Richard Gage Blueprint for Truth Rebuttals on YouTube by Chris Mohr

[MarkLindeman]

So Glenn, Mark,

I still have questions about what Chris7 is bringing up here. First of all, it is still my understanding that NIST's draft document on Building 7 did not acknowledge freefall at all. That came into the final report, and Chris7 asserts that NIST did not change their model when they acknowledged freefall. From what I can see, Chris 7 is correct when he says this.

However, Glenn quotes NIST 1-9 (above) saying complete buckling had happened within 2 seconds of the collapse, so if I understand correctly here, the original unchanged model could allow for freefall at that point.

Now Glenn, here is where I get really confused: when you said, "And for a column to break anywhere other than a connection would be a very strange event as connections are easily the weakest link. If your stick had a groove cut around it that's where the eventual break would occur, as it were. Chris7 prefers to insist on plastic buckling of the column material itself, as this allows him to claim "2% retained support" (or something) which would result in slightly < g acceleration. It's just more C7 straw-grasping to support his CD delusion." The reason this is confusing to me is because all the NIST modeling, especially figure 12-62, shows precisely what Chris7 says happened in the NIST model, which is plastic buckling of the column material itself. Isn't that exactly what I am seeing when I look at Figure 12-62?. Look at the computer model of the view from the south around the 11th floor or so. That looks like severe, extreme, plastic buckling of the column material to me.

Lest you think I am agreeing with Chris7, I am also looking at his own post 4121 at the top of page 104. There C7 shows another set of four NIST diagrams. In these model diagrams, at 13 and 14 seconds I see plastic buckling globally in floors 7-14 and columns snapping all over the place along the east side where the penthouse has collapsed. At 15 seconds, I see columns beginning to snap along the right side. One second into the global collapse, at 16 seconds, I see more columns snapping along the right side. Two seconds into the global collapse, which would be the 17th second, there is no diagram shown by Chris7, but that may be the point at which the buckling columns are globally snapping like, dare I say it, sticks. I don't know for sure. I'm just observing what I see in these two sets of NIST computer simulations.

So the to things that seem inaccurate to me at this point are: 1) saying that Chris7 is holding onto the plastic deformation of columns assertion when in fact that is exactly how NIST modeled the collapse onset and 2) Chris7's apparently inaccurate timing of the NIST models in relation to the 2.25 seconds of freefall rates. Am I wrong here?

Chris, I'm not an engineer, and I try not to play one on the internet, so my comments will be narrowly targeted.

It's appropriate and commendable that you're focusing on the substantive facts relevant to your rebuttals, etc.

I think it's somewhat tendentious to say that the draft report "did not acknowledge freefall at all." It didn't use the acceleration of the north face as an observable to check the model result. The draft report -- basically like the final report -- says that in the fire-induced damage model, the lower exterior columns buckled within 2 seconds, and at that point, the entire building above the buckled-column region moved downward as a single unit. The draft report doesn't say just what the acceleration should be once the lower exterior columns have buckled. As a non-engineer, I can't pound the table that it should equal g, but surely it should be a heck of a lot closer to g than the acceleration during the buckling. So, the draft report missed an opportunity to cite the changing acceleration of the north face as evidence for NIST's collapse sequence -- which, of course, is not how Chandler prefers to see it.

Glenn's comments about 12-62 make sense to me, but at any rate, I'm not convinced that the distinction makes much difference. (You have to sort out this "snapping like sticks" business; obviously, that isn't as important to me.) Even if I convinced myself that the lower exterior columns in 12-62 are merely bending, I don't know how I could convince myself that, from that moment on, they would bend rather slowly. There would have to be an engineering argument, not just an appeal to the evidence of the figure itself, or the nearby text.

 

[tfk]

Chris Mohr,

I'll try to get a reply to you later today.

Short (disorganized) version:

Exactly what Glenn said: when people use the word "column", they can mean two different things:

1. the individual 2 story segments (in WTC7) or staggered 3 story segments, prefabricated off site

or

2. the bolted (WTC 1 & 2) or welded (WTC7) together columns assemblies, made up of multiple units of 1. above.

When NIST says "7 stories buckled", obviously they mean 2. above, multiple column segment assembly.
___

When assembled parts break, they usually (not always, but usually) break at the connections between pieces. Because of the need to add bolt holes, screw holes, to weld pieces, etc., you end up with "stress risers" or "stress concentrations" that cause the stress in these areas to exceed the stresses in the adjacent bulk material.

