulted from momentum changes as more debris was added to the falling mass.

There are a few other complexities arising out of the Szamboti or Chandler measurements - especially their failure to identify stages. I would need to go back to source documents if you need more details of the acceleration at that earlier stage.

Refresh your memory - this is how the "ROOSD" process was first described in Nov 2007:

 

[econ41]

The Second big error affects the earlier stage. @Henkka is again referencing Chandler or Szamboti when he says:

it did not decelerate. Chandler will claim this is proof that the top is not crushing what's below, but is instead falling as its supports are being removed by something else.

Chandler is almost right when he says "not crushing". Remember that Bazant & Zhou had proposed that the Top Block dropped onto the lower tower. Which should have caused deceleration and a "jolt". BUT it didn't "drop". T Szamboti wrote a paper looking or "The Missing Jolt". Wrong model. Not what happened. BUT it confused both sides including many debunkers for many years.

The "jolt" did not occur because the falling material "missed" the columns. The part of each column in the falling Top Block did not drop onto or impact with its bottom half. That was the artifice used by Bazant & Zhou in their 2001-2 papers and which misled far too many debunkers up till 2007-8-9. A fundamental error in understanding the mechanism. More details or explanations are available if you need them. HINT - "How does a single column fail if it is either overloaded or overheated?"

Would someone kindly explain? What am I missing?

Thanks in advance.

Do you need more details or fuller argumentation??

 

[Gamolon]

The Second big error affects the earlier stage. @Henkka is again referencing Chandler or Szamboti when he says:

Chandler is almost right when he says "not crushing". Remember that Bazant & Zhou had proposed that the Top Block dropped onto the lower tower. Which should have caused deceleration and a "jolt". BUT it didn't "drop". T Szamboti wrote a paper looking or "The Missing Jolt". Wrong model. Not what happened. BUT it confused both sides including many debunkers for many years.

The "jolt" did not occur because the falling material "missed" the columns. The part of each column in the falling Top Block did not drop onto or impact with its bottom half. That was the artifice used by Bazant & Zhou in their 2001-2 papers and which misled far too many debunkers up till 2007-8-9. A fundamental error in understanding the mechanism. More details or explanations are available if you need them. HINT - "How does a single column fail if it is either overloaded or overheated?"

Do you need more details or fuller argumentation??

Thanks econ41, much appreciated.

I never understood how truthers came to the conclusion that 65% (or 2/3) of g meant zero resistance. Which to them meant columns removed by explosives.

 

[Henkka]

I never understood how truthers came to the conclusion that 65% (or 2/3) of g meant zero resistance. Which to them meant columns removed by explosives.

That's not the argument... There are two videos by Chandler you should watch to understand what I was referencing there. I didn't fully type out the arguments because I know posters like econ41 are already generally aware of these claims. Now I'm still a bit hazy on how much exactly I have to describe videos to not run foul of the "No-click" policy here, but here they are.

In the first video, Chandler measures the fall of the top of the North Tower from the Sauret footage. This is where we get the 64% of g (Not 65%, sorry) measurement from, but afaik other people have also done the measurement and this is not contested. Then he makes various arguments based on this. Now the issue as I understand it, is not that it was going at 64% of g, or 35%, or 95% or whatever number. The issue is the smoothness of the curve and the lack of a jolt. The purpose of this argument is to rebut Bazant's theory of the collapse, which posited that the top of the tower came down with a powerful crash, which should show up as a jolt in the measurement.


Source: https://www.youtube.com/watch?v=ZjSd9wB55zk


In the second video, Chandler does the same measurement on a verinage demolition, where the top half of a building is dropped on the lower half to demolish it. He demonstrates that in this case, a jolt is seen in the measurement.


Source: https://www.youtube.com/watch?v=NiHeCjZlkr8

 

[econ41]

Thanks econ41, much appreciated.

I never understood how truthers came to the conclusion that 65% (or 2/3) of g meant zero resistance. Which to them meant columns removed by explosives.

