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Moderated Steel structures cannot globally collapse due to gravity alone

funk de fino said:
No-one said you could. What pulled the columns in?
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Good question. Probaly not a sagging floor. The wall seems to be deformed plastically so one answer is that it is overloaded from above. This is unlikely as the load from above has not changed.
Has local failures occured changing the structural arrangement, e.g. lateral supports of the wall? Has the floor dropped down inside the wall? Seems unlikely as the wall seems unaffected by fire/heat.
But maybe the floor has dropped down at the core and is hinging around the bolts at the wall! Then the wall can displace inward (see Euler) - but for sure the floor is not pulling it then.
And why would the floor drop down at the core? Controlled demolition there? Cutting core columns may very well produce the deformation of the outside wall.

Actually there were plenty of telephone calls from the South Tower prior collapse that floors actually dropped down - far away from the impact zone.

http://www.youtube.com/watch?v=iNS2Mld9v24&fmt=18

http://www.youtube.com/watch?v=yTqY_dld08g&fmt=18

http://www.youtube.com/watch?v=m3CFlRVMs8g&fmt=18

So one answer may be that the visible deformation shown on the photos is result of CD!

Regardless - forget that a sagging floor pulled in the wall.

BTW - at what floor is the wall deformed?
 
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Heiwa said:
Good question. Probaly not a sagging floor. The wall seems to be deformed plastically so one answer is that it is overloaded from above. This is unlikely as the load from above has not changed.
Has local failures occured changing the structural arrangement, e.g. lateral supports of the wall? Has the floor dropped down inside the wall? Seems unlikely as the wall seems unaffected by fire/heat.
But maybe the floor has dropped down at the core and is hinging around the bolts at the wall! Then the wall can displace inward (see Euler) - but for sure the floor is not pulling it then.
And why would the floor drop down at the core? Controlled demolition there? Cutting core columns may very well produce the deformation of the outside wall.

Actually there were plenty of telephone calls from the South Tower prior collapse that floors actually dropped down - far away from the impact zone.

http://www.youtube.com/watch?v=iNS2Mld9v24&fmt=18

http://www.youtube.com/watch?v=yTqY_dld08g&fmt=18

http://www.youtube.com/watch?v=m3CFlRVMs8g&fmt=18

So one answer may be that the visible deformation shown on the photos is result of CD!

Regardless - forget that a sagging floor pulled in the wall.
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Why cant it be a sagging floor? It is observed in pictures.
 
Lennart Hyland said:
Why cant it be a sagging floor? It is observed in pictures.
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Is it? I just see the outside of a wall - floor level??? But why is the wall being deformed? Not by fire/heat. Think! Use your brain.

What happens a little later? The whole tower is destroyed by local CDs from just below the fire zone to ground, in my view. You may believe that the upper part got loose and crushes the structure below as Bazant suggests, but I do not believe that. Steel structures cannot globally collapse due to gravity alone!

So what happens before that? I believe the perpetrators are simply, locally softening up the lower structure of the upper part so it will appear as if the upper part suddenly 'drops' due local failures (due to the fire). The perpetrators are working on the core (via remote control, of course). Some floors may drop down as reported by poor people still in the vicinity ... and the outer walls deform. That's what we see.

The perpetrators could have stopped there, i.e. allowed the upper part to drop ... but it would not crush the lower structure - for that you need CD. Steel structures cannot globally collapse due to gravity alone!

So what to do with the upper part after the faked 'drop' and start of CD of structure below. The perpetrators must CD the upper part, too. That's why the upper part disappears just before the CD of the lower part begins.

The poor NIST clowns know this of course but for obvious reasons the play their roles ... clowns. They have no choice, poor clowns.

Let's see if Obama changes this circus?
 
Heiwa said:
Good question. Probaly not a sagging floor. The wall seems to be deformed plastically so one answer is that it is overloaded from above. This is unlikely as the load from above has not changed.
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Cleary you are unfamiliar with the phrase "half-arsed generalisations", albeit that you do appear to be an ardent practitioner.

Let's be quite clear. This is a complex, composite structure relying on the distribution of forces through the floor, hat trusses, core columns, and structural envelope acting together.

NIST carried out extensive computer modelling of load paths for various different scenarios, and set out the results at some length in their main report.

You, on the other hand, have failed to produce even a basic structural analysis of any relevance and instead have focused on issues such as flagpoles and pizza boxes.

You profess to being an engineer. I work with engineers every day. If there was a calculation which could give the weather forecast, they would do it. Everything is backed up by figures, facts, and analysis. But I don't see this in your work - at all.

Against that background I find it difficult, indeed impossible, to determine what weight - if any - should be attached to your professional opinion.