So they fail at the connectors or joints.

Even with welded joints, even tho the mantra is that "a proper weld is as strong as the base material", other factors generally produce embrittlement, necked down sections, intermetallics, etc. that make the weld joint weaker.

And even when you try to build up the joints by adding extra material like plates at the column weld joints, the simple fact of a transition in thickness of material will generally produce a stress riser at the thickness transition, and you've merely displaced the failure a few inches to the end of your support plate.

Look thru the pictures of all the failed components. The giant curved beam failed at the weld that joined one side of the beam to another.

NIST shows one fractured connection plate after another. Screws sheared. The vast majority of the beams failed at the joints between individual column segments.

And remember that a bunch of the curve, bent beams happened because they were caught in the chaotic rubble & bent there. That means that a lot of the bent beams did not get bent when they failed in place, but got bent when they landed in the rubble pile & then other debris landed on top of them.
___

The term buckle refers to the instant in time that the column assembly goes unstable. It doesn't pretend to define the other 99% of the process, of how each piece comes apart.

Most of the time, buckles are studied as "3 point hinges", one weak point at the top of the failure, one at the bottom and one someplace between those two. (The middle hinge point is frequently shown half-way between the other two, but this is far from a rule.)

When a multisegment column assembly buckles, the hinge points form at weak points in the assemblies, which are again at the connections.
___

A constant failing in the truther rap is the failure to recognize that, in order to get the fall characteristics of the external wall of WTC7, the resistance did not need to, and did not, go to zero.

It simply went to a very low number.

 

[chrismohr]

OK here is this evening's summary of what I am inderstanding:
1) Looking at the PDF of 12-62 in NIST, I can see when I enlarge it 400% that what looks like curves now looks like columns bending at the welding joints, but that could be just the nature of the diagrams.
2) The NIST diagrams don't resolve the question of bent/buckled columns vs. columns snapped at the joints.
3) Buckling is not defined as bending till resistance goes almost away; buckling refers to the moment of instability in a column.
4) NIST shows many fractured connection plates in their models, not curving columns.
5) I don't know what Glenn means by asking me to look up failure mode; my attempt was not enlightening.
6) I was not being tendentious when I said the NIST draft report does not show freefall rates of collapse. The final report does, but it appears that this was not the case in the draft report.
7) Some people say there is not much difference between a bent column and a snapped one as far as the very low residual resistance each provides, but to my understanding no one has been able to show this is true in detail.
So the biggest shift in my understanding is that "buckling" does not mean "bending." Buckling can also mean columns snapping in large numbers at their weakest points.

Thanks all,
Chris

PS Any more YouTube links relevant to the first big section of re-rebuttals on the chrismohr911.com site will be appreciated, esp from Alienentity and Dave but others too.

 

[GlennB]

5) I don't know what Glenn means by asking me to look up failure mode; my attempt was not enlightening.

Failure modes were built into the FEA. They included :
"..weld failure, bolt failure, plate tear-out and block shear failure.." All of which are connection failures.

No mention of fracturing within the length of any column, girder or beam section. This is because it's massively unlikely to happen.

The fact remains - C7's devotion to plastic buckling exists solely to enable him to claim that the residual resistance of plastically-buckled columns would prevent the freefall phase.

 

[MarkLindeman]

6) I was not being tendentious when I said the NIST draft report does not show freefall rates of collapse. The final report does, but it appears that this was not the case in the draft report.

I'm sorry, that's another point I should have made more clearly yesterday. What you just said you said wasn't quite what you said. It's true that the draft report doesn't "show" free-fall rates of collapse, although even that wording might be construed as implying that the draft report somehow denies that free-fall acceleration occurred. It might be clearer to say that the draft report doesn't address variations in the rate of collapse, only the average rate.

Colloquially, it's a Truth Movement frame to say that the draft report didn't "acknowledge" or "admit" free fall; it buttresses the narrative in which the brave souls of the movement occasionally wrest concessions to reality from the tools who write the "reports." (TM critics use similar words in similar ways: we all have stories.) Obviously that wasn't your intention in using the word "acknowledge," and that word has a wider range of connotations than "admit" does. But, hey, try typing "not acknowledge" into Google. Better yet, try typing it into a Bible search engine. See what I mean?

