Layman's terms please! Tower collapse issue

[Heiwa]

Why no load calculations? Only a "no big deal" hand wave.

??? I actually use the Nist calculations in my article. Read the article! Not too difficult.

 

[Heiwa]

Heiwa, how much weight do you think that a single floor of one of the World Trade Center towers could have carried before it failed? Do you understand that most of the weight and impact force of the collapsing upper levels would have fallen on the floors, and not on the support columns?




You claim in your paper that no buckled columns were recovered from the WTC wreckage. Please explain what happened to these columns, if not buckling?

According Nist a floor can carry 6-11 other floors!

Yes, if you read the article, you will see that I understand that loads are put on the uppermost floor of the intact structure below! I then explain what happens! After some further local failures any collapse is arrested.

I claim that no buckled columns from the initiation/fire/heat zones of WTC1, 2were recovered, e.g. around floor 95 of WTC1. Pls quote properly. One reason may be that they never buckled? Not seen on any videos, anyway.
Other columns may have buckled later ... and before ... initiation but they are not part of my article.

 

[DGM]

??? I actually use the Nist calculations in my article. Read the article! Not too difficult.

Please quote these for me.

 

[tsig]

According Nist a floor can carry 6-11 other floors!

Yes, if you read the article, you will see that I understand that loads are put on the uppermost floor of the intact structure below! I then explain what happens! After some further local failures any collapse is arrested.

I claim that no buckled columns from the initiation/fire/heat zones of WTC1, 2were recovered, e.g. around floor 95 of WTC1. Pls quote properly. One reason may be that they never buckled? Not seen on any videos, anyway.
Other columns may have buckled later ... and before ... initiation but they are not part of my article.

Seems to me the collapse floor had to carry at least the 22 top floors all the time.

 

[rwguinn]

Seems to me the collapse floor had to carry at least the 22 top floors all the time.

The floors didn't carry anything--other than the 150 lb/ft^2 or whatever it was they were rated for--you know-people, desks, books, cubicle walls, office equipment--that sort of thing. The columns carried the loads--and some of them (ok, a fair percentage) got busted and pretty darned hot
As R. Mackey pointed out elsewhere--1psi overpressure takes the floor just about to limit load-and dumping all the weight of the floors above on a single floor is certainly going to break things...

 

[SpitfireIX]

According Nist a floor can carry 6-11 other floors!

Yes, if you read the article, you will see that I understand that loads are put on the uppermost floor of the intact structure below! I then explain what happens! After some further local failures any collapse is arrested.

You claim that some of the mass would have slid off to the side, and that friction and entanglement of whatever was left would have arrested the collapse. Please explain how, in your scenario, free-falling objects can be subjected to significant friction due to contact with other free-falling objects, and how the building's structural elements could have become "entangled" in such a way as to stop falling.

Please also explain why you feel that the floors of the WTC would have only suffered local failures when loaded beyond their capacity.

I claim that no buckled columns from the initiation/fire/heat zones of WTC1, 2were recovered, e.g. around floor 95 of WTC1. Pls quote properly.

That's not what you wrote; if that's what you meant, you need to re-word that section. I stand by my paraphrase.

From your paper:

The major problem is that the authorities suggest that the top part, the upper block of WTC1 with assumed mean, uniform density 0.18 tons/m³ above the alleged buckled columns in the initiation zone - no such damaged, buckled, columns have been retrieved from the rubble . . . [bolding and italics original]

Further, how do you know that the columns in the linked photograph didn't come from the collapse-initiation zone? The buckled ends appear to have been exposed to fire.

One reason may be that they never buckled? Not seen on any videos, anyway.

The following video clearly shows columns in the collapse-initiation zone buckling right before the collapse:

Other columns may have buckled later ... and before ... initiation but they are not part of my article.

So how did these other columns buckle, if not from overloading?

 

[Newtons Bit]

But you have to read the whole article! Nist does not explain its 'buckling'! Buckle bending, buckle torsion, buckle crumple up? Which one? All local failures, of course. Collapse has not even started of the lower structure. So local 'buckling' leads to free fall? Sure? Anyway, after these local failures any PE may be released, but, when and if it is applied to some intact structure (a floor?) below,it is certain it is deflected sideways = does not contribute to gravity collapse any more! On the contrary = it contributes to collapse arrest. All explained in the article. Loose parts get entangled in each other. It is not one solid mass suddenly dropping down!

Topic is collapse issues - not really the initiation before that, which nobody has been able to prove. Massive local failures, free fall, impact (and then collapse should start)? Not seen anywhere!

STOP DODGING. Is that all you can do?

only a dynamic, elastic reaction force developing in the lower structure (spring) cancelling any further progressive collapse.

he compressive stress in the spring becomes temporarily 277 MPa which is above yield stress (248 MPa) but below the rupture stress. So maybe the 'spring' deforms plastically

These are mutually exclusive statements, Heiwa. Both cannot be true. Which means you were lying when you wrote one of them. Which statement of yours do you back? Was the "spring" elastic or did it delve into some plastic deformation?

