Merged Applicability of Bazant's model to the real world

[carlitos]

You are full of delusions.

When will you list your most engineers? ?

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage

.

Seriously, Tony, you are a big fan of real names and real qualifications being disclosed. Please elaborate.

 

[Major_Tom]

Pgimeno, I have given quotes by Dave, R Mackey and Newton's Bit in which the describe an intact upper structure riding the debris pile to earth like it is riding a magic carpet before "crushing up". You cannot see a mistake in that? Will we regress to conjuring up the famous upper block again?

>>>>>>>>>>>>>>..


If you want to know the most about the first 12 ft of fall of both the north facade and the antenna of WTC1, why not just measure them using the highest quality video and the most precise tracking methods possible?

Already done:

Tracking by achimspok

The Sauret drop curve of NW corner is shown in blue. It's corresponding velocity curve is shown in purple. We see there is an abrupt change in the slope of the velocity curve that can be traced back to frame 222. This is the release event for the NW corner.

The acceleration (slope of the velocity curve) quickly changes through frame 222. The traced point is now falling at 0.5g to 1.0g. There is one measured velocity reduction around frame 250. In frame 250 the positional data shows the NW corner has fallen about 3 ft.

In the pre-release region we can carefully study changes in the positional data as far ahead of frame 222 as we wish, looking for the earliest detectable deformations.

The Sauret drop curve of the black-white transition point on the antenna is in yellow. It's corresponding velocity curve is in light green. We see movement from frame 140, yet the velocity curve does not take off with a 0.5g to 1.0g acceleration until frame 215. The release event is around frame 215.

In the pre-release region we see considerable movement before frame 215. Over 2 feet of downward displacement is measure in the antenna between frames 130 and 215.

In the post-release region we detect one velocity reduction. How far has the traced point dropped when the reduction occurs? It happens around frame 228, when the positional data shows a 3 ft drop.

Notice that there is no such thing as a "global velicity reduction". The NW corner experiences velocity reductions at different moments than the antenna does. The concept of "velocity reduction" depends on the point that is traced since we can see simlar reductions in both the NW corner and the antenna, but at different times.


Tracking by femr

NW corner drop velocity reductions

http://femr2.ucoz.com/photo/6-0-372-3

red is drop in ft
orange is velocity


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

On a different forum I have watched a few people detect these jolts independently, so this is not just one person's guess. Can the pattern in the velocity reductions be a signature of some type of early collisions?

 

[GlennB]

If you do a finite element analysis of a buckling column and animate it you will see that the upper and lower ends contact after the scissor closes. The bifurcation (scissors) can only occur between stories due to horizontal bracing.

Do they? Or do they merely overlap in 2-D?

If a buckled column snaps or detaches at the weld while buckled how can the two ends ever again make contact in 3-D ?

Please explain. You never have so far, despite many requests.

Bump for Tony. We're still waiting for an answer, not a hand-wave.

 

[Tony Szamboti]

Pgimeno, I have given quotes by Dave, R Mackey and Newton's Bit in which the describe an intact upper structure riding the debris pile to earth like it is riding a magic carpet before "crushing up". You cannot see a mistake in that? Will we regress to conjuring up the famous upper block again?

>>>>>>>>>>>>>>..


If you want to know the most about the first 12 ft of fall of both the north facade and the antenna of WTC1, why not just measure them using the highest quality video and the most precise tracking methods possible?

Already done:

Tracking by achimspok

[qimg]http://img101.imageshack.us/img101/4753/image00029.png[/qimg]

The Sauret drop curve of NW corner is shown in blue. It's corresponding velocity curve is shown in purple. We see there is an abrupt change in the slope of the velocity curve that can be traced back to frame 222. This is the release event for the NW corner.

The acceleration (slope of the velocity curve) quickly changes through frame 222. The traced point is now falling at 0.5g to 1.0g. There is one measured velocity reduction around frame 250. In frame 250 the positional data shows the NW corner has fallen about 3 ft.

