Moderated Steel structures cannot globally collapse due to gravity alone

Architect said:
1. And how, pray, does that load displace? Be specific, now.



2.The last point is wrong. Failure often occurs at the lower and upper joints rather than locally within the column, depending upon the design of the column and the bracing effect of other members at the joints.



3.No, that depends upon the failure mode. See above.



4.This is just plainly wrong, I'm afraid. But do feel free to post some calculations attempting to prove it.




5. You seem to place a lot of faith in the ability of a buckled (i.e. failed) column to transmit the full load within the original design parameters.




6. Your density argument has been thoroughly debunked many, many times at JREF.


7. And yet most of the truthers say the building collapsed into its own footprint. Really, we need some consistency here.



8. Millions of people and hundreds of thousands of structural engineers, architects, fire engineers........and only you noticed. Arup and wrong. Edinburgh University is wrong. Whoever redrafted the Eurocodes is wrong. Hmmm.
Click to expand...

1. The load displaces with the upper connection of the column.
2. No, there are already three failures in the column - the plastic hinges - but OK, lets add plastic hinges at the ends. It doesn't matter - as long as there are no fractures, the load must pass the deformed column.
3. Free fall is not possible.
4. The load passes from the upper end to the contact point of the buckled column.
5. The only way the load can pass is via the buckled column. I know that Bazant opus I assumed that the columns just evaporated (free fall) but it is not possible.
6. According Bazant opus III density increases from 255 (structure) to 1025 (rubble).
7. According Bazant opus III just before crush up all rubble was inside the foot print or some was blown out when air was compressed.
8. Nobody is perfect and it is very easy to fool people.
 
Heiwa said:
2. No, there are already three failures in the column - the plastic hinges - but OK, lets add plastic hinges at the ends. It doesn't matter - as long as there are no fractures, the load must pass the deformed column.
3. Free fall is not possible.
Click to expand...

Once the column starts to buckle, one or both ends are likely to break free from their connections to the columns above and below. Free fall is possible.
 
e^n said:
1. Excellent, we agree so far.


2. Here we do not. This is not strictly true in the case of the WTC collapses, as we can see column connections breaking as the collapse initiates. However in a simplified limiting case, we should treat them as still connected.


3. Here I am not sure we agree. You say "the load from above", but surely you mean "some of the load from above"? If the column has exceeded its ultimate capacity and subsequently been deformed, its current capacity will be significantly diminished as I understand it, until it becomes essentially a flat plate.


4. Is it? Surely the force in the column depends upon its particular configuration as anything greater than its capacity would use up energy in deforming the column further?


5. Here I totally lose you. If the column is buckled yet still connected to both ends, how can it punch a hole in the floor? We are trying to deal with a best case scenario here where every column absorbs the maximum amount of energy possible. It seems a disconnected column punching through a floor would not satisfy this criteria.


6. I am equally confused here, how can load "drop outside"? Load is a measure of force, and air is not a particularly resistant structure, and so very little force could be generated on this column? If this column were the only one holding the upper section up, it would begin to descend rapidly? (within a small margin of g).


7. I agree that this is the case for a rigorous analysis, but I don't agree that we have enough data to construct such an analysis with any of the WTC towers to the level of confidence we can have in BLBG. NIST have of course done this model for WTC7 and the initiation model for WTC1+2, but I assume you take issue with them for whatever reason.


8. This does not make sense, you have explained how a failing column must carry less load, and if there is enough force to fail all alternate load paths, the upper section must accelerate downwards. I have not read your work on column buckling, unless you're referring to the calculations you posted here before which ignored the initiation mechanisms in both towers.


9. I see no evidence for this.


10. And I don't understand this.


11. Of course it cannot be seen on videos, because it is a best case scenario. The situation on the day was far worse for the towers, because an exterior wall section failed, resulting in most of the columns being misaligned.


