WTC7 Revisited

[GregoryUrich]

The worst problem is that we cannot see the lowest floors of the north or south side.

(BTW Sabrina, its the south side that faced the towers and had many broken windows.)

The east penthouse falls due to failure of one or more columns directly under it. The debris from this crushes through the building and impacts the heavy trusses at the 5 and 7th floors. This reduces the strength of the core system, those heavy trusses are there for a reason. The northern core columns support the heavy beams over the pre-existing Con-ed building and cantilever the north facade.

Fail those core columns and the entire north half of the building will be falling on top of the Con-ed building which would be akin to a person stepping on an egg carton. The south half of the building had already suufered some significant damage to the perimeter system and had little to arrest a fall if the core was damaged at the 5th to 7th level. That would mean that the entire structure would essentially fall 7 floors with very little to arrest that fall. After falling that distance the impact with the ground would essentially shatter the structure.

I believe that there was one witness that described the lower north wall as pushing out just as global collapse started. That would be consistent with those beams over the Con-ed building losing their core support.

Was this a design flaw? Perhaps, in that the initiating event would seem to have been the result of the office fires going un-fought and causing a local column failure. However would the designers ever have considered a fire that would go on unfought for so long? Would the designers have ever considered what the effect of large parts of WTC 1 falling on it? Probably not.

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

 

[GregoryUrich]

One thing you also notice in that video is the lack of significant air movement. Could the building have been so badly fractured inside as to let the majority of the air stay put?

I'm not sure I understand what you mean. Could you expand?

 

[beachnut]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

What? You have zero idea how strong the building is at 5 pm after burning all day. The building was on fire all day and that fire was not fought. You will have zero ability to apply any steel strength at the time WTC7 fails to stand due to fire and damage. There is no survival for buildings that burn and are not fought like WTC7. Please present a building, and office building that burned all day and did not have structural failure. Have you even researched WTC7; I have to say no, since your posts reflect no insight into anything about WTC7.

Your Quixotic attack lacks a knowledge of structures, and you seem to lack any experience on anything about 9/11 until you are guided by people here at JREF. Each time you come up with a new thesis, the work is done by JREF by critiquing you to correctness. Just look back to each of your projects and attempt to support 9/11 truth's lies and false information.

The more you post the more it becomes clear you lack knowledge on 9/11 issues until people, even lay people, guide your research and correct your errors. Between your brief successes at understanding, you display total lack of knowledge (you even mention PNAC, a true flag for someone who lacks fundamental knowledge on 9/11) on each new endeavor to save the 9/11 truth movement form total implosion which actually occurred 6 years ago, pre-debunked on 9/11. Does anyone in 9/11 truth study 9/11 before making all the false statements and made up theories that lack evidence?

Please study WTC7 before you post more junk and have to learn on the post, so your veiled scientific approach resembles an attempt by the engineer you claim to be. If you do not study first, you will do more damage to the prestige of being called an Electrical Engineer; you need to be more supportive of our shared degree and at least appear more knowledgeable on WTC7 even though your conclusion is wrong before you started (yes, everyone knows you have signed the petition of 9/11 truth before having real evidence, the best you can do is mention PNAC, to support the hearsay conclusion of 9/11 truth; so, yes your conclusion is known even if you want to hide behind your shallow research, as if you are really trying to find the truth, which 9/11 TM has never even got close to doing).

I can't wait to see if you think it was silent RDX, or thermite. Please study first so you look better than the no plane guys, and beam weapon dustification experts.

 

[Tweeter]

I`m thinking beachnut must of stayed at a Holiday Inn Express last night.

 

[DGM]

I'm not sure I understand what you mean. Could you expand?

I'll try:
Back in the original thread R.Mackey commented on the pressure and velocity of the air as being determining factors in the energy absorbed (if that's the right word). During those videos you don't see large releases of air through windows or large events that appear to be areas of overpressure. I guess my comment is more along the lines of the building being broken up enough as to not allow much pressure build up.

I too want to take some time to re-look at your calculations after I have a chance to let R.Mackey's post sink in.

 

[CurtC]

I'm not sure I understand what you mean. Could you expand?

I think DGM was considering the idea that maybe when the penthouse fell into the building, it didn't have to push air out of the building, and instead just moved around the air that was already contained in the building.

Instead of a piston in a cylinder analogy, think of dropping a brick into a bucket.

 

[jaydeehess]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

Inprecise choice of wording on my part.

there would be no momentum transfer if it does not hit anything on the way down.

The east penthouse fell in due to some damage occuring well donw in the building. The load could not be supported by the columns that failed. The equipment that then fell was doing so into a space that had relatively little to stop its desent since anything in that path had already collapsed or at least started moving before the penthouse debris did.

