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WTC7 and the girder walk-off between column 79 and 44

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jaydeehess said:
Wait,,,, so the NIST theory has it that the girder was pushed/walked across the seat to the point where it failed/fell off the seat. Chris now wishes to argue that the girder sagged which would pull axially along the girder and shorten the depth of girder residing on the seat. It would also reduce the stiffness of the steel of course, including that portion which sat on the seat.

In either case we have less girder steel on the seat and as Chris wishes to include the effect of the heat on that steel, we have more malleable steel on that seat , the combination of which would serve to have the seat-girder connection fail.
Click to expand...
Good point. You have found another reason why the NIST theory fails.

Assuming that the load to strength of the girder is the same as the beams, a 45' girder would expand and sag ~85% as much as a 53' beam.

@ 600oC
A 53' beam will expand 4.68" and lose 0.49" to sagging for a net expansion of 4.19"
A 45" girder will expand 3.98" and lose 0.41" to sagging for a net expansion of 3.57".

Since there is less than 2" clearance between the girder and the columns, the girder is pressing up against both columns.

@ 700oC
53' expand 5.63" shorten 4.42" net expansion 1.12"
45' expand 4.79" shorten 3.77" net expansion 1.86"

@800oC
53' expand 6.62" shorten 10.11" net shorten 3.49"
45' expand 5.63" shorten 8.59" net shorten 2.96"

The beams have pulled the girder to the east ~3 1/2"
About ~1/4" of the girder web is still over the support plate. It must be more than the thickness of the seat away from the support plate to bend the seat plate down and get past it.

@ 900oC
53' expansion 7.54" shorten 16.64" net shorten 9.1"
45' expansion 6.42" shorten 14.14" net shorten 7.72"

~850oC the girder will fail due to shortening and/or walk-off to the east but that is not the NIST theory. Thermal expansion cannot push the girder more than ~5" before sagging starts pulling it back the other way, which is why NIST lied about the width of the seat and omitted the stiffeners. How can we be sure they are lying about the width of the seat? They also lied about the stiffeners. There is no way that could be an innocent mistake.

Then there is the scenario in which the fire begins burning down and the steel cools and contracts in which if Chris is correct the sagged girder now shortens axially even more, or as the CTBUH brought up, the sagged beams cool and shorten and pull the girder off its seat.
Click to expand...
Offering alternate theories does not change the FACT that the NIST theory doesn't work so they did not explain the collapse.

If you think you have a theory that will work then write NIST and let them know.



ETA References:
Beam expansion
http://img823.imageshack.us/img823/4...spreadshee.jpg

Beam sagging and shortening [100 psf load - full dead load & 1/2 live load] [FONT=&quot]
[/FONT] http://img210.imageshack.us/img210/1644/shorteningvtempusingais.jpg

Reference data
http://www.aisc.org/WorkArea/showcontent.aspx?id=7046

Second reference [has larger sag numbers]
http://www.civil.canterbury.ac.nz/sif/paper19.pdf

 
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Christopher7 said:
Offering alternate theories does not change the FACT that the NIST theory doesn't work so they did not explain the collapse.

If you think you have a theory that will work then write NIST and let them know.
Click to expand...
Newton's theory does not explain the world as it is.

Even Relativity theory fails in some areas.

But alas, it's the best we have, even if we know it's not perfect. And for specific cases, Newton's theory is good enough. Why should we just dispose of it? Just because Newton (FEMA) and Einstein (NIST) believed in God (are government agencies) which is irrational (makes them suspicious)?

Unless you have a better replacement, even if there are some holes, NIST's is the best complete theory we have, and even FEMA's has its strong points.
 
Christopher7 said:
Thermal expansion cannot push the girder more than ~5" before sagging starts pulling it back the other way....
Click to expand...

Nope. Sagging of the girder will tend to pull it off to the north.

And the girder is carrying the weight of the beams and the beams' deadloads.

Its saggy-self only has to move 2" north away from the column and the hot-and-weakened 1" girder seat is carrying the entire combined load.
 
pgimeno said:
Newton's theory does not explain the world as it is.

Even Relativity theory fails in some areas.

But alas, it's the best we have, even if we know it's not perfect. And for specific cases, Newton's theory is good enough. Why should we just dispose of it? Just because Newton (FEMA) and Einstein (NIST) believed in God (are government agencies) which is irrational (makes them suspicious)?

Unless you have a better replacement, even if there are some holes, NIST's is the best complete theory we have, and even FEMA's has its strong points.
Click to expand...
No, the NIST walk-off theory could not and did not happen. It may be the best theory YOU have but it does NOT explain how WTC 7 collapsed.

