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NIST's WTC7 collapse models: some observations

A few days ago I posted a graphic from NIST's latest WTC7 report that depicts the exterior buckling after global collapse initiation. In no way does it resemble how the structure actually looks when it imploded. I had not noticed that this was the model for the scenario without debris impact damage. You see, NIST actually has models for the scenario without debris impact damage and for the scenario with their best estimated impact damage (the damage to the south side). They conclude that the building would also have collapsed without any impact damage.

So I checked the report for their modeling of the exterior buckling with the best estimated impact damage; the model of what actually happened. It's there but there is something missing: the top 23 floors are not shown and the north side is not shown; the side that can actually be seen in the videos and photographs of the collapse.

Without damage
Image and video hosting by TinyPic

With damage
Image and video hosting by TinyPic

It would be hard to imagine that the scenario with the asymmetrical damage to the south side would leave the top 23 floors (which are not shown) looking any better than the scenario without damage.Videos show that WTC7's walls remained straight during most of its collapse. Their model is simply not showing what actually happened, and it looks like they are trying to hide it by not showing the top 23 floors and the north side.

There are no models of the core collapse of the top of the building in the scenario with the best estimated damage. They give 12 models of the complete core collapse in the scenario without damage. Apart from a single graphic of the penthouse sinking in the roof, there are no models of the top of the building during the collapse in the scenario with impact damage.

Let's put their model of the core collapse in the no impact damage scenario next to a video of WTC7 imploding.

Clearly this scenario is way too slow. So we look to their model of the scenario with the best estimated impact damage but floors 18 and above are not shown and the last image is of all the core columns buckling at 6,5 seconds. What happens next is a mystery, they do not show a model of the actual visible collapse. Makes you wonder why they would stop at 6,5 seconds, while showing us 15 seconds of the no damage scenario.

NIST's models of the collapse are obviously no good. You only have to look at their model of the exterior buckling to see that.They are also trying to hide it by not showing any modeling of the upper floors collapsing (the floors that can be seen in the video's.) The actual exterior collapse is not shown at all.

Image and video hosting by TinyPic

Everything discussed can be found in chapter 12 of the new NIST report

Thank you arie.

Interesting...

But the non-damage collapse

is still quite deformed. Certainly, the damage scenario would not make the upper floors less deformed. So the NIST graphics still conflict with what has been documented in video.

arie

...............need we say more?

Floors Support Columns?

Since when do floors support columns? As a matter of fact the loss of nine floors around column 79 would have straightened that column because it wouldn't have to support those nine floors anymore. The NIST report on WTC 7 is dead from the start.

Columns can't be too slender

Columns buckle easier the more slender they are. There is a quantifiable characteristic of a column called the slenderness ratio which is essentially a function of its end conditions, laterally unsupported length, moment of inertia, and cross sectional area.

The floors aren't actually supporting the column in terms of it's vertical load, they are just providing lateral support and reducing the unsupported length in a sidesway fashion, making it behave like a short column by keeping it from bowing out.

Not So Slender Column

Column 79 was 7.5 tons at each floor. It was massive, and not slender at all, but your point on lateral support is understood. In 1989 three whole sequential floors were removed from WTC 7 to accommodate Salomom Brothers moving in as a tenant, and the building still had reserve capacity.

Since column 79 was firmly in place spanning floors 15 to 47 and 5 to ground level, I don't see how it could have buckled due to the loss of the lateral support of nine floors. The floors above the collapse area should have held column 79 well in place.

You would have to do the math

The slenderness ratio is a relative term and so is the load on the column, so it isn't meant literally.

I also think the beams and girders on the floors above should have kept column 79 in place but you would have to do the math on that and what the slenderness ratio would be for a 112 ft. section of column 79 without lateral support and also know what the loading on it was before you can come to a conclusion on whether it would buckle or not. Nine floors being missing is nine times worse than three as the effect of length is squared on the buckling load. The critical buckling load is given by the equation.

F= (pi**2) x (E) x (I) / (K) x (L**2)

In my opinion the easier to point out problems with NIST's theory on WTC 7 are:

- they probably don't have evidence for the heating they claim on the beams and girders.

- their finite element model does not match observation in that videos don't show deformation or bowing of the exterior wall on the upper floors of the building.

- they don't address the molten metal found in the rubble and they never tested for exotic accelerant residue.

- they have no physical evidence for their theory. None of the steel from WTC 7 was saved for test, evaluation, and a systematic forensic analysis.

- they haven't done any physical testing to prove their theory could occur.