12. This is just silly. No CD provides anywhere near enough force to laterally eject the entire mass of the upper section of the towers. You can do the calculations yourself, you know the mass of the upper section, you know the rough mass distribution. Tell me how much it would take.


13. Please submit your disagreements to a noted authority.
Click to expand...

1. Good
2. Bazant suggests 3 hinges buckling + ends connected and no fractures. I cannot see any disconnections.
3. OK - there may be some load transfers in the upper part if columns below fail at different times, but all the load of the upper part must pass through the columns. So we simplify and suggest all columns fail ait same time - no load transfers between columns. The deformed column will not become a flat plate - it becomes a twisted, bent, kneeled, column.
4. Correct, some of the potential energy (load x displacement down) is used up to damage the column. See my article.
5. The deformed column transmits load from above to below. When its deformed part, the knee, contacts something else, the load is transmitted there, e.g. to the floor.
6. OK, needs clarification. If the column deforms outside and does not meet any resistance, it will fracture - disconnect - and the load has nowhere to go.
7. I do the analysis as per agree praxis.
8. You do not make sense. The load is always passing through the column to the contact point of the damaged column on the lower structure. If column is cut off outside - load falls outside.
9. Read my article and watch the linked videos and you will see.
10. This sentence should read : "So what you see later is not some sort of progressive collapse or crush down by gravity but further CD!" Look, and you see it.
11. Tell that to Bazant.
12. No, it is not silly. Try to blow apart a core column inside an enclosed space and it blows out wall windows and everything around it.
13. I have! Twice to the FBI. Ask them what they do about it.
 
GlennB said:
My bolding.
You went from "is often" to "will" in one graceful dance step. Even though I know zip about column buckling, your fraudulent logic shines through.
Click to expand...

OK, change will to should. This is BTW just a friendly discussion in a lively way - you know what I discuss.
 
Heiwa, You have "debunked" Bazants theory and NIST and now claiming that the WTC towers came down by a CD.

Any evidence for the CD?
 
Thus, after buckling, the load from above will still pass through the now buckled column and be transmitted to structure below. No free fall will occur.
Say that the load is first transmitted to the knee of the column that is now in contact with the floor of the structure below. The force in the column is known.
The buckled column + its load (actually the force) may then punch a hole in the floor. That is a second local structural failure (that absorbs energy and starts to arrest further failures). If the floor is strong enough further failures are prevented already then.
If the column buckles outside the building, the column knee will not contact anything at all. The load on the column will drop outside.
Thus, you have to analyse the damages development step by step, keep track where the loads/forces are transferred and what failures they may cause, energy applied (force x distance) and absorbed, etc., etc.
Click to expand...
I see what you're describing here Heiwa but the description looks more like it matches the type of steel structure where there are horizontal steel members running at right angles too which offer support to the base and top of the vertical column. By your own admission the floors of the wtc were weak, if the force was strong enough to deform a single column in the manner you're describing would the connection through the damping system to the floor section and the floor section itself (aerated concrete, not high strength) be strong enough to allow that deformation and keep the top and bottom of the column aligned with the columns above and below?

If the floor/connections are not strong enough or the floor is being damaged by material falling inside how would this buckling present itself over a height of 2 columns that are bolted together in the middle?
 
alexi_drago said:
I see what you're describing here Heiwa but the description looks more like it matches the type of steel structure where there are horizontal steel members running at right angles too which offer support to the base and top of the vertical column. By your own admission the floors of the wtc were weak, if the force was strong enough to deform a single column in the manner you're describing would the connection through the damping system to the floor section and the floor section itself (aerated concrete, not high strength) be strong enough to allow that deformation and keep the top and bottom of the column aligned with the columns above and below?

If the floor/connections are not strong enough or the floor is being damaged by material falling inside how would this buckling present itself over a height of 2 columns that are bolted together in the middle?
Click to expand...

You are right! The floors, or their bolted connections, do not offer much support except transversly/horizontally in out. At core there are horizontal beams connected to the columns in two directions + brackets of different kinds, which make core columns' ends pretty solid. The whole core structure is mucht stronger than the walls in that respect At the perimeter walls we have the spandrels all around like a belt supporting in that direction.

