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David B. Benson
QUOTE (zoktoberfest+Jun 8 2008, 04:04 PM)
<a target='_blank' href='http://911review.org/Wiki/im/WTC_Demolition.jpg'>User posted image</a>

Think vertical avalanche.
einsteen
In fairness, that picture looks like everything but a vertical avalanche...

ps. the post was 3 minutes after DBBs one... don't think I'm watching each minute....
David B. Benson
QUOTE (einsteen+Jun 9 2008, 01:07 PM)
In fairness, that picture looks like everything but a vertical avalanche...

How many vertical avalanches have you seen?
einsteen
If you look at the direction of motion of an avalanche and ignore the perpendicular component isn't it then in fact a vertical avalanche...?
lozenge124
QUOTE (einsteen+Jun 9 2008, 08:07 PM)
In fairness, that picture looks like everything but a vertical avalanche...

And where's the "upper block"?
einsteen
Conservation of mass implies that it must be around somewhere...
newton
QUOTE (David B. Benson+Jun 9 2008, 11:52 PM)
How many vertical avalanches have you seen?

how many horizontal avalanches have YOU seen, david?

LOL!
David B. Benson
QUOTE (einsteen+Jun 10 2008, 03:36 AM)
If you look at the direction of motion of an avalanche and ignore the perpendicular component isn't it then in fact a vertical avalanche...?

Ignore the horizontal component.
zoktoberfest
It has been determined on this thread via (impressive) video analysis, that the collapses were particularly smooth and uninterrupted in their decent. It confirms the general impression reached during normal viewing of such videos.

I raise the question, once again, about the robust construction of the mechanical floors at levels 75-76? At the very least, a momentary resistance (loading up) should have been noted at this point. It is my understanding, that the floors were also connected to each other, across the open expanse, at regular points with vertical columns and diagonal bracing. If this can be confirmed, then levels 75-76 were a unified block and therefore more capable of exerting resistance.
Note the (MF) floor beams in the foreground (link below).

Fig 2-8
http://www.european911citizensjury.com/WTC...onstruction.jpg

"This is a view of one of the mechanical floors (they were the only floors for which the prefabricated perimeter wall units were not staggered). The mechanical floors where not supported by trusses but by solid steel beams. Composite action between these beams and the concrete slab was by welded shear studs. The concrete slab was apparently considerably thicker than that of your average floor and specially reinforced with steel beams (a stack of which are visible in the foreground of the photo?). Such floors were necessary to enable the towers to resist the significant lateral force of hurricane force winds.

We have the following quote from Engineering News-Record, January 1, 1970.

On the 41st and 42nd floors, both towers will house mechanical equipment. To accommodate the heavy loads, the floors are designed as structural steel frame slabs. All other floors from the ninth to the top (except for 75 and 76, which will also carry mechanical equipment) have typical truss floor joists and steel decking.

Typical office floors have 4-in. thick slabs of composite construction using top chord knuckles of the joists (trusses), which extend into the slab, as shear connectors. On mechanical floors, composite action is provided by welded stud shear connectors."
http://www.european911citizensjury.com/10a.htm
Chainsaw,
QUOTE (zoktoberfest+Jun 10 2008, 09:47 PM)
It has been determined on this thread via (impressive) video analysis, that the collapses were particularly smooth and uninterrupted in their decent. It confirms the general impression reached during normal viewing of such videos.

I raise the question, once again, about the robust construction of the mechanical floors at levels 75-76? At the very least, a momentary resistance (loading up) should have been noted at this point. It is my understanding, that the floors were also connected to each other, across the open expanse, at regular points with vertical columns and diagonal bracing. If this can be confirmed, then levels 75-76 were a unified block and therefore more capable of exerting resistance.
Note the (MF) floor beams in the foreground (link below).

Fig 2-8
http://www.european911citizensjury.com/WTC...onstruction.jpg

"This is a view of one of the mechanical floors (they were the only floors for which the prefabricated perimeter wall units were not staggered). The mechanical floors where not supported by trusses but by solid steel beams. Composite action between these beams and the concrete slab was by welded shear studs. The concrete slab was apparently considerably thicker than that of your average floor and specially reinforced with steel beams (a stack of which are visible in the foreground of the photo?). Such floors were necessary to enable the towers to resist the significant lateral force of hurricane force winds.

We have the following quote from Engineering News-Record, January 1, 1970.

On the 41st and 42nd floors, both towers will house mechanical equipment. To accommodate the heavy loads, the floors are designed as structural steel frame slabs. All other floors from the ninth to the top (except for 75 and 76, which will also carry mechanical equipment) have typical truss floor joists and steel decking.

Typical office floors have 4-in. thick slabs of composite construction using top chord knuckles of the joists (trusses), which extend into the slab, as shear connectors. On mechanical floors, composite action is provided by welded stud shear connectors."
http://www.european911citizensjury.com/10a.htm

You answered your own post the mechanical floors were designed to hold heavy machinery, not to arrest the collapses once initiated, the floor below them would have failed just the same as he floors above.
I actually expected to see the floors below the mechanicals failing as the mechanicals were struck, however unfortunately by that time the area is not visible.
zoktoberfest
Quote--Chainsaw
"You answered your own post the mechanical floors were designed to hold heavy machinery, not to arrest the collapses once initiated, the floor below them would have failed just the same as he floors above."

Your reference to "arrest" clearly overshoots my point. The context for which draws upon past video analysis results. My point was: why didn't a momentary (blip) deceleration register (when the collapse front met the MF's) on an otherwise smooth curve.

Something has to account for all that lateral ejection. In a gravity collapse, time and deceleration are inversely proportional (the limits being arrest and free-fall). The more rapid the descent, the less deceleration is being encountered. Less deceleration means less destructive collisions. If the building had fallen at free-fall then there would have been 0 deceleration. We saw rapid collapses (approaching free-fall) AND a level of devastation approaching total.

Quote--zoktoberfest
"And yet, without any observable deceleration, especially at the beginning, we see this????
User posted image: User posted image"
Chainsaw,
QUOTE (zoktoberfest+Jun 11 2008, 02:19 AM)
Quote--Chainsaw
"You answered your own post the mechanical floors were designed to hold heavy machinery, not to arrest the collapses once initiated, the floor below them would have failed just the same as he floors above."

Your reference to "arrest" clearly overshoots my point. The context for which draws upon past video analysis results. My point was: why didn't a momentary (blip) deceleration register (when the collapse front met the MF's) on an otherwise smooth curve.

Something has to account for all that lateral ejection. In a gravity collapse, time and deceleration are inversely proportional (the limits being arrest and free-fall). The more rapid the descent, the less deceleration is being encountered. Less deceleration means less destructive collisions. If the building had fallen at free-fall then there would have been 0 deceleration. We saw rapid collapses (approaching free-fall) AND a level of devastation approaching total.

Quote--zoktoberfest
"And yet, without any observable deceleration, especially at the beginning, we see this????
User posted image: User posted image"

A momentary blip is an arrest in fall.
The mechanical floors with higher gravitational PE were not designed to handle the machinery live load and a huge load of the collapsing building.
If anything the collapse should speed once the mechanical floors are impacted as the gravitational PE of the descending upper block is added to the mechanical floor and crushes the floor below the reinforced mechanical floor first.
That is one thing I was looking for in the videos.

It is like a semi impacting a dump truck impacting a small car, which do you think will give the most and where?
It could also be that this effect is the cause of the ejections seen.
zoktoberfest
"A momentary blip is an arrest in fall."

Semantics

In 9/11 literature, the term "arrest" is used to indicate an early and complete termination of the collapse event. Gordon Ross (for ex.) uses the term to describe how the effects of plastic deformation (in the heat of the impact zone) would reduce the acceleration component to the point of "arrest" (unless another mechanism is effect). When I use it or read it, I assume a condition of stasis.

"The mechanical floors with higher gravitational PE were not designed to handle the machinery live load and a huge load of the collapsing building."

The MF's were exceptionally reinforced platforms that unified and focused ALL the lateral and vertical integrity of the lower structure at one point. The last stand for the WTC's was at levels 75-76. Your attempt to discount this scenario, by addressing the (designed for) machine load, while ignoring the additional structural unification is a point of contention. The only time in the collapse event that the building could collectively resist with all possible means was at those levels.

Why are modern vehicles built around the concept of a crumple zone? To absorb the propagation of KE. Why can't the crushing of the core and floors structures, above the MF's, be treated as de-facto crumple zones.

The inability of those levels to even register a resistance, combined with the inexplicable nature of early lateral ejections and pulverization, can only be explained by an additional mechanism. You can't have a quick, smooth, AND concussive gravity collapse, all at the same time.

Chainsaw,
QUOTE (zoktoberfest+Jun 11 2008, 06:15 AM)
"A momentary blip is an arrest in fall."

Semantics

In 9/11 literature, the term "arrest" is used to indicate an early and complete termination of the collapse event. Gordon Ross (for ex.) uses the term to describe how the effects of plastic deformation (in the heat of the impact zone) would reduce the acceleration component to the point of "arrest" (unless another mechanism is effect). When I use it or read it, I assume a condition of stasis.

"The mechanical floors with higher gravitational PE were not designed to handle the machinery live load and a huge load of the collapsing building."

The MF's were exceptionally reinforced platforms that unified and focused ALL the lateral and vertical integrity of the lower structure at one point. The last stand for the WTC's was at levels 75-76. Your attempt to discount this scenario, by addressing the (designed for) machine load, while ignoring the additional structural unification is a point of contention. The only time in the collapse event that the building could collectively resist with all possible means was at those levels.

Why are modern vehicles built around the concept of a crumple zone? To absorb the propagation of KE. Why can't the crushing of the core and floors structures, above the MF's, be treated as de-facto crumple zones.

The inability of those levels to even register a resistance, combined with the inexplicable nature of early lateral ejections and pulverization, can only be explained by an additional mechanism. You can't have a quick, smooth, AND concussive gravity collapse, all at the same time.

QUOTE
9/11 literature, the term "arrest" is used to indicate an early and complete termination of the collapse event. Gordon Ross (for ex.) uses the term to describe how the effects of plastic deformation (in the heat of the impact zone) would reduce the acceleration component to the point of "arrest" (unless another mechanism is effect). When I use it or read it, I assume  a condition of stasis.

Gordon Ross's usage of the term arrest does not interest me, an arrest is anytime the rapid collapse is halted, for what ever period of time.
An arrest can take place and only last for micro seconds, there is no defined time limit on how long structural resistance to gravitational PE, should last at any given point.

QUOTE (->
 QUOTE 9/11 literature, the term "arrest" is used to indicate an early and complete termination of the collapse event. Gordon Ross (for ex.) uses the term to describe how the effects of plastic deformation (in the heat of the impact zone) would reduce the acceleration component to the point of "arrest" (unless another mechanism is effect). When I use it or read it, I assume  a condition of stasis.

Gordon Ross's usage of the term arrest does not interest me, an arrest is anytime the rapid collapse is halted, for what ever period of time.
An arrest can take place and only last for micro seconds, there is no defined time limit on how long structural resistance to gravitational PE, should last at any given point.