In the pre-release region we can carefully study changes in the positional data as far ahead of frame 222 as we wish, looking for the earliest detectable deformations.

The Sauret drop curve of the black-white transition point on the antenna is in yellow. It's corresponding velocity curve is in light green. We see movement from frame 140, yet the velocity curve does not take off with a 0.5g to 1.0g acceleration until frame 215. The release event is around frame 215.

In the pre-release region we see considerable movement before frame 215. Over 2 feet of downward displacement is measure in the antenna between frames 130 and 215.

In the post-release region we detect one velocity reduction. How far has the traced point dropped when the reduction occurs? It happens around frame 228, when the positional data shows a 3 ft drop.

Notice that there is no such thing as a "global velicity reduction". The NW corner experiences velocity reductions at different moments than the antenna does. The concept of "velocity reduction" depends on the point that is traced since we can see simlar reductions in both the NW corner and the antenna, but at different times.


Tracking by femr

NW corner drop velocity reductions

http://femr2.ucoz.com/photo/6-0-372-3

red is drop in ft
orange is velocity


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

On a different forum I have watched a few people detect these jolts independently, so this is not just one person's guess. Can the pattern in the velocity reductions be a signature of some type of early collisions?

What would be colliding 3 feet into the drop?

 

[Tony Szamboti]

Bump for Tony. We're still waiting for an answer, not a hand-wave.

There is nothing hard about predicting why there would be little misalignment of the plastic hinges at the ends of buckled columns in a gravity drop, as there would need to be significant lateral forces to cause the columns to be moved out of alignment.

The small tilt of WTC 1 does not cause the kind of lateral force necessary, especially when all of the columns are still interconnected and the entire upper section would need to shift sideways.

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either. A 1 degree tilt produces less than an inch of horizontal shift over 207 feet.

 

[femr2]

there would need to be significant lateral forces to cause the columns to be moved out of alignment.

The perimeter panels shifted enough such that the upper section passed either in front of or behind the lower perimeter panels.

That can be confirmed by observation of video.

The amount of lateral shift required for such is enough to state that similar levels of lateral shift could be present within the core.

Also observable from video is the global lateral shift of each tower upon initiation. Without *instant* initiation it is obvious that all actions will create lateral forces.

Initiation was not *instant*, with antenna shift numerous seconds before release.

Add to this the fact that enourmous stored strain is released upon any seprataion of upper and lower members and it's clear that lateral *springing* is quite possible.

the entire upper section would need to shift sideways.

Shift to the East beginning around the time of the Sauret footage camera shake.

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either.

You are treating the structure as a rigid virtual entity.

 

[carlitos]

An old colleague of mine even called a few weeks ago to talk about it. He said he had read my papers and after investigating the collapses himself, in other ways, he realized that the collapses were indeed due to controlled demolitions.

Does your colleague have a name? What are his qualifications in engineering? How about his citizenship?

You are full of delusions.

When will you list your most engineers? ?

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage

.

Seriously, Tony, you are a big fan of real names and real qualifications being disclosed. Please elaborate.

Dodge noted. "At least 95%" means that there are at least 19 engineers who believe in
"controlled demolition" of the twin towers and the Salomon Brothers building? Can you please list them for us? Because, I will be candid here - I don't believe you. I think that you are exaggerating. Why not encourage these engineers to register here and discuss the issue with other engineers?

 

[beachnut]

At least 95% of engineers I talk to about this, who then do their own research, soon come to the realization that the twin tower and WTC 7 collapses were actually caused by controlled demolition and not as a result of fire and damage. An old colleague of mine even called a few weeks ago to talk about it. He said he had read my papers and after investigating the collapses himself, in other ways, he realized that the collapses were indeed due to controlled demolitions.

Pure nonsense. You can't even get Bazant to return your email.

