# Does the exclusion of stiffness from Nordenson's falling girder calculations demonstrate anything?

#### Tony Szamboti

##### Active Member
I think in the case of 7wtc it seems to be a progressive failure low down which progressed east to west.. That's why it came down. What started that cascade is in question.
It can be shown it could not have been column 79 or the transfer trusses due to natural causes.

Your pickings are getting mighty slim.

#### Jeffrey Orling

##### Senior Member
You can't prove a negative... so the jury is still out and there is nothing indicating anything but fire.

#### Tony Szamboti

##### Active Member
You can't prove a negative... so the jury is still out and there is nothing indicating anything but fire.
Sorry pal, but symmetric free fall of the entire building is not indicative of failure due to fire. Never has been and never will be.

It isn't surprising that those trying to explain it as being a "progressive collapse" can't even get to first base on it once their work is seriously scrutinized.

#### Jeffrey Orling

##### Senior Member
Sorry pal, but symmetric free fall of the entire building is not indicative of failure due to fire. Never has been and never will be.

It isn't surprising that those trying to explain it as being a "progressive collapse" can't even get to first base on it once their work is seriously scrutinized.
Symmetric? Please define symmetric and how it applies to the collapse. The insides seemed to have collapsed first beginning on at the NE quadrant... the collapse of the interior progressed westward... and finally the moment frame came down and the who east side of it at least rotated counter clockwise... and of course there was the notable vertical kink in the moment frame at about column 44 or so.

Here ya go:

"An object has reflectional symmetry if there is a line of symmetry going through it which divides it into two pieces which are mirror images of each other.[5]
An object has rotational symmetry if the object can be rotated about a fixed point without changing the overall shape.[6]
An object has translational symmetry if it can be translated without changing its overall shape.[7]
An object has helical symmetry if it can be simultaneously translated and rotated in three-dimensional space along a line known as a screw axis.[8]
An object has scale symmetry if it does not change shape when it is expanded or contracted.[9] Fractals also exhibit a form of scale symmetry, where small portions of the fractal are similar in shape to large portions.[10]
Other symmetries include glide reflection symmetry and rotoreflection symmetry."

#### Tony Szamboti

##### Active Member
Symmetric? Please define symmetric and how it applies to the collapse. The insides seemed to have collapsed first beginning on at the NE quadrant... the collapse of the interior progressed westward... and finally the moment frame came down and the who east side of it at least rotated counter clockwise... and of course there was the notable vertical kink in the moment frame at about column 44 or so.

Here ya go:

"An object has reflectional symmetry if there is a line of symmetry going through it which divides it into two pieces which are mirror images of each other.[5]
An object has rotational symmetry if the object can be rotated about a fixed point without changing the overall shape.[6]
An object has translational symmetry if it can be translated without changing its overall shape.[7]
An object has helical symmetry if it can be simultaneously translated and rotated in three-dimensional space along a line known as a screw axis.[8]
An object has scale symmetry if it does not change shape when it is expanded or contracted.[9] Fractals also exhibit a form of scale symmetry, where small portions of the fractal are similar in shape to large portions.[10]
Other symmetries include glide reflection symmetry and rotoreflection symmetry."
A high school kid could look at the collapse of WTC 7 and realize it was symmetric.

It is glaringly obvious that the columns inside the building (the core) were pulled together to cause the entire exterior to come down uniformly. The only timing difference was with a slight lead in the center of the core to pull things inward in what is a classic implosion.

The east penthouse observables show it was only taken out high in the building moments before the full implosion. Proof of this is the shock wave goes top to bottom, only 15 stories of windows are broken from the roof down, there is no deformation of the exterior as there would be if the entire east interior had collapsed, there is no dust emanating from windows until the exterior came down. The vertical kink is only indicative of column 79 collapsing somewhere below the roof.

The horizontal kink on the north face is due to the core going down and the east side core being further away from the end of the building than the west side. Inertia caused that.

