Moderated Steel structures cannot globally collapse due to gravity alone

[Hellbound]

Very astute observation. Framework sections being torn apart in a violent and chaotic collapse would also have jagged, splayed ends, not finished, machined (i.e., straight) ends.

The ends of all these columns have been cut, not torn apart.

No, because the weakest points were the joins between the beam sections. One would expect the joins to fail before the beam did, unless someone or something intentionally damaged the beams.

You've, once again, got it completely backwards here.

 

[Christopher7]

Physically, Christopher, there is no difference at all. Downward force becomes horizontal velocity quite easily if there is any resistance to that downward force

Really? How in this case, not some comparison,
was the energy redirected?

 

[bill smith]

If he was right, every time the wind blew against a tall building it would keep leaning until it finally collapse (it couldn't spring back). It makes no sense. Unless he doesn't think that tall (more or less any) buildings "sway".

Try it yurself if you have a suitable cardboard box. Any size as long as it is long and slender.

 

[funk de fino]

Point taken. Bazant claims that the ejected material is not a factor after the first few seconds.

Its not a factor in the first second. Not enough is shed to allow the first floor below to withstand the weight above breaking the connections on the perimeter or the core.

Correct?

 

[DGM]

Try it yurself if you have a suitable cardboard box. Any size as long as it is long and slender.

So your saying it will not flex? And when it does flex it won't spring back? I can do this with steel like the real thing (and you stated) (remember builder).

Will a tall building sway in the wind? If so how can it if the steel structure can't store energy? Give up? It can't.

Like I said, Drop the stupid statements.

 

[funk de fino]

Very astute observation. Framework sections being torn apart in a violent and chaotic collapse would also have jagged, splayed ends, not finished, machined (i.e., straight) ends.

The ends of all these columns have been cut, not torn apart.

Incorrect they have broken at the connection. They have not been cut.

If you take a column and fix it at top and bottom and then push against it in the middle what will happen to it?

If you take the same column, cut it in half and then bolt the two pieces together and then push in the middle what will happen to it?

Will the results be the same?

 

[GStan]

Really? How in this case, not some comparison,
was the energy redirected?

By the same mechanisms that you reluctantly acknowledge could have distributed debris as far as 200 feet, (but incredulously refuse to believe could send some debris further than 200 feet.)

What calculations have you completed that affirm your belief that the energy capacity is sufficient to distribute an "expected" debris field within 200 feet but not within 500 feet?

 

[Dave Rogers]

The still-standing spires of core columns are a whole other story. For the rest I think 'deduction' is a better word than 'guesswork'.

When you advance no line of reasoning in favour of a conclusion and decline to address the line of reasoning advanced against it, it's hard to see where any deduction has taken place.

The mass was coming in a collapse wave from abpve and pushing outwards from inside. So when the columns became disconnected at the top the internal rubble would have extruded immediately and pushed the columns outwards and downwards. Even a momentary resistence from the bottom connections should have ensured a tiny delay- long enough for the mass of falling rubble to smother any spitting out of columns.

I've read this several times and the final sentence doesn't seem to make sense. Are you suggesting that the rubble flowed past the column trees and then pushed back inwards on them? That seems to me the only way to visualise smothering, and it doesn't make sense because there's no conceivable force acting back inwards on the column trees in such a situation.

It seems to me that a momentary resistance from the bottom connections will cause them to act as a hinge, allowing the lateral force to act on the tree for longer (as it rotates outwards) and hence accelerate more laterally. If the lower connection broke very quickly, there might be less lateral acceleration, because the column tree would fall away from the edge; there'd certainly be less tendency for the column tree to spin, because the turning moment would act only briefly.

Dave

 

[GlennB]

He means: When Mother Earth calls and Father Gravity says "go directly to Mother Earth", you go.

Chris7, I don't know how many times this has to be repeated, but - sitting here a while back I dropped yet another pencil on the edge of my desk. It ended up a good 3' from it's original "destination" just below its original direct line of fall. That is, it deflected sideways. It bounced. There was, no doubt, some flexing and torsion and whatever involved. We all know this happens routinely when things fall and hit other things along the way.

You know this. So why do you spout Heiwa-esque rubbish such as your quote above?

eta: my apologies - you're just explaining what the idiot bill smith meant. Glad to hear you don't subscribe to the same gibberish.

 

[bill smith]

So your saying it will not flex? And when it does flex it won't spring back? I can do this with steel like the real thing (and you stated) (remember builder).

Will a tall building sway in the wind? If so how can it if the steel structure can't store energy? Give up? It can't.

Like I said, Drop the stupid statements.

