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Failure mode in WTC towers

Heiwa said:
Full story at http://heiwaco.tripod.com/nist.htm and http://heiwaco.tripod.com/nist1.htm . Takes 10 minutes to study. The PE of the upper block is very small! Cannot produce any total, gravity driven collapse of avalanche type of the structure below. The structure below is much too strong for that and the strength below is located where any PE from above will never be applied.
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The World Trade Center was built like a bird cage? I'm not sure if I want to be in a building designed by Hagen...
 
Heiwa said:
No, horizontal wind forces on one wall are transmitted by the floors to the core and then to the opposite wall via the floor pin joints to the columns.

Evidently these intermittent (wind) axial forces in the floors produces shear forces and thus bending moments in the perimeter columns. But they are ... intermittent.

The floors would not drop down due to that. Or anything else for that matter, incl. air plane crashes, fire, etc.

No total, global collapse of structure below is ever possible due to some local collapses up at the top.

More questions? Hopefully, intelligent ones.
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Either your english is terrible and you fail to put across what you really mean, or that statement is hilarious given the following statement

Or you could also be lying?

Its about evens at the moment
 
On column moment

Newtons Bit,

Thanks again for the diagrams.

Isn't N7-N8 more representative of what realcddeal is describing than N1-N2? Perhaps I'm not following.

Max
 
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Thanks for the diagrams, NB.

Now lets see if they are consistent with what was observed.


Curiouso Number 4: Characteristics of Collapse Initiation and Progression Along The East Face of the South Tower.

The only perimeter portions seen being pulled inward on the South Tower were along this face. It can be seen in the following clip:

South Tower Stabilized. NBC High Quality South Tower Collapse. High quality stabilized video of the east face, floors 75 to 85, at the moments of collapse initiation. The camera then zooms out to capture the ejection patterns along the collapse front of the east face.
http://www.youtube.com/watch?v=a7e79Tjt5Gk&feature=related


The inward pulling was a rather fast process. It is immediately followed by a rather forceful OUTWARD pushing. Please recall that curiouso number 3 notes that the mechanical room perimeter column sections just under the collapse initiation point were discovered unbucked, speared into the earth and were some of the furthest displaced perimeter sections found to the east.


Contradiction: If these perimeter sections were seen being pulled inwards during collapse initiation, why were the perimeter sections just below them found to be some of the farthest displaced sections from the footprint?

If they were being pulled inwards, this means that they were being pulled in by flooring that was still firmly attached.

The following 3 clips are excellent recordations of ejection patterns seen during and just after collapse initiation along this face. All incorporate slow motion and repetition to record these ejections in detail


9/11: South Tower NBC Closeups. The camera is fixed on the north and east facades. The editor crops and uses slow motion and repetition to reveal the ejection patterns along these 2 faces during collapse initiation and progression.
http://www.youtube.com/watch?v=xtpWu-XZ7kM


9/11: South Tower NBC Closeups Version 2. Same as above using some different editing.
http://www.youtube.com/watch?v=COpfvXj_BVo


9/11: History Channel South Tower. From the northwest. Wonderful compliment to the two previous clips. Collapse initiation and ejection patterns with slow motion editing.
http://www.youtube.com/watch?v=AXak_ok9Vqo&feature=related



The first thing we notice is that the first 2 noticable horizontal rows of ejections are separated by about 3 floors.

Contradiction: Why do the ejections clearly skip a few floors?

Contradiction: What is happening along the northeast corner in the 3 clips above?

According to the silly idea of floors hitting the floor below, thereby cleanly separating the floor from the perimeter, we wouldn´t expect the ejections to skip floors. We also wouldn´t expect the ejections along the northeast corner to skip a few floors, forcefully eject "dust" all the way to the very corner on some floors while not doing so on other floors.

Why do I say that the perimeter was cleanly separated from the flooring? Because we have seen in curiouso number 3 that the east facade fell away from the building largely as a single interconnected piece below the collapse initiation zone.

These ejection patterns seen in the group of 3 clips mentioned above can go a long way in helping us understand the collapse mechanism along WTC 2, east face.