So the question may be - can the floor bolts keep the perimeter column in position, while it is buckled from above? Or will it shear off and the perimeter column buckle/deflect outwards, where the broken bolt was?

Not seen of course on any video. I maintain the upper part above floor 97 is destroyed prior to anything happening to the columns below floor 97.

No wall columns are buckled or damaged by gravity (vertically). Whole wall sections are later seen being blown out sideways during destruction after shearing off from other wall sections. Everything clearly points at CD in the core - from top to bottom.
 
When you talk of a column buckling and kneeling is that over it's whole height (3 floors) or does it do that over each 3rd of it's height?
 
Heiwa said:
...Everything clearly points at CD in the core - from top to bottom.
Click to expand...
No, you failed to present any proof.

You waved you hands spewed bs and claim CD without evidence. Not one single piece of steel had blast effects.

Your delusion begins with no planes?

Tell me how planes would bounce off the WTC towers. Please explain so I can understand your great paper.
 
Heiwa said:
And what does it look like for you - global collapse or crush down/crush up?
Click to expand...

I have never seen a building like that go down before, so I have no reference point. I do know where all the evidence points...
 
phunk said:
Did you forget that a large section of the core was the last thing standing?
Click to expand...

No, Bazant does! The partially standing core is another fact that contradicts his crush down model. In my model the upper part gets stuck up top.
 
alexi_drago said:
When you talk of a column buckling and kneeling is that over it's whole height (3 floors) or does it do that over each 3rd of it's height?
Click to expand...

Between floors. The columns are continuous from ground to roof. Reason why the columns allegedly failed locally were due to overload when column properties changed due to heat, i.e. the initial failure should be in the heated section.

The columns could never buckle unless they were heated (a lot). I doubt it of course - no signs of any buckled columns anywhere.
 
Heiwa said:
No wall columns are buckled or damaged by gravity (vertically). Whole wall sections are later seen being blown out sideways during destruction after shearing off from other wall sections. Everything clearly points at CD in the core - from top to bottom.
Click to expand...

You're as wrong as a person can be. Repeating nonsense will never, ever bring you closer to reality.
http://video.google.com/videoplay?docid=2873871255585611926#1m10s
http://video.google.com/videoplay?docid=2873871255585611926#14m37s


Heiwa said:
If several DIME 250 kgs bombs were planted in WTC by criminal perpetrators as part of an inside job, you only need one at every 3rd floor i.e. total say 30 or 40 to get the expected result!! Quite a lot 7500-10000 kgs but easy to smuggle in in paper boxes one at a time. Quick installation job, thus.
Click to expand...


34 kg of demolitions explosives detonating.

160 kg of TNT detonating

A single 227 kg bomb detonating.


In 1993 a truck bomb of approximately 450 kg TNT equivalent detonated in the parking garage of the World Trade Center. Not a single column was destroyed. It did, however, make an enormous boom.
 
Last edited:
Gravy said:
You're as wrong as a person can be. Repeating nonsense will never, ever bring you closer to reality.
http://video.google.com/videoplay?docid=2873871255585611926#1m10s
http://video.google.com/videoplay?docid=2873871255585611926#14m37s
http://video.google.com/videoplay?docid=2873871255585611926#11m55s
Click to expand...

You seem to be worried, Gravy. Instead of posting videos, why not just copy/paste anything from Björkman's articles on his web site and explain why it is nonsense.
 
Gravy said:
You're as wrong as a person can be. Repeating nonsense will never, ever bring you closer to reality.
Click to expand...

I'm afraid that I have to second this. Like his analysis (ahem) of the videos, the structural comments seem to be based on the same faulty premise that might lead to one concluding that 2+2=5. As you say, no matter how oft it is repeated it will still be wrong.
 
You must log in or register to reply here.

Back
Top Bottom