Building Collapses in Rio

Originally posted by ANOK
Bazant does not account for the fact that the top would receive as much damage as the bottom during impact.

Please examine this document. It's an excerpt from an article in the Journal of Engineering Mechanics. There are three sections. The first two are attempts at formally expressing the thing you say above, in an attempt to refute Bazant on this point. The third section is Bazant's reply.

1) You should have read this article (with understanding) BEFORE you made your statement to me, if you were serious, because it addresses your point EXACTLY
2) Bazant tears them apart

I reiterate: Equal and opposite destruction is NOT Newton's law.


I said above that the upper block in Bazant's model does not directly impact the lower block. There is a MOVING debris layer formed from the initial failed story.....


Wait a ********ed minute! I'm just repeating myself again!

I go and type all that and all you do is say "Wrong"? **** off, read what I wrote and try to refute it with something other than just saying no.

Originally posted by ANOK
You can't just throw Newtons 3rd law away...

I didn't.

...and pretend it doesn't matter because of momentum...

I didn't.

Momentum will change the forces on BOTH objects, the forces are ALWAYS equal...

The forces in Bazant's model are acting between the upper block and debris layer, and between debris layer and lower block. Both the debris layer and the upper block have momentum. The lower block experiences the force imparted by both the debris layer and the upper block, both their static weight and momentum change. The upper block does NOT experience the static weight or momentum of the debris layer because it is BELOW the upper block.

This is a very fine force difference which does NOT violate Newton's 3rd because the opposing forces are equal at each point in the structure, yet they differ at the points of contact against the debris layer above and below. If you look at the upper left curve in Fig 1 of Bazant's text in the above cited article, you see the point which is annotated "Crush up ends". Please note how close this point is to the horizontal dashed line. The dashed line represents a resistive force equal to the static load imposed. If the upper block had deformed to the dashed line (mere centimeters), it would've failed, too.

According to Bazant's calculations, there was almost crush up. Very nearly so. But the lower block, BEING SUBJECT TO A GREATER FORCE THAN THE UPPER, reached ultimate yield before the upper, so the resistive force dropped and the upper survived the first impact.

This is according to Bazant's mechanics. I don't support his conclusion for a variety of reasons, but that doesn't matter. You leveled a specific charge of violation of physical laws and your charge is false.

Leave physics to those who know it.

All the time you've spent applying your intuitive brand of pseudo physics, I've spent applying real physics to the very problem that troubles you so. That's only one thread, started late 2009. It ends with me embarrassed, because Bazant was not only correct (For his model! Only!), the answer was there in front of me all along.

NEVER have I approached the issue of bidirectional crush with the ham-fisted notion that Newton's 3rd law was violated; I could see it wasn't from the very beginning.

Originally posted by ANOK
And yet hilariously you didn't.

Bazant does not account for the fact that the top would receive as much damage as the bottom during impact.

You can't just throw Newtons 3rd law away, and pretend it doesn't matter because of momentum, that is completely stupid. Momentum will change the forces on BOTH objects, the forces are ALWAYS equal...

Dammit man, read the paper and try to understand it. Newton's third law is NOT VIOLATED, because:

(A) EQUAL AND OPPOSITE FORCES DOES NOT MEAN EQUAL AND OPPOSITE DAMAGE
(B) BAZANT CLAIMS A COMPACTED LAYER OF RUBBLE ACTED AS A SHOCK ABSORBER FOR THE UPPER BLOCK.

and last but not least

(C) IRISHWRISTWATCH DOES NOT SUBSCRIBE TO ALL OF BAZANT'S PREMISES AND CONCLUSIONS BUT INSTEAD CLAIMS HIS PAPER INTERNALLY CONSISTENT.

I agree.

You don't understand Bazant's paper outside what misinformation has been SPOONFED to you by the 9/11 'Truth' Movement.

Bazant is LAUGHING AT YOU, because your CRITICISMS ARE THAT OF A LAYMAN, hence his sarcastic jab that his critics should READ PHYSICS AND ENGINEERING TEXT BOOKS BEFORE CRITIQUING HIS WORK AGAIN.

That's quite devastating considering some people leveling those criticisms at Bazant have bachelor or masters degrees in physics or structural engineering.

Don't think I don't understand where you're coming from, I once loudly clattered "NEWTON'S THIRD LAW!!" too, because I didn't think actually reading Bazant's paper or understanding it would be required.

You are digging a hole you can never get out of each time you invoke Newton's third law without understanding it in the context of Bazant's paper.

