Use of Scale Model or Full Sized models for investigating 9/11 collapses

[econ41]

There was a LOT of weight above the impact points (referring to WTC 1 & 2). The simple FACT that WTC 2 collapsed BEFORE WTC 1 is evidence.

I do NOT understand why the "truthers" ignore this fact. It is so bleeding OBVIOUS!!!

Agreed. The "...LOT more weight above..." is also why WTC2 tilted a "LOT more".

As for my use of "bleeding obvious" - it is one of my trigger phrases which OneWhiteEye is familiar with from our long acquaintance. I have about 4-5-6 of them which are things which SHOULD be bleedingly obvious and are after you pass the "eureka" point -- "Why didn't I see that before".

Here is another example:
"At the stage where the WTC1 and WTC2 "top blocks" start to fall bodily downwards ....all the columns had failed."

That and several others are IMO best experienced in a real discussion where the slap forehead "Doh...why have I missed that bleeding obvious fact for so long...." experience can be savoured.

 

[OneWhiteEye]

@jaydeehess: an excellent scenario, certainly one of the most plausible I've heard.

Are you expecting that as the core failed, that the interior floors to the north of the core reached an equilibrium before onset of global collapse?

I'm expecting the connections to fail rather quickly in rotation. This would not only limit the duration over which such an effect could occur, but also limit the component of vertical force which could be applied. If (and this is a big if) the connections fail at a small angle, the floor assemblies would not be able to attain much speed before connection is lost. Maybe they wouldn't need to as the floors would be a considerably greater mass.

Your scenario differs from other suggestions, if I understand correctly, because you have the connections to the core failing which allows free rotation on one side; as opposed to the core descending and pulling the exterior through the floors. The problem I have with this alternate scenario is the elongation and subsequent survival of the connections floor assemblies as the differential displacement between core/exterior occurs. All the force is initially in the horizontal direction, only attaining a sufficient angle for a significant downward component after an unrealistic amount of stretch. Your scenario avoids that problem by letting the connections to the core lapse as the stretch increases.

You're probably right. This is definitely another scenario which can be investigated with some simple 2D exploration. I admit to not having a good gut feeling for how it would turn out.

 

[OneWhiteEye]

I will point out that your scenario is at odds with the "hollow shell" theory, which is something a lot of people (including a number of those whose opinion I respect) adhere to. With all due respect to hollow shellers, I have a real hard time with that, for reasons other than descent dynamics.

 

[OneWhiteEye]

I guess your scenario is basically the Chris Mohr scenario which amalgamates suggestions obtained at JREF.



For sure, something happened, haha!

(I love that big, blue bladder in there)

 

[OneWhiteEye]

This floor pan rotation would also ensure toppling to the south.

If it happened asymmetrically, yes. If only the north side had internal rotation, or else greater angular momentum at release, there would be a bias to tip south.



The whole exterior tipped to the south, for sure.

 

[OneWhiteEye]

The stiffer the structure, the more downwardly directed force can be applied early at small angles by an already moving assembly, but the less differential motion between the moving assembly and exterior can develop. 2+ seconds of applied force with an assumed negligible resistance at the bottom of the unit structure; it's an interesting problem to consider.

 

[OneWhiteEye]

Drifting back to the topic, I much prefer thought experiments and simple idealizations of isolated aspects or subsystems to full scale detailed models. Physical or computational. I think Mick dealt the death blow to scaling down physical models in this post.

 

[econ41]

I guess your scenario is basically the Chris Mohr scenario which amalgamates suggestions obtained at JREF.

[Graphic Removed]

For sure, something happened, haha!

(I love that big, blue bladder in there)

Remember that the explanation presented by me to Chris Mohr was needed in a scenario where both sides - "truthers" AND (quite a few) "debunkers" - were rejecting the plausibility of "over G". And on JREF where the provider of the accurate measurements showing "over G" at WTC7 - femr2 - was still facing denigration of all he did because he had been declared a truther.

The Challenge was to show how "over G" was plausible both as a generic concept and in specific setting of WTC7 and in the setting of that historic situation over marketed as Chandler "forcing" NIST to admit something which was a non-event anyway.