Your movement has less than 0.001 percent of all engineers. You call this most, but like your CD delusion, it is a delusion you have.

Hope Bazant answers your email/letter; can't wait to see what he says about your realcddeal. Best of luck. Why does using Bazant's model give a time of collapse very close to the WTC towers; why does using simple physics give a collapse time for a gravity collapse close to what happen on 911? Why are models applicable to reality? Because they are models. Models!

If you had reality based engineering support you would have evidence. Only a few fringe engineers, less than 0.001 percent of us, fall for the lies and delusions you spin, evidence free, unable to publish in real journals because the nonsense and delusional claims would be exposed.

List those engineers - the most. funny stuff.
Again:
On topic; explain how your jolt dovetails with Bazant's model?

 

[carlitos]

As I already stated, the tilt does not produce the misalignment necessary for the columns to miss each other by its rotation either. A 1 degree tilt produces less than an inch of horizontal shift over 207 feet.

OK, as I stated I'm no engineer, but how did you figure this? I calculated it a few different ways, and I figure it would shift by somewhere between 1.5 and 3 feet. Am I wrong?

Plus, that only talks about horizontal displacement, and the towers had three dimensions, not two.

 

[pgimeno]

Knowing someone's real name and background does have something to do with credibility in a discussion.

Knowing the background would help in case of appeals to self-authority, not for plain logic or fact-checking or other kinds of arguments. Knowing the name does not help in any way, except maybe if you are presuming bad faith in the stated background, as an aid to research it. But if they claim to be in your field, it should be easy to expose them with specialized questions without the need to know the name, shouldn't it? Say, tfk, who refuses to tell his whole name, do you have any doubts that he's an engineer? It should be easy for you to expose him if he isn't.

In this situation dual citizenship might cause a motivation beyond a desire for the plain truth of the matter and might be a conflict of interest.

Oh, yes it MIGHT, but it also MIGHT NOT be the case, and as you say yourself,

What you are talking about here is a complicated situation where one would need to know a lot more about the circumstances to make a judgement. I don't think you can make a sweeping guilt by association verdict and be confident of its accuracy.

Since knowledge about anyone's personal circumstances usually goes out of the scope of most or all threads about 9/11 in forums, the safest, less smearing, less defaming and most rational and polite approach is to avoid asking. Which you failed to do, making you seem to have an intention of smearing and defaming.

At that point one would need to ascertain what a person's true motivation was from other information. Most people wonder about the other party's motivations when engaged in a debate with them. It is only natural.

It may be natural for some to wonder, but not to ask, when that's off topic and when the context is a forum where anonymity and privacy are a right and, as Carlitos already said, the norm and not the exception.

Obviously you were joking about credit card number as that does not affect anything.

Neither does the name, but you don't seem to agree. Would the validity of my arguments change if my name was Jaime Soler instead of Pedro Gimeno? And if my credit card number started with 9 instead of 0?

I say it matters where it was after one story, that the 1 degree or less tilt would not produce a significant horizontal misalignment, and that there would certainly be a significant amount of column on column impact and there would have been a serious deceleration, if the collapse were natural.

Correct me if I'm wrong, but the 1 degree or less of tilt is for the instant of release, not for the instant of first possible column impact, right? Do you happen to know the tilt at that point?

The column you chose from WTC 5 isn't representative of what we are discussing.

It's a random sample of how a failure can occur. It's due to fire alone, so it's probably creep that caused it. The NIST simulation showed how creep had an important influence in many core columns exceeding their capacity as it did in WTC5, so I don't think it can be left out as an example.

 

[pgimeno]

The key point is that the top bit of column is bypassing the bottom bit. AND there is no mechanism to put the two parts back into axial contact. AND, even if there was, the column ends are near certainly rounded or distorted so that axial transfer of load would cause the two to "slip off".

