WTC Demolition: The Spire and the Staircase

http://www.youtube.com/watch?v=h21SDx3RmoE

you might also be interested in this:
http://www.youtube.com/watch?v=_s8JGCGQ_9E

the music in the background is a vast improvement.

because? No explanation?

At least that video proves that there wasn't a concrete core. I saw C is still peddling that else ware on the internets.

those were good times

Without him, we'd never have gotten to see this pic over, and over, and over, and over



Sid

Is the guy playing the piano humming the melody at the same time? I'd swear he was.

Glenn Gould was infamous for that

That cleared up every question the video raised for me.

Gawd, what a haunting picture.

There stands the spire. The remains. The skeleton. A naked steel spire looking so very alone and forlorn.

And then it is gone, leaving only dust and smoke in its place.

You would think that since it still stood that it would stand forever.

You could think that at its base lie the rubble and that rubble would hold it there, standing, forever.

But you would be wrong. It just drops straight down as if it was dissolving.

Where did it go? It didn't lean over and fall, it just goes straight down. Unbelievable! Incredible!

Was it a force of nature? No, what happened was unnatural.

Was the bottom cut out from underneath it? That is the only thing that makes any sense. It had to have been cut from below by some force.

Seven years later, the spire is still a haunting picture.

No, it was counter-intuitive.

Why should something without any way of dealing with lateral forces stay standing at all?

Once it began to move to the side, the immense weight of the core would have snapped off at the pivot point -- at the base.

It then would have fallen down, crushing itself up.

Once you begin to understand the actual forces at work there, you understand what it is that you are seeing. You are not left to your own devices, making up crap about things you don't understand. You learn what reality is.

The way it seemed to simply dissolve.

It was like the ground just swallowed it up. Like a big hole opened underneath it. Never moving to the side, it appears to drop straight down. Not like a tree that "timbers" over to the side.

"It's a wonder tall trees ain't a'laying down."

and dissolving are not the same thing...to think otherwise is simply missguided.

It wasn't a tree, and it didn't dissolve.

and you can use it to support your own personal mythology.

But a natural explanation exists. It doesn't involve bombs or nukes or ray beams. Its own recommendation is that it's true.

That's what they tell us, eh? There is a simple explanation and since it is so simple it must be true, and, because they recommend that it is true it must be true.

Does the recommendation say that it fell over sideways? Did you see that? Is that what they say? It didn't look like it fell over sideways like a tree would. Of course, trees are heavy. And they have no lateral support once you cut the bottom in two. It would make timbering a whole lot easier if they fell straight down like the spire seemed to fall.

And what was eerie was how the lower part off to the side looked like it fell straight down too. Imagine if you only had to cut one tree and the whole forest fell. Man, that would make logging easier, eh?

At least try.

Not even close.... duh! But I will tell you a few difs...

The core was a hell of lot stronger than any tree. And cores can't be cut with a chainsaw.

Surprised I had to tell you this. But that's alright. I've cut steel and trees, too, so I probably know more about them than you.

Now when you learn to recognize how those differences contribute to the different ways both would fall, and the different stresses each would be subject to, you might be able to understand this.

I'm sure that you can. It's not hard to understand. A tree could not crush itself up with its own weight. A building could.

The core can carry its own weight, and the weight of a building, too! You aren't saying a core can crush itself, are you? Nah, of course not, that would be stupid.

But you do say: "A tree could not crush itself up with its own weight. A building could." And that is why I ordered you to stick to the subject: Cores, not the whole building.

Not only that, a core gives lateral strength to a building. A tree has nothing to give, although it does give, right? Either one, tree or steel, you take out the bottom, it falls over.

The similarities as to how either would fall is what we are talking about. I've seen trees fall, and I've seen steel fall. They both fell over the same way. Naturally. Never seen steel fall like that one did.

Tweren't natural.

"a core gives lateral strength to a building"

Not the towers. 100% of lateral loads in the towers was handled by the perimeter columns. There is no crossbracing in the towers' cores to deal with lateral loads. Please look into these structures before you make embarrassing comments like that again.

Straight up and down? Those huge, thick columns were for nothing but straight up and down. Yet they fell straight down? Wow. That really is weird, huh?

Man, this whole thing just gets weirder and weirder, eh?. I mean, if what you say is true, then the bottoms had to have been cut for the spire to fall like it did.