In the words of Jon Stewart: please stop.

If you want to critique Bazant, focus on his 'compacted rubble shock absorber' argument, rather than a primitive fixation on a violation of Newton's third law that isn't there.

That's all I can say.

Said very well, in one sentence.

reply to post by IrishWristwatch


Don't waste your time, it has already been explained in detail to Anok. Next we will hear that rubble between lower and top section disappeared. It is of course not explained how it disappeared, nor is any evidence shown. Oh, maybe he will post the FEMA diagram showing how far the debris fell.

Suppose, for a moment, that Bazant is correct and there is no violation of Newton's laws or any other laws. Suppose instead that, despite being correct and self-consistent, his model simply fails to describe the actual collapse mechanics.

Then someone who has a beef with the OS and how Bazant is used to defend it could use that line of attack to try to disqualify it without stepping on their gonads every time they speak. It's very obvious that his model is a gross simplification; even Bazant says something like that more than once. Too gross to use for proof of gravity collapse?

The problem with this approach, despite being grounded in fact instead of fancy, is that Bazant puports to describe a limiting case, the limit of dissipating the greatest energy possible in collapse. As such, it represents a case biased in many ways towards survival: columns compress axially in perfect alignment, full FOS invoked, etc. He claims it is the most optimistic, but that's not strictly true. It is, however, so optimistic that you'll be very hard pressed to find any means by which arrest can occur. Plenty have tried. Szamboti came the closest, Ross did but over-counted on the way.

Does it matter? No. All of these approaches simply build on the Bazant model in a topsy-turvy fashion. Bazant takes a case heavily biased towards survival and shows collapse is inevitable. Others take the same case and bias it even more heavily towards survival, and eventually reach a point where it does survive, hahahaha!!!! See the difference?

Bazant's 1D perfect axial alignment, which provides the greatest capacity possible, is sooooooooooooooooo far from what happened. That's not a problem for what he sets out to prove. Taking it even further to totally unrealistic (and even erroneous) assumptions for survival, and then have it BARELY survive, is a big problem for those trying to prove gravity collapse impossible.

Tony Szamboti's analysis requires ALL columns to afford MAXIMUM capacity. Perfect axial strike. Didn't happen. You can see that with your own eyes. But, you know what? Even in a perfect 1D world, his analysis still has it collapsing! Tell that to his colleague, David Chandler, who can't figure out why it doesn't arrest!

At least Szamboti is light years beyond these knuckle walking arguments about Newton's 3rd law. He's way ahead of the rhetoric here... and he failed.

What have you got to go on? So what if Bazant is wrong about exclusive crush down? Does that mean the towers would survive? Why don't you do the calculations and find out?

Originally posted by -PLB-
reply to post by IrishWristwatch

 

Don't waste your time, it has already been explained in detail to Anok. Next we will hear that rubble between lower and top section disappeared. It is of course not explained how it disappeared, nor is any evidence shown. Oh, maybe he will post the FEMA diagram showing how far the debris fell.

The sad thing is, I already know it's pointless. I've been around this BS long enough to know how rare it is to find someone who turns around on this subject. Sometimes it happens. Remember Akareyon? Here's how that turned out. I don't think he was entirely satisfied, but he definitely gets it. I think his dissatisfaction was with the slim margin of safety engineered into modern high rise structures!

He/she was different, I could tell that from the start. Akareyon came in here, guns a blazin, saying exactly the same stuff we see here. The difference was, this person spoke the language of math and understood basic engineering concepts. The issue arose because there were details he didn't know about this subject. Once those details were accepted and processed, suddenly the objections went away. The reason the details were accepted is because they make sense against the context of common physics principles, and there were unambiguous consequences.

Originally posted by psikeyhackr
The variation in the top 20 stories of the WTC should be similar to that in a 20 story building.

Doesn't that suggest that the top 10 stories should crush the 10 below them?

Nice graphic.

Originally posted by psikeyhackr

Originally posted by DrEugeneFixer

Originally posted by psikeyhackr
If by "composite slab and truss system" you are talking about the floor assembly outside of the corepsik

Of course I am.

Originally posted by psikeyhackr
I disagree. That had nothing to do with the structural strength of the core. The idea that the core needed anything outside of itself for support is nonsense.

You're just wrong about that.