The MF's were exceptionally reinforced platforms that unified and focused ALL the lateral and vertical integrity of the lower structure at one point. The last stand for the WTC's was at levels 75-76. Your attempt to discount this scenario, by addressing the (designed for) machine load, while ignoring the additional structural unification is a point of contention. The only time in the collapse event that the building could collectively resist with all possible means was at those levels.

Why are modern vehicles built around the concept of a crumple zone? To absorb the propagation of KE. Why can't the crushing of the core and floors structures, above the MF's, be treated as de-facto crumple zones.

Comparing the structure of the buildings to crumple zones in cars is the most stupid thing I have heard so far, basically because force will be transmitted though a stiff metal structure more faster than though a material designed to resist compression loading.
Crumple zones are weak areas connected to stronger areas designed to bend and fold in certain directions to absorb impact energy!
The towers were built like 1950s Autos they had no crumple zones, the energy was transmitted down the tapered beams and intensified as the Impact frequency and gravitational PE was converted to gravitational KE .

QUOTE
The inability of those levels to even register a resistance, combined with the inexplicable nature of early lateral ejections and pulverization, can only be explained by an additional mechanism. You can't have a quick, smooth, AND concussive gravity collapse, all at the same time.

Your own crumple Zone model points out that you can, that is exactly what should happen in a stiff energy transmitting structure, that is exactly why cars now have crumple Zones, to keep impact energy from being transmitted down the frame of the vehicle into the passenger cabin.

The idea is to protect the passenger cabin from impact energy, no such softening of the frame work would be designed into buildings the whole Idea shows a lack of understanding of the towers design and the reason for the stiffening to prevent sway and over loading of the floors from the mechanical live load.

The towers were a unified structure they acted as a unit and were destroyed when that unity failed, do to transmission of massive Gravitational Energy though the structure over coming the structures resistance to collapse on multiple levels.

Energy is being transmitted down the core columns with each impact, that energy goes into work to destroy the structure below, at the mechanical floors the energy should go into destroying the floor below the mechanicals before the mechanical floor itself is totally destroyed.

The energy should simply transmit though the stronger structure to the weaker structure below, since most of the bracing is not even for building strength but to support machinery and prevent sway at the mechanical floor itself, as well as support heavier concrete necessary to put the machinery on.

Crumple Zones simply redirect energy, if the Twin Towers had crumple Zone like effects, The energy would have been re directed, to he side the buildings would have toppled over and the collapses would have been totally arrested because the top block would have fallen off and crushed on the ground on impact.

The columns were tapered to concentrate the load in a downward direction this also concentrated the energy of the collapse in a downward direction.
You basically have a very good geometrical shape for intense energy transfer down the beams to the welds, and when the welds fail the buildings fail.
Grumpy
zoktoberfest

QUOTE
Gordon Ross (for ex.) uses the term to describe how the effects of plastic deformation (in the heat of the impact zone) would reduce the acceleration component to the point of "arrest" (unless another mechanism is effect). When I use it or read it, I assume a condition of stasis.

Gordon Ross is an idiot, his calculations and assumptions are full of holes you could drive semis through. Citing him will not get you any credibility outside the insular world of the troother sites. Ross, Jones, Ryan and Woods have prostituted their integrity to fleece the flock of ignorant Conspiracy nuts.

The fact is that once the top blocks fell 12 feet, the fate of those buildings was sealed, and no additional resistance of the mech floors would make a visible difference.

Grumpy
David B. Benson
zoktoberfest --- An analysis of Frank Greening's measurements for WTC 2 suggests that the collapse of that structure had less acceleration whilst crushing the partially and totally beamed floors. However more data would have to be collected before this hint might be confirmed.

In any case, for the first few seconds, WTC 2 accelerated at about (3/4)g, hardly 'near free fall'.
einsteen
An interesting question is what would be the acceleration if there is a symmetrical failure at all sides without tilting.

David, what do you think about that last picture posted ? It's hard to estimate the amount of ejected mass, I remember that 20% was used somewhere in a paper but can't remember how this conservative value was determined.
NEU-FONZE
Einsteen:

The trouble with those collapse photographs is that they don't show that the cloud of debris was mostly glass fiber insulation, vermiculite, and pulverized gypsum wallboard. Only about 25 % of the WTC dust was found (by Lioy, Meeker, etc), to be crushed concrete ......
David B. Benson
QUOTE (einsteen+Jun 11 2008, 02:07 PM)
An interesting question is what would be the acceleration if there is a symmetrical failure at all sides without tilting.

David, what do you think about that last picture posted ? It's hard to estimate the amount of ejected mass, I remember that 20% was used somewhere in a paper but can't remember how this conservative value was determined.

The same one-dimensional crush-down equation applies. The acceleration is never actually constant, but the same approximate values can be used.

What are you asking about the picture? I'll say that for the first few seconds so little mass is ejected that, while it is certainly impressive looking, it can be ignored. Later, when perimeter wall sections break free, one might bother to include the effect. In any case, sensitivity studies show that it makes little difference to the total crush-down time.
einsteen
QUOTE (NEU-FONZE+Jun 12 2008, 12:03 AM)
Einsteen:

The trouble with those collapse photographs is that they don't show that the cloud of debris was mostly glass fiber insulation, vermiculite, and pulverized gypsum wallboard. Only about 25 % of the WTC dust was found (by Lioy, Meeker, etc), to be crushed concrete ......

I remember you bought Aftermath in which you could see floor slabs. Do you have the possibility to scan or photograph such a picture ? That would be very interesting to see.

Do you mean that 25% of it contained pulverized concrete ? That doesn't say anything about the amount of mass that left the 64mx64m footprint before hitting the ground.
einsteen
QUOTE (David B. Benson+Jun 12 2008, 12:47 AM)
The same one-dimensional crush-down equation applies. The acceleration is never actually constant, but the same approximate values can be used.

What are you asking about the picture? I'll say that for the first few seconds so little mass is ejected that, while it is certainly impressive looking, it can be ignored. Later, when perimeter wall sections break free, one might bother to include the effect. In any case, sensitivity studies show that it makes little difference to the total crush-down time.

I mean that some people believe it is a pure hinge in the beginning, in that case the loss of potential energy can say something about the resistance, maybe in the beginning there was no resistance, I guess it still has not been worked out.

It is indeed impressive and if you watch the movies it is even more impressive. Do you seriously think that this is solely due to air pressed out ? I would say conservation of momentum, not only vertical but also horizontal.
David B. Benson
QUOTE (einsteen+Jun 12 2008, 07:44 AM)
I mean that some people believe it is a pure hinge in the beginning, in that case the loss of potential energy can say something about the resistance, maybe in the beginning there was no resistance, I guess it still has not been worked out.

It is indeed impressive and if you watch the movies it is even more impressive. Do you seriously think that this is solely due to air pressed out ? I would say conservation of momentum, not only vertical but also horizontal.

For WTC 1 the collapse appears to be a 'pure hinge'. WTC 2 is too messy for me, at least, too say much. For WTC 1 I worked out the initial resistance for the first 25-50 cm of drop. High, but not enough to stop the collapse. After that, the crush-down equation gives a very good fit.

Essentially all of that impressiveness is due to (dirty) air being pressed out.
einsteen
That's nice, I now know how to impress people, not with hot air but with dirty air!
Chainsaw,
QUOTE (einsteen+Jun 12 2008, 09:34 PM)
That's nice, I now know how to impress people, not with hot air but with dirty air!

Be careful einsteen, as I related to Dr. Jones years ago dirty air can be explosive dependent on the composition of the dirt.
Especially black carbon smoke.
David B. Benson
So he can be explosively funny when he tells his dirty joke?
David B. Benson
QUOTE (newton+Jun 10 2008, 08:55 AM)
how many horizontal avalanches have YOU seen, david?

I once had to pass around the remains of an avalanche which had come down one side, across the valley floor, and part way up the other side. Does the valley floor portion count?

Seriously, the resistive force for a flowing snow avalanche is a sum of two terms: the first is proportional to the kinetic energy and the second to the cosine of the angle. Turns out that using a resistive force proportional to the KE fits the drop data for WTC 1 quite, quite well. Hence vertical avalanche.
desol
Hey fellas,

I'm new here. First post...and i'm not a scientist! So please go easy.

There are 650 pages to this thread, so i presume i'm asking an already covered topic. Nonetheless.

Speculations aside about the ejected matter from the towers, can somone shed some light for me on how building 7 'completely' collapsed in the manner it did?

Why didn't the other buildings of similar or smaller stature, within the same proximity, fall as well?

And why did Silverstein say they 'decided to pull it' on tv?

Chainsaw,
QUOTE (desol+Jun 16 2008, 09:10 PM)
Hey fellas,

I'm new here. First post...and i'm not a scientist! So please go easy.

There are 650 pages to this thread, so i presume i'm asking an already covered topic. Nonetheless.

Speculations aside about the ejected matter from the towers, can somone shed some light for me on how building 7 'completely' collapsed in the manner it did?

Why didn't the other buildings of similar or smaller stature, within the same proximity, fall as well?

And why did Silverstein say they 'decided to pull it' on tv?

I believe it was damaged in the collapse of the towers to the point where it collapsed.

You can read the post about it in the thread if you want, just use the search function.
desol
QUOTE (Chainsaw+,Jun 16 2008, 11:04 PM)
I believe it was damaged in the collapse of the towers to the point where it collapsed.

You can read the post about it in the thread if you want, just use the search function.

Little off topic here but, weren't 'the physics' surrounding the building and safety concerns already accounted for years ago? The buildings appear to have been 'over-engineered' for the very purpose to withstand a plane crash...

A 707 to be exact.

White paper released on February 3, 1964

"The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact."

Feburary 13, 1965
"Richard Roth, partner at Emery Roth & Sons, the architectural firm that was designing the Twin Towers:"

THE STRUCTURAL ANALYSIS CARRIED OUT BY THE FIRM OF WORTHINGTON, SKILLING, HELLE & JACKSON IS THE MOST COMPLETE AND DETAILED OF ANY EVER MADE FOR ANY BUILDING STRUCTURE. THE PRELIMINARY CALCULATIONS ALONE COVER 1,200 PAGES AND INVOLVE OVER 100 DETAILED DRAWINGS.
...
4. BECAUSE OF ITS CONFIGURATION, WHICH IS ESSENTIALLY THAT OF A STEEL BEAM 209' DEEP, THE TOWERS ARE ACTUALLY FAR LESS DARING STRUCTURALLY THAN A CONVENTIONAL BUILDING SUCH AS THE EMPIRE STATE BUILDING WHERE THE SPINE OR BRACED AREA OF THE BUILDING IS FAR SMALLER IN RELATION TO ITS HEIGHT.
...
5. THE BUILDING AS DESIGNED IS SIXTEEN TIMES STIFFER THAN A CONVENTIONAL STRUCTURE. THE DESIGN CONCEPT IS SO SOUND THAT THE STRUCTURAL ENGINEER HAS BEEN ABLE TO BE ULTRA-CONSERVATIVE IN HIS DESIGN WITHOUT ADVERSELY AFFECTING THE ECONOMICS OF THE STRUCTURE.
Capracus
QUOTE (desol+Jun 16 2008, 09:10 PM)
Hey fellas,

I'm new here. First post...and i'm not a scientist! So please go easy.