Assuming though that the core structure west of that location and the system of load transfer members at 7th floor and below were still intact it is the transfer trusses at 7th/5th floor below the 'shaft' through which that debris was falling that would be crushed. That is essentially free fall fo rthat debris.

Assume a 1000 kg of rooftop equipment is falling for 5 seconds at gravitational acelleration.
It will be going 50 m/s (rounded up)
Its kinetic energy would be over 1.2 million J

That's for basically one ton of debris.

Compromise the core and transfer system at the 7th/5th floor and the entire building will fall 5 to 7 floors with very little to stop resist it. the air in the bottom 7 floors has ample exit channels through the south side which has almost all of the windows on that side torn away as well as gashes that go deeper into the structure that just the facade/perimeter structure.

 

[Newtons Bit]

Hey Greg,

Can you point me towards the method you used to calculate the energy required to move the air? Thanks.

 

[Newtons Bit]

If the east penthouse "crushes" through the building, how long will it take to get to the 7th floor? I think a momentum/energy calc will show that it can't reach the 7th floor in 6-7 seconds.

I think you're confusing failure mechanisms. The penthouse dropped because the framing below it failed. The framing below it failed because a column near the bottom of the tower dropped.

It shouldn't be confused with a WTC1/2 mechanisms with a large upper block. The penthouse in WTC7 dropping first is indicative of large structure failures lower down in the tower rather than at that floor. This failure is something that the tower could resist at least momentarily while the penthouse itself. could not.

 

[GregoryUrich]

The east penthouse collapse must have caused internal damage.

See here: http://www.youtube.com/watch?v=Y5_e5yROoqY

Beneath the penthouse we see a shockwave travel to ground level, the building bulges and flexes, then global collapse ensues.

Inprecise choice of wording on my part.

there would be no momentum transfer if it does not hit anything on the way down.

The east penthouse fell in due to some damage occuring well donw in the building. The load could not be supported by the columns that failed. The equipment that then fell was doing so into a space that had relatively little to stop its desent since anything in that path had already collapsed or at least started moving before the penthouse debris did.

Assuming though that the core structure west of that location and the system of load transfer members at 7th floor and below were still intact it is the transfer trusses at 7th/5th floor below the 'shaft' through which that debris was falling that would be crushed. That is essentially free fall fo rthat debris.

Assume a 1000 kg of rooftop equipment is falling for 5 seconds at gravitational acelleration.
It will be going 50 m/s (rounded up)
Its kinetic energy would be over 1.2 million J

That's for basically one ton of debris.

Compromise the core and transfer system at the 7th/5th floor and the entire building will fall 5 to 7 floors with very little to stop resist it. the air in the bottom 7 floors has ample exit channels through the south side which has almost all of the windows on that side torn away as well as gashes that go deeper into the structure that just the facade/perimeter structure.

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

 

[GregoryUrich]

Hey Greg,

Can you point me towards the method you used to calculate the energy required to move the air? Thanks.

Hi NB,

Basic inertia. I give a simple explanation in the OT and the spread-sheet has the details. I think you'll understand it if you look at the spread-sheet. By the way, I have over-estimated somewhat because I used a square building instead of trapezoidal.

 

[SDC]

We are looking at videos and photos which are evidence. You seem convinced that the inside collapsed based on that we can "see" the east penthouse collapsing. We can't see what's happening in the building. At least I'm talking about stuff I can see.

So I'm late.

I'm pointing out that when you talk about what you think you see you have no special credibility. An engineer, which is what I gather you are, should understand that what seems to appear on the surface of an event is not what is actually going on.

The eye is a liar.

 

[SDC]

SDC, I didn't provide an opinion. I pointed out the sticking points many people would naturally have with the fall of WTC 7.

I provided a photo library and asked if anyone has the originals of the following 2 images. That's all.

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

One of these 2 images is a fake. Someone has tried to lie to us. This is a fact and not an opinion.
Given the original images we can learn which one is a fake.


Why is this information useless?

From what I have read of your comments in recent months, you appear to have no special expertise; just a determination to prove that the buildings were destroyed by some sort of controlled demolition. I think that is bilge. As to the quality of these 2 photos I have no opinion.

ETA: see Norseman's post, #73. I do not accept your "fact." Perhaps you could start explaining the problem with the pictures rather than making assertions.

ETA again: I may have tangled up the quote feature. I apologize for this.

 

[jaydeehess]

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

No, I do not think you see that there was a column failure and thus a hole in the building that precipitated the east penthouse collapse.

The east penthouse was a large structure taking up approx 1/4 of the roof of the building. Seems to me someone else in another thread had shown that an upward progresssing flexing is seen in the structure that lines up with the original 'kink' in the building and the spot at which the penthouse folds into.
Before the roof of the east penthouse begins falling in there is already debris that was in the east penthouse falling through the hole created by the column failure.