And as I explained, a lateral force comes along, pushes them slightly -- but they are still connected at the bottom. They snap at the pivot point very quickly. They then do fall straight down, acclerated by gravity. And just like the mass of the upper section bashed through the structure below and ended by crushing itself up, the mass of the core then continued to fall and crush the structure of the core up.

That's correct, you wrote: "..as I explained, a lateral force comes along, pushes them slightly... "

But what lateral force was there? A 12mph wind? And what is this you wrote "They snap at the pivot point", (they being the massive steel core columns) you speak of? It would take, I imagine, a 500mph wind to make steel 'snap'. You see, steel doesn't 'snap' like a piece of wood. It will bend, however. But you say snap, not bend. So as the steel bends, it goes sideways. If I seen it once, I seen it a hundred times! Sideways.

So, you're wrong, at least naturally wrong.

Then you write: "...the mass of the core then continued to fall and crush the structure of the core up." The core, you say, crushed itself? It couldn't handle its own weight?

Man, this sure is confusing for a steel cutting guy who also logs. You science types sure do make it hard. Why is that? It just don't seem natural.

as you do to misunderstand it, we might be able to have a discussion.

Its just hard to assimilate all this conflicting evidence.

I mean, I know what I've seen happen with steel, and the general knowledge of how buildings are built and stay standing is not unknown to me, but what you are saying pretty much goes against of that real world, hands on experience.

I dunno, maybe you just used all the wrong words, ya know, different than what most people use to describe how steel naturally reacts to forces?

That's probably all it is, you see things differently than most people and use your own terms. That's cool, everybody is different and they are entitled to doing things differently. It is just a pisser when folks go about being nasty, eh?

And when they are nasty, discussions are hard to have, especially if one side makes shit up? Right?

Get serious and cut the catty remarks and bullshit and we can have a discussion.

You asked me to stop viciously attacking you, remember? So, I tried catty. Now we've had a fairly nice conversation.

Thing is, if you tried as hard to understand steel as you do to misunderstand it then we would have had a really good conversation.

Please, Bolo, look into steel structures before you make embarrassing comments like those again.

I'm sure that you can. It's not hard to understand how steel does not snap. Steel bends.

At least try.

Once you begin to understand the actual forces at work, you understand what it is happening. You are not left to your own devices, making up crap about things you don't understand.

Yes, Bolo, I am saying that you don't know what you're talking about. That you are making stuff up about how steel reacts just to support your own personal mythology. Your depiction would be laughed right out of the steel yard.

Having seen steel fail in shear before, I cannot agree with your statement that "steel does not snap. Steel bends."

Explain your 'shear' term. I think I know what you mean, but knowing you, I probably don't, so, if you'd be so kind?

Oh, is sheared steel the same thing to you as snapped steel? You do seem to infer the two terms are similar.

Question: What does sheared 110 story columnar steel look like? There must be hundreds of WTC pics of sheared steel, if it sheared, so finding one pic should be easy.

Ya know, in the columns, if it was thermite, the molten steel could flow down the inside of a column and pool up at a place of obstruction, say of concrete or a barrier of steel so thick that it didn't have time to burn through.

Whatever, the spire sure looked like it melted.

:eyes:

It has multiple meanings, which contributes to the confusion. In this particular case, I'm referring to the failure mechanism similar to that induced by a mechanical shear. Of course, almost all mechanical failures (even bending failures) occur because the shear stress exceeds the yield strength of the material.

ETA: A good example of a shear failure can be seen in a concrete column failure, because the failure occurs along (or close to) the plane of maximum shear stress for an axially loaded column.

Example:

This stuff is kind of fun. But I don't know the language at all, so let me learn something.

Am I right to think that most of the failures here ultimately are shear failures via brittle failure, although many began as ductile deformation or bends?

Figure 3.8 here indicates how steel deforms first elastically at relatively low stress, then plastically through ductile deformation above its elastic limit, then is subject to brittle failure as its yield strength is exceeded.

I think BeFree is right that when steel "snaps," those are shear failures, although we might not regard all steel shear failures as "snaps."

That's why I went into engineering in the first place - lots of interesting and fun stuff!

If you look at the failure surfaces of the various steel samples shown on that web page, you'll notice that there is a difference between the surface on one part versus the rest. The rougher part is where the initial crack propagated through the object. This generally takes place over a long period, often through several loading cycles. The more regular surface is where the rest of the object's cross-section failed at once when the applied forces caused stresses that greatly exceeded the ultimate strength of the material, resulting in a brittle fracture.

