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B7 collapse/curtain wall discussion (split from Girder walk-off)

Analysis of fire and collapse theories and examination of related evidence.

B7 collapse/curtain wall discussion (split from Girder walk-off)

Postby SanderO » Thu May 03, 2012 5:10 pm

The beam walk off makes little sense and several people have demonstrated this. And whether this would even cause column 79 to fail (buckle) and that to lead to other columns buckling and so on is another leap of faith. The NIST column 79 tale has been pretty well shown to be just that... a fantasy.

And then there's the AE911T fantasy of 81 columns being exploded on 8 floors all at once so the building can drop like a feather... in free fall. Yet another fantasy.
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Re: Girder walk-off between column 79 and 44

Postby Pavlovian Dogcatcher » Fri May 04, 2012 4:25 am

SanderO wrote:And then there's the AE911T fantasy of 81 columns being exploded on 8 floors all at once so the building can drop like a feather... in free fall.

That's not consistent with what I've seen of AE9/11T's position on the matter. Where exactly can one find them making the specific assertion you ascribe to them here?
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Re: Girder walk-off between column 79 and 44

Postby SanderO » Fri May 04, 2012 10:47 am

I believe I've heard Gage says this in some of his talks and it may not be on their web site or in their materials. He and other AE991T supporters of CD basically say (said) something to effect... the only way to account for a 2.25sec 100' free fall descent is if there was no resistance for 8 floors and that resistance would be the columns which had to made structurally invisible in an instant... freeing the upper part of the building to drop at FF.

Such a statement may be heard in interviews or recorded presentations or even the debate with Chris Mohr. Since so much of their statements are flawed I can't be bothered to take them seriously and they do not respond to specific questions.

Ron Brookman PE of AE911T led a technical analysis of the NIST report of B7 and others such as Tony Szamboti have shown NIST thinking to be flawed. Check.. got it.. The the tin foil hats go on and they come up with the above *theory* which is supported by:

sounds of explosions
nano thermite
logic explaining only something which has nothing by air below it can fall at free fall - ergo the something below it was blown up
fore knowledge of the collapse equates to a tip off that they exploded it
Larry Silverstein's remark - "pull it"
Jane Stanley's BBC report as the tower was dropping
symmetry of the collapse
how skillfully it was made to drop without damaging Verizon adjacent
pyroclastic flow
no slabs in the debris

etc... taken together spell CD
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Re: Girder walk-off between column 79 and 44

Postby Pavlovian Dogcatcher » Fri May 04, 2012 6:47 pm

Sander, your "81 columns being exploded on 8 floors all at once" is a flagrant misrepresentation of what I've heard Gage and others from AE9/11T say on the matter of WTC 7''s free fall. So, absent you quoting AE9/11T making the that specific claim which you've attributed to them, it only stands to reason that you're actually the one engaging in fantasy here.
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Re: Girder walk-off between column 79 and 44

Postby SanderO » Fri May 04, 2012 11:25 pm

Pav...

No... I am not going to spend the time to find a published quote. Perhaps you ask him to explain how the building dropped 8 floors at free fall acceleration. I don't do quote sniping and tit for tat arguments on the internet. I am reasonably certain he made the statement because at the time he said it... it occurred to me that the columns didn't even have to be destroyed at the same time... but over 2.25 seconds...
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Re: Girder walk-off between column 79 and 44

Postby Pavlovian Dogcatcher » Sat May 05, 2012 6:07 pm

SanderO wrote: Perhaps you ask him to explain how the building dropped 8 floors at free fall acceleration.

There's no need for that when just a few moments with Google will pull up examples of him explaining the matter, for instance:

...the columns had to have been be removed, and removed virtually simultaneously on each floor, synchronistically timed so the building had no resistance, virtually, on the way down.