So the situation was:
A) Accurate measurements showed that Chandler and NIST were both correct on "falling at G" but with limited accuracy due to their measurement methods;
B) The more accurate measurements confirmed "G" and showed some "over G";
C) Neither "average G" not "over G" are surprising to anyone who comprehends the relevant physics;
D) (AFAIK no one has said this >> "If it was AVERAGE G - it automatically means must have been over G" cannot have average without some above and some below. Add that example to the "bleeding obvious" list.)

So the "big bladder" was simply an indication of any sort of weight/mass however structured. I cannot remember how Chris Mohr got the final graphic - sure the component including "bladder" was from my explanatory rough drawing - cannot remember who put the rest of the details on.

Speculating about specific details as you and jaydeehess are now doing goes significantly further than the original explanation intended or needed to go. And it is probably into the territory of "will probably never be sure".

Certainly explore the possibilities but my caution goes to "forests v trees" when the original purpose was to explain that a forest is a group of trees BUT not to define the species or location of every tree.

 

[econ41]

Drifting back to the topic, I much prefer thought experiments and simple idealizations of isolated aspects or subsystems to full scale detailed models. Physical or computational. I think Mick dealt the death blow to scaling down physical models in this post.

I am aware of your preferences and from your perspective that "death blow" is correct for you and for any other persons who, like me, follow/accept/understand the applicability of said physics as illustrated by the models referred to so far.

BUT my purpose as stated in my recent posts is to bridge the understanding of a specific member who is clearly asking for more and wants the more in some form of additional model. What I am seeking to clarify with that member is whether or not such a model is possible, practical and/or necessary - for him.

 

[Mick West]

This thread is for the discussion of models. Please keep it on topic

 

[Mick West]

@lemonmann has been banned for repeatedly posting off-topic after several warnings.

 

[psikeyhackr]

The single greatest failure in Psikey's model is that he is modeling failure of the support system of his washer/paper loop set up. This is underlined by his doubling of the paper support further down.
That is simply not the manner by which the towers failed.

The towers failed due to , as Mackey states, when the dynamic loading on the floorspace caused the floors to fail thus destroying lateral support for column structural systems (perimeter and core).

The floors were all the same construction all the way from bottom to top(except for a few mech floors which had to carry extra mass). Thus the same ability to transfer a load to columns all the way down.

If Psikey wished to build a better representation using washers, cardboard and wooden dowels he could have.

First of all only 84 floors within the towers used the standard 4 inch slab on trusses design. The mechanical floors were different, the mezzanines and basements were different. There is no evidence whatsoever of floors outside the core ever falling on other floors outside the core. That is just the speculation everyone spouts.

I have already suggested the better way to make a model, 3D printers. That would allow tremendous control of the strength of all columns, beams and connections. How strong were the connections between the floors and the core and the perimeter columns? Do you expect to duplicate that with any precision with TAPE. But that still leaves the problem of the distribution of mass down the building.

It is so curious that with all of the engineering schools in the nation that put men on the Moon, none discusses needing to know the tons of steel and tons of concrete on every level of the towers. Gregory Urich's spread sheet does not have a table for the heights of each level. If you divide his Potential Energy for each level by the mass you find he has the roof lower than the top 10 stories. LOL

I had no choice but to use double and triple paper loops lower down in my model. My intent was to make the support structure as weak as possible. I tested the loops to determine the maximum static load they could hold. Weaker loops would be crushed and I left the model standing for 4 days.

Are you saying the core of the upper portion of the north tower did not come down on top of the core of the lower portion?

I consider it totally dishonest for our engineering schools to not have demonstrated this supposed collapse with a good physical model and yet men rushed off to Iraq and Afghanistan over this. But now they would look pretty stupid to have models fail. The NIST does not even specify the total amount of concrete in the towers. So how can a decent model be made without that. But data from before 9/11 says there was 425,000 cubic yards.

psik

 

[psikeyhackr]

Drifting back to the topic, I much prefer thought experiments and simple idealizations of isolated aspects or subsystems to full scale detailed models. Physical or computational. I think Mick dealt the death blow to scaling down physical models in this post.

The funny thing about physical experiments is that they do not give a damn what people think.

How does anyone PROVE that a thought experiment is valid? Especially when we do not even have accurate data on the object that the thought experiment is supposed to be about.

At least other people can duplicate a physical experiment even if they do not agree with the validity of the model. Argument about thought experiments resolve nothing.

psik

 

[psikeyhackr]

And a practical illustration of this.


The can is holding 30 lb, it can easily hold 100lb, or 150lb if very carefully added. I take a 2.5 lb weight and drop it from about three feet up. The can fails.