As far as I am aware I was the first person to identify "debris missing the columns" as the key feature explaining the 2/3rds "g" progression. That was Nov 2007 - my second week on online activity. And I thought it was obvious. Never realised that most people on both sides of the debate had it wrong. A long and complex history of "both sides wrong"

 

[econ41]

The issue is the smoothness of the curve and the lack of a jolt. The purpose of this argument is to rebut Bazant's theory of the collapse, which posited that the top of the tower came down with a powerful crash, which should show up as a jolt in the measurement.

I'm well aware of the confusions leading to the error. I was a key player in sorting it out in 2007 identifying the correct mechanism. Then 2009 supporting "Major_Tom" who has been a member here. He came from the truth movement side but was a highly competent researcher who rebutted a number of truth movement false claims. In fact, a "genuine truth-seeking truther"....

So, remember my advice to understand the real mechanisms?
Bazant & Zhou wrote a paper first released 9/13 2001 >> first to publish. Formally peer reviewed and published in early 2002. It was a limit case analysis that assumed the Top Block dropping so that all the falling top block columns impacted in axial alignment with their lower tower bottom parts. Again remember how many times I've suggested that you understand that feature.

Bazant (andZhou) in THAT first paper did not say it was what happened. It was a deliberate artificial scenario to set a "Limit Case".

BUT T Szamboti and D Chandler and about 95% of debunkers all misunderstood and thought Bazant meant it literally happened.

NEITHER of those factors was real. Viz: (a) Dropping to land on" OR (b) impacting with column ends in line AKA "aligned".

So Szamboti and Chandler (independently) went looking for the jolt that would have happened if in reality the top block had dropped and impacted. (And I'm, thinking I"ve told you all this in previous posts)

So the key points:
1) Bazant in the paper Szamboti and Chandler referred to did not posit it as a "theory of collapse";
2) Both Chandler and Szamboti (and Coles and probably more) took it as what literally happened. So they looked for a Jolt. (And most debunkers made similar errors - my advice don't ever get caught in the middle between two sides who are both wrong. )
3) That mechanism didn't happen so the"Missing Jolt" that Szamboti went looking for never existed. It wasn't a "missing jolt" it was a "jolt that was never going to occur".

That much corrects the false premise underpinning much of your commentary in post #5. Give it a bit of thought and possible reframe your comments on the basis of a corrected premise or two.

 

[Henkka]

Bazant (andZhou) in THAT first paper did not say it was what happened. It was a deliberate artificial scenario to set a "Limit Case".

Well regardless of what they intended, their study is still presented as what happened to the public on mass platforms like Wikipedia:

When the columns failed, the entire building above fell onto the first intact floor beneath impact. The vertical capacity of the connections supporting an intact floor below the level of collapse was adequate to carry the load of 11 additional floors if the load was applied gradually and 6 additional floors if the load was applied suddenly (as was the case). Since the number of floors above the approximate floor of collapse initiation exceeded six in each WTC tower (12 floors in WTC 1 and 29 floors in WTC 2), the floors below the level of collapse initiation were unable to resist the suddenly applied gravitational load from the upper floors of the buildings.

From there collapse proceeded through two phases. During the crush-down phase, the upper block destroyed the structure below in a progressive series of floor failures roughly one story at a time. Each failure began with the impact of the upper block on the floor plate of the lower section, mediated by a growing layer of rubble consisting mainly of concrete from the floor slabs. The energy from each impact was "reintroduced into the structure in [the] subsequent impact, ... concentrate[d] in the load-bearing elements directly affected by the impact." This overloaded the floor connections of the story immediately beneath the advancing destruction, causing them to detach from the perimeter and core columns. The perimeter columns peeled away and the cores were left without lateral support.

This continued until the upper block reached the ground and the crush-up phase began. Here, it was the columns that buckled one story at a time, now starting from the bottom. As each story failed, the remaining block fell through the height of the story, onto the next one, which it also crushed, until the roof finally hit the ground. The process accelerated throughout, and by the end each story was being crushed in less than a tenth of a second.

https://en.wikipedia.org/wiki/Collapse_of_the_World_Trade_Center#Total_progressive_collapse

And it's just totally absurd that it still includes language like "This continued until the upper block reached the ground", even though even a cursory glance at close-up videos of the collapse will tell you there was no intact upper block riding on top of the collapse wave. Since the study was submitted 13th of September, it's likely Bazant had only seen the collapse from a few, distant angles on TV.