Likewise I am well aware that you have made errors elsewhere (for example the fire resisting qualities of structural steelwork) and without sight of a full study cannot be sure that you have not repeated them in such work as you have undertaken.

So, in short, put up or shut up.
 
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Heiwa said:
Is it? I just see the outside of a wall - floor level??? But why is the wall being deformed? Not by fire/heat. Think! Use your brain.

What happens a little later? The whole tower is destroyed by local CDs from just below the fire zone to ground, in my view. You may believe that the upper part got loose and crushes the structure below as Bazant suggests, but I do not believe that. Steel structures cannot globally collapse due to gravity alone!

So what happens before that? I believe the perpetrators are simply, locally softening up the lower structure of the upper part so it will appear as if the upper part suddenly 'drops' due local failures (due to the fire). The perpetrators are working on the core (via remote control, of course). Some floors may drop down as reported by poor people still in the vicinity ... and the outer walls deform. That's what we see.

The perpetrators could have stopped there, i.e. allowed the upper part to drop ... but it would not crush the lower structure - for that you need CD. Steel structures cannot globally collapse due to gravity alone!

So what to do with the upper part after the faked 'drop' and start of CD of structure below. The perpetrators must CD the upper part, too. That's why the upper part disappears just before the CD of the lower part begins.

The poor NIST clowns know this of course but for obvious reasons the play their roles ... clowns. They have no choice, poor clowns.

Let's see if Obama changes this circus?
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Okay, I'll cut you a deal.

Only a fool would think that they, and they alone, had identified a mistake overlooked (complicitly or otherwise) by every other expert in the world.

This would be especially the case where, as at the towers, the results of the investigation and underlying cause had been circulated widely - globally - and formed the basis for a significant body of further research work.

I note, for example, the studies done by Arup and Edinburgh University regarding fire modelling and collapse initiation causes, both of which were reported widely (for example in NCE).

So, if you want me to take your opinion seriously, find me a credible engineer with expertise in tall structures who supports your case. Not someone who designs gym halls, or retired 30 years ago, but a solid name. Someone from Arup, or Mott MacDonald, or Jacobs Babtie, or Atkins, and so on.

Find me a paper in any of the mainstream engineering journals - NCE might be a good starting point - which casts significant doubt on the NIST structural analysis or actively supports those issues raised in your own paper.

Now, just to stresss, I'm quite happy with non-US sources and given your clear concerns about USG manipulation of the construction community I'm sure you would prefer to bring forward European or even Far East expertise. I will, however, be looking for fully detailed stodues and not - to coin a phrase - half-arsed generalisations.

If you can't produce this kind of background, then tell me why you - and you alone - are able to see the glaring errors and obvious lies which every other respected engineer in the world has missed. Tell me why you, a naval architect with limited expertise in standing buildings work and apparently no grasp of tall structures, picked it up.

I shall await your doubtless evasive reply with anticipation.
 
Heiwa said:
Is it? I just see the outside of a wall - floor level??? But why is the wall being deformed? Not by fire/heat. Think! Use your brain.
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Well they are in the NIST report but apperantley you havent read it.

Stop babbeling about CD! You cant hear or see any bombs going before/during the collapse!
 
Architect said:
Cleary you are unfamiliar with the phrase "half-arsed generalisations", albeit that you do appear to be an arden practitioner.

Let's be quite clear. This is a complex, composite structure relying on the distribution of forces through the floor, hat trusses, core columns, and structural envelope acting together.

NIST carried out extensive computer modelling of load paths for various different scenarios, and set out the results at some length in their main report.

You, on the other hand, have failed to produce even a basic structural analysis of any relevance and instead have focused on issues such as flagpoles and pizza boxes.


You profess to being an engineer. I work with engineers every day. If there was a calculation which could give the weather forecast, they would do it. Everything is backed up by figures, facts, and analysis. But I don't see this in your work - at all.
Against that background I find it difficult, indeed impossible, to determine what weight - if any - should be attached to your professional opinion.

Likewise I am well aware that you have made errors elsewhere (for example the fire resisting qualities of structural steelwork) and without sight of a full study cannot be sure that you have not repeated them in such work as you have undertaken.

So, in short, put up or shut up.
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You say:

Let's be quite clear. This is a complex, composite structure relying on the distribution of forces through the floor, hat trusses, core columns, and structural envelope acting together.

No - it is a very simple structure. A load on a floor is carried to a column and down to ground. Cannot be simpler than that.

You say:

NIST carried out extensive computer modelling of load paths for various different scenarios, and set out the results at some length in their main report.

No - NIST just says that PE>SE (see my previous posts).

You say:

You, on the other hand, have failed to produce even a basic structural analysis of any relevance and instead have focused on issues such as flagpoles and pizza boxes.