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#### Oystein

##### Senior Member
Actually, the girder cannot be 547 inches long as that is the center to center distance between columns 44 and 79. It seems Nordenson had a slight error there also. ...
...
I was doing the 20,000 pounds from memory while writing the post. I think I checked the mass in the FEA, which would have been very accurate. By hand I get

33 x 130 girder A2001 = 45 feet x 130 lbs./foot = 5,850 lbs.
24 x 55 beams K3004, C3004, B3004, A3004 = 53 feet x 55 lbs./foot = 2,915 lbs. each
21 x 44 beam G3005 = 52 x 44 lbs./foot = 2,288 lbs.
12 x 19 lateral support beams K3007, G3007, S3007 = 4 feet x 19 lbs./foot = 76 lbs. each

So I get 5,850 + (4 x 2,915) + 2,288 + (3 x 76 lbs.) = 20,026 lbs.

The reason I get 6,633 lbs./inch with the little higher frequency here is that I used the steel mass as it is what is relavent and what the natural frequency is dependent on. In the earlier calculation I had used the Nordenson load of 46,000 lbs. and that was not correct. If the slab were included it would make the natural frequency and stiffness even lower as without shear studs it adds nothing but mass. You can't use the slab mass with the 0.52 Hz frequency in the frequency equation as the frequency will go down in the FEA due to the greater mass and no addition of stiffness.

You can make the steel weight 21,000 if you like, as I do some rounding and averaging here. However, beam G3005 is a 21 x 44, not a 24 x 55, and your estimate loses 11 lbs. per foot for it, and the beam is actually a couple of feet shorter than the K3004 beam, so that would be about 600 lbs.. Adjustment of your estimate for that beam alone takes it down to about 20,200 lbs.. Just to show you that this is not significant, for 21,000 lbs. the stiffness is 6,960.5 lbs./inch., deflection is 31.6 inches, and generated load is 219,881 lbs.. This is only a few percent difference and does not change things at all and the weight was much closer to 20,000 lbs. anyway as you had the G3005 error.

...

I am editing this post to add a more accurate weight calculated in the attached spreadsheet. The drawings are also provided for anyone who would like to check the figures. I used drawing 4349 in lieu of A2001, but with a 537 inch length. The weight of the steel frame turns out to be 19,795 lbs., which is just a little under 20,000 lbs. and would have made my analysis conservative as the stiffness would have been slightly higher using 20,000 lbs..
Hi Tony,
I appreciate you going into the details of beam and girder dimensions, and I somewhat apologize for nitpicking the steel mass - whether 21,000 lbs or 19,795 lbs, that's within 5% of your rounded 20 kips and thus only borderline significant. I like to keep numbers as precise as we have them at every step, to keep errors from piling up unnecessarily, but stay aware that the numbers that we have are prone to differ from reality anyway.

I still want others to help me vet Tony's approach (FEA model -> natural frequency -> stiffness is a function of mass and frequency), and his assessment that the floor slab better be left out of the model when determining the stiffness.

Please folks, don't develop this into a general debate thread. This here is not the ISF - Mike West demands that all threads stay very close to the OP's topic, which in this case is the stiffness of the falling floor assembly and how a reasonable and technically correct treatment thereof changes the outcome of Nordenson's Appendix B (and perhaps, eventually, Nordenson's report as a whole - but first things first).

In short: In the OP, Tony claims that Nordenson ought to have included the falling floor assembly's stiffness, and doing so would refute his result that the girder connection on floor 12 would fail - and the floors below in due sequence.
The sole purpose of this thread is to either uphold or debunk this claim.

#### Jeffrey Orling

##### Senior Member
A high school kid could look at the collapse of WTC 7 and realize it was symmetric.

It is glaringly obvious that the columns inside the building (the core) were pulled together to cause the entire exterior to come down uniformly. The only timing difference was with a slight lead in the center of the core to pull things inward in what is a classic implosion.