A box column has a front plate, a back plate and two side plates .So if itis pushed from the front that side goes into tension but the back plate goes into compression. God knows what happens to the side plates. So it may flex a very little before kinking. Not enough to store potential energy for springing though.

In the Twin Towers they were bolted into 1300 foot units and assemblies closely spaced and braced against the concrete floor slabs at 12' intervals. top to bottom and all around. In this configuraton they gave the building tremendous strength and considerable flexibility- just not to the point of the box columns kinking though.

 

[Dave Rogers]

A box column has a front plate, a back plate and two side plates .So if itis pushed from the front that side goes into tension but the back plate goes into compression. God knows what happens to the side plates. So it may flex a very little before kinking. Not enough to store potential energy for springing though.

Any structural member has a front, a back and two sides, and when it flexes the front goes into tension and the back into compression. That's the mechanism by which an elastic solid resists flexure. Flexing a structural member stores potential energy in it, however little it flexes, and as long as it hasn't reached the elastic limit that energy is available as kinetic energy when the stress is removed. Therefore, there is no such concept as "not enough to store potential energy for springing".

In the Twin Towers they were bolted into 1300 foot units and assemblies closely spaced and braced against the concrete floor slabs at 12' intervals. top to bottom and all around. In this configuraton they gave the building tremendous strength and considerable flexibility- just not to the point of the box columns kinking though.

So a box column can't flex, but a much bigger compound box column can? This is absurd. If the whole building flexes, then the columns have to flex. As for the building having "tremendous strength and considerable flexibility- just not to the point of the box columns kinking though", what is this actually supposed to mean? The strength of the building is a measure of how much it can resist a deforming force without permanent deformation; in other words, it's a measure of how far it is to the point of the box columns kinking.

Do you have even the vaguest idea what you're talking about?

Dave

 

[NutCracker]

Really? How in this case, not some comparison,
was the energy redirected?

Please C7, all those examples you have been shown are not "comparisons" as you claim. Rather, they serve to illustrate a general principal that applies to any structure, including the WTC towers.

The validity of which you can verify experimentally and by noting how hard it is to break things without parts flying off into all directions.

A general principal that is easily understood when one realizes that force is a vector that when a object is under stress is decomposed into its x, y and z components at every inhomogeneity or asymmetry in the object's structure or shape or placement wrt the vertical.

"Redirected energy" is a meaningless concept. Objects are under stress, they deform, the stress in the material is decomposed into x,y and z components over the object's structure and when the limits of the material has been reached, it breaks, the decomposed stress being released and by F=ma accelerating the parts in x,y and z directions. The acceleration results in the parts having kinetic energy.

Your stubborn refusal to accept such an easy to understand and verify concept has not quite brought you on the road to victory, I might say.

 

[DGM]

A box column has a front plate, a back plate and two side plates .So if itis pushed from the front that side goes into tension but the back plate goes into compression. God knows what happens to the side plates. So it may flex a very little before kinking. Not enough to store potential energy for springing though.

I know what they are I BUILD WITH THEM (and fabricate them). The bold could not be possible if they could not store energy. Why do you keep stating things you have no clue about? I'm really embarrassed for you.

In the Twin Towers they were bolted into 1300 foot units and assemblies closely spaced and braced against the concrete floor slabs at 12' intervals. top to bottom and all around. In this configuraton they gave the building tremendous strength and considerable flexibility- just not to the point of the box columns kinking though.

How without storing energy? (bold)

 

[Christopher7]

There were a lot of collisions during the collapse, and a lot of forces at play. Unless you want to make the statement that every part of the building hit every other part perfectly square and imparted force only in a direct, downward angle (something trivally disproven simply because the top of the buildings tilted slightly at collapse initiation), then you are simply ignoring the laws of inertia and momentum.

That is precisely what Bazant does.

For a simple example, what happens when the mass of rubble impacts a floor? The rubble will be deflected sideways until the floor fails, this seems pretty simple.

Bazant's theory requires: " the maximum possible density of compacted debris."

He makes no allowance for energy being redirected other than air pressure ejecting " dust plus large fragments".

 

[bill smith]

When you advance no line of reasoning in favour of a conclusion and decline to address the line of reasoning advanced against it, it's hard to see where any deduction has taken place.



I've read this several times and the final sentence doesn't seem to make sense. Are you suggesting that the rubble flowed past the column trees and then pushed back inwards on them? That seems to me the only way to visualise smothering, and it doesn't make sense because there's no conceivable force acting back inwards on the column trees in such a situation.

It seems to me that a momentary resistance from the bottom connections will cause them to act as a hinge, allowing the lateral force to act on the tree for longer (as it rotates outwards) and hence accelerate more laterally. If the lower connection broke very quickly, there might be less lateral acceleration, because the column tree would fall away from the edge; there'd certainly be less tendency for the column tree to spin, because the turning moment would act only briefly.