- the non-operational sprinkler system story has holes in it.

- they probably did not include friction in the finite element model which would have a large effect on whether any local collapse propagated. There would be a large chance that frictional forces in the jumbling of columns and beams would severely limit the ability to generate the large dynamic loads needed for collapse propagation.

Wouldn't amaze me!

Invent thermal expansion (differential even!)
Drop friction!

Only a guess of course.

Where is The Heat Sink Analysis?

I agree. Also the NIST reports have no analysis of the heat sink capabilities of WTC 7 that I could find (have you searched?). I therefore suspect (like you) the high temperatures for the floor sections. If the floor temperatures were not weakened due to fire, then the 14th floor in the vicinity of column 81 would have been strong enough to carry any debris from the collapse of floors around column 79, thereby preventing the collapsing of floors around column 81, thereby halting the progressive collapse of WTC 7 that began at column 79. This would be the second time NIST has failed to carry out the heat sink capabilities of a steel building collapse due to fire. The first was the WTC towers investigation.

OT

What happened to the link to the Greening letter to NIST which was here earlier in the day? I was unable to print it in full and would like another try at it.

It's in the blogs section.

Take a look through the comments section for some viewpoints as to why.

thanks

Now, how does one do structural analysis of a tangled web?

I don't know why it got

I don't know why it got taken off the front page, but here is the link:

http://the911forum.freeforums.org/withering-critique-of-the-new-wtc7-rep...

Argued hypothesis for collapse of WTC 7

As a possible overall frame for further analysis of WTC 7's collapse, I would like to lay out my hypothesis (!) for the event, supported by observations and arguments and a line of speculation:

First the observations (initial premises):

1) Fires were seen on different floors - separated from each other by several other floors - where no fire is visible. (See fx. here: http://www.truthalliance.net/Portals/0/Archive/Gallery/26/wtc7-fires-clo...)

2) There is no visible deformation of the outer facade of (at least) the north side of the building, when it collapsed.

3) It is hard to see with a fair degree of certainty that any - for demolition with explosives caracteristic- squibs are jutting from the building immideately before and during collapse.

4) The evidence of damage to the south facade strongly suggests that it was limited to a (rather) linear and clearcut slice of the facade and immideately adjacent area.

5) The northern facade of the building was not buckled or showed any pulling from the inside before or during collapse.

Arguments and hypothesis.
A)
There are logically 3 possible ways of explaining the positions of the fire: 1) The fires on diffferent floores, separated by several other floores, originated at one floor and jumped several floors to other floors. 1a) The place (or gateway) of spreading from one floor to others is out of sight (i.e. to the south), and the intermediate floors have blocked the fires from entering (that is: the fire spread through stairwells or the like) 2) The fires originated separately on different floors.

1) seems out of the question, since the fire could not have jumped through floors without igniting them. 1a) takes that the fire funneled through stairwells or elevators and busting in at some floor above it - but is there anything in these "gateways that can burn and spread the fire several floors up? 2) takes that (as the story goes) falling debris) would somehow have caused fires (in several, separate places even), but how likely is that?

I've not forund any pictures or descriptions of a building on fire with the fire localised to widely separated places/floors) in the building.

It seems that a good hypothesis here is, that fires were ingnited by design (or possibly by unintended results of a deliberately placed fireignighting element in the building).

B)
If the interior of WTC 7 collapsed in a progressive collapse so severe, that it took down the building from the bottom up in free fall speed (at least concerning the outer, visible facade), why is there no sign of any pulling or buckling on the facade?. If the floorcollapse between the vertical beams was so severe, that it pulled them horisontally, why did the collapsewawe not pull at the outer wall at all? - and if it (i.e. the progressive floorcollapse) did NOT pull horisontally, why did the building (i.e. the entire vertical structure of heavy steelbeams) buckle and collapse so suddently, and why did no outer facadestructure show any sign of buckling at all if the vertical structure connected to it buckeld instantaniously?.

Hypothesis: 1) The fires in the building originated from non-explosive cuttercharges (fx. thermite), which would both account for the fires, the dramatic failure of the vertical colums and the missing signs og pulling and buckling of the outer facade. Furthermore, they are consistent with the apparent lack of squibs and (multiple unmistakable) explosions 2) That the damage to the south side was (apparently) so clearcut could (perhaps) indicate, that it was a result of a designed collapse - and if it was not, the clearcut nature could have resultet from a particular set of floors collapsing due to debrisdamage, taking the outer wall immediately adjacent to them with itt - but why did the same thing not happen to the facade of the north side, when the entire floorsystem inside collapsed, then? If it was the first possibility, then the building was supposed to have gone down earlier (perhaps in the shadow of the collapse of wtc 1 or 2), and the entire demolitionsequence was perhaps halted by error.