Originally posted by psikeyhackrThe core provided the rigidity of the building. The perimeter columns provided the vertical support to the outer edge of the floor assemblies. The wind impacted the perimeter but the force was transferred to the core via the floor assemblies.
psik

All wrong and backwards. Look at any decent source. They will tell you the lateral forces were borne 95% by the Perimeter colums and spandrels. The core columns were designed to hold vertical loads only.

I have seen a number of sources making such idiotic claims. They are obviously full of crap.

The perimeter columns and spandrels are four two-dimensional arrays of steel. They can withstand forces from directions parallel to the surface. The downward force due to gravity from all of the attached floors is the primary one. A perpendicular force would make them bend. The concrete slabs were a big square donuts. If the core applied outward stress on opposite sides it would cause cracks in the floor. The core was a THREE-dimensional array of steel It could take stresses from any direction, like from the wind. The wind impacted the perimeter. But the force was transferred to the core via the floor assemblies. And the visco-elastic dampers attached to each end of all of the trusses helped absorb energy to damp out the building's oscillation begun by the wind under normal circumstances.

This whole notion that a "3 dimensional array" of steel can automatically reisist lateral loads to a significant degree is just false. I don't even know what to say at this point, except to start a remedial building structures lecture, but I don't have the breath. You obviously haven't taken the time to read any books on building structures, nor done any academic work, or even worked in the construction industry to any great extent. You actually need to make an effort to understand this stuff. but I guess you'd rather shout "bullcrap" at any idea that strikes you as inconvenient.

I was going to suggest that you read "why buildings stand up", or "why buildings fall down", or "structure in architecture". but you already reject any source that tells you anything you don't want to hear.

There's really nothing that can be said to you except "read a book and take a class" Preferably several of each.

Originally posted by IrishWristwatch

Originally posted by psikeyhackr
The variation in the top 20 stories of the WTC should be similar to that in a 20 story building.

Doesn't that suggest that the top 10 stories should crush the 10 below them?

Nice graphic.

That is why the Verinage technique works on short building though I don't know if it would work on a short steel frame building.

I didn't make the graphic. It was made by someone I have contended with of various boards. He has used 3 different handles. He calls himself Kat Dorman on Rational Skepticism.

www.rationalskepticism.org...

psik

Originally posted by DrEugeneFixer
This whole notion that a "3 dimensional array" of steel can automatically reisist lateral loads to a significant degree is just false. I don't even know what to say at this point, except to start a remedial building structures lecture, but I don't have the breath. You obviously haven't taken the time to read any books on building structures, nor done any academic work, or even worked in the construction industry to any great extent. You actually need to make an effort to understand this stuff. but I guess you'd rather shout "bullcrap" at any idea that strikes you as inconvenient.

I was going to suggest that you read "why buildings stand up", or "why buildings fall down", or "structure in architecture". but you already reject any source that tells you anything you don't want to hear.

There's really nothing that can be said to you except "read a book and take a class" Preferably several of each.

We already know we are talking about a skyscraper so I don't see any point in talking about how the joints are connected in that 3-D array.

The 2-D array of the perimeter can't offer much resistance to a force applied perpendicular to it. Are you disagreeing with that?

psik

Originally posted by psikeyhackr

We already know we are talking about a skyscraper so I don't see any point in talking about how the joints are connected in that 3-D array.
psik

More like you don't understand anything about it, and therefore don't see its importance. Take a class.

Originally posted by psikeyhackr
The 2-D array of the perimeter can't offer much resistance to a force applied perpendicular to it. Are you disagreeing with that?
psik

Obviously, it has already been explained to you how the perimeter columns and spandrels assemblies resisted lateral loads, with the help of the floor-slab assemblies, which is why you bothered to deny it was possible, despite having read it in many sources. It won't do any good for me to explain all this again. You're just in some kind of denial.

Read a book on the subject, that's my recommendation.

Question: have you read a single book on the subject of building structures, and if so, which one. 9/11 books don't count.

Originally posted by DrEugeneFixer

Originally posted by psikeyhackr

We already know we are talking about a skyscraper so I don't see any point in talking about how the joints are connected in that 3-D array.
psik

More like you don't understand anything about it, and therefore don't see its importance. Take a class.

Originally posted by psikeyhackr
The 2-D array of the perimeter can't offer much resistance to a force applied perpendicular to it. Are you disagreeing with that?
psik

Obviously, it has already been explained to you how the perimeter columns and spandrels assemblies resisted lateral loads, with the help of the floor-slab assemblies, which is why you bothered to deny it was possible, despite having read it in many sources. It won't do any good for me to explain all this again. You're just in some kind of denial.