 

[econ41]

Well regardless of what they intended, their study is still presented as what happened to the public on mass platforms like Wikipedia:

We are NOT discussing what is on Wikipedia. In fact, in this thread, I am responding accurately to the OP request from @Gamolon. So please desist from your derailing. IF you want to discuss that Wikipedia article - OP a thread and ASK. (YES the general belief in Bazant & Verdure's "Crush Down/Crush Up" hypothesis applied to WTCV collapses is WRONG. I've already told you that at least once and @Thomas B many more times. AND I'm probably the only sceptic or debunker who will disagree with Bazant on that issue. Most debunkers regard both NIST and Bazant as infallible. I don't.)

https://en.wikipedia.org/wiki/Collapse_of_the_World_Trade_Center#Total_progressive_collapse

And it's just totally absurd that it still includes language like "This continued until the upper block reached the ground", even though even a cursory glance at close-up videos of the collapse will tell you there was no intact upper block riding on top of the collapse wave.

Yes it is BUT you are "off-topic" - again.

Since the study was submitted 13th of September, it's likely Bazant had only seen the collapse from a few, distant angles on TV.

Wrong study. 13th SEpt 2001 was the first informal release of the paper by Bazant & Zhou "Why did the World Trade Center collapse? - Simple analysis." which was formally published January 2002. The "CD/CU" hypothesis was published by Bazant & Verdure in 2007 "Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions". Yes it is wrong. Yes a lot of peoole believe it is right. Truthers are not the only ones to make false explanations.

 

[Gamolon]

That's not the argument...

Then you need to explain the red portion of your quote below:

The top of the North Tower accelerated down smoothly at about 65% of g as long as it was visible, it did not decelerate. Chandler will claim this is proof that the top is not crushing what's below, but is instead falling as its supports are being removed by something else.

"Supports being removed" means zero resistance does it not?

 

[FatPhil]

I see this statement from time to time, but most recently posted by Henkka:


I'm trying to understand how a falling object, with no resistance and being affected only by gravity, can only fall at 65% or 2/3 of g? Doesn't this mean that there is resistance of some kind that is keeping the object from falling at freefall?

Would someone kindly explain? What am I missing?

Thanks in advance.

Forces, and accelerations, sum linearly. If an object is falling - on average - at 0.65g, then it's being decelerated - on average - by 0.35g. The spells of acceleration and deceleration will of course be peaky. You're correct, it is not falling "with no resistance".

 

[Gamolon]

AND I'm probably the only sceptic or debunker who will disagree with Bazant on that issue. Most debunkers regard both NIST and Bazant as infallible. I don't.

I don't either.

 

[Henkka]

Then you need to explain the red portion of your quote below:

"Supports being removed" means zero resistance does it not?

No, why would it... It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block, even though previously it had held 100% of its weight for decades. Though if "zero resistance" interests you, you should check out a video of his titled "WTC7: NIST Finally Admits Freefall".

 

[Gamolon]

No, why would it... It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block, even though previously it had held 100% of its weight for decades. Though if "zero resistance" interests you, you should check out a video of his titled "WTC7: NIST Finally Admits Freefall".

Because you made no mention of supports being removed to weaken the structure to a point that it would start to collapse. I was just clarifying what you meant.

 

[Gamolon]

The issue is the smoothness of the curve and the lack of a jolt. The purpose of this argument is to rebut Bazant's theory of the collapse, which posited that the top of the tower came down with a powerful crash, which should show up as a jolt in the measurement.

As has been explained by econ41 in this very thread (and others), there was not going to be a jolt.

 

[Gamolon]

It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block, even though previously it had held 100% of its weight for decades.

So what, in your opinion, was happening during the North Tower collapse initiation and a few seconds after?

David Chandler quoted below. "It" being the upper block.
https://davidchandler-61838.medium.com/free-fall-part-5-a0f77bff4c68

It is nearly 50% demolished internally before it starts moving into the lower section of the building.