There are 650 pages to this thread, so i presume i'm asking an already covered topic. Nonetheless.

Speculations aside about the ejected matter from the towers, can somone shed some light for me on how building 7 'completely' collapsed in the manner it did?

Why didn't the other buildings of similar or smaller stature, within the same proximity, fall as well?

And why did Silverstein say they 'decided to pull it' on tv?

Like Chainsaw suggested, use the search function. As you suspected, it's been extensively covered in previous posts. Here's one example.
http://www.physforum.com/index.php?showtopic=13029&st=10
einsteen
http://i27.tinypic.com/28k1qme.jpg

A natural collapse.
stundie
QUOTE (desol+Jun 17 2008, 04:03 AM)

Little off topic here but, weren't 'the physics' surrounding the building and safety concerns already accounted for years ago? The buildings appear to have been 'over-engineered' for the very purpose to withstand a plane crash...

A 707 to be exact.

White paper released on February 3, 1964

"The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact."

Feburary 13, 1965
"Richard Roth, partner at Emery Roth & Sons, the architectural firm that was designing the Twin Towers:"

THE STRUCTURAL ANALYSIS CARRIED OUT BY THE FIRM OF WORTHINGTON, SKILLING, HELLE & JACKSON IS THE MOST COMPLETE AND DETAILED OF ANY EVER MADE FOR ANY BUILDING STRUCTURE. THE PRELIMINARY CALCULATIONS ALONE COVER 1,200 PAGES AND INVOLVE OVER 100 DETAILED DRAWINGS.
...
4. BECAUSE OF ITS CONFIGURATION, WHICH IS ESSENTIALLY THAT OF A STEEL BEAM 209' DEEP, THE TOWERS ARE ACTUALLY FAR LESS DARING STRUCTURALLY THAN A CONVENTIONAL BUILDING SUCH AS THE EMPIRE STATE BUILDING WHERE THE SPINE OR BRACED AREA OF THE BUILDING IS FAR SMALLER IN RELATION TO ITS HEIGHT.
...
5. THE BUILDING AS DESIGNED IS SIXTEEN TIMES STIFFER THAN A CONVENTIONAL STRUCTURE. THE DESIGN CONCEPT IS SO SOUND THAT THE STRUCTURAL ENGINEER HAS BEEN ABLE TO BE ULTRA-CONSERVATIVE IN HIS DESIGN WITHOUT ADVERSELY AFFECTING THE ECONOMICS OF THE STRUCTURE.

Hi Desol,

To be fair to Chainsaw, you did asked about shedding some light on the WTC 7 collapse, when he replied to you, you then bring up quotes regarding WTC 1 & 2?

Thats hardly fair is it??

The quotes are in relation to WTC 1 & 2, but not WTC 7 as it was designed differently.

As to why WTC 7 collapsed, nobody knows. NIST has not produced a report yet so there is no official explanation. However, the debate as people split into a fire induced collapse theory or a demolition.

Evidence to support the demolition theory is much stronger than the fire induced theory. For a start, there are numerous reports of explosions at WTC 7, the buildings appear to collapse in a similar way to a implosion.

The fire induced collapse theory relies on inferno like conditions throughout WTC7 which were not seen by any video or photographic evidence, reported by FEMA or even NIST. The only evidence which supports this claim are witness statements taken out of context. Even NIST suggest that this had a very low probability of occurring.

I would recommend you do some research before you come to a conclusion. Based on the evidence and arguments I have seen from both sides, a CD theory is more of a plausible than a fire induced collapse theory.

As for WTC 1 & 2, the NIST report do not have a scientific theory of how the towers collapse and neither do the defenders of their theory. NIST was paid to determine how the towers collapse, they tell us up to the point of collapse initiation, then it gets all unscientific.

I too am not a scientist, but until someone can explain how it collapses without ignoring evidence or simple physics which contradicts it. Then for me, a demolition theory will always be a possibility.

Good luck.

Cheers

Stundie
David B. Benson
Poster stundie has it all wrong.

The collapse of WTC 2 and especially WTC 1 has been thoroughly analyzed on this thread and its two predecessors.

For that matter, so has WTC 7. But briefly, no steel-framed building is designed to survive many hours of unfought fire. Its amazing that it stood as long as it did.
einsteen
Wtc7 was designed to collapse fast, symmetrically and completely after a single column failure. Its amazing that it didn't collapse immediately after wtc1 debris hit wtc7.
Grumpy
einsteen

WTC 7 was CANTILEVERED over the power station. As long as it was undamaged it was fine, but damaged and heated for over 7 hours, it was not fine.

Grumpy
forthetrees
QUOTE (Grumpy+Jun 18 2008, 12:30 PM)
einsteen

WTC 7 was CANTILEVERED over the power station. As long as it was undamaged it was fine, but damaged and heated for over 7 hours, it was not fine.

Grumpy

OK, fine. But if it is as simple and straight forward as that, why hasn't NIST or anyone else in a position of authority published a professional/official statement saying just that?
Skeptik
If WTC7 was cantilevered over the power station why didn't it fall in that direction,(i.e.topple ever asymmetrically) instead of falling down, as it did, in a straight line?
DavidD
Stupidity is to build so high buildings
David B. Benson
QUOTE (Skeptik+Jun 18 2008, 09:44 AM)
(i.e.topple ever asymmetrically)

It did. South fell, then north wall fell.
desol
QUOTE (David B. Benson+Jun 17 2008, 06:42 PM)
Poster stundie has it all wrong.

The collapse of WTC 2 and especially WTC 1 has been thoroughly analyzed on this thread and its two predecessors.

For that matter, so has WTC 7.  But briefly, no steel-framed building is designed to survive many hours of unfought fire.  Its amazing that it stood as long as it did.

It has been throroughly discussed.

It is quite possible that these three buildings would completely, perfectly fall, from their injuries, in a single day. Even though they were precisely engineered NOT to react this way. The vertical core would seem theoretically, to be resistant to 'pancaking', the proposed explanation. But there are other problems, things that people said, maybe things that they shouldn't have. Maybe things misunderstood.

Either way, the event does deserve to be reopened and re-examined by a larger community.
einsteen
If wtc7 collapsed due to the North tower we should at least admit it is not only dirty air ejected.
Capracus
QUOTE (desol+Jun 19 2008, 06:26 AM)
It has been throroughly discussed.

It is quite possible that these three buildings would completely, perfectly fall, from their injuries, in a single day. Even though they were precisely engineered NOT to react this way. The vertical core would seem theoretically, to be resistant to 'pancaking', the proposed explanation. But there are other problems, things that people said, maybe things that they shouldn't have. Maybe things misunderstood.

Either way, the event does deserve to be reopened and re-examined by a larger community.

desol, if you had read the previous posts in the threads more thoroughly, or, simply read some of the relevant material referenced in those threads,( http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm ) then you might conclude otherwise.

If you accept material like this( http://www.daily.pk/world/americas/99-amer...unt-of-911.html ) as reasonable, then your lack of understanding makes sense.
Skeptik
Looks pretty symmetrical to me.
WTC 7 Collapse

Where is the toppling over to one side which should have happened over the power station?

p.s. What's happen to Arthur? He been sent to Guantanamo?
David B. Benson
QUOTE (einsteen+Jun 19 2008, 02:14 AM)
If wtc7 collapsed due to the North tower we should at least admit it is not only dirty air ejected.

It appears that the perimeter wall just peeled apart and sections of it then broke off. I see no reason to further consider 'ejection' of those massive pieces.
David B. Benson
QUOTE (Skeptik+Jun 19 2008, 07:48 AM)
Looks pretty symmetrical to me.

You're just seeing the north wall. Checking the NOAA vertical overhead photos, one can see portions of the south wall draped over the remains of WTC 6.
Skeptik
So the building split into two parts? If so what made it split? If the South wall fell first, I assume that this is not shown in the video. What the video shows is, what you call, the the North side falling straight down. Still looks like a total symmetrical collapse to me.

Can you explain why there is no resistance from the building to the collapse of the upper floors?
David B. Benson
QUOTE (Skeptik+Jun 19 2008, 10:52 AM)
If so what made it split?

If the South wall fell first, I assume that this is not shown in the video.

Can you explain why there is no resistance from the building to the collapse of the upper floors?

The assumption is that the south wall cantilevers failed first.

Video was shot from essentially due north of the building.

Just how much resistance the building offered is unknown. Once the floors started collapsing (likely ripping away from the north wall), the north wall came down as well. More generally, buildings are designed to stand up, not resist something massive being dropped on them.
OneWhiteEye
QUOTE (einsteen+May 28 2008, 04:07 PM)
Graeme MacQueen seems to plot the acceleration of the north tower's antenna

http://911blogger.com/node/15793

For what it's worth, here are some graphs of early motion of the antenna mast. The data is not as good as it could be, but it exceeds the accuracy and resolution of anything I've produced (or seen) by a significant margin. I'd say that 5 inches of motion is reliably discernable under certain circumstances. This is a testament to the incredible quality and stability of the Sauret video; a tip of the cap to you, Mr. Sauret.

The data is taken from the top center dish antenna on the mast and runs from frame 800 to 980, where frame 0 is the first frame of chapter two in sequence three. There is a point for each frame. Displacements expressed in pixels. The known and potential sources of error:

- camera motion
- obscuring smoke
- thermal refraction
- camera-based recording artifact
- varying illumination (in this case, mostly shadow edge from the smoke plume)
- not necessarily the best possible rip from DVD

Some of these are amenable to correction of varying degree. For example, there are sufficient qualifying stationary points available to determine camera motion (angular/pixel displacement of the scene coordinates) with greater precision than the target feature. Such artifact can then be subtracted out of the data with extreme confidence. Of all the items, the last two have the greatest potential magnitude.

Vertical position (up is downward displacement, obviously)
http://i30.tinypic.com/o585ys.jpg
Zoom of frames 880-920
http://i32.tinypic.com/x2nwbb.jpg

No comment.

Horizontal position (down is left/easterly)
http://i28.tinypic.com/s4swlg.jpg

The displacement back towards the right evident from frame 965 forward is tantalizing but I take it with a grain of salt. This is approximately the time the feature enters the shadow of the plume. The method I'm using is not positionally sensitive to global illumination but entering this particular shadow may introduce localized variations that cause the drift back. Or not.

Cropped, enlarged animation showing placement of feature with bright green dot (GIF, <1.2MB)
http://i29.tinypic.com/4kch02.gif

Self-explanatory. It's the only independent confirmation of accuracy I have, but it looks pretty good so I'm not sweating any other proof.

