Merged Applicability of Bazant's model to the real world

[Major_Tom]

I never denied inward bowing in WTC2. You put all "truthers" into one big box?

I make my own arguments as a human being. You can have those labels back, they aren't mine.


AE post 2038: "M_T that is a strong argument for the ROOSD mechanism for at least some of the collapse."

Why only some?

If such a process forms in the OOS corridors, type 12 beam construction floors shown in red are the only discontinuous barriers all the way to the basements.

Once established, what can alter the process?

Why only some? What other propagation mechanism can you identify other than this that matches the visual record?

 

[Gravy]

You put all "truthers" into one big box?

Yes, but the glue came undone when it was underwater, and some of them escaped. I'm using more weights and more twine next time.

 

[alienentity]

Yes, but the glue came undone when it was underwater, and some of them escaped. I'm using more weights and more twine next time.

 

[alienentity]

I never denied inward bowing in WTC2. You put all "truthers" into one big box?

Quite right. I was responding to Patriots4Truth.

He was the one whose first post contained this whopper 'NIST comes up with pure hooey about sagging truss pulling the facade in leading to collapsing floors I suppose.'

You may want to remind him that the photographic record says otherwise. And that not all 'Truthers' feel the same way. Or just continue to give him tacit encouragement...

 

[carlitos]

Quite right. I was responding to Patriots4Truth.

That's why you used the quote function and included Patriots4Truth's quoted point in your post, right? That's very helpful. Thanks.

 

[Major_Tom]

Quite right. I was responding to Patriots4Truth.

He was the one whose first post contained this whopper 'NIST comes up with pure hooey about sagging truss pulling the facade in leading to collapsing floors I suppose.'

You may want to remind him that the photographic record says otherwise. And that not all 'Truthers' feel the same way. Or just continue to give him tacit encouragement...

I agree that it is pure hooey, but not because the images of IB are fake.

(A subject more for the "WTC1 features list, initaition model" thread or it's WTC2 equivalent.)

I don't think the original commenter, SanderO, thinks they are fake either.

 

[Major_Tom]

I never denied inward bowing in WTC2. You put all "truthers" into one big box?

I make my own arguments as a human being. You can have those labels back, they aren't mine.


AE post 2038: "M_T that is a strong argument for the ROOSD mechanism for at least some of the collapse."

Why only some?

[qimg]http://www.sharpprintinginc.com/911/images/photoalbum/13/WTC1_model.jpeg[/qimg]

If such a process forms in the OOS corridors, type 12 beam construction floors shown in red are the only discontinuous barriers all the way to the basements.

Once established, what can alter the process?

Why only some? What other propagation mechanism can you identify other than this that matches the visual record?

An honest answer now could save all of us months of wasted time.

 

[carlitos]

An honest answer now could save all of us months of wasted time.

So would logging off the internet entirely. I'm not optimistic, though.

 

[Patriots4Truth]

At what temperature and duration of time would there be enough heat to cause enough sag for the floors to collapse? I'm sure NIST must have done some work on this.

 

[DGM]

At what temperature and duration of time would there be enough heat to cause enough sag for the floors to collapse? I'm sure NIST must have done some work on this.

Although studying the "duration of time" is a bit redundant. Yes, they did look in to this.

 

[ozeco41]

At what temperature and duration of time would there be enough heat to cause enough sag for the floors to collapse? I'm sure NIST must have done some work on this.

Take care to not swap contexts.

There is neither a claim for nor a need for heat weakened sagging trusses in the "global collapse"/"collapse progression" phase. Both belong in the "initiation" phase.

 

[Patriots4Truth]

Take care to not swap contexts.

There is neither a claim for nor a need for heat weakened sagging trusses in the "global collapse"/"collapse progression" phase. Both belong in the "initiation" phase.

Yes, all my questions appear to be about "initiation". I'll start another thread to pose qustions about sagging trusses if I can't find a good thread

 

[beachnut]

I agree that it is pure hooey, but not because the images of IB are fake.