You're correct regarding shear failures vs. "snaps". One of the most common shear failures is from bolts and connector pins, which can be in single shear or double shear configurations (good explanation here). I would not regard the bolt failures as "snaps", although they are excellent examples of shear failures.

And you always get the kinds of discussions you like. Congratulations, once again.

... from the rubble pile itself, trying to flatten itself out when it hit the ground with a lot of kinetic energy that had no place else to go except sideways. The general direction would be outward for all of the rubble, so rubble that fell inside the core footprint would push outward on the columns. The fact that the spire stood for a couple of seconds seems to indicate that it was a marginally stable situation, and if conditions had been only slightly different -- say, if a few more beams holding the core columns together had held up against that lateral force -- the spire might not have collapse immediately.

You said sideways and outwards. The spire dropped straight down. Not sideways or outwards. Straight down.

Back to the drawing board!

This force would have been on the base of the spire, not on the top. When that buckled, it came straight down. Do you want me to draw you a picture?

There was no connection? If they were not welded together then it may be possible. Ya think they were connected somehow, or just stacked up like leggos?

If you push something sideways and outwards, especially steel, it will bend sideways and outwards and lean over, sideways an outwards, like a tree falling.

Of course if there is something holding it laterally, it may not. But remember Bolo said the columns had no lateral bearing? So what was keeping it from going laterally?

One, no lateral bracing.

Two, a pivot point.

Now when you're cutting down a tree, you leave it connected to the root and carefully cut into the tree until its own weight pivots over the remaining connection and falls out.

In the case of the core, what connection below could have withstood the weight of the core columns long enough to provide a pivot point all the way down?

The core was only an up and down structure. When lateral forces come in, the weight of the core itself snapped loose any connection below (or sheared the columns off) and then straight down is the only way to go. There would have been some lateral momentum, but nothing compared to the instant acceleration of gravity on the core columns severed at the bottom.

You ask: "what connection below could have withstood the weight of the core columns long enough to provide a pivot point all the way down". The foundation was underneath it and held the massive core up in the air. You take out the foundation and if falls straight down. The question is: How was the foundation removed?

You say the steel snapped. Is that what NIST says?

What does sheared 110 story columnar steel look like? There must be hundreds of WTC pics of sheared steel, if it sheared, so finding one pic should be easy.

Get busy.

Message removed by moderator. Click here to review the message board rules.

It did lean over before starting to fall straight down, much like the collapse of the tower tops. That tilt indicates that one side failed first and started to fall, while the other side briefly held. But when that side failed, too, it came straight down -- still rotating from the angular momentum, but now with the center of mass coming straight down rather than continuing to move to the side. That sequence indicates that this was another "progressive horizontal collapse". At least one column failed first, its load was dumped on adjacent columns, the resulting tilt caused further redistribution of loads (by shifting the center of mass), and the tilting also caused bending of the columns which weakened them or possibly broke them at splice points. So after that initial failure, all the remaining columns failed in rapid succession.

I don't think anyone can say with any certitude what caused that first failure, because it was probably a combination of things. My point was simply that there would have been lateral forces which could have contributed to the failure. The core was designed as a "gravity frame" (carrying vertical load only) rather than as a "moment frame" (which would resist bending and twisting, as for example a free-standing tower would need to be). When the structure was intact, the floors held the column ends from moving laterally in any direction. After the main part of the tower collapsed, the floors between the core and the perimeter were completely gone, and the floors and beams within the core appear to be heavily damaged but not entirely gone. So there was some residual partial resistance to lateral movement from the remaining core floor structure, but apparently not enough: If a column end wasn't restrained in all directions, the column could buckle by bending in an unrestrained direction.

steel cutting guy?

Shear is a stress, as is compression, tension, torsion, et al. Google may help.

Steel cutting often involves using something like this:





called...wait for it... a shear.

Your theory is that there was one of these shears in the basement shearing the steel as it fell straight down? Just chewed it up, eh?

Is that the best yall can do? My Gawd, yall are terrible. Can't find any pics of sheared steel from the WTC can you? But you show a shearing machine and concrete posts from who knows where. I guess google ain't yall's friend?

BWahahahahahaha!!!!!!!!!!!

you (remember you?), said:



except that is demonstrably not true. So untrue that the process is commonly used in steel shops around the world. Hence the image of a steel SHEAR.

So just what steel have you been working with?

Is that all you got? There was a shear press in the basement eating the steel away?

That little press you showed would break itself into pieces on the one inch+ thick columnar steel of the WTC. The shear you showed is for thinner gauged material. The max for a shear like that is 1/8 inch, probably less. Haven't been around one in a while. Have you?