Feature bounding box coordinates (vertical)
http://i25.tinypic.com/20zof0g.jpg
Feature bounding box coordinates (horizontal)
http://i31.tinypic.com/2agoupt.jpg

These show the smallest rectangle containing the feature, a measure of its overall apparent size. It is also the band of 100% certainty for location of the feature, thus representing the maximum error the method can produce. The real accuracy is much, much better than these curves imply, which is +/-2 px vertical in the worst case. This is more useful to assist in judging the stability of aspects of the extraction.

There is more auxiliary data (feature pixel count, avg intensities, etc) that helps to characterize the displacements obtained, but I'm probably the only one who wouldn't find those a crushing bore.
NEU-FONZE
OneWhiteEye:

Very interesting plots, but of limited value unless they are converted to vertical distances and times.

However, the smoothness of the antenna drop curve does suggest that it is largely a tipping motion that we are seeing (which would be very uniform if governed by the "falling pencil equation":

d(theta)/dt = Sqrt{ (3g/h). [1 - cos(theta)]}
desol
QUOTE (Capracus+Jun 19 2008, 10:42 AM)
desol, if you had read the previous posts in the threads more thoroughly, or, simply read some of the relevant material referenced in those threads,( http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm ) then you might conclude otherwise.

If you accept material like this( http://www.daily.pk/world/americas/99-amer...unt-of-911.html ) as reasonable, then your lack of understanding makes sense.

Well, for one thing i appreciate your response, but on the other hand your
response seems slighly condescending. I'll assume you didn't intend it to be so.

Regardless, there are 650 pages to this thread, i got tired after 50.

As to where i get my information, that's for me to know, and you not to assume.
There is ALOT of contest surrounding these events and only 1/2 of them have to do with Physics.

If you really must know, i DO have appreciation for the opinion of the over 400 architects and engineers at the site below, that you may not be aware of.

ae911truth.org

As i said, i do not believe that there was a thorough enough investigation done...either for or against. It does seem that things were finished up rather quickly and much more of the emphasis was placed on the resulting war. There are hundreds if not thousands of professionals that apparently think the same? Also, much of the controversy surrounding this comes from the mouths of the officials themselves. Contradicting statements...things that do not add up...etc..

If people have nothing to hide...it should not be a problem. They should welcome it openly to the professional community and to the american people. This is only common sense.

Right?
OneWhiteEye
QUOTE (NEU-FONZE+Jun 19 2008, 11:38 PM)
Very interesting plots, but of limited value unless they are converted to vertical distances and times.

So true.

David B. Benson had some perspective correction code specifically for the dark band which I appropriated and modified for arbitrary feature and camera location. As I recall, I couldn't get the two outputs to totally agree and never had time to chase down the bug. I could dredge it up, fix it, and run with this feature location, but it would be even less valuable, I think, since it's only one dimensional. And, as you point out:

QUOTE
However, the smoothness of the antenna drop curve does suggest that it is largely a tipping motion that we are seeing (which would be very uniform if governed by the "falling pencil equation":

d(theta)/dt  =  Sqrt{ (3g/h). [1  - cos(theta)]}

If you take frame 917 as the time of initial descent, the zoom-in of frames 880 - 920 is all tip. The perspective correction needs to result in a transformation matrix for the upper block as a whole, not some point on the antenna with exclusive vertical displacement assumed. Since a single video cannot determine all the degrees of freedom, what I'm shooting for eventually is output in a parametric form where the transformation reduces to meters vertical only after you've plugged in assumptions for the hinge location, camera location, etc. I don't know where the camera was, exactly, do you?

The frame rate is 29.97fps.

Edit: the point of showing the graphs was actually to beat a dead horse - to demonstrate that any 'whaeme' is limited to no more than the magnitude of known errors in the dataset.

Edit2: I believe the conversion for the dark band in its first pixel of motion was about 0.26m/px, if that's of any immediate use. This feature is very close to the dark band, a little below.
David B. Benson
QUOTE (desol+Jun 19 2008, 04:40 PM)
If you really must know, i DO have appreciation for the opinion of the over 400 architects and engineers at the site below, that you may not be aware of.

Many of us are aware and have debunked the misinformation which appears on that site.

While NIST didn't do a perfect job in analyzing WTC 1 & 2, its not bad. Just rather verbose and sometimes hard to understand. Give that a try and I'll answer questions as best as I can until the real expert, Arthur, returns from his vacation (or whatever).
Chainsaw,
QUOTE (desol+Jun 17 2008, 04:03 AM)

Little off topic here but, weren't 'the physics' surrounding the building and safety concerns already accounted for years ago? The buildings appear to have been 'over-engineered' for the very purpose to withstand a plane crash...

A 707 to be exact.

White paper released on February 3, 1964

"The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact."

Feburary 13, 1965
"Richard Roth, partner at Emery Roth & Sons, the architectural firm that was designing the Twin Towers:"

THE STRUCTURAL ANALYSIS CARRIED OUT BY THE FIRM OF WORTHINGTON, SKILLING, HELLE & JACKSON IS THE MOST COMPLETE AND DETAILED OF ANY EVER MADE FOR ANY BUILDING STRUCTURE. THE PRELIMINARY CALCULATIONS ALONE COVER 1,200 PAGES AND INVOLVE OVER 100 DETAILED DRAWINGS.
...
4. BECAUSE OF ITS CONFIGURATION, WHICH IS ESSENTIALLY THAT OF A STEEL BEAM 209' DEEP, THE TOWERS ARE ACTUALLY FAR LESS DARING STRUCTURALLY THAN A CONVENTIONAL BUILDING SUCH AS THE EMPIRE STATE BUILDING WHERE THE SPINE OR BRACED AREA OF THE BUILDING IS FAR SMALLER IN RELATION TO ITS HEIGHT.
...
5. THE BUILDING AS DESIGNED IS SIXTEEN TIMES STIFFER THAN A CONVENTIONAL STRUCTURE. THE DESIGN CONCEPT IS SO SOUND THAT THE STRUCTURAL ENGINEER HAS BEEN ABLE TO BE ULTRA-CONSERVATIVE IN HIS DESIGN WITHOUT ADVERSELY AFFECTING THE ECONOMICS OF THE STRUCTURE.

NO.
lozenge124
Apollo20 (who posts here as NEUFONZE) made an interesting comment on the NIST report in the jref forum recently. I hope he doesn't mind if I post it here (if it's a problem let me know and I will remove it).

QUOTE
The main body of the NIST Report is a description of the design and construction of the towers and some tests that were carried out on components or assemblies such as office comparments. Oh yes, and some modeling based on unverifiable assumptions ...... and lots and lots of computer-generated simulacra! However, I see no creep buckling tests reported that attempt to reproduce the temperatures and loads experienced by columns in the impact zones of the towers. In the end I still say that the NIST Report was written to provide a "feel-good" document for Congress to pass on to the American public. Very few engineers or scientists appear to have any interest in the NIST Report, or indeed any investigations into what happened to the Twin Towers. Bazant expressed the same view to me concerning the fact that so little has been published in scientific/engineering journals on the WTC collapse and suggested it's because no one wants to fund research on such an emotionally and politically charged topic.

forthetrees
QUOTE (forthetrees+Jun 18 2008, 02:54 PM)
OK, fine.  But if it is as simple and straight forward as that, why hasn't NIST or anyone else in a position of authority published a professional/official statement saying just that?

Since there was no response to my question from the other day quoted above, I kept looking and found this:

http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

QUOTE
14. Why is the NIST investigation of the collapse of WTC 7 (the 47-story office building that collapsed on Sept. 11, 2001, hours after the towers) taking so long to complete? Is a controlled demolition hypothesis being considered to explain the collapse?

When NIST initiated the WTC investigation, it made a decision not to hire new staff to support the investigation. After the June 2004 progress report on the WTC investigation was issued, the NIST investigation team stopped working on WTC 7 and was assigned full-time through the fall of 2005 to complete the investigation of the WTC towers.  With the release and dissemination of the report on the WTC towers in October 2005, the investigation of the WTC 7 collapse resumed. Considerable progress has been made since that time, including the review of nearly 80 boxes of new documents related to WTC 7, the development of detailed technical approaches for modeling and analyzing various collapse hypotheses, and the selection of a contractor to assist NIST staff in carrying out the analysis.

It is anticipated that a draft report will be released for public comment by July 2008 and that the final report will be released shortly thereafter.

The current NIST working collapse hypothesis for WTC 7 is described in the June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (Volume 1, page 17, as well as Appendix L), as follows:

*

An initial local failure occurred at the lower floors (below floor 13) of the building due to fire and/or debris-induced structural damage of a critical column (the initiating event) which supported a large-span floor bay with an area of about 2,000 square feet;

*

Vertical progression of the initial local failure occurred up to the east penthouse, and as the large floor bays became unable to redistribute the loads, it brought down the interior structure below the east penthouse; and

*

Triggered by damage due to the vertical failure, horizontal progression of the failure across the lower floors (in the region of floors 5 and 7 that were much thicker and more heavily reinforced than the rest of the floors) resulted in a disproportionate collapse of the entire structure.

This hypothesis may be supported or modified, or new hypotheses may be developed, through the course of the continuing investigation. NIST also is considering whether hypothetical blast events could have played a role in initiating the collapse. While NIST has found no evidence of a blast or controlled demolition event, NIST would like to determine the magnitude of hypothetical blast scenarios that could have led to the structural failure of one or more critical elements.

I wonder if they will make the anticipated July, 2008 release date, and if the report will address the curious and premature BBC announcement. Common sense would seem to suggest that if the collapse was expected and anticipated several minutes (if not considerably longer) in advance, that any number of official entities as well as news sources would have prepared to video the inevitable collapse from as many vantage points as possible and that there would be numerous videos of the event. Then again, common sense suggests that the dozens of security cameras in the vicinity of the Pentagon would have captured more of that event than the 5 frames we've seen.
David B. Benson
lozenge124 --- Structural engineers are mostly interested in designing to avoid progressive collapse, even when some part of the supporting structure is damaged/destroyed. Indeed both GSA and DoD requires this for federal buildings thought to be at risk. (California, etc., are also interested, mostly with regard to earthquakes.)

These newer designs are not much like WTC 1, 2 and the old 7. Indeed, consider the design of the new 7. So I find little surprise in that the structural engineering community has (mostly) moved on the other things.

forthetrees --- Maybe NIST will actually make it by July. They've been delaying for quite some time now, so don't hold your breath. Also, appropriately calculating the collapse of such a space frame is not easy, and AFAIK has never been done before.

The collapse was anticipated by the fire chiefs about 11:30 am. The building fell about 5 hours later.
OneWhiteEye
NEU-FONZE, after a little more consideration on:

QUOTE (NEU-FONZE+Jun 19 2008, 11:38 PM)
Very interesting plots, but of limited value unless they are converted to vertical distances and times.

I say...

Units of frames and pixels are perfectly adequate to determine if there are any bumps in the curve though, as I said, I could have made that purpose more clear. It was good enough for putting bounds on any whack experienced by the upper block as its center of mass and leading edges descended, very slowly, through the first few floors. Whether such is expected or not is not the point, the point is there's not much if anything to see. Likewise, the graphs, as they are, are suitable for any similar qualitative evaluation, as suitable as distance and time.