The east penthouse observables show it was only taken out high in the building moments before the full implosion. Proof of this is the shock wave goes top to bottom, only 15 stories of windows are broken from the roof down, there is no deformation of the exterior as there would be if the entire east interior had collapsed, there is no dust emanating from windows until the exterior came down. The vertical kink is only indicative of column 79 collapsing somewhere below the roof.

The horizontal kink on the north face is due to the core going down and the east side core being further away from the end of the building than the west side. Inertia caused that.

1. something fails low down on the NE side - EPH descends
2. first failure collapses the transfers on the east side (if they weren't the initial failures) and those failures pull the massive girder on the north of the core down... which collapses the west truss #3 - WPH descends
3. complete collapse of the interior structure below floor 8 - pulls the east and west braced frame inward - moment frame collapses unsupported from ground to floor 8

By the time the moment frame came down... there was nothing left standing in the interior.

#### drommelsboef

##### Member
This symmetry definition game has also been played at the 911forum. The symmetry is obvious even compared with the class of known controlled demolitions. It is not like Jeffrey suggests a symmetry that is valid for solid mathematical objects. If a phantom jet crushes at an absorbing wall the part that is not crushed keeps its shape. That's the same behaviour that wtc7 had the first few seconds. Of course there is some internal failure which doesn't make it perfect but the symmetry is obvious. No discussion is needed about that. That is pure denial.

#### Oystein

##### Senior Member
So the falling girder deflects 31.6"?

Presumably in the middle?

Seems like a lot....
Argument from incredulity.
Upthread, I argued with the help of three graphics that a rotating girder, supported simply on the hinge and free at the far end and experiencing an opposing force 1*F at the free end, would be equivalent to a beam that's supported simply on both ends and experience a force of 1.5*F at a point 2/3 of its length from the girder. Considering the girder alone, my result using this model and the properties of the girder as I knew it, I came up with a stiffness that's about 7 times Tony's value, and this would lead to a deflection of 12 inches near the point I described.

For Tony's value, 32 inches is correct - somewhere near the middle, presumably.
But is Tony's value correct? That's what I am asking you guys to help scrutinize, and no, I will not accept incredulity or guesses.

It appears plausible to me that the "system" stiffness of the assembly "girder+5 main beams+supporting beams" is somewhat lower than the stiffness of the girder alone: The beams are longer but but less beefy than the girder and would thus be expected to be less stiff. Lower by how much I cannot evaluate - it's currently outside my ability to solve this analytically, and I don't have the software to verify Tony's FEA model and results.

#### Polly Math

##### Member
This thread is about the exclusion of the stiffness of the falling girder. I just looked and the internet seems to be littered with threads that are about your truss theory. The topic focus level seems to have dropped somewhat since Tony presented an analysis that confirmed his suspicions with respect to exactly what difference the inclusion of the stiffness would have made.
I personally think it is proved way beyond a reasonable degree that the inclusion of stiffness would have made a huge difference to the conclusions Nordenson came to on the basis of his erroneous assumption of infinite stiffness. An objection at trial or in discovery would have been legitimate and would have forced Nordenson to conclude that the failure of the girder would not fail the girder connection below as per his analysis.
This has the most serious of impacts (no pun intended) on NISTs stated theories regarding progressive collapse from a single point of failure. They should revise their analysis and account for what has transpired.

#### DGM

##### New Member
It can be shown it could not have been column 79 or the transfer trusses due to natural causes.

Your pickings are getting mighty slim.
So write it up so it can be looked at with the same level of scrutiny as you use on the NIST and everyone else you disagree with. You are making a claim of fact, disproving the NIST is not proving your claim. Then present your in depth theory.

People have been asking you to do this for years now.

#### Tony Szamboti

##### Active Member
So write it up so it can be looked at with the same level of scrutiny as you use on the NIST and everyone else you disagree with. You are making a claim of fact, disproving the NIST is not proving your claim. Then present your in depth theory.

People have been asking you to do this for years now.
Your request for me to provide a full explanation of the collapse is ridiculous and pure unadulterated nonsense on its face.