ETA: All this is just to prove this part of the NIST theory doesn't work. The fire had burned out so there was no thermal expansion at 5:20 p.m. anyway.
 
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Christopher7 said:
No, the NIST walk-off theory could not and did not happen. It may be the best theory YOU have but it does NOT explain how WTC 7 collapsed.

ETA: All this is just to prove this part of the NIST theory doesn't work. The fire had burned out so there was no thermal expansion at 5:20 p.m. anyway.
Click to expand...

You cannot prove the NIST theory won't work without a systemic approach.
 
DGM said:
I don't really believe that designing a way to allow the explosives to survive the explosions and fires would be all that difficult.

The real problem is controlling the blast wave and sound pressures when the charges were detonated. This is their "kryponite".
Click to expand...
The charges would have to survive the WTC 1 and 2 plane impacts first. There was quite an extensive discussion with Java Man recently about the difficulty of such. He eventually said that his theory did not require the explosives to survive the plane impacts, and vowed to return with said theory someday.
 
Christopher7 said:
No, the NIST walk-off theory could not and did not happen. It may be the best theory YOU have but it does NOT explain how WTC 7 collapsed.
Click to expand...

If that is the case, why has nobody in the "massive" truth movement come up with an 800 page document with calculations showing an alternative method? All these engineers that supposedly support any number of conspiracy theories and not one has come up with something better. You mean to tell me that nobody has the balls to put a method to paper that matches the events we see in videos and photographs? How hard is it? How much money was sucked up by Gage as his "compensation" that could have been used to come up with a thermite/explosives theory complete with calculations and a step by step explanation of how it took place?

For example, what columns or beams needed to be demoed in order for the east penthouse to collapse as shown? Was the girder connected to column 79 cut with thermite to fall upon the other floors below causing the damage we see? Was then column 79 cut somewhere to cause the east penthouse to collapse into the building? How were the fires started? They had to be started intentionally right? What components were cut with thermite/explosives to cause the building to lean as observed via transit an eyewitness accounts?

All you folks attempt is to shoot holes into NISTs theory instead of coming up with an alternative that works.

Why?

Is it because if you do come up with an alternative with explanations and calculations, you'd get your butts handed to you, leaving you with nothing?

Everyone in your group wants to say it was something else, but nobody wants to put the math behind it. That's pretty lame in my book. Every time you back a truther into a corner and ask for an scientific explanation complete with step by step analysis and calculations, they always balk and say "I'm just asking questions."
 
Gamolon said:
All you folks attempt is to shoot holes into NISTs theory instead of coming up with an alternative that works.

Why?

Is it because if you do come up with an alternative with explanations and calculations, you'd get your butts handed to you, leaving you with nothing?
Click to expand...

In all fairness, Chris7 did make a start when he categorically stated "The free-fall phase of WTC7 collapse can only be explained by the simultaneous removal of all vertical support over several floors. This can only have been achieved by CD"*

But he stopped there when everybody started laughing. He continues to claim it, but never develops it into how or when or why....


*paraphrased from memory, though if challenged I will look up the exact wording.
 
GlennB said:
In all fairness, Chris7 did make a start when he categorically stated "The free-fall phase of WTC7 collapse can only be explained by the simultaneous removal of all vertical support over several floors. This can only have been achieved by CD"*

But he stopped there when everybody started laughing. He continues to claim it, but never develops it into how or when or why....


*paraphrased from memory, though if challenged I will look up the exact wording.
Click to expand...

Is this true Chris7?

Does this stand true of ANY steel structure? Do you believe that there could NEVER be a scenario where a load, above a structural steel support frame, could exceed said support frame to a point that the load descends at free fall?

Another question. If all the vertical supports were removed at the same time, why is there .8 seconds of no free fall prior to when the free fall actually started?

Did the structure hang in the air like we see in Looney Tunes cartoons? Is that the kind of physics we are discussing here?
 
Gamolon said:
Another question. If all the vertical supports were removed at the same time, why is there .8 seconds of no free fall prior to when the free fall actually started?
Click to expand...

C7 has explained that this was an optical illusion. The camera was looking upwards and the roofline began by folding backwards, giving the impression that it was falling. So, in C7-land, it was free-fall from the outset :boggled:

Exactly why it might fold backwards at the start he doesn't make clear ;)
 
GlennB said:
C7 has explained that this was an optical illusion. The camera was looking upwards and the roofline began by folding backwards, giving the impression that it was falling. So, in C7-land, it was free-fall from the outset :boggled:

Exactly why it might fold backwards at the start he doesn't make clear ;)
Click to expand...