If your theory is contradicted by these ejection patterns, then it will have to be abandoned.


NB, do your ideas of inward bowing followed by collapse initiation and progression along the east face of WTC 2 match these ejection patterns?

If you don´t apply your model to this facade, which is the only noticable inward bowing observed on WTC 2, where would you apply it?

This facade would be the perfect place to apply your model, no?
 
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The first thing we notice is that the first 2 noticable horizontal rows of ejections are separated by about 3 floors.
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WTC2_3floors.jpg
 
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It seems rather silly to me to label that an explosion given that the building is already in the process of collapsing. Furthermore, if that was an explosion, it was not a very powerful one. Look how little disruption there is in the smoke, and notice how there is no sign of shrapnel departing from the building at high speed.
 
Heiwa said:
Sorry, as joints N1, N2, etc are pin joint there is no bending moment in left column N, anywhere! Just compression. OK, if top joint N4 moves transversly there is some moment ... but negligible. And your model cannot calculate that! But your are 100% right - horizontal floor beams bends more when the connection to the column is a pin. Reason? The bending moment is zero at the pin. More intelligent questions?
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When did you realize that you had no head for physics and decide to become a mere charlatan?
 
Major_Tom said:
Please recall that curiouso number 3 notes that the mechanical room perimeter column sections just under the collapse initiation point were discovered unbucked, speared into the earth and were some of the furthest displaced perimeter sections found to the east.


Contradiction: If these perimeter sections were seen being pulled inwards during collapse initiation, why were the perimeter sections just below them found to be some of the farthest displaced sections from the footprint?
Click to expand...

If, indeed, this is in fact a contradiction - which is by no means established - it depends entirely on your correct identification of the specific perimeter sections, and on the assumption that they were indeed "speared into the earth" and not being lifted by a crane as your photograph seems to suggest. Do you feel that you have satisfactorily established either of these assertions as fact?

Dave
 
pomeroo said:
When did you realize that you had no head for physics and decide to become a mere charlatan?
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He doesn't realize that in the real world, the beams are connected to the side of the column and not the centerline.
 
Newtons Bit said:
He doesn't realize that in the real world, the beams are connected to the side of the column and not the centerline.
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In a pure beam model all members are connected (pin or fixed (or with a spring)) at the centerline of the members - as there are no sides of the model beam members. (You can evidently fit an extra, small beam to simulate the distance from the centreline and the side of a column ... if you know what properties to define this little beam).

The pure (2D) beam model only indicates how the loads applied become forces (axial, transverse (shear) and bending moments that are transmitted through the model beams to some fixed supports (the ground!). In 3D beam models, torsion can be of interest.

A good check that the analysis is correct is evidently that the loads applied correspond to the reaction forces at the fixed supports.

The 2D analysis can also be done long-hand, if you are clever.

For more detailed analysis of, e.g. a connection of a vertical column and a floor truss, FEM is recommended, where the sides of the column can be included as separate elements, etc.

I have only done this type of analysis for 40 years so I am probably a charlatan.
 
Major_Tom said:
[qimg]http://www.sharpprintinginc.com/911_math/WTC2_3floors.jpg[/qimg]
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I like the photo of the Lower Explosion where the corner column of the rigid upper block above is inclined say 10°! It is vertical on Upper Explosion photo a second earlier. Quite quick rotation, to say the least, of an upper block that is supposed to drop straight down intact!

If you continue looking at the videos you will note that the rigid upper block above actually disintegrates after 2 more seconds, so you wonder what potential energy from above could then ensure that the alleged gravity collapse continued.

Gravity collapses require an input of potential energy from above! The input from above is not supposed to disintegrate as shown in the WTC collapse.

Another smoking gun to add to the collection!
 
Heiwa said:
If you continue looking at the videos you will note that the rigid upper block above actually disintegrates after 2 more seconds, so you wonder what potential energy from above could then ensure that the alleged gravity collapse continued.
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Which weighs more, a 30,000 ton building or 30,000 tons of rubble?

Dave
 
Dave Rogers said:
Which weighs more, a 30,000 ton building or 30,000 tons of rubble?