Aside: IF the hypothesis that WTC 1, 2 and 7 was a CD is right, then it is obvious that the perpetrators would have tried to hide it as much as possible, wich means that explosives would have been kept at a minimum, replacing explosives with thermite where possible (perhaps entirely and with more or less explosive types of thermite). The apparent (relative) absence of explosive sounds (wich does not apply to WTC 1 and 2, which could probably not have been done without, at least some, heavier explosive cuttinngdevies than thermite, due to the massice and compact core in these towers) is therefore not a good argument from the "debunkers", since it is implied in the hypothesis that WTC 7 was a demolition, designed to atrract as little attention as possible.

Fires, thermite and demolition

Just a short (repetition of a) point:

If NIST says, that fire, which works slowly - much slower than thermite - could demolish the building in such a perfect way, why should thermite not be able to do the job (and even better, since its weakening - indeed cutting - of beams is much faster and, on top of that, controllable)?!
NIST, therefore, seem to have finally refuted (x) one argument from the debunkers, namely the argument that you can not use thermite in controllable demolition of (steel)buildings!!
( (x) Refuted in the sense that the "debunkers" can't have it both ways: accepting NIST's explanation AND argue that thermite can't be used to demolish buildings in a straight down fashion, since thermite is, like fire, non-explosive heat)

Explosives is probably needed in buildings with loadbearing structures of concrete, since it can not be cut with thermite, but WTC 1, 2 and 7's loadbearing structures were made completely of steel.

Simple idea...

... they have no clue what kind of fires were going on inside. They could not say if there were any explosions, no matter what "eye witnesses" said. They were charged to "debunk conspiracy theories" more than to really investigate the event itself.

So, no matter what, if we are expecting a government agency to "investigate" something like this---with total transparency and objectivity---we are fooling ourselves.

Thermite/thermate, whichever version you choose, would be a far better choice to bring a building down in this scenario, than "typical explosions". First, once you've gotten rid of all the steel, you just make up a bunch of incredulous nonsense about out-of-control fires. They already knew the "Achilles heel" of WTC7 and that it was exploited, so somebody already did the analysis for them... they just pretend their examination was "exhaustive". You produce some ANIMATIONS of a structural collapse to quell the masses (most of whom have never seen WTC7 go down), while keeping your ability to sleep intact by simply not testing for "thermite" or whatever.

Thermite will cause MASSIVE thermal expansion. Thermite will cause sagging, melting and quick deformity of steel. Thermite does not need to make massive noise. Thermite makes fire, makes fires worse... etc, etc.

So technically, aside from not testing for thermite (since all the steel was missing), they can safely say "it came down from fire" and still sleep at night, I guess.

I agree that they probably knew the achilles heel

I have wondered myself if NIST was given the achilles heel and just had to make a plausible argument for how it could happen in a natural collapse, without some form of artificial inducement.

They did not fully succeed as the demolition still had characteristics they could not find a natural replacement for, such as the lack of exterior column bowing, especially in the upper floors when the penthouse comes down.

Achilles Heel

there's some merit to it.

In all cases we have security analysis done before to examine that achilles heels.

WTC 7

The New York Police Department produced a detailed analysis in 1998 opposing plans by the city to locate its emergency command center at the World Trade Center, but the Giuliani administration overrode those objections. The command center later collapsed from damage in the Sept. 11 terrorist attack.

“Seven World Trade Center is a poor choice for the site of a crucial command center for the top leadership of the City of New York,” a panel of police experts, which was aided by the Secret Service, concluded in a confidential Police Department memorandum.

The memorandum, which has not been previously disclosed, cited a number of “significant points of vulnerability.” Those included: the building’s public access, the center’s location on the 23rd floor, a 1,200-gallon diesel fuel supply for its generator, a large garage and delivery bays, the building’s history as a terrorist target, and its placement above and adjacent to a Consolidated Edison substation that provided much of the power for Lower Manhattan.

The memorandum sets out in detail the reasons why the Police Department concluded that the site was a poor choice for a command center, including its vulnerability to a biological attack and the ease with which a bomber could have damaged the building and crippled the center.

It has nine sections, the longest one headed “Explosives.” It describes a blast analysis conducted by the Police Department’s bomb squad, aided by the Secret Service, which looked at the likely impact of bombs of varying sizes, from one that could be carried in a car or a van to a large truck bomb.