So, that's part of the context in which I characterized the wording "did not acknowledge" as "somewhat tendentious." I was reacting to that phrase as a recurring trope, not intending to attribute it to you. In fact, to the extent that I thought about it at all, I assumed that you were echoing C7, as one often does when trying to communicate across tribal lines.

 

[chrismohr]

fair enough Mark. And Glenn et al, I'm "getting" that the columns' buckling usually meant some kind of break at the welded connections, not a long curving arc (which was my initial understanding of the meaning of the word buckling, which in my layman's mind was different from snapping apart). However, MM and others are showing pictures of bent steel columns (MM has one that appears to have bent until most of it snapped). I still have a question: in the WTC7 debris, were there a lot of extremely bent steel columns or were almost all of them relatively straight and broken off at the welded connections?

 

[GlennB]

fair enough Mark. And Glenn et al, I'm "getting" that the columns' buckling usually meant some kind of break at the welded connections, not a long curving arc (which was my initial understanding of the meaning of the word buckling, which in my layman's mind was different from snapping apart). However, MM and others are showing pictures of bent steel columns (MM has one that appears to have bent until most of it snapped). I still have a question: in the WTC7 debris, were there a lot of extremely bent steel columns ........ ?

I don't know. The best I can offer is "I can think of no reason why that would be the case". But I'd suggest that the existence of only a few "horseshoe" column section photos argues against the idea that it was a common occurrence.

Meanwhile you can scan that huge overhead of WTC1+2 debris all day and struggle to find a single bent column section.

p.s. don't download it with dial-up

 

[tfk]

Chris,

I feel like Bill Clinton.

You've got a mistake here.
It depends on what the word "mean" means.

OK here is this evening's summary of what I am inderstanding:
1) Looking at the PDF of 12-62 in NIST, I can see when I enlarge it 400% that what looks like curves now looks like columns bending at the welding joints, but that could be just the nature of the diagrams.

Don't trust this. Guys that draw pictures don't worry about getting this level of detail into the pictures, they are remote to the engineers, and errors OFTEN appear in diagrams.

They stay there because marketing decides that fixing them ain't important.

This has shown up here over & over again, because the BBC hires some graphic artist to draw up some animation, it's wrong because nobody with the qualifications to know what to look for check it out, and it stays that way because … well, because from the BBC's POV, "who cares that some tiny detail is wrong".

Well, truthers care. They conclude that, rather than being a tiny, irrelevant screwup, it's a giant conspiracy.

Or, C7's latest, that he "forced NIST to correct their fraudulent story". Because a bunch of career PhD's in Structural Engineering have nothing better to do than to monitor a store clerk for his opinion about their

2) The NIST diagrams don't resolve the question of bent/buckled columns vs. columns snapped at the joints.

Their diagrams may not, but their dialog does. The vast, vast majority of the fractures happened at the weak points at beam ends, not within the beam itself.

Chris, it's important to get an idea of how strong the connections are when they are loaded normally (in pure compression) compared to how weak they are when when loaded improperly.

In pure compression, the joints are almost as strong as the base material. If you stacked 3 columns bolted together in a compression test, they are still going to ultimately fail at the joints, but they will (if held in alignment) come up to a significant percent (maybe 50%, depending on how good the alignment is) of the same test run with a single piece of steel that was made 3x longer (i.e., no joints).

In bending, that situation is no longer true. The bolted joints were never designed to take this load configuration, so they will fail at loads that may be 1% or so of the loads taken by a piece that has no joints.

It is the CHANGED GEOMETRY of the loading condition that makes this huge difference. Not any characteristics (strength, etc) of the components.

3) Buckling is not defined as bending till resistance goes almost away; buckling refers to the moment of instability in a column.

Yes. EXACTLY right. You must have gotten this from some genius…!!

(… or a legend in his own mind.)

;-)

6) I was not being tendentious when I said the NIST draft report does not show freefall rates of collapse. The final report does, but it appears that this was not the case in the draft report.

1. "Freefall" didn't really happen. (It was close, but nothing like real freefall. "Dog" is close to "God". But not really…)

2. Pure, REAL freefall (i.e., instantly going to G & staying there) would have been impossible, and required some real explaining.