Dave
Click to expand...

Evidently they weigh the same and if they drop from the same height they release the same amount of potential energy, PE.

Take WTC1 for example. The upper block above the initiation zone weighs 33 000 tons. It has a uniform density of 0.18 ton/m3.

Let's assume it is denser, like water, 1 ton/m3 and that you drop 33 000 tons of water on the WTC1. Do you expect that WTC1 gravity collapses if you drop 33 000 tons of water on it? Evidently not! The water splashes on WTC1 when it comes in contact with it and drops to the ground beside it. No total, global gravity collapse of WTC1 will occur in spite of the fact that you dropped 33 000 tons of weight on it and its associated PE.

Of course, it was not water that was dropped on WTC1. It was something with much less density - a big upper block with uniform density only 0.18 ton/m3 - but still it weighted 33 000 tons. Same PE.

Nist suggests in its 10000 pages report that as the PE of the mass (block) above exceeds the strain energy of the structure below, the latter collapses. But it doesn't work for water with density 1! Does it work for an upper block with density 0.18. In my opinion not, Nist disagrees.

In my opinion, the PE or the weight of the mass above is irrelevant. You have to look deeper, e.g. study the structure of the mass above and its strain energy that keeps it together. Water has apparently very little inherent strain energy if you drop it. It just splashes in contact with something more solid, rigid or stiff.

But has the upper WTC1 block more inherent strain energy? As far as I am concerned it disintegrates before it impinges on the structure below (as seen on all videos) and cannot cause any global, total gravity collapse.

So the PE released above is irrelevant. I have asked Nist to go back to the drawing board and design something more realistic and they suggested that some floors in the upper block dropped down????

I have seen no evidence for that.
 
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Heiwa said:
Let's assume it is denser, like water, 1 ton/m3 and that you drop 33 000 tons of water on the WTC1. Do you expect that WTC1 gravity collapses if you drop 33 000 tons of water on it? Evidently not! The water splashes on WTC1 when it comes in contact with it and drops to the ground beside it. No total, global gravity collapse of WTC1 will occur in spite of the fact that you dropped 33 000 tons of weight on it and its associated PE.
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So, large masses of moving water cannot damage steel structures? Are you certain of that? Never seen it happen, in your 40 years of professional experience?

Your 33,000 tons of water is an eight meter deep layer over the area of an entire floor. "Dropped" on the floor below, it would deliver an enormous impulse. (Of course, if you poured it out a little at a time, it would do no great damage. But that's irrelevant; you're comparing it to the impact of the upper structure which was all at once.) Changing the direction of all that water so that it spills off the sides would require a lot of force. I think the structures, especially the floors, could not exert sufficient force and instead would fail, so the water would keep moving downward, collapsing the tower. You'd have to show calculations to convince me that the structure could withstand it. Handwaving won't do it.

Respectfully,
Myriad
 
Heiwa said:
In a pure beam model all members are connected (pin or fixed (or with a spring)) at the centerline of the members - as there are no sides of the model beam members. (You can evidently fit an extra, small beam to simulate the distance from the centreline and the side of a column ... if you know what properties to define this little beam).

The pure (2D) beam model only indicates how the loads applied become forces (axial, transverse (shear) and bending moments that are transmitted through the model beams to some fixed supports (the ground!). In 3D beam models, torsion can be of interest.

A good check that the analysis is correct is evidently that the loads applied correspond to the reaction forces at the fixed supports.

The 2D analysis can also be done long-hand, if you are clever.

For more detailed analysis of, e.g. a connection of a vertical column and a floor truss, FEM is recommended, where the sides of the column can be included as separate elements, etc.

I have only done this type of analysis for 40 years so I am probably a charlatan.
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No, Heiwa. I posted a full fledged 3d Finite Element Model. It has properly modelled fixed end offsets from column to beam which represent how the beam is attached to the side of the column. You do not need to model the sides of the column with seperate elements to do this. Single lines (elements) can represent a vast amount of information in FE, the fact that you don't understand this tells of your ignorance on the subject. And no, you haven't done this analysis for 40 years. 40 years ago FEM wasn't available to anyone except the airline industry, specifically in turbines and universities who were still trying to figure the concept out.