Not really - my papers at http://heiwaco.tripod.com/nist.htm are quite clear incl. structural damage analysis. Flagpoles and pizza boxes just behave in the same manner.

You say:

You profess to being an engineer. I work with engineers every day. If there was a calculation which could give the weather forecast, they would do it. Everything is backed up by figures, facts, and analysis. But I don't see this in your work - at all.

What kind of engineers are you working with? Meteorologists? Sorry, I cannot predict weather but I am quite good at structural analysis.

You say:

Against that background I find it difficult, indeed impossible, to determine what weight - if any - should be attached to your professional opinion.

Likewise I am well aware that you have made errors elsewhere (for example the fire resisting qualities of structural steelwork) and without sight of a full study cannot be sure that you have not repeated them in such work as you have undertaken.

That's your opinion. I can assure you all work I have undertaken is without error (at the end). Happy?

You say:

So, in short, put up or shut up.

Edited by Gaspode: 
Removed personal attack.


Doesn't impress me at all.
 
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Heiwa said:
What happens a little later? The whole tower is destroyed by local CDs from just below the fire zone to ground, in my view.
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Now you are obviously advocating the therm?te theory, because there were ZERO explosions heard in any of the phone calls from inside the towers or on any of the hundreds of videos taken by news camera crews on the street.

You may believe that the upper part got loose and crushes the structure below as Bazant suggests, but I do not believe that. Steel structures cannot globally collapse due to gravity alone!
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When key elements are pushed out of alignment by sufficient force, they do, for the same reason that grounded ships are always in peril of breaking up in heavy surf.

The perpetrators could have stopped there, i.e. allowed the upper part to drop ... but it would not crush the lower structure - for that you need CD.
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No, but you would need an arresting mechanism to stop it once it started. There was none. The forces applied to succeeding floors increased mathematicly once the first floor collapsed.

Steel structures cannot globally collapse due to gravity alone!
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Well, DUH! Of course not. You have to add structural damage at some key point. Couple hundred tons of aluminum travelling at the speed of a shotgun blast ought to do that.

And don't look for Obama to take your side. He insists that scientific papers for government use be written and reviewed only by scientists.
 
Heiwa said:
Let's see if Obama changes this circus?
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obama_frowning-sml.jpg
 
Heiwa said:
1. Evidently, when you remove a floor and the load it carries to a column, you also remove possible lateral support of the column provided by the floor. Everything changes ... and you have to reanalyse.

2. Structural integrity evidently changes when you remove or disconnect parts. This is normal part of structural damage analysis.

3. The effects of loose parts contacting other parts is also normal part of structural damage analysis.

You may recall that NIST never did any stuctural damage analysis of WTC1/2 and that's the reason why the subject is still being discussed. NIST just suggested without any evidence that potential energy, PE, released (no calculations or explanations) due to gravity alone exceeded the available strain energy, SE, of the structure (no calculations) or PE>SE=global collapse.
I simply suggest that SE > 1000*PE and explain why in my papers. And then we have friction, PE lost by deflections, etc.

What NIST simply suggest is that if you drop something on a steel structure, the latter collapses!

Simple lab tests prove that wrong immediately. Drop anything on anything and see what happens! Or do my demonstrations for children. In most realistic cases the upper part just bounces.

This whole suggestion that a top part of a building suddenly drops is absurd. I have not seen any video of a top part of a building dropping free fall except WTC7 and for that to happen the whole bottom structure must have been removed! NIST agrees that WTC7 top part drops free fall ... and then they make structural analysis of this this!! However, no loads are acting on a free falling structure = all stresses are ZERO!

I really hope Obama will ensure that NIST makes a new attempt to explain its previous, funny findings. The previous attempt under Bush is just an embarrassing failure by Sunder & Clowns at the National Institute of Stupid Technicians, NIST.
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My God. Barely any of that drivel even addresses, let alone contradicts what I wrote. Yes, removing a floor removes possible lateral support. That's exactly the whole problem! The lack of lateral support severely degrades the structural integrity!

Sheesh! When the structural integrity reduces to the point where the exterior columns cannot take any lateral movement, any new analysis conducted doesn't have to move beyond the qualitative. The perimeter columns are unsupported when the floors are removed.

On top of that, how can you say that NIST did not do any structural damange analysis? NCSTAR 1-2 dealt with the structural damage from the impact, NCSTAR 1-5 dealt with the structural compromises the fires induced. There's the analysis you claim didn't occur. 1,200 pages for NCSTAR 1-2 and it's subreports, and over 2,700 pages for NCSTAR 1-5, plus A through G. Awful lot of pages for a supposed non-analysis of structural damage.