Who has the responsibility and authority to investigate the collapse of WTC 7 properly and with integrity in a transparent way?

I would hope that in all the time you have spent on this subject you would at least be aware that none of the 2000 series or fieldwork drawings were released to the public. Those of us who have scrutinized the NIST WTC 7 report have had to improvise like I did using drawing 4349 in lieu of drawing A2001. We were also told we couldn't have calculations and analysis related to the alleged walk-off to the west of the girder as it "might jeopardize public safety". It didn't matter in the end and it has now been proven to be impossible by the ARUP analysis.

The reality that the NIST WTC 7 report has been shown to be incorrect should mean nothing more than them going back and correcting it. Instead we are getting a song and a dance. Why?

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#### Jeffrey Orling

##### Senior Member
And the collapse was not symmetrical and symmetry is not a proof of anything regardless or a characteristic of CD.

#### DGM

##### New Member
Your request for me to provide a full explanation of the collapse is ridiculous and pure unadulterated nonsense on its face.
Will you now withdraw your claim?
"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

That's the claim you make that you can not support.

#### Tony Szamboti

##### Active Member
Will you now withdraw your claim?
"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

That's the claim you make that you can not support.
I actually have already written it up for anyone to look at by posting my work here and it was scrutinized. You didn't seem to have any comments with any specificity or merit.

I can write it up and send it to NIST. Is that what you meant?

#### DGM

##### New Member
I actually have already written it up for anyone to look at by posting my work here and it was scrutinized. You didn't seem to have any comments with any specificity or merit.

I can write it up and send it to NIST. Is that what you meant?
You have written a report to back up this statement?

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

Where?

#### Polly Math

##### Member
The OP statement has clearly been proven.
Drifting from the topic isn't going to change that.

#### Tony Szamboti

##### Active Member
You have written a report to back up this statement?

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

Where?

I showed right here that even with a girder falling off its seat it will not shear the seat at column 79 on the floor below and thus there can be no cascading collapse of floors, so column 79 is not left unsupported. You did read it and implied that it had merit because you asked after that post I made if there was any other natural mechanism which could be attributed to fire.

There is no evidence of fire on the 5th floor where the transfer trusses were located, so that knocks it out of contention right off the bat, regardless of what some try to assert without a basis.

Who has authority and responsibility for a transparent investigation and explanation of why the building completely collapsed?

#### DGM

##### New Member
I showed right here that even with a girder falling off its seat it will not shear the seat at column 79 on the floor below and thus there can be no cascading collapse of floors, so column 79 is not left unsupported. You did read it and implied that it had merit because you asked after that post I made if there was any other natural mechanism which could be attributed to fire.
Do you plan to include the floor slab in your calculations at anytime? You know, so your models will be the same?

Maybe you could amend your claim to include only the models and conditions you chose to include. You make a blanket statement you can't support.

#### DGM

##### New Member
Who has authority and responsibility for a transparent investigation and explanation of why the building completely collapsed?
So far there has been no one that has presented a case that fire and damage was not the cause. The NIST made reasonable recommendations to prevent this sort of thing from happening again. That was what they were tasked with.

#### Tony Szamboti

##### Active Member
So far there has been no one that has presented a case that fire and damage was not the cause. The NIST made reasonable recommendations to prevent this sort of thing from happening again. That was what they were tasked with.
The NIST hypothesis has been shown to include impossibilities. Their task was to explain the collapses and they have not done so yet.

#### Tony Szamboti

##### Active Member
Do you plan to include the floor slab in your calculations at anytime? You know, so your models will be the same?

Maybe you could amend your claim to include only the models and conditions you chose to include. You make a blanket statement you can't support.
I used the Nordenson energy of 3,473,000 inch pounds, which would have included his mass over the drop height. It included some of the slab.

I think you are confused by the frequency analysis. Adding the slab to it will lower the frequency and cause more deflection and an even lower force. You don't seem to appreciate that this would be a dynamic load that is the weight load amplified by an impact. The frequency and stiffness analysis tell you how much the static load is amplified.