Again, if you take statements like that to imply "81 columns being exploded on 8 floors all at once", you're the one engaging in fantasy here.
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Re: Girder walk-off between column 79 and 44

Postby OneWhiteEye » Sat May 05, 2012 6:52 pm

Is there a practical difference between synchronized removal ahead of descending mass, or removing them all at once? Not really; same result, slightly different timing.
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Re: Girder walk-off between column 79 and 44

Postby Pavlovian Dogcatcher » Sat May 05, 2012 8:15 pm

OneWhiteEye wrote:Is there a practical difference between synchronized removal ahead of descending mass, or removing them all at once? Not really; same result, slightly different timing.

The important difference is between NIST and AE9/11T's explanations for why WTC 7 came down, NIST's being fanciful while AE9/11T's is quite the opposite.
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Re: Girder walk-off between column 79 and 44

Postby OneWhiteEye » Sat May 05, 2012 9:10 pm

Okay. I guess I misunderstood. Both of the scenarios I was contrasting in the previous post were CD scenarios. One in which all supports at a given level are removed ahead of load impacting from above sequentially for 8 stories, and the other in which all 8 levels are removed simultaneously. There is a wee bit of difference in the dynamics (depending on initial conditions) but not so much as you'd notice and none if the removal were the intiator. I think SanderO just lumped the two in together, but the issue is - how does this differ from the official stance of both Gage and AE911T?

I think Tony would argue that the supports must be removed (artificially) in a very short period of time to produce the observed dynamics. I don't want to put words in his mouth but, if that his is position, I'd consider him to be a spokesperson for that faction.

I thought you were trying to say that there isn't an argument for near-simultaneous removal of support to produce the near/at/over g interval, being made from AE911T. My understanding of their collective position is just the opposite. If I'm wrong, now would be the time to set me straight.
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Re: Girder walk-off between column 79 and 44

Postby SanderO » Sat May 05, 2012 11:00 pm

pav... A bit of splitting hairs... If the 81 columns over 8 floors... 324 to be exact were not taken at the same instant... removing all resistance... then as you say the were taken out in a free fall sequence.. which I am assuming you to say that there were sets of timed explosions of each 2 floors columns (they were 2 stories tall). Let's take a look

time distance
0 0
0.5 5
1 16
1.5 36
2 64
2.5 100

To allow for FF over the distance of the first column (26').. after a little more than 1.25 seconds the second set of columns would have to be blasted... Not there are 52 feet clear and it's 2 sets of explosions about 1.25 seconds apart. But after 1.6 seconds another set of blasts would have to go off because the 3 set of columns from 52-78 feet are in the way.. So blast 3 blows the 3 set at about 1.6 seconds into the fall and we've destroyed 78 feet of column. The collapse is now moving pretty fast and just after second 2 the collapse has traveled the 78 feet and the columns from 78-104 feet must be cleared out of the way... so another blast of the 4 set goes off at just past the 2 second mark clearing out the 108 feet of column ht....

That's some set of precision time of 4 sets of 81 explosions in under 2 seconds. Wouldn't it be heard? Why not just blow them at once? Why the sequence?
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Re: Girder walk-off between column 79 and 44

Postby T_Szamboti » Sun May 06, 2012 3:53 am

SanderO wrote:pav... A bit of splitting hairs... If the 81 columns over 8 floors... 324 to be exact were not taken at the same instant... removing all resistance... then as you say the were taken out in a free fall sequence.. which I am assuming you to say that there were sets of timed explosions of each 2 floors columns (they were 2 stories tall). Let's take a look

time distance
0 0
0.5 5
1 16
1.5 36
2 64
2.5 100

To allow for FF over the distance of the first column (26').. after a little more than 1.25 seconds the second set of columns would have to be blasted... Not there are 52 feet clear and it's 2 sets of explosions about 1.25 seconds apart. But after 1.6 seconds another set of blasts would have to go off because the 3 set of columns from 52-78 feet are in the way.. So blast 3 blows the 3 set at about 1.6 seconds into the fall and we've destroyed 78 feet of column. The collapse is now moving pretty fast and just after second 2 the collapse has traveled the 78 feet and the columns from 78-104 feet must be cleared out of the way... so another blast of the 4 set goes off at just past the 2 second mark clearing out the 108 feet of column ht....