But speaking of not doing something, you did not even address your amazingly silly mistake in interpreting the "... it can carry 5 times the load from the floors" as meaning it would take the blow from the upper segment. Again, the design was for a static load, not a moving, accelerating one!

This is why I can't accept that you actually believe what you post here. The mistakes you make are so obvious and fundamental that even a total non-engineer like me can identify them. How a working engineer can not only fail to see mistakes on fundamental principles of collapse, but can also ignore basic matters of the towers construction to make the argument escapes me. I do not believe that you yourself thinks that any of your hodgepodge of incorrect generalizations and basic conceptual misinterpretations has any validity. No engineer can screw up to the degree that you do without seeing the problems inherent to the proposals you produce.
 
Whoops. Ignore me. All I'm doing is pointing out the same old mistakes you always make. Well get nowhere with that, since you refuse to acknowledge them. Read this. Take Architect's challenge.

Architect said:
So, if you want me to take your opinion seriously, find me a credible engineer with expertise in tall structures who supports your case. Not someone who designs gym halls, or retired 30 years ago, but a solid name. Someone from Arup, or Mott MacDonald, or Jacobs Babtie, or Atkins, and so on.

Find me a paper in any of the mainstream engineering journals - NCE might be a good starting point - which casts significant doubt on the NIST structural analysis or actively supports those issues raised in your own paper.

Now, just to stresss, I'm quite happy with non-US sources and given your clear concerns about USG manipulation of the construction community I'm sure you would prefer to bring forward European or even Far East expertise. I will, however, be looking for fully detailed stodues and not - to coin a phrase - half-arsed generalisations.

If you can't produce this kind of background, then tell me why you - and you alone - are able to see the glaring errors and obvious lies which every other respected engineer in the world has missed. Tell me why you, a naval architect with limited expertise in standing buildings work and apparently no grasp of tall structures, picked it up.
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Find the support. Cite authorities who also agree with your hypothesis. Ones who've published in reputable journals (no, Architects and Engineers for 911 Truth, the Journal of 911 Studies, or anything like that does not count. I mean reputable when I say "reputable").
 
Heiwa said:
No, debris is just falling vertically due to gravity. No horizontal component there. Drop anything on something using gravity - test yourself.
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Just did.

Having dinner, accidentally dropped knife straight down onto edge of table. Knife landed well away from table.

Happens every time.
 
GlennB said:
Just did.

Having dinner, accidentally dropped knife straight down onto edge of table. Knife landed well away from table.

Happens every time.
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Bounced. Nothing to do with gravity. According NIST table should collapse though. You know PE of knife > SE of table edge.
 
ElMondoHummus said:
My God. Barely any of that drivel even addresses, let alone contradicts what I wrote. Yes, removing a floor removes possible lateral support. That's exactly the whole problem! The lack of lateral support severely degrades the structural integrity!

Sheesh! When the structural integrity reduces to the point where the exterior columns cannot take any lateral movement, any new analysis conducted doesn't have to move beyond the qualitative. The perimeter columns are unsupported when the floors are removed.

On top of that, how can you say that NIST did not do any structural damange analysis? NCSTAR 1-2 dealt with the structural damage from the impact, NCSTAR 1-5 dealt with the structural compromises the fires induced. There's the analysis you claim didn't occur. 1,200 pages for NCSTAR 1-2 and it's subreports, and over 2,700 pages for NCSTAR 1-5, plus A through G. Awful lot of pages for a supposed non-analysis of structural damage.

But speaking of not doing something, you did not even address your amazingly silly mistake in interpreting the "... it can carry 5 times the load from the floors" as meaning it would take the blow from the upper segment. Again, the design was for a static load, not a moving, accelerating one!

This is why I can't accept that you actually believe what you post here. The mistakes you make are so obvious and fundamental that even a total non-engineer like me can identify them. How a working engineer can not only fail to see mistakes on fundamental principles of collapse, but can also ignore basic matters of the towers construction to make the argument escapes me. I do not believe that you yourself thinks that any of your hodgepodge of incorrect generalizations and basic conceptual misinterpretations has any validity. No engineer can screw up to the degree that you do without seeing the problems inherent to the proposals you produce.
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Re fundamental principles of collapse:

NIST suggests PE > SE = global collapse (of both WTC 1 and 2) as only cause of global collapses in both cases.

Pls advise where NIST calculates PE and how.

Pls advise where NIST calculates SE and how.

Pls advise where PE > SE = global collapse is established as a fundamental principle of collapse.

BTW - do you know what structural damage analysis really is?

Re FoS=5 for perimeter columns means that static compressive stress = 0.2 of critical stress.

Pls advise how any upper segment can apply a blow to a column.

To start with!

BTW Who is your God? Expert of structural damage analysis?
 
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