The last part was the reason I posted the WTC5 image, precisely, and I think that justifies an initial horizontal deviation of the core. I think that indeed there is a mechanism to put two parts (of the SAME column in the first floor drop) into axial contact: the girders would keep the column in place, and the inertia of the top would exert opposition against a significant horizontal displacement.

But it's important to remember that the lateral support was already somewhat compromised as some floors had sagged to the point of pulling the perimeter. And that if a column failed because of heat, a nearby girder could fail as well for the same reason, and give way as a result of the collision. Due to the tilt (even 1 degree), the first contact in the North tower had to happen in the south side, precisely where the lateral support was more compromised.

And, for the outer tube columns, that bypassing relationship will continue throughout the collapse. Same goes for core columns but the explanation is more complex.

According to FEMA, the perimeter columns were "peeled off" as the connections failed. MT's study agrees with that, and some photos also support that. As for core columns, over time a small horizontal deviation of more than 1 column's thickness is perfectly expectable. Not so much for the first floor, though. But, as jolts have already been found (not by Tony), it's not too surprising. Anyway, I wonder how the core's jolts would be reflected in the corners of the building.

 

[pgimeno]

Pgimeno, I have given quotes by Dave, R Mackey and Newton's Bit in which the describe an intact upper structure riding the debris pile to earth like it is riding a magic carpet before "crushing up". You cannot see a mistake in that?

While discussing the theory behind Bazant's model? No, not at all. What's the mistake in that? You tell me.

 

[bill smith]

This is all very interesting I'm sure but why is nobody talking about what happened to the 250-odd intact columns both core and perimeter that still connacted the upper part and the lower part after the plane had crashed ? Well over 85% of the connecting columns were still solid .

We can't talk about columns in the upper part impacting theit opposite numbers in the lower part until we decide what happened to the intact connecting columns.

 

[Myriad]

The figure showing calculated descent rate versus observed in BLGB, which is conveniently posted in post 158.

The "slowest possible descent" is not directly claimed, but it follows from consideration of kinetic energy that a descent time calculated based on parameters reflecting the best case for collapse arrest (maximum energy absorption by the structural members, that is, 3-hinge buckling of every single column, one of the model's basic assumptions that does not change over the sequence of papers) must also be the slowest. (One must also read "possible" as constrained by known characteristics of the specific collapses in question; for instance, slower collapse would be possible if earth's gravity were different, or if there were more floors spaced closer together, or if the columns were reinforced concrete adding a significant additional energy sink.)

DIrect quotes of Bazant are useful so we can separate what he writes from what you imagine he writes.

That is why you can find no example from BV to support your claim that he is deriving equations 12 and 17 for a theoretical best case scenario.

Missed responding to this before taking the 9/11 weekend off from this subforum.

I never claimed the derivation of those equations represented a theoretical best case scenario, or any scenario. Any such claims would make no sense. Those are equations of motion; as such, they are derived directly from the free-body diagram of the scenario, and the laws of physics. What I've claimed -- you can spot the word in the quote above -- is that the parameters applied to those equations reflected a best case scenario; specifically, bucking of (and absorption of kinetic energy by) all of the columns.

A significant portion of BV is a parametric study of those equations of motion -- that is, they tried them out with a range of parameters, some that could be considered plausible estimates for applying to the WTC towers and some that could not, to see what effects those changes would have on the motion. The range of parameters tested well exceeds any best case that could be reasonably applied to the actual towers.

There is one set of parameters that they describe in figure 6 as "typical of WTC" and one might think that if certain parameter values are "typical" they cannot also be "best case." And yet, in the text describing the load-displacement curves (which determine the crucial F(z) of the differential equations of motion) we read:

For single column buckling, the inelastic deformation localizes into three plastic or softening hinges Sec. 8.6 in Bažant and Cedolin 2003; see Figs. 2b,c and 5b in Bažant and Zhou 2002a. For multistory buckling, the load-deflection diagram has a similar shape but the ordinates can be reduced by an order of magnitude; in that case, the framed tube wall is likely to buckle as a plate, which requires four hinges to form on some columns lines and three on others see Fig. 2c of Bažant and Zhou.