The analysis, a standard practice used routinely to determine street closings when the president or another dignitary is in New York City, uses a computer system derived from the military and based on projections by the Bureau of Alcohol, Tobacco, Firearms and Explosives.

It concluded that the largest of such bombs would have led to the collapse of the building.

http://www.911blogger.com/node/13549#comment

***

And on WTC 1 and 2: The first attack in 1993 was conducted as in a highly secure security analysis allegedly known only to a few people.
That brought Securacom and SAIC Tridata in- and now all the vunarabilities were presented on the table.

Securacom, beginning with its previous incarnation, Stratesec, unlike many other security firms, did not separate security consulting from providing security services. As a single-source provider of end-to-end security services, it offered everything from a diagnosis of existing systems, to hiring subcontractors, and to installing video and electronic equipment. It also offered armored vehicles and security guards.

"After the bombing, we had the top security consultants in the nation, Kroll Associates, do a complete security analysis for us, and we followed their recommendations." Doug Karpiloff, WTC head of security

http://securitysolutions.com/mag/security_world_trade_center/

Explosives vs. fire

Yes, the NYPD's report was concerned that a bomb could cause the collapse of building 7; whereas NIST would have us believe this was accopmlished by office fires. Post-9/11, explosives were placed beyond the realm of consideration. Not so pre-9/11.

Great work!

It's no wonder they did not include the outside walls in any of the 'simulations' they presented. The buckling of the outside walls is ridiculously cartoonish and impossible.

With you in the struggle,
Bruno
WeAreChangeLA - http://www.wacla.org

WTC Demolition

East penthouse compared to known CD

It is sometimes argued from the "debunking"-side, that the east penthouse falls long time before the rest of the building, wich is (apparently) supposed not to happen in CD's and is supposed to be a good argument for a "slow" progressive "natural" collapse.

In this known CD http://www.youtube.com/watch?v=khD2gZkkSu0&feature=related, I count (conservatively) 5 seconds from a cornersection begin to fall untill the rest of the building follows (and here are off course explosions clearly audible, but this is also an event, where nothing have to be hidden).

I count roghly 7 seconds with the east penthouse in WTC 7 http://www.youtube.com/watch?v=1bjrAJVp4ds

Where can we find videos, photos of WTC7 from the south side ?

John A MITCHELL
Herblay FRANCE

bonjour ,

how is it there if very little footage or photos of the WTC7 falling down from the south side ?

We can expect even to have more people taking photographs from Liberty Street, Ceder Street etc side looking towards the hole left by the missing WTC1 and WTC2. WTC7 being behind the WTC6 we should have lots of photos of WTC7 showing the damage and fire in this tower.

It would be very helpful to have photos of the East Penthouse from the south side especially when it was sinking into the roof.

Is there any one liviing in the flats LIberty Street side who has taken photos towards WTC7 looking over the destroyed WTC1 and WTC2 ?

Almost all the footage is from the north side and we just see the East Penthouse sinking into the roof.

http://www.911blogger.com/node/17361#comment-195832

Here is a ground plan of the WTC

Image Hosted by ImageShack.us

update
Found interesting photos at the following link
http://www.debunking911.com/WTC7.htm
and
http://forum.reopen911.info/t267-wtc-7-demolition-indiscutable.html
and
http://www.studyof911.com/articles/winstonwtc701/

Yours

John

NIST the ostrich

NIST really don't want to investigate, do they?

Here's an excerpt from a letter I'm preparing for activists to send to building industry professionals and related experts:

'NIST's pseudoscience also led them to avoid investigating forensic evidence of Thermite, as reported by Professor Steven Jones in http://wtc7.net/articles/WhyIndeed09.pdf. This physical evidence exists; NIST reject it a priori. Jones, on the other hand, recommends further research:

“I (with colleagues) have done the experiment with thermite + sulphur (often called "thermate") acting on a piece of WTC steel. In fact, I did the experiment with the BBC filming it! Then we looked at the steel, including use of electron microscopy, and found the same characteristic corrosion as found by Barnett et al. in WTC 7 steel. “On the other hand, I know of no experiment done to test whether gypsum and heat would have this effect -- I would be VERY surprised, as the sulphur in gypsum is not elemental Sulphur, but is bound as a sulphate (very difficult to reduce to sulphur.) We should do the latter experiment to rule out such nonsense."

(http://911blogger.com/node/16564#comment)'