3. The near freefall that we saw (i.e., gradually coming up to a valued that was close to G, then hit G, then exceeded G, then dropped below G, bounced around & then decreased) is surprising to nobody knowledgeable in the field.

7) Some people say there is not much difference between a bent column and a snapped one as far as the very low residual resistance each provides, but to my understanding no one has been able to show this is true in detail.

As mentioned above, it depends on the orientation of the columns when the resistance of the columns is tested.

It the column assembly looks like this, straight vertical with side supports, then the assembly is going to perform pretty much like a single column.

_ I _
_ I _
_ I _
_ I _
_ I _
_ I _


Once the buckle points form, like below, then the resistance is going to be close to zero, compared to the assembly above.


|
.\
..\
...\
.../
../
./
|

In WTC 1 & 2, the bolts are 3/4" high strength bolts. That may seem big to you, but not when you think about the size, weight & length of the columns. The columns in those two buildings were 36 feet long & weighted tons.

The columns, with their plates in the bottom acted like claw hammers pulling up a nail.

Next time you're in a hardware store, go look at a 3/4" bolt. It'll look pretty substantial. Now put one (or better, imagine one on the floor at the end of an aisle. Pace off 36', if you can. Now imagine that you've got a claw hammer shaft that is that long. If it were to take 50,000 pounds of force to pull the head off of that bolt, then (assuming the bolt was 4" from the outside edge of the column) it would take about (50,000*4/(12*36) = 350 pounds of leverage to strip the bolt. One well braced person could do that with a leg press.

Do you think that a falling 50 ton girder could do it too?

So the biggest shift in my understanding is that "buckling" does not mean "bending." Buckling can also mean columns snapping in large numbers at their weakest points.

Here is "what does 'mean' mean".

No, no, no…

Go back to that "genius" comment above.

Buckling means the point in the process when the column go unstable. Not when they break.

Columns (not in the towers, but in other applications) can go unstable, i.e., can "buckle", and have nothing break. LIke the demonstration of buckling that MIT professor showed in the video where he had 2 assemblies with 4 wooden rods, one with intermediate lateral supports & one without. And showed how the one with lateral supports could hold up a load of weights, but the one without the supports could not.

Those wooden rods buckled. They did not break.

As a result of the buckle, parts subsequently break.

___

An assembly of parts can also fail by having the connecting screws snap before the assembly reaches an unstable geometry. By the explicit definition, this is not a buckling failure. It's an overload failure.

But the above may be casually, commonly called a buckling failure nonetheless.


tom

 

[tfk]

I still have a question: in the WTC7 debris, were there a lot of extremely bent steel columns or were almost all of them relatively straight and broken off at the welded connections?

Chris, good math exercise for you.

Figure out how many columns were in the towers & in WTC7.

What does "a lot" mean? 1%? 10%? 25%?

Figure out how many constitute a meaningful percentage (say 5%) of the total.

Compare that to the number of unique bent columns you've seen in pictures. (Unique means "not the same column shown in 500 different pictures".)

 

[chrismohr]

Chris, good math exercise for you.

Figure out how many columns were in the towers & in WTC7.

What does "a lot" mean? 1%? 10%? 25%?

Figure out how many constitute a meaningful percentage (say 5%) of the total.

Compare that to the number of unique bent columns you've seen in pictures. (Unique means "not the same column shown in 500 different pictures".)

Thanks Tom,

So if there were 85 columns supporting WTC7, I would say that finding 35 badly bent columns in the WTC7 debris pile would be significant. In the diagrams from NIST it looks like each column has one really bad "bend" in it, usually around floors 7-13. But I am inclining to believe that there are few examples of a WTC7 structural column bending in a smooth curve as opposed to cracking at the welded joints, yes? It certainly makes sense that the solid steel part of a column would not usually bend when the stress of a lateral pressure on a column could just snap the bolts and the welded connections aty the columns' weakest points.

 

[Christopher7]

I am tired of this debate with Chris7 but here we go again. I do want to be clear: am I mistaken in my belief that in Building 7 many columns actually buckled according to the NIST Report? I kind of thought the columns snapping like sticks at the welded points was more common in the Twin Towers and that there were in fact many buckled columns from Building 7. Do correct me if I am wrong.