 

[DC]

Yes!

ETA Sorry Newtons Bit, This answer was the only one that came to mind. I figured you're probably shaking your head.

FEMA WTC Building Performance Study
Chapter 7
page 18

Picture of a Steel Coloumn, buckling damage but not failed.

 

[Heiwa]

STOP DODGING. Is that all you can do?






These are mutually exclusive statements, Heiwa. Both cannot be true. Which means you were lying when you wrote one of them. Which statement of yours do you back? Was the "spring" elastic or did it delve into some plastic deformation?

Both! There is not one spring (as assumed by NIST & Co) but 280+ vertical springs to start with (and many horizontal ones). Most of them will probably behave elastically, i.e. no failure, some plastically, i.e. failure in one location (assuming loads are actually applied and do not slip off). After these initial reactions, the loads on the plastically deformed springs will be diverted somewhere else, maybe sideways, and will then not participate in the vertical collapse. And my reasoning is that they will participate in what is described as collapse arrest. Read the article as a whole and the conclusions and you will understand. I find it strange that NIST does not consider collapse arrest as a possible outcome of the local failures in the initiation zone. This is what normally happens.

And, please, do not use emotional words like lie, etc. in your comments. Virulent passion does not contribute to solving technical questions.

 

[Minadin]

Buckling IS failed.

 

[DC]

Buckling IS failed.

for a single coloumns yes, but when that coloum is part of a structure. the load will be shiftet to the other coloumns.

i was wrong first, i thaught with buckling the bowing is ment, but its indeed the point of failure, (Knicken)

 

[uk_dave]

Buckling IS failed.

Not if your ship doesn't sink. Apparently.

 

[Heiwa]

Not if your ship doesn't sink. Apparently.

I have this plastic garden table with four legs. We BBQued and put a lot of weight on the table (you know; bottles, plates, glasses = weight). And then one guest dropped a plate of grilled steaks on the table (impact) and one leg of the table failed (design fault) - buckled - and the table tipped ... and all the weight shifted ... and ended up on the ground.
The other three table legs ... miraculously didn't globally collapse due to this impact. I wonder why?

 

[Architect]

So we can compare the structural performance of a preformed plastic garden table with the complex composite structure of the WTC?

Do you realise just how unprofessional and poorly educated that would be??

 

[tsig]

The floors didn't carry anything--other than the 150 lb/ft^2 or whatever it was they were rated for--you know-people, desks, books, cubicle walls, office equipment--that sort of thing. The columns carried the loads--and some of them (ok, a fair percentage) got busted and pretty darned hot
As R. Mackey pointed out elsewhere--1psi overpressure takes the floor just about to limit load-and dumping all the weight of the floors above on a single floor is certainly going to break things...

Sorry i was using floor to mean the whole thing including supporting columns.

 

[Heiwa]

1. So we can compare the structural performance of a preformed plastic garden table with the complex composite structure of the WTC?

2. Do you realise just how unprofessional and poorly educated that would be??

1. Yes! (Who said it was pre-formed?)

2. No! Actually it is very educational to start with simple structures (4 columns in 3-D) to learn the basics and then go to more complex structures (280+ columns) to apply the basics in a professional manner. NWO physics 1-D theories like Bazant/Seffen have nothing to do with this.

 

[DGM]

1. Yes! (Who said it was pre-formed?)

2. No! Actually it is very educational to start with simple structures (4 columns in 3-D) to learn the basics and then go to more complex structures (280+ columns) to apply the basics in a professional manner. NWO physics 1-D theories like Bazant/Seffen have nothing to do with this.

Please start by anchoring all of the legs to the ground before you start this test. Does the table still tip? If not what happened to the other legs.

Are we sure he's an engineer?

 

[Architect]

He's certainly not sane, if he thinks that a plastic - presumably preformed - piece of garden furniture can be used as a structural metaphor or meaningful comparison for a complex structural system.

I'm gobsmacked, frankly.

 

[Newtons Bit]

Please start by anchoring all of the legs to the ground before you start this test. Does the table still tip? If not what happened to the other legs.

Are we sure he's an engineer?

Actually, we're pretty sure he's not. We've challenged him a number of times to prove that he is (I've done it twice in this thread), he completly ignores those comments. He acts like they don't exist.

I suppose he thinks that ignoring anything that could shed light into whether or not he actually has the expertise he claims he has is an effective tactic. If there's nothing technical for us to debunk (or even analyze to see if it he can do it correctly) there's no way we can challenge his claim that he is a "structural engineer".

 

[Architect]

In all fairness, didn't he say he was a naval architect who was qualified in structural engineering?

But I doubt even this latter part now, I must admit. There's nothing at all in his posts that shows any grasp of structural design and analysis issues, and the garden furniture analogy is just incredibly inappropriate.