Therefore we can conclude that about 90% of the strength of the supporting columns has been removed.

If 90% of the support structure was weakened to start the upper block moving downward "smoothly", what structural components were intact in the lower section that "demolished" 50% (5 or 6 floors) of the lower section of the top block as it descended?

 

[Gamolon]

It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block, even though previously it had held 100% of its weight for decades.

That's not what Chandler claims:
https://davidchandler-61838.medium.com/free-fall-part-5-a0f77bff4c68

That is because 90% of the underlying structure had been removed, so it was not there for it to impact. It was falling into the void. Uniform downward acceleration is not free fall, but it has the same implications for WTC 1 as free fall has for WTC 7: explosives were being used to pre-pulverize the building allowing the top section, or what was left of it, to fall with negligible resistance.

90% of the underlying structure was REMOVED, not weakened, by explosives.

 

[Jeffrey Orling]

Not much of the structure was removed... and none in the collapse phase after the top blocks hit the lower blocks. Columns were bypassed,

Structure at the plane strike zone was destroyed by the plane and further by the effect of the fires... which led to the tops dropping.

 

[Henkka]

That's not what Chandler claims:
https://davidchandler-61838.medium.com/free-fall-part-5-a0f77bff4c68


90% of the underlying structure was REMOVED, not weakened, by explosives.

Isn't the idea there that the remaining 10% is still putting up some resistance, resulting in a downward acceleration 2/3rds of g?

Btw, the page you linked happened to include this clip of WTC 2...


Source: https://www.youtube.com/watch?v=BQmaGCxHxj8

WTC 2 was hit in a corner, and the upper block clearly started rotating at first. But just look how perfectly evenly the destruction progresses across the two faces. It's uncanny. The corner seems to stay intact for a while as the destruction passes it by, though.

 

[Gamolon]

Isn't the idea there that the remaining 10% is still putting up some resistance, resulting in a downward acceleration 2/3rds of g?

What I'm asking you is to address what Chandler has said.

He said 90% of the underlying structure was removed by explosives. He also says that the bottom 50% of the upper block was destroyed as the roofline descended before it actually moved into the lower block.

Removing 90% of the underlying structure means that when the upper block started to descend, there were only 5 core columns (of 47) and 24 perimeter columns (of 244) remaining. How did those remaining components completely destroy the bottom 50% (5 or 6 floors) of the upper block?

Are you suggesting that the first floor of the lower block stayed intact while 5 floors worth the upper block was crushed against it and destpyed and then that floor failed?

 

[Henkka]

What I'm asking you is to address what Chandler has said.

He said 90% of the underlying structure was removed by explosives. He also says that the bottom 50% of the upper block was destroyed as the roofline descended before it actually moved into the lower block.

Removing 90% of the underlying structure means that when the upper block started to descend, there were only 5 core columns (of 47) and 24 perimeter columns (of 244) remaining. How did those remaining components completely destroy the bottom 50% (5 or 6 floors) of the upper block?

Are you suggesting that the first floor of the lower block stayed intact while 5 floors worth the upper block was crushed against it and destpyed and then that floor failed?

I don't know, I can't see inside the building.

 

[Gamolon]

I don't know, I can't see inside the building.

You support Chandler and what he says. Can you explain how Chandler's claims in post #20 are possible when used together?

 

[Henkka]

You support Chandler and what he says. Can you explain how Chandler's claims in post #20 are possible when used together?

Honestly I'm having a bit of a hard time comprehending exactly what you're asking in post #20...

He also says that the bottom 50% of the upper block was destroyed as the roofline descended before it actually moved into the lower block.

Like for example this just seems to be a factual observation of what happened in the first second or two of the collapse, not some argument Chandler is making. Do you not agree that this happened?

 

[Gamolon]

Honestly I'm having a bit of a hard time comprehending exactly what you're asking in post #20...

Like for example this just seems to be a factual observation of what happened in the first second or two of the collapse, not some argument Chandler is making. Do you not agree that this happened?