And a press like that uses 1,000's of pounds of pressure to cut the steel by mechanically shearing the steel. Thin steel can be sheared, but not the thick columnar steel we are talking about. See, the thicker steel is the harder it is to cut. Shearing, in the sense of the mechanical press you showed, on the steel we are talking about, is impossible.

Are we done yet?

I'd like your version of just how the core was melted away in a few seconds.

No, wait....















OK, popcorn ready. Have at it.

I'm surprised at you, Bolo, did you lose the capability of reading ALL the words and putting them together? Try it again. You did this on another thread and put your foot in your mouth, and here you are again.

Quoting me: "Whatever, the spire sure looked like it melted."

I didn't claim it melted, I said it 'looked' like it melted. Its called using rhetoric. And it did look like the spire just melted away. Maybe it did, maybe it didn't. I dunno.

The mythology that the steel snapped doesn't cut it.

Are you amused, again?

What does sheared 110 story columnar steel look like? There must be hundreds of WTC pics of sheared steel, if it sheared, so finding one pic should be easy.

But NIST NCSTAR 1-3C contains plenty of photos of other failures, if you're so inclined to check it out.

Of course they would, because that is the weakest part of the column.

But for the spire to have gone straight down, sections would have to have been removed from below, right? Basically vertical gaps would have had to appear.

Buckling is an excellent way to "remove" a section.

How does steel go about buckling?

I suggest you spend a little time reading about it. Wiki has an okay article here, but there are plenty of other resources out there (Google should help).

Cat got you tongue? Quit playing games. At least try.

Please be a little more specific in your requests.

Quit playing games. Either that or go away.

Perhaps if you were more clear, we wouldn't have this problem. You seem to think I am playing games, yet I'm not the one asking vague questions.

Total bullshit. You should be ashamed. Go tell your Mama you've been bsing again.

Of struggling to understand what you're trying to say? Maybe if you were more clear in your questions, we wouldn't have this problem.

are you stipulating that shear as a stress does in fact exist, or are you still in "steel only bends"-land?

Question: What does sheared 110 story columnar steel look like? There must be hundreds of WTC pics of sheared steel, if it sheared, so finding one pic should be easy.

Impossible? No, merely requiring larger forces.



Your call, Sparky.

What does sheared 110 story columnar steel look like? There must be hundreds of WTC pics of sheared steel, if it sheared, so finding one pic should be easy.

Are you stipulating that shear as a stress does in fact exist, or are you still in "steel only bends"-land?

Shear as a stress is real. Steel, the type of steel that made up the cores would not snap as was claimed, or be sheared by your press. The 'steel snaps' claim was not rhetorical, it was a stated as fact.

If the column pivoted, it would mean the column above the pivot moved laterally. Such a lateral force would force the upper column sideways making the metal bend at the pivot. The weight of the steel, once in motion, would carry it even further sideways. Like a tree falling. That's not what happened with the spire. It dropped straight down looking as if it melted.

Did it melt? I dunno. There is good reason to doubt that it melted, but it sure looked like it did.

ETA: 'Type of' steel would have been a typo. Replace it with 'thickness' and we're good to go.

Were the core columns made of stronger steel than the perimeter columns? How about the steel that composed the floor trusses?

But you knew that.

Was that a trick question? Take Bolo's advice that he gave in this thread and quit playing games. Yall are making me pick up your bad habits.

Recall that you said:


If the cores weren't made of some super-steel, then is it possible your statement is incorrect?

Could you shear such a thickness in that machine?

The "would not snap as was claimed" part is where I have the problem.

The columns would not snap. Are you claiming the columns snapped?

Look, I know you're playing games, why don't you just spit it out and tell me what you're going on about.

Trying to engage you in a productive and interesting dialogue? Most certainly. (although it has proven to be quite a struggle)

I am more interested in how you know that the columns would not have snapped. Perhaps you have some calculations you'd like to share? I, for one, would like to see them.

As it relates to steel?

You're an expert on steel, right?

Then why play these games, be brave, come out and say what you want. Cat got your tongue?

Bwahahaha

Damn, I keep picking up yalls bad habits. Ughhh

If I had my druthers we wouldn't be using it.

Where do you get the idea I'm an expert on steel?

"Everything has to be accompanied by a self-pitying grievance lest the victimization be undermined."

Greenwald was talking about how rightwingers whine about the liberal media.

One more reminder of the safety and sanity of GD and the Lounge.