You are not wrong. In the NIST computer model, the columns are buckling [not snapping like sticks] well into the FFA. Therefore the NIST model is not falling at FFA. It's clearer in Fig 12-62 than the video. The only breaking is at the SW corner where the debris damage was.

If the joints did snap, it was at the end of or after the free fall portion of the collapse.

Buckling is not snapping. They are two entirely different things.

Euler's formulae, TFK's graph, etc. all show that a buckling column loses something like 98% of its strength.

The 98% loss occurs when the column has bent almost completely [fully formed hinge]. It does not go from 100% to 2% strength instantly, it decreases as the bending becomes more pronounced.

Whatever vestigal resistance a fully-buckled column provides to as building's collapse can be overcome by local torquing and leveraging of the undergoing chaotic collapse and still attached in places to one another.

I ain't budging on this Chris7 because all evidence points to what I am saying as being true.

What you are saying is true but the buckling columns provide resistance from 100% to 2% as they buckle until they have fully buckled. But by that time the building has fallen ~70 to 80 feet. The NIST model is not falling at FFA.

 

[GlennB]

You are not wrong. In the NIST computer model, the columns are buckling [not snapping like sticks] well into the FFA.

Why would a column plastically hinge when the welds would yield long before?

 

[Christopher7]

Why would a column plastically hinge when the welds would yield long before?

Structural engineers tell me that connections are made strong enough so that the member will bend before the connection fails. The philosophy is to have a failure be gradual to give the occupants time to exit.

 

[DGM]

Structural engineers tell me that connections are made strong enough so that the member will bend before the connection fails. The philosophy is to have a failure be gradual to give the occupants time to exit.

An SE told you this? I think you're just making **** up.

 

[GlennB]

An SE told you this? I think you're just making **** up.

Be fair, DGM. It would be a very useful safety feature if a building just gradually squished downwards this way. Folks would notice the ceiling getting lower and the walls bowing and they'd be all, like, "Whoa! The building is squishing! Better skedaddle pronto!"

(you only managed to post before me because I'd passed out from laughter )

 

[tsig]

Be fair, DGM. It would be a very useful safety feature if a building just gradually squished downwards this way. Folks would notice the ceiling getting lower and the walls bowing and they'd be all, like, "Whoa! The building is squishing! Better skedaddle pronto!"

(you only managed to post before me because I'd passed out from laughter )

I was imagining one of those pictures Chris posts of squiggly buildings with little people running out.

 

[chrismohr]

OK gang, here's where my own confirmation bias can be a problem. Do I believe TFK Tom and Glenn, who are guys who agree with me, even though my original understanding of the meaning of "buckling" was closer to that of Chris7's?

Where I definitely disagree with Chris7 is in his timing. in post 4121 http://www.internationalskeptics.com/forums/showpost.php?p=8209690&postcount=4121
he copies off some NIST diagrams that take us only up to one second into the global collapse. Since FFA commences another second later, these diagrams tell me nothing about what was happening according to NIST DURING freefall. Since the collapse started slowly, even if I accept Chris7's assertion that buckling and snapping are fundamentally different, at some point that bending kind of buckling yields only some 2% of its initial strength. I can see that this may well have happened later in the collapse, when the collapse rate was in the vicinity of freefall, as TFK explained (and that part I have always asserted: that multiple forces beyond just gravity and resistance yielded approximately net-zero resistance).

So here's where the debate stands in this layman's brain: is my layman's understanding of buckling (as in deep bending) right, as Chris7 says, or is the buckling we see here dominated by actual failures at the various welded and bolted connections? Were most of the few deep bends in steel columns we find caused by stresses from collisions and massive collapsing? Even if Chris7 is right about what kind of buckling is actually asserted in the NIST Report, I still believe his timing is off (and several posts above agree with me).

As for chris7's assertion, "Structural engineers tell me that connections are made strong enough so that the member will bend before the connection fails. The philosophy is to have a failure be gradual to give the occupants time to exit." Well, I didn't just laugh, being the layperson I am, but it made no sense. Seems to me that once failure starts (assuming with this kind of C-7-style bending first), you'd be lucky to make it across the room, let alone down a flight of stairs! Did chris7 actually talk to at least two structural engineers? Maybe. I talked to 14 physicists (not on JREF) in a one-year period about all this stuff.

I dunno, maybe I need to take this question away from JREF and just pester a structural engineer at a party, like I used to do before being on JREF.