So, we have just 2% of the maximum static load causing failure, because it's a dynamic load. And this is just a three foot drop.

I don't know what the maximum static load for the can is.

What would happen with a stack of cans alternating with loads? The dropped load would have to accelerate a series of stationary loads with crushable supports in between that would absorb some of the kinetic energy.

That is why a bigger model than mine would be useful. It would be easier to design each level to be close to its limit. I raised my drop mass as high above the stack as the height of the stack. But the very top loops were stronger than necessary to support 6 or fewer washers. I could double the washers but that would reduce the drop height or I would have to get a longer dowel.

But after all of this time I don't think it would matter. Only a very large model done by a recognized institution would matter after this much time.

But such an institution would look pretty stupid if it could not make the model collapse after 13 years of this crap. They certainly do not have any incentive to do it.

psik

 

[Mick West]

I don't know what the maximum static load for the can is.

It's at least 150 pounds

 

[psikeyhackr]

It's at least 150 pounds

My paper loops have basically the same structure as the can. The single loops collapse under a static load of little more than one pound. But the hole in the washers provided a means for me to make a vertical stack that would stand straight up and remain aligned during the collapse. Even if I could make the stack of 33 stand up the falling top would probably go off the side.

Multiple loops were able to absorb the energy leaving most of them intact.

The pop can demonstration is less informative than my paper loop stack.

But the only way I can imagine making a good tube-in-tube model is with a 3D printer.

psik

 

[psikeyhackr]

Doctors bury their mistakes - engineers tend to make them in full public view.
Tacoma Narrows Bridge and Westgate Bridge as examples.

And Tacoma is "on topic" - they did physical modelling in the post collapse studies.

AND model testing was better then "explaining" in that instance.

Actually the physical model of the Tacoma Bridge was built before the collapse. It was used to test their theories about what to do to stop the galloping. But the real bridge collapsed about two weeks before they were to start making modifications.

There is no reason not to make physical models of the WTC. [...]

psik

 

[Mick West]

The pop can demonstration is less informative than my paper loop stack.

What paper loop stack?

 

[psikeyhackr]

What paper loop stack?

If you watch the second video in the OP starting at 3:44 you will see the collapse experiment that was the point of the video.

psik

 

[jaydeehess]

First of all only 84 floors within the towers used the standard 4 inch slab on trusses design. The mechanical floors were different, the mezzanines and basements were different.

I think we can safely leave the mezzanine and basement levels out of the discussion and I did make note of the mech floors.

There is no evidence whatsoever of floors outside the core ever falling on other floors outside the core. That is just the speculation everyone spouts.

There's no way around the fact that once collapse initiated the falling mass could not be impinging significantly directly on the columns. Where does that leave it? On the floor pans, both in and outside the core.
That means that if arrest is to be realized, the floor pans, trusses, and connection to columns must be able to absorb the forces generated. They can't, plain and simple.
As far as simple models of this concept, Mick did just that. Might be in this thread, its been a while.

I had no choice but to use double and triple paper loops lower down in my model. My intent was to make the support structure as weak as possible. I tested the loops to determine the maximum static load they could hold. Weaker loops would be crushed and I left the model standing for 4 days.

As I said, it doesn't model the manner of collapse of the twins. Nice model but its irrelevant.

Are you saying the core of the upper portion of the north tower did not come down on top of the core of the lower portion?

If you mean did the upper section low end of columns hit the lower section upper column ends, no, how could they? They were a continuous column, then the upper section began moving. In order to do so they simply cannot be aligned any longer. The upper columns miss the lower columns. If you wish to debate how that came about its a separate discussion. We are dicussing propagation of collapse and that bypasses column strength. You modeled column strength.

 

[Mick West]

If you watch the second video in the OP starting at 3:44 you will see the collapse experiment that was the point of the video.

psik

Which does not in any way resemble that actual process by which the towers collapsed, so it's irrelevant.

The towers do not collapse by crushing the columns, and then having the columns remain between floors to act as a buffer.

The towers collapsed in a complex process of the floors being stripped away from columns, the outer wall peeling away, and the inner core collapsing in large part due to slender column bucking. Your little model does not show this at all.

 

[Mick West]

The topic here is the use of scale models. Please stay on topic.