Almost as if it were asymmetrical!
 
GlennB said:
...the roofline began by folding backwards, giving the impression that it was falling. So, in C7-land, it was free-fall from the outset :boggled:...
Click to expand...
...which is geometric nonsense, is it not?

scratch.gif
 
C7 you are free to consider any of my proposals above in your quest

You and AE911T are free to produce your own technical study, perhaps an FEA on the beam/girder/floor system in response to fire

if the fire was burned down and both beams and girder had sagged then you can do what the CTBUH suggested and determine if the girder could pull away to the west and/or north
If the beams and girder first expanded then sagged you could determine if it was pushed and pulled and how much, to the west and north

If you actually do an FEA you could determine where the CD (explosive or incindiary) would have to have been, the size of the charges and the timing

I have no problem with the proposal that large unfought fire caused the initial collapse and the building design allowed this local failure to progress to global collapse so I haveittle impetus to perform said studies
You otoh have that impetus!

BTW, it would be advisable, when writing up the paper for this study you refrain from your habit of calling the NIST report authors 'liars' if you wish to be thought of as something other than a fanatic.
 
Its obvious that the western 2/3 of the structure fell to the south,"" backwards if you wish
Diid it do so at the ouset of global failure? Given the structural damage to the south it would be expected to, imo.
Indeed the eastern 1/3 fell to the NE and the south face of that portion was intact after WTC 1 came down
 
Christopher7 said:
Good point. You have found another reason why the NIST theory fails.

Assuming that the load to strength of the girder is the same as the beams, a 45' girder would expand and sag ~85% as much as a 53' beam.

@ 600oC
A 53' beam will expand 4.68" and lose 0.49" to sagging for a net expansion of 4.19"
A 45" girder will expand 3.98" and lose 0.41" to sagging for a net expansion of 3.57".

Since there is less than 2" clearance between the girder and the columns, the girder is pressing up against both columns.

@ 700oC
53' expand 5.63" shorten 4.42" net expansion 1.12"
45' expand 4.79" shorten 3.77" net expansion 1.86"

@800oC
53' expand 6.62" shorten 10.11" net shorten 3.49"
45' expand 5.63" shorten 8.59" net shorten 2.96"

The beams have pulled the girder to the east ~3 1/2"
About ~1/4" of the girder web is still over the support plate. It must be more than the thickness of the seat away from the support plate to bend the seat plate down and get past it.

@ 900oC
53' expansion 7.54" shorten 16.64" net shorten 9.1"
45' expansion 6.42" shorten 14.14" net shorten 7.72"

~850oC the girder will fail due to shortening and/or walk-off to the east but that is not the NIST theory. Thermal expansion cannot push the girder more than ~5" before sagging starts pulling it back the other way, which is why NIST lied about the width of the seat and omitted the stiffeners. How can we be sure they are lying about the width of the seat? They also lied about the stiffeners. There is no way that could be an innocent mistake.

Offering alternate theories does not change the FACT that the NIST theory doesn't work so they did not explain the collapse.

If you think you have a theory that will work then write NIST and let them know.



ETA References:
Beam expansion
http://img823.imageshack.us/img823/4...spreadshee.jpg

Beam sagging and shortening [100 psf load - full dead load & 1/2 live load] [FONT=&quot]
[/FONT] http://img210.imageshack.us/img210/1644/shorteningvtempusingais.jpg

Reference data
http://www.aisc.org/WorkArea/showcontent.aspx?id=7046

Second reference [has larger sag numbers]
http://www.civil.canterbury.ac.nz/sif/paper19.pdf
Click to expand...

Why don't you try to post this as a competent person would present it.

Provide a sketch of your problem.
Explain your analysis method. (e.g., explicit equation or FEA)
List your assumptions.
List your equations, NOT just the results.
List the qualifications (not the identity) of the person who did the analysis.

This is an absolute minimum for any analysis to be considered by anyone.

Meanwhile, without that info, I only suspect that there are about a half dozen mistakes in this.

I know that YOUR assumption that the deflection is linear with beam length is wrong. But I wouldn't want to blame your analyst for your failings.
 
Gee, Chris7.

You post a bunch of data.

All of it clearly beyond your technical background to generate or comprehend in any detail.

I ask you to get your source to expand on the methods & assumptions that he used to generate this.

And you go silent...

One might jump to the conclusion that you don't want that information disclosed.
 
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