So in this model, all the columns buckle and fracture, absorbing kinetic energy from the falling mass along the way (though less so when multiple stories buckle as a unit). There is no mention of the likely real-world possibility of columns absorbing no kinetic energy at all due to having their floor connections sheared away with no further impediment to the falling mass. So even BV's "typical of WTC case" formulation of this crucial function continues to embody the best-case assumption that all the columns absorb energy in buckling.

And of course, the parametric study itself shows that global collapse ensues even for parameters far more favorable to collapse arrest than any that could reasonably be applied to the towers as actually constructed.

I should also note that BV exhibits no actual measurements of any real-world building collapse to justify its conclusions (or for any other reason) and makes no quantitative predictions of collapse behavior for any real-world building. So there is no basis for any accusations about improperly applying an idealized model to actual collapses. Perhaps you meant to be discussing BLGB?

Respectfully,
Myriad

 

[ergo]

This is all very interesting I'm sure but why is nobody talking about what happened to the 250-odd intact columns both core and perimeter that still connacted the upper part and the lower part after the plane had crashed ? Well over 85% of the connecting columns were still solid .

We can't talk about columns in the upper part impacting theit opposite numbers in the lower part until we decide what happened to the intact connecting columns.

I agree, Bill, but that's usually handwaved away with the Really Very Hot Fire theory, that states that no, the fire didn't melt anything, ("nobody said it did, dammit!!") but it was sufficient for columns to "lose strength." Of course no one bothers explaining how 240-something heat-weakened steel box columns would provide no resistance to the other heat-weakenend descending columns of the upper block, but never mind that. It was a "free fall", according to some "debunkers", through the impact zone. They need that for the SuperMegaGigajoules! to do their stuff.

 

[ozeco41]

Remembering the premise "...there could not be any significant axial contact of column parts..." I will explore each of those options briefly:
[HERE I POSTED CONSEQUENCES OF THE PRECEDING PREMISE]

The column from WTC 5 is not representative of those collapsing over an entire floor such as what would have needed to occur in the collapse of WTC 1 where it uniformly collapsed at the 98th floor.

The columns and beams would still be interconnected during buckling and the rounding you describe at the upper and lower plastic hinges would not cause a light load and slip off. The force of impact would have caused plastic deformation at contact and produced a large deceleration.

Tony you either overlooked or ignored the opening statement which was the premise on which my later comments rested. So your detail comments do not follow what I actually said and you quoted. This is the key premise:

As the top block fell in the initial collapse "...there could not be any significant axial contact of column parts..."​

That statement is true whether you accept my "no demolition" explanation OR your hypothesis which includes "unnatural causes". There is no way forward for legitimate debate until you either agree with that claim OR show that it is wrong.

Therefore your detailed responses are unsupported or do not follow from the premise that I set and that you quoted without comment either pro or against.

So let me again be explicit. At the time that you are looking for a jolt following a brief period of top block falling there cannot be any significant column on column axial alignment. Either the column parts have pushed past each other OR a section of column has been removed. Yes there could be a few columns still in the process of failing but such does not detract from the overall validity of the explanation.

You claim it was because of "unnatural causes" which I read as a euphemism for demolition and presumably means a section of column removed. I claim it was because the column ends were already bypassing each other. But, whichever of those reasons, we should be on common ground of "no significant axial contact".

...My theory, based on observation and measurements, is that at the time the first impact should have occurred the lower portion of the upper section was being broken up by unnatural causes and therefore was unable to apply a shock load....

Thanks for that much. I start to see where you are coming from. However, apart from identifying the top block being demolished, that statement says little. I would hope you had given it a lot more thought but let it pass for now.