 

[jaydeehess]

Aside from his diatribe against engineering schools it was on topic re;models

 

[Mick West]

Aside from his diatribe against engineering schools it was on topic re;models

I was referring to another post, which I deleted. But yes, that was off topic-too.

 

[Redwood]

First of all only 84 floors within the towers used the standard 4 inch slab on trusses design. The mechanical floors were different, the mezzanines and basements were different. There is no evidence whatsoever of floors outside the core ever falling on other floors outside the core. That is just the speculation everyone spouts.

Jaydeehess has already handled this one pretty well; I'll just add a photo of "pancaked" floors in the rubble:

I have already suggested the better way to make a model, 3D printers. That would allow tremendous control of the strength of all columns, beams and connections. How strong were the connections between the floors and the core and the perimeter columns? Do you expect to duplicate that with any precision with TAPE. But that still leaves the problem of the distribution of mass down the building.

I assume you mean construction of a scale model for the collapses. The problem is, you still have the scaling conundrum because of the squared-cubed relation between cross-sectional area and mass. 3-D printing won't get you around that. The engineering world has no problem with understanding that once the Twin Towers began their collapses, nothing in the world could stop them. Rather than your scale model being a test of whether or not the towers would have continued their fall, the actual collapses of the towers would be a test of your scale model.

It is so curious that with all of the engineering schools in the nation that put men on the Moon, none discusses needing to know the tons of steel and tons of concrete on every level of the towers. Gregory Urich's spread sheet does not have a table for the heights of each level. If you divide his Potential Energy for each level by the mass you find he has the roof lower than the top 10 stories. LOL

Engineers do take account of the weight of the concrete and steel that goes into constructing a building. It's called "dead load". There have been engineering disasters where the engineer neglected to take that into account. (http://en.wikipedia.org/wiki/Collapse_of_the_Hotel_New_World) But that has nothing to do intrinsically with the strength of a building.

I consider it totally dishonest for our engineering schools to not have demonstrated this supposed collapse with a good physical model and yet men rushed off to Iraq and Afghanistan over this. But now they would look pretty stupid to have models fail. The NIST does not even specify the total amount of concrete in the towers. So how can a decent model be made without that. But data from before 9/11 says there was 425,000 cubic yards.

psik

Engineering schools have no say in the deployment of the military, and once again, the amount of concrete in the towers is irrelevant to their collapses.

 

[psikeyhackr]

I assume you mean construction of a scale model for the collapses. The problem is, you still have the scaling conundrum because of the squared-cubed relation between cross-sectional area and mass. 3-D printing won't get you around that. The engineering world has no problem with understanding that once the Twin Towers began their collapses, nothing in the world could stop them. Rather than your scale model being a test of whether or not the towers would have continued their fall, the actual collapses of the towers would be a test of your scale model.

The model would still have to be weighted but we can't do that if we don't have accurate weight distribution data on the real buildings.

But when do "collapse" believers ever demand such information?

I do not personally care about scaling. I did not make the title of the thread. The author used my YouTube video however. But 3D printers should enable making columns as weak as possible relative to the static load. If 110 levels can be made as weak as possible with the same mass distribution as the WTC but still will not come close to complete collapse the people claiming the real building could do it have a problem.

psik

 

[NoParty]

Actually the physical model of the Tacoma Bridge was built before the collapse. It was used to test their theories about what to do to stop the galloping. But the real bridge collapsed about two weeks before they were to start making modifications.

There is no reason not to make physical models of the WTC. [...]

psik

Money and time strike me as the two most obvious counterexamples to your "no reason" claim.

Since we have the WTC collapse on film, and know that fires were begun by planes seen hitting
the towers, yes, there is little justification--at this point--to incur the expense.

You, of course, are free to spend your time and money, if you truly believe that it would be worthwhile.





Also, your Tacoma Narrows info is a bit misleading in multiple ways:
You imply ("the real bridge collapsed about two weeks before they were to start making modifications")
that danger was known, but not yet acted upon. This is wrong in two ways:
Workers installed "four hydraulic jacks ("buffers") at the towers to act as shock absorbers"
and when that did not do enough, cables were later attached to the side spans.
"Farquharson and state bridge engineers believed they had solved the problem."
Yes, a model was made, and it was studied before and after the collapse.

http://www.wsdot.wa.gov/tnbhistory/connections/connections3.htm#1

 

[WeedWhacker]

I do not personally care about scaling.