The proposal in appdx "L" of the NIST report is that one or two columns failed below the 13th floor and that the load on that(those) columns could not be redistributed causing an upwards progressing failure along those columns. This may have been due to a particularily massive load in the penthouse directly over on or two columns and which had not been sufficiently spread to other columns.
So you have a hole in the building only at that area along those columns all the way to the east penthouse. Anything directly over that spot would now be falling through that hole. Then the roof cannot hold the load in the penthouse and it starts to fold into the now ever widening hole collapsing the floor span under that widening hole and progressing downwards through the building. Floor pans fail in a downward progressing 'shockwave' from the falling debris but anything that fell into the first hole caused by the original column failure has already been falling and is not hitting anything until it gets to the level of the original column failure.

So far the local failure has been halted, probably by the floor pan beams, from too much of a horizontal progression. If this was as far as it got there would have been a large hole in the building but it would have stayed upright.
However, the debris that started falling as soon as the column failure opened up the rooftop has been acellerating with pretty much nothing opposing it. It then hits the transfer truss system and fails that, which pulls or otherwise compromises the core column system at the 7th floor which holds the beams that are over the Con -ed building and tied into the Con-ed's column system. But the Con-ed building could not be expected to hold up the mass of 40 storeys above it, it needed the core columns to do that by holding one end of those transfer beams. Those beams also hold the north perimeter columns above the 7th floor in short cantilever. So now you have a 40 storey building coming down on the original 7 storey building.

This is, as I stated above I believe, akin to a human stepping on an egg carton. Yes there would be some resistance, I am sure an egg carton offers some resistance to a 200 lb man stepping on it too, but would it be significant?

At this point the entire structure over the Con-ed building will fall 7 storeys. It is attached to the south part of the building only by the floor pans and the south perimeter is compromised from the impact of WTC 1 debris. The southern part of the building is thus not going to offer much in the way of resistance. The eastern portion of the building is also attached via the floor pans except in the area where the hole had opened up. If there was sufficient column strength the eastern portion might have ripped loose from the rest of the building and remained upright. There was not. Instead we see the structure kink and the eastern portion buckle as the western portion falls. Indeed much of the eastern portion fell north and east rather than into the 'footprint' of WTC 7.

 

[Mancman]

Check out Mancman's observation that an impulse is visible in the facade traveling downward. I interpret this as the falling east penthouse hitting the 47th floor. I think that if the was failure lower down to the extent you are describing we would see some flexing of the facade traveling upwards.

Other footage indicates the penthouse fell much further than one floor, in this you see nearby smoke is dragged down towards the hole:


To me, this indicates the hole was of substantial depth.

 

[Sizzler]

bump...

 

[Major_Tom]

Thanks for the info, Norseman, quoted below'

Both images are genuine. I debated this in great detail with Christopher7 last year here (post #3673) and on the following pages including post #3751 in that thread.

You will find the photo on the left hand side in NIST interim report on WTC 7. And the photo on right hand side you will find here, it is the last one before the night shots at the bottom of the page:
http://www.amanzafar.com/WTC/index.shtm

For some real good examples on light refraction effects look at the photos on page 66 and 63 (PDF page 78 and 76) in the report on One Meridian Plaza fire.

The 2 photos in question are reproduced below

The close-up and cropped comparison is once again shown below

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.

 

[Major_Tom]

Double posted..,.deleted

 

[WildCat]

The Zafar and NIST-NYPD photos cannot possibly both be real.

I don't see why not.

 

[pomeroo]

Thanks for the info, Norseman, quoted below'



The 2 photos in question are reproduced below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/copyofsw11th7.jpg

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7_damage.jpg

The close-up and cropped comparison is once again shown below

http://www.sharpprintinginc.com/911_old/Photo_archives/wtc_7/wtc7cornercomp2ahireswx4.jpg

The Zafar and NIST-NYPD photos cannot possibly both be real.

As Norseman pointed out, this was discussed in great detail by Christopher7 around here

The counter-arguments given be Norseman and Dave Rogers, among others, were basically that the difference in the 2 photos is merely an optical illusion created by light refraction produced by the extreme heat. In other words, you can't beleive your eyes.

This is absurd (not the people but the counter-arguments).

Since this was discussed elsewhere, I wouldn't want this thread to be dominated by this discussion. I just want to point out to Gregory that NIST and is implanting a falsified photo (with a New York Police Dept stamp) into their report to exaggerate the damage to WTC 7.

This is serious in itself and something you should keep in mind.

As with Christopher7, Dave Rogers may insist that this is indeed the effects of light refraction and tell us to simply read a physics textbook on optics. I have a couple of degrees in physics myself, and you don't need to do that in order to understand that there is NO WAY IN HELL that the difference is attributable to refraction of light within the heated atmosphere around the building.

If you have "a couple of degrees in physics," why can't you-- Never mind. Forget it. It's been said many times. Just--never mind.