With the Sauret video, the difference from linearity in the correction over the range of early motion is such that you would not likely detect the difference, visually, between linear and 'correct' conversions to meters unless they were overlaid. [Just a guess.] So the practical difference between pixels and meters on a graph is... the labels on the axes. Graphs can be sized, shaped and scaled in any way for either unit. Apologies if this is so obvious, but removing all doubt and misunderstanding is essential. I think you meant 'valuable' for analysis. Of course, that requires records of numbers and not a graph like what was posted, a distinct matter from conversion from image space and frames to the real-world coordinates of vertical distance and time.

The data underlying the graphs is not just accurate, it is objective and repeatable, and as absolute as the raw data from any particular recorder measuring the frames themselves. Acquisition precedes ANY analysis of image data, thus has the distinction of universal applicability going forward. To scale distance would be to add another layer (dare I call it impure?) unnecessarily for the purpose of the post. I should have left the units off entirely, as it wouldn't have diminished the 'value' at all. If the purpose had been numerical analysis, there would have been no post, as I don't feel the numbers should be used yet.

And now a few words on conversion...

The FIRST step in analysis is conversion to time and something, after the raw data has been obtained. The conversion from frames to seconds uses a constant scale factor of 1/29.97fps, so scaling is trivial. I've found that thinking in frames is handy, at least when only dealing with one video. Frame 917 is exactly precise, unabiguous, and easy for me to remember. By contrast, 3.9 seconds is just easy to remember. That could be t = -0.13 seconds in another context. Clearly the consumer of the data must establish their own t0 by whatever desired means, anyway, so what's the extra step of multiplying by a constant? Seriously? Likewise, for distance, if all you need is eyeball accuracy (as with a graph) and are of the ilk to ignore tilt, use 0.25m/px.

Good enough for you? If not, aren't you glad I didn't just do it? As with establishing t0, it's up to the consumer of the raw data, as a pre-processing step, to perform the conversion to distance or something else intermediate. It would be at that point the parameters regarding the tilt would be incorporated by a consumer needing high levels of accuracy in analyzing early motion; use it if you've got it, I don't have it right now.

If tilt information is not available, then the process (for any given video) stops at producing a bounded area on a surface described by, you guessed it, pixels in the image! And it only applies to motion of that feature, nothing else! So additional features must be tracked and correlated to arrive at a partially constrained rigid body transform for the upper block, peculiar to the video. With feature data from at least one other video, expressed in the same fashion, the matrices can be transformed to common world coordinates and a path produced (finally a vector function of t to meters) from intersections of surfaces corresponding to the same physical location. This could yield the trajectory of a point in the block if desired, but that's because you now have the six degrees of freedom in position for the rigid body, translational and rotational, specified over time. Don't forget to propagate error all the way through, so a path becomes a volume bounded by surfaces in such a calculation.

There are a host of assumptions, simplifications, and estimates that can allow one to play with real distances, and I do that, but forgive me if I won't post them as data per se, now or ever. It's such a small effort to do the crude calculations but such a large expenditure for each successive escalation in quality, it's anything from trivial for the consumer or their life's work - regardless, it's their job. I will now play the role of consumer and show why consumers must take responsibility for conversion.

A proposed working model:

- Planar geometry, such that all tilt is directly away from the camera (OK with Sauret)
- Perfect hinge located on the north wall (maybe OK, I don't know)
- Tracked feature has motion in only vertical dimension, with fixed distance determined by initial conditions

The last one looks like a killer for any feature not on the hinge axis, but I don't have tilt data... can't just make it up (without a well configured iterative solver). How bad will the error be if I just blow off the tilt entirely? Let me first refer you to a couple of images of a diagram which reflects the model geometry but includes coplanar tilt as well (nothing to scale, illustrative purposes only):

Model geometry - http://i25.tinypic.com/3493rpk.jpg
Close-up of tracked feature - http://i25.tinypic.com/24414zs.jpg

The real dx and dy of a feature on the antenna mast with tipping only is depicted by the dashed blue line, the apparent dy of my model is depicted by the broken yellow line running vertically along the tower's initial centerline between intercept points with the vectors to camera. Obviously, the yellow line is taller than the blue line (that's what graphics are for!), but let's plug in some numbers and see what falls out:

Height of feature - 440m
Height of hinge - 370m
Distance to camera - 1560m

BAM! more graphs, this time calculations as a function of tip angle theta over 0-10 degrees:

Tilt and non-tilt displacement curves - http://i25.tinypic.com/30k85jo.jpg
Percent difference between tilt and non-tilt - http://i28.tinypic.com/t821s0.jpg

That's a lot of difference, too much to ignore for anything I'd want to do on early motion with that data. Until I have tilt data, pixels are as far as I can go. I understand you have some data on tipping, I don't know if you've posted or published it, but you are certainly in a position to do something with pixels whether I can or not. Value is a very subjective thing, I'm sure you'd agree.
David B. Benson
OneWhiteEye --- Well done. Two requests, if you are interested:

(1) Plot your (very fine) vertical data (from around 917 only) with the older Pixel Column 447, 448 and 449 data. I'd like to see it and it should help point up the superiority of your current technique.

(2) Longer term, can you find a feature along the roof line to track. (I'd prefer as far to the left [east] as possible)? If so, there should be enough data to determine the tilt, yes?
OneWhiteEye
QUOTE (David B. Benson+Jun 21 2008, 12:17 AM)
OneWhiteEye --- Well done.  Two requests, if you are interested:

(1) Plot your (very fine) vertical data (from around 917 only) with the older Pixel Column 447, 448 and 449 data.  I'd like to see it and it should help point up the superiority of your current technique.

(2) Longer term, can you find a feature along the roof line to track. (I'd prefer as far to the left [east] as possible)?  If so, there should be enough data to determine the tilt, yes?

Thanks.

1) Sure. If I can't tonight, it'll be early next week. There is one reason why they may not agree, and another reason they won't. If there's some variance from 29.97fps in either the internet copy or my frame dump, then the time scales will be off a little. I don't expect that. They will defintely disagree some, though, because the features are at different locations on the mast, and there is that tilt business...

2) And sure. A little (lot) harder, but it will come. And yes, tilt should be derivable.
David B. Benson
QUOTE (OneWhiteEye+Jun 20 2008, 05:58 PM)
If I can't tonight, it'll be early next week.

Thank you. I'm not in a big rush, because this other urgent project is taking much longer than expected. However, it is coming to a slow-down, if not an end.
OneWhiteEye
QUOTE (David B. Benson+Jun 21 2008, 12:17 AM)
(1) Plot your (very fine) vertical data (from around 917 only) with the older Pixel Column 447, 448 and 449 data.  I'd like to see it and it should help point up the superiority of your current technique.

And a good exercise it was. Even with frames for time, there is still the possibility for confusion. Turns out the new frame dump is offset by 10 frames from the old, so frame 800 in the new dump is frame 810 in the old. What was frame 917 is now 907. Good thing to know, eh?

Here's the old and new data together in the general range of frame 915 (by the old standard) forward:

http://i27.tinypic.com/wrm738.jpg

The new data is red with connecting lines. It doesn't go as far as the dark band data, the dishes disappear sooner. The C447 - C449 dark band is blue, green and pink. Since they pretty much lay on top of each other over this range, here's a zoom on the early portion:

http://i25.tinypic.com/2s7dkwx.jpg

As if to add to the confusion, the scale on these graphs is labeled in units of (frame - 800) in the old standard, i.e., 117 is the old 917, haha.
----------------------

Zooming in on the new data set alone was pretty interesting. Have a look at this:

http://i29.tinypic.com/2802onr.jpg

The horizontal scale is 100 frames (~3 1/3 sec), ending just before your t0, Dr. Benson. The vertical scale spans ONE pixel (~0.25m). That's a hundred data points to move one pixel but, even with the noise, there's a pretty obvious curve. Sub-pixel. Toldja.

Zooming out to 4 pixels (~1m) travel, same starting frame as before:

http://i27.tinypic.com/2cmq5hd.jpg

And finally, the whole set (about 70px travel, sorry no meters here):

http://i32.tinypic.com/34npf7n.jpg

Looks like a smooth transition at all scales. It may not be antenna motion, it could be the tripod relaxing after the cessation of vibration. But that can be ruled out with more work, and if it also shows up on the other antenna features (especially a retake on the dark band) then I would call it real.
David B. Benson
QUOTE (OneWhiteEye+Jun 20 2008, 10:04 PM)
And a good exercise it was.

It may not be antenna motion, it could be the tripod relaxing after the cessation of vibration.

Very well done.

Could you explain further?
OneWhiteEye
QUOTE (David B. Benson+Jun 21 2008, 06:40 PM)
Could you explain further?

It's purely conjecture on my part, not based on anything I know. I'm grasping for alternatives to real antenna motion, something that explains a drift of under one pixel in a time of over 3 seconds. Let me first explain what it is not.

It's not an artifact of the extraction process. Example, it can't be cumulative floating point error; each frame is examined independently, nothing is retained from the previous frame. Nothing else programmatically would even qualify as an explanation, it just does what vision does, only much better.

It's not smoke or refractive distortion, the period is too long for those and several other lesser candidates. The maximum apparent extent of the feature is 2x6 pixels, so any such disruption has to be moving across the face of this infinitesimal dot and taking over three seconds to move a meter and a half (if it's right in front of the dish, slower otherwise). That's what constitutes 'localized' distortion for this feature.

The method is not sensitive to global illumination change or intensity distortions as such. There are some potential specular reflection issues with global illumination that are hard to rule out, but sampling prior to the camera shake should give an idea of what can be expected there. Global intensity changes include things that the camera might do with respect to auto-adjust of dynamic range, say if the subject gets brighter over a period of seconds and there's nonlinear detection. It wouldn't matter. The sun could rise during those three seconds and the data would be fine, except for the specular issue.

All that's left is real motion. It could be the antenna, or it could be the camera. It's hard to imagine too many things that could result in that slow drift when it comes to camera motion. I suppose the operator could have shifted their weight near the tripod on a slightly yielding surface. Knowing the camera has just settled out from significant vibration less than a second earlier, I speculate that the joints of the tripod exhibit something of a damping effect and, being dissipative, would obey a power law on resistive force and would possibly have a very weak restoring force as strain equilibrium is approached in a joint. So the initial perturbation results in a very slight offset which restores slowly compared to the high frequency oscillations and continues for a short period after the vibration is fully damped.

It's a stretch. But no matter, all camera motion can be reliably eliminated from the data by focusing the technique on stationary features. Beyond that, the specular possibility can be resolved by baseline measurements and measurements of other features not having the same appearance (like the dark band). When all else is eliminated, then there's no choice but to accept it as real motion of the antenna, as radical as it is to see an inch of motion from a mile away!

There are a few outliers that prevent a 10 sample average (1/3 sec period) from being purely monotonic, but I haven't even done multiple passes spanning a threshold range - the data is still relatively crude. Multiple passes should somewhat diminish spurious noise, as will compositing the motion of multiple features.