 

[MarkLindeman]

OK gang, here's where my own confirmation bias can be a problem. Do I believe TFK Tom and Glenn, who are guys who agree with me, even though my original understanding of the meaning of "buckling" was closer to that of Chris7's?

Chris, I was very consciously and explicitly hedging my bets earlier, for much the same reasons you are -- but I don't think this is just a matter of confirmation bias. Simply put, the people who have reason to know what they are talking about agree. (ETA[2]: It isn't just that they agree about something, but that they agree about something as relatively straightforward as the meaning of "buckle.")

That said, it seems reasonable to talk with people who aren't invested in the debate. If you're willing to use Wikipedia's article on buckling as a (ETA: short-term) proxy, I think it supports the JREF engineers on this point. (I wouldn't be surprised if engineers sometimes colloquially use "buckling" to describe the events just before buckling as well as the buckling itself. See also below.)

I also think the NIST report itself strongly supports the interpretation that "buckling" refers to a sudden loss of resistance, not a process of gradual bowing. Many passages support this interpretation, but NCSTAR 1-9 Figure 12-43, upper right, seems to settle the issue. As I construe this figure as a non-engineer, positive displacement can be seen at "buckling initiation" prior to the instant(s) of buckling, but the columns are said to have "buckled" at particular times, and the displacement curves shoot upward near those times.

We could still question exactly what some of the diagrams show (and whether it matters), but I don't see reasonable doubt that buckling primarily refers to (in Wikipedia's words, FWIW) "a sudden failure," not a gradual giving way. I think this also comports with ordinary English. If my knees buckle, I fall down fast. That's sort of the point.

 

[Miragememories]

OK gang, here's where my own confirmation bias can be a problem. Do I believe TFK Tom and Glenn, who are guys who agree with me, even though my original understanding of the meaning of "buckling" was closer to that of Chris7's?

Where I definitely disagree with Chris7 is in his timing. in post 4121 http://www.internationalskeptics.com/forums/showpost.php?p=8209690&postcount=4121
he copies off some NIST diagrams that take us only up to one second into the global collapse. Since FFA commences another second later, these diagrams tell me nothing about what was happening according to NIST DURING freefall. Since the collapse started slowly, even if I accept Chris7's assertion that buckling and snapping are fundamentally different, at some point that bending kind of buckling yields only some 2% of its initial strength. I can see that this may well have happened later in the collapse, when the collapse rate was in the vicinity of freefall, as TFK explained (and that part I have always asserted: that multiple forces beyond just gravity and resistance yielded approximately net-zero resistance).

So here's where the debate stands in this layman's brain: is my layman's understanding of buckling (as in deep bending) right, as Chris7 says, or is the buckling we see here dominated by actual failures at the various welded and bolted connections? Were most of the few deep bends in steel columns we find caused by stresses from collisions and massive collapsing? Even if Chris7 is right about what kind of buckling is actually asserted in the NIST Report, I still believe his timing is off (and several posts above agree with me).

As for chris7's assertion, "Structural engineers tell me that connections are made strong enough so that the member will bend before the connection fails. The philosophy is to have a failure be gradual to give the occupants time to exit." Well, I didn't just laugh, being the layperson I am, but it made no sense. Seems to me that once failure starts (assuming with this kind of C-7-style bending first), you'd be lucky to make it across the room, let alone down a flight of stairs! Did chris7 actually talk to at least two structural engineers? Maybe. I talked to 14 physicists (not on JREF) in a one-year period about all this stuff.

I dunno, maybe I need to take this question away from JREF and just pester a structural engineer at a party, like I used to do before being on JREF.

At a party?

Of course that would be an improvement over wallowing in the false praise and support from anonymous Official Story zealots.

You might also like to talk with a few lawyers while you are embibing. Try asking them about how much fun and easy it is to argue a lie when the judge permits dishonest testimony.

MM

 

[MarkLindeman]

You might also like to talk with a few lawyers while you are embibing. Try asking them about how much fun and easy it is to argue a lie when the judge permits dishonest testimony.

?!

Are you suggesting that someone here is lying about the meaning of the word "buckle"?

If so, who, and how do you think you know?

If not, what point do you think you're making -- or is it just a generalized FUD?

Are there other obvious questions I've forgotten for the moment?