In your opinion, what was that mechanism or process that caused the 6 lower floors of the upper block to be crushed/destroyed? What prevented the lower boundary of the upper 12 floor block to move into/past the top/upper floor of the lower block until AFTER 6 floors were sandwiched and crushed?

Did what Chandler is states below happen in regards to the lower block?

The two sections would destroy each other at the same rate, so by the time the top 12 floors of the bottom section were destroyed, the top section would also be destroyed, leaving nothing to crush down the rest of the building.

 

[econ41]

@Henkka You are deliberately posting false claims which have already been debunked in this thread.

This one is false:

No, why would it... It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block,

No it wasn't "weakend" for the reason I have now identified for you at least 6 times in this and other threads. Read THESE and re-read until you understand what they mean:
"The falling material missed the columns."
"The columns were still full strength BUT the falling material missed them"

Now @Henkka:
1) Do you understand that I said "The falling material missed the columns."?
2) Do you agree that is a true explanation?
IF you disagree post your reasoning and stop your unsupported false claim denials.

even though previously it had held 100% of its weight for decades.

Yes. Moot point despite the patronising implied dishonesty.

And this next bit intrduces a differnt Chandler false claim. This one:

Though if "zero resistance" interests you, you should check out a video of his titled "WTC7: NIST Finally Admits Freefall".

Again you change topic to another Chandler lie. The true situation was that in the draft NIST Report into the collapse of WTC 7 NIST identified a small period of Free Fall Acceleration ["FFA"] by crude measurements of the upper facade of WTC7. Chandler in commenting on the draft report asked for more detail of that FFA. NIST obliged by providing further details. Of the period of FFA. (NOT "Freefall" but that is another aspect of Truth Movement common lies. FFA is NOT "Freefall"...)

Chandler's claim "admits" is false - intended to fool his gullible truther audience. The reason is more fundamental dishonesty that the TM relies on. The presumption that "FreeFall" PROVES CD. It doesn't. So a couple of lies by Chandler to support one of the foundation lies that the TM relies on.

Remember I have offered to explain each one of Chandler's false claims to you. One at a time. I have now shown two of Chandler's claims to be wrong in this thread. Please stop quoting Chandler's false claims unless you are prepared to defend them. He is wrong.

 

[econ41]

In your opinion, what was that mechanism or process that caused the 6 lower floors of the upper block to be crushed/destroyed? What prevented the lower boundary of the upper 12 floor block to move into/past the top/upper floor of the lower block until AFTER 6 floors were sandwiched and crushed?

Did what Chandler is states below happen in regards to the lower block?

The two sections would destroy each other at the same rate, so by the time the top 12 floors of the bottom section were destroyed, the top section would also be destroyed,

That much is true. If we interpret this graphic it proves why Chandler is correct (and Bazant was wrong) on that claim.

But not this last part:

leaving nothing to crush down the rest of the building.

.. which is ridiculous. The preceding "two sections would destroy each other at the same rate" leaves a lot of debris to continue ROOSD progression.

 

[Mendel]

Forces, and accelerations, sum linearly. If an object is falling - on average - at 0.65g, then it's being decelerated - on average - by 0.35g. The spells of acceleration and deceleration will of course be peaky. You're correct, it is not falling "with no resistance".

Are the kids on a see-saw falling at less than 1 g because of resistance?

Or is it because they're not actually in free fall?



If you support one end of a lever on a fulcrum and let the free end fall, different parts of the lever will accelerate at different rates (some exceed 1g, some don't), although there is no resistance.

 

[Mendel]

. It means the lower structure is being weakened to the point it can no longer hold up even 36% of the weight of the upper block, even though previously it had held 100% of its weight for decades.

I'm sorry, I don't understand this statement. Which "lower structure", exactly, is being weakened? What is the "upper block"? Are you implying that weakened structure would support 35% of the weight of the upper block? How do you know?

 

[Henkka]

No it wasn't "weakend" for the reason I have now identified for you at least 6 times in this and other threads. Read THESE and re-read until you understand what they mean:
"The falling material missed the columns."
"The columns were still full strength BUT the falling material missed them"

Now @Henkka:
1) Do you understand that I said "The falling material missed the columns."?
2) Do you agree that is a true explanation?
IF you disagree post your reasoning and stop your unsupported false claim denials.