(A subject more for the "WTC1 features list, initaition model" thread or it's WTC2 equivalent.)

I don't think the original commenter, SanderO, thinks they are fake either.

Pure hooey? That would be your demolition paranoid conspiracy theory.

Why do you have a problem understanding models and Bazant's work?

At what temperature and duration of time would there be enough heat to cause enough sag for the floors to collapse? I'm sure NIST must have done some work on this.

You should read NIST, you didn't? The same problem seems to plague 911 truth, no wonder they have the demolition delusion. I think failure to understand Bazant's work is due to 911 truth having the fantasy of a demolition, an inside job; what do you think?

Good luck, when did you graduate from engineering school? I graduated in 74 and got my masters in 82. Good luck again with 911 issues.

 

[tfk]

oz

Those pictures alone show that the collapse front was at least several storeys ahead of the "peel off" for that part of the tower. And there is nothing to suggest that the east perimeter was unique.

Please explain your logic.

Since this discussion seems to hinge on the specific definition of the words "still standing", perhaps you should specify the specific definition that you use.

After that, please explain how you believe the fact that large segments fell as large connected sheets can tell you where the crush front was at the moment that they detached from the rest of the building.

While you're at it, do you agree with MT that the air pressurization is "a cartoon"?

So the perimeter columns were left standing up to at least several storeys high after the crush front had passed, which corresponds to what I thought was the accepted position.

Once again, WHOSE "accepted position"?

The ONLY "accepted position" that amounts to anything more than a fart in a hurricane is the accepted position of qualified, experienced structural engineers.

Can you cite, or just remember, any person with those qualifications expressing this as their accepted position on this issue.

I frankly haven't heard ANY qualified structural engineer splitting this meaningless hair. The accepted position of the vast majority of structural engineers, being burdened with all of that silly knowledge & frivolous experience, is that Bazant got it right. And that once the collapse started, there was nothing going to stop it. And that worrying about what specific pieces flew off in what order during the crush down (not during initiation) is brainless.

 

[tfk]

At what temperature and duration of time would there be enough heat to cause enough sag for the floors to collapse? I'm sure NIST must have done some work on this.

Meaningless question.

Parts (including floors) don't fail because of "sag".

They fail because of local stresses exceeding local strengths.

Rather than spoon feed you, you'd do well to think about the various factors that affect both of those.

 

[tfk]

Bump for MT...

Great theory.

Now please explain the fact that, when WTC 2 collapsed, firemen in WTC1 stairwells were knocked to the ground by the force of the blast that traveled ALL the way down WTC2, thru a bunch of underground service tunnels, and up WTC1.

Explain why there is incontrovertible evidence of WTC1 fire & smoke being pushed out of the upper floors of WTC1 by sudden overpressures when WTC2 collapsed.

Great theory, tho...

 

[ozeco41]

Those pictures alone show that the collapse front was at least several storeys ahead of the "peel off" for that part of the tower. And there is nothing to suggest that the east perimeter was unique....

oz
Please explain your logic....

we see lots of big sheets of perimeter columns, mostly lying on the ground but some pictures of them flying through the air. Plus there is video evidence that the combination of pressure front and crush front proceeded downwards several storeys ahead of the peel off of the perimeter sheets of columns. Whatever conclusions we draw about the separation of pressure front and crush front can wait for now.

The sheets of columns are not bent in the inwards/outwards direction relative to their original position on the outer face. The floor joist attachment points indicating that the floor joists were sheared off at least several floor levels before the outward bending of the columns. That outward bending appears to have caused failure at the bolted joints as evidenced by the staggering of the fracture line corresponding to the offset of the bolted joints. Since there has been no bending of the multi storey sheets it follows that there was no significant outward banding until the sheet fell and that only occurred several storeys after the front causing the floor joist shear off had passed. And the front causing those failures was not a pressure pulse rather the physical impact of falling structure - therefore the crush front.

...Since this discussion seems to hinge on the specific definition of the words "still standing", perhaps you should specify the specific definition that you use....