10 sample average with time scale of seconds 0 = Frame 907: http://i28.tinypic.com/mmxtft.jpg
David B. Benson
Got it. I think the first thing to do is eliminate the possibility (or correct for) camera motion or air density/temperature effects. I like the idea of using the technique on a stationary feature not far from WTC 1.
einsteen
wow, there is a lot to go through. Some plots look smooth as silk, you got some spare hours OWE... A new method ? I'll check it later and hope I'll understand.

FYI, at 6 july there will be a BBC show about wtc7, in other words that show is already finished but will be casted at 6 july.
OneWhiteEye
QUOTE (einsteen+Jun 22 2008, 09:46 PM)
wow, there is a lot to go through. Some plots look smooth as silk, you got some spare hours OWE... A new method ? I'll check it later and hope I'll understand.

A refinement of an old method; since that will be the case every time, it is a new method. Indeed I had only a few spare hours recently and I wanted to get some results without making a major production out of it. The big difference between this and the code used on the F4 tail target is one line that should have been there all along: a simple subtraction in the proper location. Not that there's a bug without it. I was keeping the chaff with the wheat, so to speak.

In the video, the measurements McQueen (sp? Mac? eene?) used were not fine enough resolution to see anything but a pretty large wham. The very first smear-o-gram you posted revealed far more detail than that - at a glance - and decided the issue. Funny how little research people do into what information is available before they give lectures on a subject. With tipping, something he seems not to consider (I didn't make it through the whole video, so I may have missed it), there may not be any reason to expect a 'wham' at all. Even then, I'd imagine some pretty fine resolution would be required to see it.

QUOTE
FYI, at 6 july there will be a BBC show about wtc7, in other words that show is already finished but will be casted at 6 july.

Hosted by Jane Standley, I'll bet.
OneWhiteEye
QUOTE (NEU-FONZE+Jun 19 2008, 11:38 PM)
However, the smoothness of the antenna drop curve does suggest that it is largely a tipping motion that we are seeing (which would be very uniform if governed by the "falling pencil equation":

d(theta)/dt  =  Sqrt{ (3g/h). [1  - cos(theta)]}

This is the really interesting comment from your post, one I need to spend some time with.
NEU-FONZE
OneWhiteEye:

Yes, it's fun to play with that equation but it works best for WTC 2 because the upper section is so much taller (and approximates a pencil better!) .... for small angles the equation reduces to:

Theta = {Theta}sub zero . exp [bt]

Where {Theta}sub zero is the initial tilt angle at the moment of collapse initiation, and b approximates Sqrt {2h/3g}
David B. Benson
QUOTE (NEU-FONZE+Jun 25 2008, 06:01 AM)
Theta = {Theta}sub zero . exp [bt]

Then drop is

d(t) = cos(Theta(t)) ~ cos(k(1 + bt + ...)) = k0*cos(bt) + k1*sin(bt) ~ k0*bt

I'm not sure I tried that, although I think I did. However, the best fit, by far is

d(t) = (1/2)AT^2

where A is about 5% or so of the acceleration due to gravity acting alone. That's during the slow-moving pre-crushdown phase for WTC 1.
einsteen
QUOTE (OneWhiteEye+Jun 24 2008, 09:28 PM)
Funny how little research people do into what information is available before they give lectures on a subject. With tipping, something he seems not to consider (I didn't make it through the whole video, so I may have missed it), there may not be any reason to expect a 'wham' at all. Even then, I'd imagine some pretty fine resolution would be required to see it.

Absolutely, and especially when you are allowed to write Prof. or Dr. in front of your name. What I also don't get is that someone like Richard Gage talks about the free fall of the top section, he mentions it even in a very recent talk, he should have corrected that or someone should give him that information.
einsteen
Neu, David, nice equation, never seen that falling pencil equation, is that the same as the chimney one ? Does it also apply to 2d/3d object ? It would be a nice problem to use the old smear-o-grams where the roof and antenna's drop are compared and check if there is still a 0.3 second difference. And doesn't there exist a primitive for [1-cos(x)]^(-1/2) ??
NEU-FONZE
Einsteen:

The falling pencil (stick) is nominally similar to the falling chimney except the chimney always breaks. Some good papers are available but they may not be on the internet:

F. P. Bundy "Stresses in Freely Falling Chimneys and Columns" Journal of Applied Physics 11, 112 (1940).

H. Hartel "The Falling Stick with a > g" The Physics Teacher 38, 54 (2000).

However, there may be something more on this at:

metamars
Charles M. Beck has a new paper on arxiv.org re WTC 7

QUOTE

(Submitted on 29 Jun 2008)

Abstract: We use finite differences and the mathematical model of ``crush-up'' mode of progressive collapse proposed by Bazant and Verdure (2006) to examine anonymously published WTC 7 descent curve. We find that the collapse of the building consisted of two phases: a free-fall phase for the first 16-26 m of descent, followed by a deceleration phase that lasted till the end. The free fall phase directly contradicts the Federal Emergency Management Agency (FEMA) hypothesis (2002) regarding the initiation of collapse in WTC 7, by which the load-bearing structure slowly lost its strength due to environmental factors. We estimate the magnitude of the resistive force (the force with which the moving part of the building resisted its destruction) and find that it supports two possibilities: one put forth by Bazant and Verdure (2006), by which the moving part was intact, and the other put by Beck (2007), by which the strength of the moving part was reduced by \$\sim50\$%. The FEMA analysis suggests that the moving part was severely damaged prior to collapse.
einsteen
I asked him some time ago to participate in the discussion here, that would probably lead to more accurate smearogram_wtc7 data...

Crush-up is indeed what Shagster used here also with his PDE toolkit but here only the collapse time as function of collapse per story has been determined.
I don't know much about FEA and it will take time to go through it (the man really knows his math) but as far as I can see he tries
to prove that there is a difference between the collapse as an "intact whole" and a "weakened whole", Amirightorwrong ?
Hambone
NEU-FONZE,

I wanted to send you a PM about a new 9/11 forum I have started but your mailbox is full.

/Gregory U.
NEU-FONZE
GU:

If you contact Max Photon at JREF (by PM), and tell him I posted this at PhysOrg, he should be able to provide you with a way to contact me.

Einsteen:

You are so right about JREF!
einsteen
Did I mention them ?
NEU-FONZE
Einsteen:

You mentioned a while back that you would never go on JREF again. I just wanted to say that having now been banned at JREF, I fully understand your feelings about that forum. In fact I am thinking of writing a book about it...
stundie
QUOTE (NEU-FONZE+Jul 3 2008, 03:27 PM)
Einsteen:

You mentioned a while back that you would never go on JREF again. I just wanted to say that having now been banned at JREF, I fully understand your feelings about that forum. In fact I am thinking of writing a book about it...

You have been BANNED from the JREF Forum??

Was there any reason given for your banning Dr Greening??

OneWhiteEye
QUOTE (NEU-FONZE+Jul 3 2008, 03:27 PM)
Einsteen:

You mentioned a while back that you would never go on JREF again. I just wanted to say that having now been banned at JREF, I fully understand your feelings about that forum. In fact I am thinking of writing a book about it...

I don't know whether to offer condolences or congratulations. I predict your blood pressure will go down, and your productivity up.
NEU-FONZE
stundie:

After posting over at JREF for over a year I came to realize that there is a coterie of posters, (I have compiled a list of the worst offenders if you are interested), who are incapable of having a civilized debate about 9/11 and certainly are more likely to respond to a criticism of the NIST Report or a question regarding the physics of the collapse of WTC 1 & 2 with a bunch of personal insults and off-topic abuse, than address the issue being raised. Most unfortunately, JREF moderators such as Chillzero were happy to turn a blind eye to such abuse even though it was in clear violation of the JREF forum rules. Eventually I wrote to one of the worst offenders - who just happens to be a lawyer working in the city where I live - and informed her that I considered some of her statements to be defamatory. For this I was banned without warning ... pretty sad really. But I can see JREF's true colors come shining through!

While on this topic I must say that the PhysOrg forum posters are (on the whole) far more civilized than most JREFers although some posters (Grumpy comes to mind!) remind me of the JREF goon squad .... I would certainly like to see such behavior disallowed on the PhysOrg forum, for example, whenever a poster resorts to childish tactics like changing another posters name, or calling a poster stupid or an idiot. I believe many of these "attack-dog" posters only do this because they feel protected behind their hidden web-identities. I have no problem with someone using a nom-de-plume, but anonymity should never become a license to abuse a fellow poster even when extreme differences of opinion are being debated.
David B. Benson
QUOTE (Hambone+Jul 2 2008, 01:13 PM)
/Gregory U.

But not at JREF.

NEU-FONZE --- At least an article for some magazine?
einsteen
That's heavy Neu! She must be a good lawyer if she can get you banned from that public forum! I left because of the climate, I was not really insulted the last days. It is strange that they banned you, I'm sure you will be missed by some of the folks there, you could sign up again using the name Apollo2O (O instead of 0)... or is the cup really full now ?

NEU-FONZE
Einsteen:

I am not an American, but I thought lawsuits were a way of life in the US. Thus it's very strange that JREF should "run for the hills" when the possibility of litigation rears its ugly head, even when its only a mere hint of legal troubles for one of its members, (NOT JREF ITSELF!), ... and a member who is in fact a practicing lawyer. Oh the irony!

And I also thought that in the US, Canada, and the UK, a man is innocent until proven guilty. This dictum apparently does not apply to internet forums run by control freaks, .... Perhaps this is because JREF is happy to condone ad hominem attacks on posters who have the temerity to question the official story of 9/11. Apparently the Official Story must be defended at all costs! So I guess, now that I'm gone from JREF, its back to business at usual: Lashl-ings will continue until morale improves.....

And I do confess to one and all that I have indeed questioned the NIST Report at JREF, (AND ON THIS SITE!). Over here I have been "given the gears" by the Great Arthur many times for criticising NIST, but although Arthur has crossed the line a few times he has demonstrated a keen knowledge of all things 9/11 so I am inclined to forgive him. This is NOT the case at JREF where the technical issues are hardly ever addressed by the "NISTIANS" who prefer to "shoot the messenger' when they don't like the message.

Gregory:

I have freed up my Personal e-mail box over here and I would certainly like to discuss WTC collapse issues with you, David B, and even the dreaded Arthur!

Grumpy
NEU-FONZE

I'm sorry if you see my...short fuse with stupidity as being intolerant of logical debate. It is not. If you wish to question NIST in an intelligent manner, that is fine. But the example set by stundie(and his offensive manner)shows no intelligence, and the "troother" movement and their conspiracy theories are pure crap.

Since you were involved in the energy calculations, I find it strange that you would have anything other than quibbles with NISTs findings. Do you too think that NIST has no falsifiable theory??? Will you please explain the difference between being falsifiable and being falsified to stundie, maybe he'll get it if you do, he sure doesn't get it when I (or anyone else, for that matter)explain his obvious lack of understanding. And correct the many false facts he keeps spewing.