Read a book on the subject, that's my recommendation.

Question: have you read a single book on the subject of building structures, and if so, which one. 9/11 books don't count.

I didn't deny it was possible I said the core didn't need it. The perimeter needed it because it was 2-dimensional. It was the core that provided the buildings rigidity and was able to do so because it was THREE DIMENSIONAL. Vertical Columns and two sets of Horizontal Beams perpendicular to each other.

psik

reply to post by psikeyhackr


how did the core resist lateral forces?

Read a book.

Originally posted by DrEugeneFixer
reply to post by psikeyhackr

 

how did the core resist lateral forces?

Read a book.

You are not claiming a two-dimensional array can handle perpendicular forces.

Skyscrapers have had 3-D arrays of steel since they have been built. The WTC is different from usual in the so called tube-in-tube design. The core is not a tube but a more concentrated 3-D array and the perimeter is 4 perpendicular 2-D arrays.

You have made no attempt to explain what is incorrect about anything I have said you just imply I am stupid with this read a book crap. I do not give a damn about those details of structural engineering but the fact that there are so many skyscrapers around the world is proof that this is commonly known in the industry.

The Empire State Building is EIGHTY YEARS OLD. This knowledge is old sh#. Structural engineers are just pretending it is complicated. But they are allowing this simple trash to drag on year after year.

psik

Originally posted by psikeyhackr
I do not give a damn about those details of structural engineering..
psik

Apparently not, or you would know something more about it by now than what you read on ATS.

Originally posted by psikeyhackr

Structural engineers are just pretending it is complicated...

It's all a plot to make you look dumb.

Have you ever considered that the four "2d arrays of steel arranged perpendicularly" taken along with the slab and truss systems, constitute a "3D array of steel and concrete". Thus, by your own (faulty) logic, it should be able to resist lateral loads.

reply to post by IrishWristwatch

I am sincere and I don't care about your apology. It means nothing.

Actually, sorry for the mistake, I retract that apology since you kinda failed to meet the terms I offered. Apologies for failing to notice at the time.

This justifies the assumption of a rigid block since it IS effectively rigid. Effectively rigid means strong enough to crush the lower, not indestructible. Shall we now proceed?
[...]
It is NOT unbreakable.

"Rigid" is a euphemism for effectively indestructible. Either way there is a phase change.

But I read through your thread
the911forum.freeforums.org...

I'm not saying any real collapse would arrest because of a sensitive bifurcation in this simplified, ideal world of analysis. Oh no, it's nearly the inversion: this ideal analysis has virtually nothing meaningful or useful to say about crush direction in any real collapse. Even more, it suggests the notion of crush direction is not itself a meaningful or useful notion in studying the dynamics. Defending the idea of exclusive crush down as done in B&L is willfully embracing almost inevitably inapplicable model/mechanics/parameterization!

I really don't understand why you are arguing with me when you make statements like this, it is just an informal way of saying what I am trying to find a way to say formally.

Maybe the problem is that you don't know what "formal" means?
en.wikipedia.org...
(that would certainly explain the derision of "stick figures")

The reason why why bifurcating crush direction model is not a useful notion in dynamics is because it implies a decrease in entropy at the instant of bifurcation with no plausible (disclosed) source. The only reason why a model would be mechanically plausible but invalid on the whole is because of some violation of the second law of thermodynamics. That is exactly the same issue that bedevils perpetual motion devices.

At least that is the only reason I can think of, maybe you know of others.

The reason why I am trying to state it in those terms rather than yours is that in your terms it just means that the B&L are embracing an inapplicable model.

In my terms, at least this is what I am going for, you could use the fact that such a violation takes place to generalize the principle. If a bifurcating model is required to explain the collapse and a bifurcation implies a violation of the second law of thermodynamics (which I believe it does), then it follows necessarily that gravity alone could not have been the sole actor.

If you could show that a bifurcation does not imply a violation (either empirically or by some other means) then the problem is solved in the other direction. But I wouldn't hold my breath on that score.

Either way the use of formal language is the key that gets you out of the logical contortion you are trying to make your ideas go through.

reply to post by Darkwing01


What I don't accept though, and what I find to be a position utterly without merit and destructive of meaningful inquiry is the argument that the crush-up/crush-down model is not informative.

You can't just dismiss the model and offer nothing substantial up to replace it.

Curling up into a the circularity of non-empirical antecedent confirmation is nothing but defeatism, even if you won't admit it to yourself.