That's some set of precision time of 4 sets of 81 explosions in under 2 seconds. Wouldn't it be heard? Why not just blow them at once? Why the sequence?


Just for the sake of accuracy, there were 82 columns in WTC 7. 58 on the exterior and 24 in the core. They apparently added a column 14A to the exterior after everything was done for 57 exterior columns, and the diagrams still show the highest exterior column number as 57. Column 14A was inserted in the diagrams, but it is easy to just see the number 57.
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Re: Girder walk-off between column 79 and 44

Postby Pavlovian Dogcatcher » Sun May 06, 2012 7:21 am

OneWhiteEye wrote:I think SanderO just lumped the two in together

Clearly not, as he explains his contest to the stance he ascribed to AE9/11 here:

SanderO wrote:it occurred to me that the columns didn't even have to be destroyed at the same time... but over 2.25 seconds...

But again, what I've actually seen from AE9/11T on the matter does suggest destruction taking place over a such a span of time, while I've yet to see anything from them to support "81 columns being exploded on 8 floors all at once" stance Sander ascribed to them. As for practical differences between the two senerios, the latter wouldn't have resulted in the penthouses coming down first, nor the explosions picked up by Ashley Banfield's mic starting in the moments prior to that, nor would it explain how Barry Jennings got trapped in the building before the towers came down and various other tidbits of evidence that have slipped though the coverup.

SanderO wrote:then as you say the were taken out in a free fall sequence..

I didn't say that. It's certainly a possibility, but not something I've seen evidenced as fact.
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Re: Girder walk-off between column 79 and 44

Postby uglypig » Sun May 06, 2012 9:49 am

The fire in that corner lasted only about 30 minutes and died down 90 minutes before the collapse. The 13th floor was on fire a little bit longer, so I expect the maximum temperature reached by the members to be 350°C and the actual temperature before the collapse around 100°C.

The NIST scenario is bogus and as I have shown in the vertical shockwave thread the building suffered a very large partial collapse at least two minutes before the collapse initiation and was possibly experiencing partial collapses during the final ~ 30 mins. IMHO by the time of global collapse the building was standing on straws -> freefall etc.

Jennings can be explained via loose wallboard that came of or by transformer explosion? And yes, I am aware of the northern location of that stairwell.
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Re: Girder walk-off between column 79 and 44

Postby SanderO » Sun May 06, 2012 1:18 pm

Tony,

Thanks for the info about 14a.

I still suspect that the collapse sequence began on the mech floors 6&7 from failed transfer trusses and cantilver girders which led to the core to collapse inside the tower pulling enabling the floors to drop inside.

I also suspect that when 6&7 structure collapse it separated the curtain wall at floor 8 as the entire structure from 8 down likely collapsed just prior to what we see as the FF descent of the facade... which had nothing below it from floor 8 down... hence the 100 feet of free fall descent of the curtain wall.. with or without the perimeter columns and the spandrels attached.

The inward bowing of the north curtain wall seems to indicate that at least the floor plates behind it were missing and the columns and spandrels were not rigid enough to maintain a vertical plane if they were not gone themselves as the curtain wall dropped. Since the north wall center was above the cantilever girder supported perimeter columns it seems like the failure of the girders might be a clue to the inward bowing.
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Re: Girder walk-off between column 79 and 44

Postby SanderO » Sun May 06, 2012 1:25 pm

QUOTE
Within the building, the diesel tanks were surrounded by fireproofed enclosures.

NIST
Fireproof enclosures are typically rated for 1, 2 or in some cases 4 hrs. The building was experiencing fires from as early as 8:46 when the 13kv line shorted.
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