By criticizing NIST for the small stuff without the caveat that they were mostly right(and they were), you have provided fuel to the troother "fire" and that fire is diverting the blame from the people solely responsible(the fundamentalist muslims who attacked us) and blaming others who at worst were merely incompetent(I call it forming a circular firing squad). You should be ashamed for allowing this to occur, I find your quotes being used to support CD theories all over the net because you have failed in the responsibility to be intellectually clear and honest, you should know better.

Surely you haven't sold your scientific integrity for the fleeting fame like Steven Jones or Judy Woods, have you???

The bottom line is that the plane impacts and fires were responsible for all the events of 911, period. No other conclusion is scientifically or logically tenable. This is what NIST concluded using the available evidence and the latest techniques. I really doubt that you actually know better, and I KNOW stundie doesn't, so when he shows his butt with his attitude, he can expect to get it kicked! I will meet logic with logic, but I will also meet uninformed attitude with informed attitude! If you step into the kitchen, expect the heat.

Grumpy
NEU-FONZE
Grumpy:

Interesting response, ....... and to be expected. But you treat the NIST Report like some kind of absolute scientific truth, when we all know it was the result of a building safety study.

So get off your high (scientific) horse Grumpy and drop the "I am a victim, pity me" crap..... Are you interested in science or petty emotions?

I could point out some of the flaws in the NIST Report but I know you wont listen,... perhaps you shoud go back to JREF where you belong.....

Or, on the other hand you could consider this:

The heat-weakening of the steel on the fire affected floors...... Let’s look at NIST’s “science” dealing with this topic as presented in NCSTAR 1-3 and 1-3D. In the Executive Summary of NCSTAR 1-3 we discover the sad truth about NIST’s sample collection as a source of evidence of elevated temperatures experienced by WTC steel members. Thus we read on page xli:

“More than 170 areas were examined on the recovered perimeter columns; however, these columns represented only 3 % of the perimeter columns on the floors involved in fire and cannot be considered representative of other columns on these floors. Only three locations had evidence that the steel reached temperatures above 250 deg C.”

Notice the “disclaimer” by NIST that the samples were not “representative” when it was NIST scientists that selected these samples and claimed they were adequate as “physical evidence” for their planned investigations. Anyway, NIST go on to admit that it also found “limited exposure to temperatures above 250 deg C” for all the core columns recovered from the fire-affected floors of the towers.

Now you would think that such a dearth of evidence of high temperature exposures of the WTC steel would make NIST look a little harder for collapse mechanisms involving steel at low temperatures, say less than 400 deg C. But NIST does not do this, and even states in Chapter 6 of NCSTAR 1-3D:

“Creep at temperatures less than 400 deg C is insignificant, so the specifics of the behavior at low temperatures will not affect the measurable strain.”

Now this is a very sad thing for NIST to say since there are PLENTY of experimental studies that show creep buckling of steel columns can be VERY significant at temperatures well below 400 deg C. (See for example Zhan-Fei Huang et al. in Engineering Structures 28, 805 (2006) and J.L. Zeng et al. in Journal of Constructional Steel Research 59, 951, (2003).)

Nevertheless, NIST, in its wisdom, carried out creep tests at temperatures as high as 650 deg C, even though it has no physical evidence that any WTC steel reached such temperatures. But NIST’s research only gets further from reality when we read that in its creep tests specimens were heated for at least 2 hours when we know that any individual steel member in the WTC was heated by the fires for less than an hour. Worse yet we find that NIST’s creep tests were on truss-rod “A-242 steel” which turned out to have Cr and Ni alloying additions that did not actually conform to ASTM A-242!

But buried deep within NCSTAR 1-3D, on page 137 to be precise, we find NIST’s ultimate non sequitur in its consideration of steel at high temperatures. Thus, after assuring us that steel WEAKENS when exposed to high temperatures, NIST glibly admits that:

“Some steels initially increase in strength with increasing temperature, through the process of dynamic strain-aging, but this behavior is not a priori predictable”

So let me get this straight Grumpy!

For NIST’s investigation of 9/11, the “scientific method” consists of:

1. Rejecting anything that is unpredictable as being unimportant.
2. Looking at the available physical evidence and when it fails to deliver on expectations conclude it is of no value because it is not statistically significant.
3. Relying on the results of tests carried out under conditions that were never realized in the towers.
4. Creating computer-generated “simulations” of the aircraft impacts and fires and tweaking them until the desired result (the towers collapse) is found. This is called “validating the simulation”.

OneWhiteEye
Caught you when you were busy with other things, but...

QUOTE (NEU-FONZE+Jun 25 2008, 01:01 PM)
OneWhiteEye:

Yes, it's fun to play with that equation but it works best for WTC 2 because the upper section is so much taller (and approximates a pencil better!) .... for small angles the equation reduces to:

Theta  =  {Theta}sub zero . exp [bt]

Where {Theta}sub zero is the initial tilt angle at the moment of collapse initiation, and b approximates Sqrt {2h/3g}

Yes, it's much more appropriate for WTC 2. The North Tower is closer to a cube rotating about an edge, which is a pendulum, too, but twice the MOI (of a thin rod)and an initial angle of 45 degrees from vertical (135 degrees deflection from straight down). The block would have non-zero and increasing acceleration magnitude at Tzero, if rotating freely. The biggest difference, though, is the non-negligible width of the upper block allows the lower portion to provide significant resistance to rotation, so it is not rotating freely.

I put the edge of a big block on top of a wall made of little blocks, and let it go. It looks like this:

http://rapidshare.com/files/126929835/OneW...ipping.avi.html

http://rapidshare.com/files/126930844/NoTi...Height.avi.html

Then I put in some initial tilt:

http://rapidshare.com/files/126933404/Very...Height.avi.html

I'm not under the illusion that these mean much but it was fun and the work is precursory to some more interesting simulation. I have a tipping rod and chimney, too, which breaks (in two or three places if tall enough).
David B. Benson
NEU-FONZE --- NIST is correct in their statement regarding statistical significance.

You may certainly blame their steel sample collection methods. That, it turns out, was not well done.

As for the matters regarding the behavior of steel at elevated temperatures, one would expect the NIST building safety group to know the relevant literature. In any case, in all the public comment sessions, none of the engineers present seem to have brought up your concerns.

I'm not saying those criticisms are not valid; they may well be. But science progresses typically by writing papers which are then read. At least you are reading the NIST report with a critical eye.
newton
former senator mike gravel calls for justice

canadian parliament hears petition for 9/11 truth (scroll down for: "Open Civil Engineering Journal publishes letter by scientists Steven E. Jones, Frank M. Legge, Kevin R. Ryan, Anthony F. Szamboti, James R. Gourley, who hypothesize that on 9/11, World Trade Center Towers 1, 2 & 7 were brought down by controlled demolition
")
newton
Grumpy
NEU-FONZE

QUOTE
Grumpy:

Interesting response, ....... and to be expected. But you treat the NIST Report like some kind of absolute scientific truth, when we all know it was the result of a building safety study.

I know the NIST reports are not perfect, however, there will NEVER be a better scientific study done due to the paucity of the physical evidence(not NIST's fault, they were called in late). Once first responders determined that the cause was not explosives the scene was treated as a disaster site, not a crime scene. Rescue and recovery were their primary goals, not preservation of forensic evidence.

NIST found MANY samples of steel that was exposed to high temps, but their conservative sampling procedures rejected them all because they were unable to determine whether the exposure to high temps was a pre or a post collapse exposure. Instead they relied on thermal imaging and their extensive data base and tests on fire investigations to determine the temps the steel was exposed to during the fires. Less accurate, sure, but within the ballpark, nonetheless.

QUOTE (->
 QUOTE Grumpy:Interesting response, ....... and to be expected. But you treat the NIST Report like some kind of absolute scientific truth, when we all know it was the result of a building safety study.

I know the NIST reports are not perfect, however, there will NEVER be a better scientific study done due to the paucity of the physical evidence(not NIST's fault, they were called in late). Once first responders determined that the cause was not explosives the scene was treated as a disaster site, not a crime scene. Rescue and recovery were their primary goals, not preservation of forensic evidence.

NIST found MANY samples of steel that was exposed to high temps, but their conservative sampling procedures rejected them all because they were unable to determine whether the exposure to high temps was a pre or a post collapse exposure. Instead they relied on thermal imaging and their extensive data base and tests on fire investigations to determine the temps the steel was exposed to during the fires. Less accurate, sure, but within the ballpark, nonetheless.

So get off your high (scientific) horse Grumpy and drop the "I am a victim, pity me" crap..... Are you interested in science or petty emotions?

I said nothing about me being a victim, but I would ask you the same question, Are you interested in science, or in supporting the emotional response of conspiracy theorists that "It must have been_____!"?

State plainly whether you think the impacts and fires were solely responsible for the collapses. Stop giving the idiots of the lunatic fringe ammo for their delusions!!!(see newton's last). THEN you can criticize NIST all you like and your criticisms will be taken seriously. Your ambiguity and lack of clarity on this point is really the only conflict of importance we have(though you are also wrong in many of your criticisms IMHO, example, Of what use is any computer sim(in any discipline) that produces results which DO NOT match with reality, other than to tell you that your initial parameters are off???).

QUOTE
Nevertheless, NIST, in its wisdom, carried out creep tests at temperatures as high as 650 deg C, even though it has no physical evidence that any WTC steel reached such temperatures

No steel samples does not mean no evidence, NIST had to work with what it had, not what it wanted.

QUOTE (->
 QUOTE Nevertheless, NIST, in its wisdom, carried out creep tests at temperatures as high as 650 deg C, even though it has no physical evidence that any WTC steel reached such temperatures

No steel samples does not mean no evidence, NIST had to work with what it had, not what it wanted.

So let me get this straight Grumpy!

For NIST’s investigation of 9/11, the “scientific method” consists of:

1. Rejecting anything that is unpredictable as being unimportant.
2. Looking at the available physical evidence and when it fails to deliver on expectations conclude it is of no value because it is not statistically significant.
3. Relying on the results of tests carried out under conditions that were never realized in the towers.
4. Creating computer-generated “simulations” of the aircraft impacts and fires and tweaking them until the desired result (the towers collapse) is found. This is called “validating the simulation”.

1. It's called being conservative. If it is unpredictable it cannot be known precisely and MUST be left out of the equation. Would you prefer if they had just speculated???

2. Untrue.

3. Also untrue.

4. Again, of what use is any simulation whose results do not match the observations except to tell you your initial parameters were wrong. NIST's fire models come from their extensive experience in structure fires and have been validated over YEARS. They may not be perfect, but given the lack of detailed evidence of the exact damage and fire behavior it is as close as you will ever get.

Again, you need to be clear first on where you DO agree with NIST, it is your responsibility because as long as this is unclear your words of criticism will be used by nutters to support their idiocy.

Grumpy
einsteen
QUOTE (OneWhiteEye+Jul 4 2008, 12:42 AM)
Caught you when you were busy with other things, but...

Yes, it's much more appropriate for WTC 2.  The North Tower is closer to a cube rotating about an edge, which is a pendulum, too, but twice the MOI (of a thin rod)and an initial angle of 45 degrees from vertical (135 degrees deflection from straight down).  The block would have non-zero and increasing acceleration magnitude at Tzero, if rotating freely.  The biggest difference, though, is the non-negligible width of the upper block allows the lower portion to provide significant resistance to rotation, so it is not rotating freely.