Hmmmm.....odd, since that is the topic, here.

I think it's safe to presume that in order to "model" the complexity of the WTC Towers' collapse, it will be in a computer. There are SO MANY dynamics to factor in...this will take many generations of Humans to work on it....so, in about 300 years (or so, give or take) someone, some-WHEN will stumble upon this thread, and have a short chuckle.

 

[jaydeehess]

The model would still have to be weighted but we can't do that if we don't have accurate weight distribution data on the real buildings.

But when do "collapse" believers ever demand such information?

I do not personally care about scaling. I did not make the title of the thread. The author used my YouTube video however. But 3D printers should enable making columns as weak as possible relative to the static load. If 110 levels can be made as weak as possible with the same mass distribution as the WTC but still will not come close to complete collapse the people claiming the real building could do it have a problem.

psik

Make your model columns as weak or as strong as you want. The strength of the columns was bypassed in the mode of collapse of the twin towers.

 

[WeedWhacker]

I am at a loss as to exactly what member "psikeyhackr" is alleging in the first place. Maybe we should get down to "brass tacks"?? (Meaning, same page?)

 

[jaydeehess]

He is saying that his paper loop model demonstrates that due to the strength of the columns, the tower collapses should have arrested.
He further complains that no one else has modeled the collapses. He rejects computer modeling and demands physical scale models.

 

[Mick West]

I do not personally care about scaling.

There's your problem!

 

[psikeyhackr]

Make your model columns as weak or as strong as you want. The strength of the columns was bypassed in the mode of collapse of the twin towers.

That would be the point of using a 3D printer to make a tube-in-tube design. Such a printer would make it possible to control the strength of the columns in the core and on the perimeter and the strength of the connections between the floors and the columns.

Then your EMPTY CLAIM could be tested.

As it is all you have is TALK!

psik

 

[WeedWhacker]

That would be the point of using a 3D printer to make a tube-in-tube design. Such a printer would make it possible to control the strength of the columns in the core and on the perimeter and the strength of the connections between the floors and the columns.

Great idea! Now, if only it can be modelled. To scale. Oh, but there still remains this pesky thing about gravity....one G, which ALSO must be modelled. (to scale, of course....does this make sense?)

 

[NoParty]

That would be the point of using a 3D printer to make a tube-in-tube design. Such a printer would make it possible to control the strength of the columns in the core and on the perimeter and the strength of the connections between the floors and the columns.

Then your EMPTY CLAIM could be tested.

As it is all you have is TALK!

psik

Dude, you're 8 messages in, and I still can't tell what you're trying to say.

Are you claiming that--if only we had moxie and a 3D printer--we'd learn
something that contradicts what the whole world saw happen on 9/11/2001?

 

[Mick West]

That would be the point of using a 3D printer to make a tube-in-tube design. Such a printer would make it possible to control the strength of the columns in the core and on the perimeter and the strength of the connections between the floors and the columns.

Then your EMPTY CLAIM could be tested.

As it is all you have is TALK!

psik

Have you read this entire thread?

 

[psikeyhackr]

He is saying that his paper loop model demonstrates that due to the strength of the columns, the tower collapses should have arrested.
He further complains that no one else has modeled the collapses. He rejects computer modeling and demands physical scale models.

Where is this computer modelling where complete data on the model has been provided?

Got a link?

Data from before 9/11 says there was 425,000 cubic yards of concrete in the towers. The 10,000 page NIST report does not even specify the total amount of concrete. I know about the SAP2000 model that the NIST says it did but does not provide complete data for.

psik

 

[Mick West]

Where is this computer modelling where complete data on the model has been provided?

Got a link?

Data from before 9/11 says there was 425,000 cubic yards of concrete in the towers. The 10,000 page NIST report does not even specify the total amount of concrete. I know about the SAP2000 model that the NIST says it did but does not provide complete data for.

psik

Can you confirm if you've read this entire thread or not? Otherwise your posts lack meaning.

 

[OneWhiteEye]

Can you confirm if you've read this entire thread or not? Otherwise your posts lack meaning.

Otherwise??? Hahaha....

 

[OneWhiteEye]

How does anyone PROVE that a thought experiment is valid?

I can't imagine why anyone would want to do that. I'd rather have an interesting discussion which ends up with more questions than to prove something trivial (like crushing of support columns was not the dominant failure mode in the towers).