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#### DGM

##### New Member
Adding the slab will lower the frequency of the frame and cause even more deflection and lower force. You don't seem to appreciate that this would be a dynamic load that is the weight load amplified by an impact.
So no composite action from the slap contributing to the girder stiffness? Calculations?

#### Tony Szamboti

##### Active Member
So no composite action from the slap contributing to the girder stiffness? Calculations?
The slab could not contribute stiffness with broken shear studs.

#### DGM

##### New Member
The slab could not contribute stiffness with broken shear studs.
How many were broken on the beams leading into the girder?

#### Tony Szamboti

##### Active Member
How many were broken on the beams leading into the girder?
NIST says all of them, otherwise the beams can't push the girder.

#### DGM

##### New Member
NIST says all of them.
You don't trust the NIST why use them for reference? How about the distribution of weight from the broken slab on the girder?

You must have considered these things to make this claim:

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

#### Tony Szamboti

##### Active Member
You don't trust the NIST why use them for reference? How about the distribution of weight from the broken slab on the girder?

You must have considered these things to make this claim:

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."
I am saying NIST needs to redo their investigation and analysis and you don't seem to want that but want shear studs even though NIST says they are broken. You can't have it both ways and that is what you seem to want.

#### DGM

##### New Member
I am saying NIST needs to redo their investigation and analysis and you don't seem to want that but want shear studs even though NIST says they are broken. You can't have it both ways and that is what you seem to want.
No, I want you to support the statement you made.

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

#### Tony Szamboti

##### Active Member
No, I want you to support the statement you made.

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."
I have and you agreed that the falling girder couldn't break through the floor below when you then asked if there were other mechanisms. Do you remember saying this?
So, Is there an alternative that can withstand the same scrutiny as the one discussed here?

#### DGM

##### New Member
I have and you agreed that the falling girder couldn't break through the floor below when you then asked if there were other mechanisms. Do you remember saying this?
Where have you supported this statement?

"It can be shown it could not have been column 79 or the transfer trusses due to natural causes."

A post number will do.

#### Mick West

Staff member
This thread is being paused as it seems like the details of the original questions have been mostly agreed upon, and the discussion has veered off in multiple direction.

#### Tony Szamboti

##### Active Member
Is this thread open again? I don't see a lock?

#### Mick West

Staff member
It is, providing people can stay on topic.

#### Jazzy

##### Closed Account
I have and you agreed that the falling girder couldn't break through the floor below when you then asked if there were other mechanisms. Do you remember saying this?
Were there any other mechanisms?

#### Oystein

##### Senior Member
Four months later, I am still wishing someone would help me scrutinize Tony's FEA presented in Post #200, which he recently also presented in his AE911Truth webinar.

By "scrutinize" I mean any reasonable questions that can be asked; or someone who knows how to do FEA coud look at Tony's model (what does that even mean in a FEA software? What would one have to look at?) and check whether he models correctly the floor assembly in question here. I think Tony left out the floor slab in his model - was that a valid decision? How might the result (the stiffness of the falling floor assembly) change if floor slab were included?
What margin of error are we talking about?

Tony's result is that the impact load at the girder connection below is about 1/3 of connection capacity - therefore, he concludes, collapse would arrest.
Is that factor 3 significant - does it allow to draw the conclusion as a proven fact? Or is it still in "maybe" territory (as in "connection would more likely survive, but may fail with some bad luck, or if actual conditions were sufficiently different from our assumptions")?

#### Tony Szamboti

##### Active Member
Oystein, since the shear studs on the beams were broken, according to NIST and ARUP, adding the concrete slab to the natural frequency analysis would have only added mass and no stiffness, giving a lower natural frequency. The natural frequency analysis I performed was conservative in the direction of overestimating the impact load.

The floor slab is included in the potential energy, which was the value used by Nordenson.

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#### Oystein

##### Senior Member
Thanks Tony - makes sense, answers one question. There are more - especially questions that I don't know how to ask - to scrutinize your FEA.

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