I put the edge of a big block on top of a wall made of little blocks, and let it go.  It looks like this:

http://rapidshare.com/files/126929835/OneW...ipping.avi.html

http://rapidshare.com/files/126930844/NoTi...Height.avi.html

Then I put in some initial tilt:

http://rapidshare.com/files/126933404/Very...Height.avi.html

I'm not under the illusion that these mean much but it was fun and the work is precursory to some more interesting simulation.  I have a tipping rod and chimney, too, which breaks (in two or three places if tall enough).

Your toolset must be big, how do you make that ?

http://i32.tinypic.com/hra1cx.gif

impressive!

ps. I stopped using rapidshare (you can download only one file per time period), megaupload doesn't have that limit...
NEU-FONZE
Grumpy:

I cannot prevent truthers from reading anything I write and putting their own particular "spin" on it. Please show me an example of where I have provided truthers with what you call "ammo".....

9/11 was a terrible event; you may consider it "solved" but I still have lots of questions about it. However, if it makes you feel better I will say that I do not believe explosives were used to topple WTC 1 & 2. Nevertheless, I am still puzzled by the collapse and especially its initiation.

I now believe that the upper block did not drop one floor and hit the structure below. I and others may have used this idea in calculations of the collapse times, but for me it was an approximation I made to simplify the math! The upper block was connected to the lower block by at least 40 core columns and hundreds of perimeter columns. The load of the upper block could not be suddenly taken off the lower structure; thus the upper block could not drop under free fall onto the structure below.

Also NIST's argument that the PE released by the descent of the upper block overwhelmed the strain energy absorbing capacity of the structure below lacks computational confirmation. How was the strain energy distributed? How much strain energy went to the upper block? If the fires heat-weakened the steel, the columns ABOVE the impact floors would have been weakened the most because they were thinner and would have received the greatest heat flux. Why did the upper block not simply crumple while it remained attached to the lower block?

It's questions like these that keep me researching the collapse of the towers. If I encourage others to ask similar questions, so be it!
stundie
QUOTE (NEU-FONZE+Jul 3 2008, 05:19 PM)
stundie:

After posting over at JREF for over a year I came to realize that there is a coterie of posters, (I have compiled a list of the worst offenders if you are interested), who are incapable of having a civilized debate about 9/11 and certainly are more likely to respond to a criticism of the NIST Report or a question regarding the physics of the collapse of WTC 1 & 2 with a bunch of personal insults and off-topic abuse, than address the issue being raised. Most unfortunately, JREF moderators such as Chillzero were happy to turn a blind eye to such abuse even though it was in clear violation of the JREF forum rules. Eventually I wrote to one of the worst offenders - who just happens to be a lawyer working in the city where I live - and informed her that I considered some of her statements to be defamatory. For this I was banned without warning ... pretty sad really. But I can see JREF's true colors come shining through!

While on this topic I must say that the PhysOrg forum posters are (on the whole) far more civilized than most JREFers although some posters (Grumpy comes to mind!) remind me of the JREF goon squad .... I would certainly like to see such behavior disallowed on the PhysOrg forum, for example, whenever a poster resorts to childish tactics like changing another posters name, or calling a poster stupid or an idiot. I believe many of these "attack-dog" posters only do this because they feel protected behind their hidden web-identities.  I have no problem with someone using a nom-de-plume, but anonymity should never become a license to abuse a fellow poster even when extreme differences of opinion are being debated.

Thanks for the reply and I am surprised by your banning but I'm not surprised at the reasons given, simply because you were not following JREF Groupthink TM and your accusations of defamatory statements were against a Forum Donor no doubt?

My experience with JREF was very brief, I decided to join and see if I could open up the minds of these so called sceptics. I was debating quite a few people and one who stood out was Gravy, (At the time I didn't have a clue who he was!) according to him and JREF Groupthink, Mineta statement was ignored by the 9/11 Commisson because Mineta had got his times all his wrong, when I asked for evidence of this, I got told that the plane which was "50 miles, 30 miles" etc etc was UA93, even though Mineta states, that they no information on UA93 until after it had crashed.

So I pointed out this contradiction and it was all going so well, highlighting these ridiculous excuses as to why Mineta statement was wrong, when all of a sudden, I logged on one morning to discover a message saying I am banned. I contacted the Admin, but I never received a reply, so after a few days, I gave up trying to contact them and ended up joining the Screw Loose Change Forum.

A poster came on the SLC forum to tell how he had been banned from the Loose Change forum, so I told them about how I got banned from the JREF forum and explained that I didn’t have a clue as to why! Then someone called Orphia Nay emailed me at the SLC forum to tell me why I had been banned. Its funny how people knew about my banning before I did.

The Moderators thought I was a sock of a poster called "Pdoherty" (Again, I had no clue who he was at the time!) and had banned me. How they came to this conclusion??...I have been told that I had a similar IP address to him, even though I was posting from 2 different computers in 2 different areas.

That was the only proof they needed, the accusations of others. if you had seen my posts, it was clear that I had limited experience of forums as a poster called Maccy would often tell me off for posting in the wrong thread and opened a couple for me. In my eyes, this was definitely a face saving exercise from the other members and the moderators in order to protect their beloved spiritual leader Gravy as his lies were being exposed.

Since my banning, I have seen numerous people banned for nothing more than not following JREF Groupthink, I've seen accusations accusing poster of being sock puppets of me, pdoherty and others without a single shrapnel of evidence being acted upon and then subsequently banned.

The moderators allow the groupthink lynch mob to run riot by attacking anyone who doesn't follow the official line, if a "twoofer" retaliates, then they are threatened or banned, while the lynch mob sometimes do get warned, but more often than not, it is over looked. Chillzero being the worst from my point of view, just recently she warned a labelled "Twoofer!" to stop attacking, but when it was pointing out (By Greg Ulrich I think?) that this "Twoofer!" was just defending themselves from other attacks, the thread was sent to Abandon All Hope and I believe, not a single "debunker" was warned, or banned to my knowledge.

To this day, the moderators are fully aware that I am not Pdoherty or a sock of his. Yet my banning as never been overturned for the simple reason that if it was, then The Stundie Awards would have to be scrapped as it would contradict their own rules about attacking members.

If you need to see an example of this bias, then look no further than this current thread where Red Ibis is being attacked and labelled as an Anti-Semite by none other than the ranting, foaming at the mouth Pomeroo and others, even though Red Ibis as never made a single derogatory remarked about Jewish people or their religion.

They allow this to continue without any intervention. Maybe it is because of their own biased which wants to believe that all twoofers are or must be Anti-Semite/Nazis. This whole thread is nothing more than an attack without a single shrapnel of evidence to support it. Of course, being a Forum Donor like Pomeroo, gives you more freedom to attack and forum donors know this, it's not like the Moderators are going to ever ban someone who contributes money to the foundation, because the moderators will never bite the hand that feeds them.

You are right about this forum and it is definitely more civilised. The reason I ignored Grumpy posts is because I do not want to bring this forum down to the levels of JREF or even worse, the SLC forum. However, I do not think it's necessarily the protection that their hidden web-identities give them for their need to abuse people who don't conform to their personal beliefs, I feel it's a more of psychological issue as outlined Anna Freud in her analysis of the ego and defence mechanisms.

I am sorry to hear about your banning, I am sure I will be one of many who will actually miss your posts over there but hope that you continue to contribute towards this forum or another in discovering the truth surrounding 9/11. Even though we disagree on the CD theories, I have always admired the fact that you have the intellectual honesty and integrity to see through the groupthink herd which flocks at the JREF Forum, even at the expense of being labelled a "Twoofer!"

Cheers

Stundie
p.s. Please feel free to post the list of names, although I get a feeling I can guess most of the name already on it.
lozenge124
QUOTE (OneWhiteEye+Jul 4 2008, 12:42 AM)

I put the edge of a big block on top of a wall made of little blocks, and let it go.  It looks like this:

http://rapidshare.com/files/126929835/OneW...ipping.avi.html

http://rapidshare.com/files/126930844/NoTi...Height.avi.html

Then I put in some initial tilt:

http://rapidshare.com/files/126933404/Very...Height.avi.html

I'm not under the illusion that these mean much but it was fun and the work is precursory to some more interesting simulation.  I have a tipping rod and chimney, too, which breaks (in two or three places if tall enough).

That's great! I look forward to more of your simulations.

What software are you using?
Grumpy
NEU-FONZE

Wow, heat caused a damaged steel structure to collapse, how strange. Not really!!!

There is no mystery about the tower collapses, it didn't take any investigation to know the cause. In fact it is likely that if 747s had been used the buildings(especially 2) would have fallen immediately. Buildings are never built with that much redundancy or excess strength, it's just not economic nor necessary. It is really a testament to their excellent design that they stood as long as they did.

But as to your claimed lack of responsibility for the misuse of your words, I don't buy it. In fact it is beginning to look as if you have been deliberately obtuse and ambiguous, trying to seem to be a "skeptic" while at the same time maintain some scientific credentials.

Sorry, that cannot be done. Either chose to maintain your scientific integrity or lose it, it's up to you.

Grumpy
newton
QUOTE (Grumpy+Jul 4 2008, 08:53 AM)
NEU-FONZE

Stop giving the idiots of the lunatic fringe ammo for their delusions!!!(see newton's last).

Grumpy

"newton's last" had absolutely nothing to do with neu-fonze's post.

do you even know what day it is? i know you can't think for yourself.

i posted some updates on the state of the argument as it is evolving in the real world. you may have heard of it. it's the world where there are no armies of sock puppets.
you have nowhere near the scientific reasoning skills of NF. and you are attacking him because his very valid critique of the NIST report doesn't fit within your highly rhetorical, dogmatic approach to reality.

newton
collapse simulator vid 1

collapse simulator vid 2

i 'wonder' why this was too hard for the 'experts' at NIST to manage.
newton
newton
QUOTE (OneWhiteEye+Jul 4 2008, 12:42 AM)
Caught you when you were busy with other things, but...

Yes, it's much more appropriate for WTC 2. The North Tower is closer to a cube rotating about an edge, which is a pendulum, too, but twice the MOI (of a thin rod)and an initial angle of 45 degrees from vertical (135 degrees deflection from straight down). The block would have non-zero and increasing acceleration magnitude at Tzero, if rotating freely. The biggest difference, though, is the non-negligible width of the upper block allows the lower portion to provide significant resistance to rotation, so it is not rotating freely.

I put the edge of a big block on top of a wall made of little blocks, and let it go. It looks like this:

http://rapidshare.com/files/126929835/OneW...ipping.avi.html

http://rapidshare.com/files/126930844/NoTi...Height.avi.html

Then I put in some initial tilt:

http://rapidshare.com/files/126933404/Very...Height.avi.html

I'm not under the illusion that these mean much but it was fun and the work is precursory to some more interesting simulation. I have a tipping rod and chimney, too, which breaks (in two or three places if tall enough).