Explain to me again how a connection like the one below induces zero moment into the column:



^That detail is similar (not exact) to what was at the WTC. You said it doesn't because it's pinned. Mr. Szamboti says it can't because the columns are fixed. At least one of the two of you must be wrong since you're arguing mutually exclusive concepts. Though in reality, you're both wrong. You just don't understand how buildings are put together, and he doesn't understand basic newtonian physics.
 
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Dave comments:

If, indeed, this is in fact a contradiction - which is by no means established - it depends entirely on your correct identification of the specific perimeter sections, and on the assumption that they were indeed "speared into the earth" and not being lifted by a crane as your photograph seems to suggest. Do you feel that you have satisfactorily established either of these assertions as fact?
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Yes. Norseman asked a similar question when curioso number 3 was introduced. I referred him to photo libraries that show the same column sections were in the same place while firemen were walking around in an understandably dazed state on 9-11-01. He understood and admitted my claim of the original locations and states of these column sections was indeed correct.

There are many photos of these same column sections, always in the exact same location, in the following 2 albums.

http://www.sharpprintinginc.com/911...p=view&PHPWS_Album_id=12&MMN_position=102:102

http://www.sharpprintinginc.com/911...p=view&PHPWS_Album_id=27&MMN_position=139:139

Many, many photos of the same column sections, some of which were taken on 9-11.

The spacings of the mechanical room floors relative to typical office flooring are distinctive. I reproduce curioso number 3 below for easy reference.

Curioso #3: There is evidence that the east facade of WTC 2 from the 80th floor downwards fell as an interconnected single sheet of unbuckled perimeter column sections. The spandrel plate connections and column-to-column bolt connections remained largely intact until far into it's fall or upon hitting the ground.



Proof:



In the following photo please notice the location of the mechanical room relative to floor 81 where the inward bending will form.

mech_room.jpg





The mechanical room has noticably higher ceilings than the other floors both above and below.

I believe I have located where a number of perimeter columns of this mechanical room were found in the rubble, shown below.

mech_room_perimeter.jpg



These perimeter columns are clearly speared into the earth.

They were pushed outwards and fell close to 80 floors. They were then speared into the earth with obvious extreme force.

Despite this, they held up well and exhibit no noticable buckling along their lengths.

As odd as that may seem, it is the location at which they were found that is even more surprising.

The following 2 photos will help us identify their location.

mech_room_perimeter_2.jpg


mech_room_perimeter_3.jpg





These columns were located on the edge of the street on the other side of WTC 4.

They were some of the farthest columns spotted in that direction.

Lets look at a map of the complex.

wtc_map.jpg




These columns cleared the entire WTC 4 building and ended up speared into the ground on the edge of the street.


The following video clip shows a large sheet of intact perimeter columns seen falling away from the building after the "upper block" had escaped view.


http://www.youtube.com/watch?v=nLHGLI1Ihv0


Please note the visible perimeter sheet at 0:17 of this 0:21 second clip.

This sheet is the intact perimeter columns of the LOWER BLOCK falling outwards. It is not in freefall. It is being pushed outwards just as if it is just the top of an intact sheet peeling away from the building.

It is easy to see that the top columns are from the 78, 80th floor area. Therefore we expect to find (and do find) the tops of these columns among the farthest displaced debris directly to the east.


Once again, no collective buckling seen among the members of this sheet as they are seen in the rubble. The single sheet peeling away means that perimeter connections largely survived the initial peeling process.

The connections seemed to "fail" just along the collapse initiation area and along the 2 edges of the east facade, hence the single sheet.
Click to expand...


NB, once again thanks for your efforts to create a model. This model needs to be tested by seeing whether it is consistent with observed phenomena.

I personally cannot see how your model can explain the observed phenomena mentioned in curiosos 3 and 5, but I will await your explanation with interest.


If they are inconsistent, which do you abandon, your model or the observed phenomena?
 
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