Dave

The front of the collapse wave breaks the connection at the top of the column. The rubble is pressing outwards from inside as well and naturally forces the still bottom-attached column outwards and downwards The rubble in the rest of the collapse wave (which was already 0.9 m thick at the 96th floor according to Bazant) catches the now protuding column smothering or hindering any ejection.

Are you suggesting that the type of bolt-snapping we are discussing might have the potential to throw a 4-ton chunk 500 feet or so ? If not can you suggest a reasonable mehanic for how the unidirectional gravitational force cold partially convert into sideways energy that could spit columns weighing tons out at 70 mph and for long distances ?

 

[Dave Rogers]

The front of the collapse wave breaks the connection at the top of the column. The rubble is pressing outwards from inside as well and naturally forces the still bottom-attached column outwards and downwards The rubble in the rest of the collapse wave (which was already 0.9 m thick at the 96th floor according to Bazant) catches the now protuding column smothering or hindering any ejection.

How? Is a pile of rubble somehow supposed to snag the column and pull it inwards? There is no plausible mechanism by which the rubble in the collapse wave can exert an inward force on a structure displaced outside its outer edge.

Are you suggesting that the type of bolt-snapping we are discussing might have the potential to throw a 4-ton chunk 500 feet or so ?

No, and it would take an act of deliberate obtuseness to read any such suggestion into anything I've posted.

If not can you suggest a reasonable mehanic for how the unidirectional gravitational force cold partially convert into sideways energy that could spit columns weighing tons out at 70 mph and for long distances ?

I have, several times, as have several other people. I can understand your fascination with 4-ton lumps of dense metal; I feel like I'm talking to one.

Dave

 

[Gravy]

Well, Chris, since you were again unable to answer the most basic questions about your own claims – questions that are never going away and that demonstrate the absurdity of your arguments – it's back on ignore you go. You've had the same line for years now. How sad.

 

[Dave Rogers]

He means: When Mother Earth calls and Father Gravity says "go directly to Mother Earth", you go.

Unless you weigh 30,000 tons, in which case you're allowed to do a quick 200-foot sidestep first.

Dave

 

[Gravy]

Are you suggesting that the type of bolt-snapping we are discussing might have the potential to throw a 4-ton chunk 500 feet or so ? If not can you suggest a reasonable mehanic for how the unidirectional gravitational force cold partially convert into sideways energy that could spit columns weighing tons out at 70 mph and for long distances ?

Bill, you're running into Christopher 7 territory here. The towers were tubes, the outer walls of which consisted of tightly-bound sections. When those tubes are violently destroyed from the inside by millions of pounds of accumulating, accelerating, falling debris, and the walls of the tubes essentially burst, which way do you expect the wall sections to travel?

Next, how far should such wall sections travel in a collapse that's not aided by anything but gravity? If you don't know how to answer that, you need to reconsider your objections to the videos and physical evidence.

Next, tossing thousands of tons of steel around would require explosives thousands of times larger than are used in building demolitions. The idea that such enormous detonations are undetectable is absurd on its face. If you disagree, then please explain what weapon you think was used to destroy the towers, and the effects we'd expect to see from it. I'm very curious to know how you think this might be possible. Christopher 7 and Heiwa can't answer that question, and they've been doing this for years.

 

[bill smith]

Any structural member has a front, a back and two sides, and when it flexes the front goes into tension and the back into compression. That's the mechanism by which an elastic solid resists flexure. Flexing a structural member stores potential energy in it, however little it flexes, and as long as it hasn't reached the elastic limit that energy is available as kinetic energy when the stress is removed. Therefore, there is no such concept as "not enough to store potential energy for springing".



So a box column can't flex, but a much bigger compound box column can? This is absurd. If the whole building flexes, then the columns have to flex. As for the building having "tremendous strength and considerable flexibility- just not to the point of the box columns kinking though", what is this actually supposed to mean? The strength of the building is a measure of how much it can resist a deforming force without permanent deformation; in other words, it's a measure of how far it is to the point of the box columns kinking.

Do you have even the vaguest idea what you're talking about?

Dave

Would you describe a box-column made of 1/4'' steel plates as an 'elastic solid' ? And I would LIKE an answer to this question to establish whether you are being disingenuous or not.


In these enormous lengths the connected box column sections are one and the stress is shared. No one box column section has to flex beyond it's capacity. So the buildng can sway by meters at it's top and no individual box column section will fail. Bending at one face of the building is counteracted by resistance at the opposite face and the two sides of the building. Backing all this up is a massive structural core All carefully calculated of course and with a very large margin of safety built in.