Do you acknowledge this is just a personal theory of yours, right? I don't think NIST for example comments at all on whether or not the falling material missed the columns.

 

[Mendel]

Do you acknowledge this is just a personal theory of yours, right? I don't think NIST for example comments at all on whether or not the falling material missed the columns.

Shouldn't the material still be up there on the spire if it hadn't missed the columns?
View attachment 47183

 

[FatPhil]

Are the kids on a see-saw falling at less than 1 g because of resistance?

Or is it because they're not actually in free fall?

It's not an "or": they aren't in free fall *because* there's resistance. And no part of a see-saw, supported by a fulcrum, is in free fall.

 

[Mendel]

Do you acknowledge this is just a personal theory of yours, right? I don't think NIST for example comments at all on whether or not the falling material missed the columns.

That's false.

NIST NCSTAR 1-6, p.323:

The likelihood of the falling building section aligning vertically with the columns below was small, given the observed tilting

This means that the top section tilted, and as result did not align with the columns below. 'Not aligning with the columns' means 'missing the columns'.

 

[Mendel]

they aren't in free fall *because* there's resistance

I don't follow.

 

[Henkka]

That's false.

NIST NCSTAR 1-6, p.323:

The likelihood of the falling building section aligning vertically with the columns below was small, given the observed tilting

This means that the top section tilted, and as result did not align with the columns below. 'Not aligning with the columns' means 'missing the columns'.

Ok, I stand corrected on that then... That's probably referring to the South Tower though, right?

 

[econ41]

Ok, I stand corrected on that then... That's probably referring to the South Tower though, right?

Maybe. But the explanation is dubious. The "column ends missing" scenario was set in place BEFORE tilting of the top block***. I'll repeat my advice again. Learn to understand the actual mechanisms AND don't assume NIST is always correct.
.
.
*** Because "tilting" was caused by columns failing - with more failing on one side. And those columns failed by buckling under overload possibly assisted by overheating. The failed column gets shorter. So the column ends "missing" is already in place BEFORE tilting. Columns "missing" causes tilt. NOT "tilt" causes columns missing....

Don't take NIST explanations as infallible.

 

[FatPhil]

I don't follow.

Anything with resistance *definitionally* isn't in free fall. Free fall is being acted upon solely by gravity.

 

[Jeffrey Orling]

*** Because "tilting" was caused by columns failing - with more failing on one side. And those columns failed by buckling under overload possibly assisted by overheating. The failed column gets shorter. So the column ends "missing" is already in place BEFORE tilting. Columns "missing" causes tilt. NOT "tilt" causes columns missing....

I believe core columns failed
plane severed some
plane damaged some
heated beams and girders pushed columns, warped them causing them to buckle

There was only "overloading" when there were fewer columns and the loads had of course not changed. This became a "Self sustaining/ fulfilling process" as more columns failed while the service loads remain unchanged.

Tilting was possible because a large portion of the upper blocks were rigid because of the hat truss and intact floor plates.... being supported "asymmetrically" as a result of how the columns were / had failed.

I think the column "weakening" was less from strength being driven down by heat and more by being distorted by expanded beams.

 

[Mendel]

Ok, I stand corrected on that then... That's probably referring to the South Tower though, right?

NIST notes that in both towers, the top tilted as a rigid block.

 

[Mendel]

Anything with resistance *definitionally* isn't in free fall. Free fall is being acted upon solely by gravity.

Yes.

But you seem to claim the reverse—that anything not in free fall has resistance.
A—>B is not the same as B—>A.

Wikipedia: "In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it." No mention of resistance.

Which definition of free fall are you using that involves resistance?

 

[FatPhil]

Yes.

But you seem to claim the reverse—that anything not in free fall has resistance.
A—>B is not the same as B—>A.

?!?!?!?

"they aren't in free fall *because* there's resistance""

I even *emphasised* the "because". Clearly, resistance is the cause of the non-free-falling.