I don't see how it 'hinges' on it but try 'remain in its essentially vertical location despite the removal of the horizontal bracing of the floor joists'

...After that, please explain how you believe the fact that large segments fell as large connected sheets can tell you where the crush front was at the moment that they detached from the rest of the building....

see previous.

...While you're at it, do you agree with MT that the air pressurization is "a cartoon"?...

It seems to have been a reasonable choice of word in the context he used it.

...Once again, WHOSE "accepted position"?...

I speak from the experience of following or taking part multiple debates/arguments with conspiracy theorists and genuine sceptics on the details of WTC Twin Towers collapse. The framing of 'global collapse' being the Bazant style or several equivalent findings that 'global collapse was inevitable' - the NIST version and mine. Of those who have supported no demolition and sought to explain in more detail than Bazant, NIST etc It is my perception that the peeling of perimeter as I have described it was the broad, accepted consensus. My statement was "...what I thought was the accepted position..." so if you don't find it acceptable don't. It still remains my view.

...The ONLY "accepted position" that amounts to anything more than a fart in a hurricane is the accepted position of qualified, experienced structural engineers...

Nonsense. (My favourite Aussie word for bovine faeces falls foul of the language censor IIRC.) If you want a rigorous "accepted position" then the only "accepted position" is one that is right. Irrespective of the "mines bigger than yours" battle over qualifications...

...Can you cite, or just remember, any person with those qualifications expressing this as their accepted position on this issue....

not relevant for reasons given.

...I frankly haven't heard ANY qualified structural engineer splitting this meaningless hair. The accepted position of the vast majority of structural engineers, being burdened with all of that silly knowledge & frivolous experience, is that Bazant got it right. And that once the collapse started, there was nothing going to stop it. And that worrying about what specific pieces flew off in what order during the crush down (not during initiation) is brainless.

Watch your tendency to try to redefine the topic under discussion into the topic you would prefer to discuss. Yes there seems to be a body of engineering opinion which accepts the limit of curiosity at the place you define. But you are veering of the track of the statement I made and you were querying.

 

[Patriots4Truth]

Meaningless question.

Parts (including floors) don't fail because of "sag".

They fail because of local stresses exceeding local strengths.

Rather than spoon feed you, you'd do well to think about the various factors that affect both of those.

What caused local stress to exceed local strength on the first floor that collapsed? (I know this is not related to Bazant but to "initiation")

 

[rwguinn]

Are those structural panels or decorative facades?

 

[tfk]

What caused local stress to exceed local strength on the first floor that collapsed? (I know this is not related to Bazant but to "initiation")

First, you need definitions.
Keep it simplified.

Stress = load per unit area. There are several different types of stress (tension, compression, bending, shear.)
Strength = max stress levels that the material can withstand without breaking.

Put in a little effort. It'll be good for you.
As I suggested, for a lattice-work structure like the towers, try to figure out:

1. What are the factors that determine stress at any given point. Think especially about the situation where many components all carry portions of the total load.

1A. Intact, the building had beautifully balanced (approximately equal) stress in all its members. This means that, where the loads were high, the material was thicker, so that the load per unit area was approximately a constant. (Typically about 1/3rd the strength level.)

What factors can change this balanced stress levels to unbalanced stress levels. (increasing some stresses, decreasing others.)

Hints: think before & after the plane impact. Think before & during the fires. Think creep.

2. What factors can locally (i.e., in one spot) decrease a particular material's strength?

Hint: The strength of a material depends on its molecular bonds. What factors might affect the molecular bonds of a metal?

__

BTW, the collapse of one floor would have been (certainly was) a result, not a cause. The failure of a floor would take the failure of hundreds, perhaps thousands of individual components. This certainly could not happen simultaneously, if the failures were independent events, unrelated to each other.

The failure of a floor could EASILY - certainly did - result from the failure of just one item. One bolt, one weld, one unknown part that fractured, snapped, or buckled.

But the parts near it could not pick up the load that the failed part shed, and therefore the failure rapidly "progressed" into dozens, hundreds & then thousands of other elements. This is the very definition of a progressive failure.