I find your next comment interesting:

...Afterward I think the lower section was being weakened by similar unnatural causes precluding high g impacts and deceleration by the upper section for the nine stories we could measure the fall...

I would be interested to explore where you think this "weakening" ended and if it did. Because your statement clearly leads well into the "global collapse" and you seem to think that "weakening" was needed in the global collapse stage.

Now going back to the start where we both accepted that the top block was falling. Naturally I have a view as to the mechanisms probably involved and not requiring demolition. Have you commented on what started that "initial collapse". Do you hold that there were "unnatural causes" involved. I cannot recall if your have addressed that in one of your earlier papers.

 

[Tony Szamboti]

OK, as I stated I'm no engineer, but how did you figure this? I calculated it a few different ways, and I figure it would shift by somewhere between 1.5 and 3 feet. Am I wrong?

Plus, that only talks about horizontal displacement, and the towers had three dimensions, not two.

The horizontal shift would be the difference between the adjacent side and the hypotenuse of a 1 degree angle in a right triangle.

The towers were 207 feet on a side above the ninth floor and 207 feet is equal to 2,484 inches.

Take the cosine of 1 degree and multiply it by 2,484 inches to get the length of the adjacent side. Then subtract that from the hypotenuse which would be 2,484 inches and you will have your answer.

Don't forget this is at the extreme other side from the north face which was the hinge of the tilt. Everywhere else the shift would be less and it would be essentially zero at the north face.

Now for those who want to say the tilt was greater by the time it descended one story, we can do the same easy calculation for 3 degrees. The tilt would not have been anymore than 3 degrees maximum at that point. The greatest possible horizontal shift which would be at the opposite side of the building for a 3 degree tilt at impact would have been only 3.4 inches. So 14 inch box columns aren't missing each other there let alone 17 inch columns in the core with a smaller shift, or 14 inch box columns at the north face with no shift and those of the east and west walls with a maximum 3.4 inch shift at the south side and less shift as one got closer to the north side.

The small tilt in WTC 1 could not cause the columns to miss each other and those who try to make that argument have no basis for it.

 

[ozeco41]

...We can't talk about columns in the upper part impacting theit opposite numbers in the lower part until we decide what happened to the intact connecting columns.

Not so Bill.
We know that the "Top Block" started to fall and therefore sufficient columns had been compromised so that the remaining ones could not carry the load.

That statement is true whether you are pro-demolition OR anti demolition. Both sides depend on the "Top Block" falling. They may differ on why it fell.

Then they can legitimately discuss the next stage - something I am endeavouring to do in discussion with Tony Szamboti.

Sure at some stage an answer to "demolition or not?" has to explain how those columns were compromised. But it does not have to be finalised before discussion of later stages can start.

 

[Tony Szamboti]

Not so Bill.
We know that the "Top Block" started to fall and therefore sufficient columns had been compromised so that the remaining ones could not carry the load.

Unfortunately for your point of view, the NIST report only shows the columns of the south perimeter wall of WTC 1 being compromised at the 98th floor where the collapse initiated. No core columns were damaged there although you could try to argue that there were a few below it on the north side, but that wouldn't be nearly enough to cause a collapse.

Interestingly, the extra load distributed on the east and west perimeter walls, from the allegedly failed south wall, only increased their capacity usage to about 30% of their yield strength. So how do the failed columns of the south wall cause a collapse to propagate across the rest of the building? Please bear in mind that NIST just makes a simple assertion that it happens in a natural way, without providing any analysis which would support it.

 

[ozeco41]

What columns besides those of the south perimeter wall of WTC 1 were compromised at the 98th floor where the collapse initiated?

I wouldn't have a clue. "Enough" is what we know. Whether "demolitionists" who say it was "helped along" OR no demolition folks who say "that's the way it happened".
I'm puzzled why you ask the question - the top block fell. Both sides of the debate know that. So compromising of columns should be common ground as a premise for rational debate.