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Layman's terms please! Tower collapse issue

Heiwa said:
4. Here is a crunch! The columns only occupy 0.14% of the total cross area of the tower.
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BINGO! And those columns are the only thing that can hold up the weight of the upper block!

What loads are put on them? None? OK. The uppermost floor of the lower structure thus occupy 99.86% of the cross area. What loads are put on it and where and when? See 1. There are many masses dropping down. Which one will be applied first? Right - the one that was closest above. Will there be ONE impact or many?
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It doesn't matter if it's one impact or many. If you take the mass off the columns and place it anywhere else in the structure, even if you gently lower it so there's no KE, the structure will fail! The columns are the only thing that can hold up that mass, the floors are designed only to hold their own contents, not the rest of the building above them! So once that upper mass moves, it is nearly impossible for it to end up on top of the columns in such a way that they can still hold it up.
 
Heiwa said:
Read my article - an intact wall column carries 70 tons and can handle 350 tons. An average itact core column carries 280 tons and just to compress it to yield you need a force of 1000 tons.

Where would it come from? Dropping from the sky? How would it be applied to the column?
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Heiwa, as an engineer, can you tell me if the lower structure be able to deflect downward from the impact the the falling mass.

If so, then how much deflection downward would be acceptable before the structure failed?


1 meter?

0.5 meter?

0.1 meter?

Remember we are talking about the strucutre as a whole, which incudes bolted connections as well as welded clip angles, etc.

For instance, I don't know off hand the distance from the bolt holes to the edge of the clip angles, but I think we can assume that it is less than 0.1 meter.


if we drop a 70 ton mass, 3.66 feet (one floor height) and we only allow a deflection of 0.1 meter to absorb the impact, the impact force will be equivelent to a load of 2560 tons.

What will fail first, the floor or the columns?
 
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Heiwa Self-Debunks.

This is hilarious, but I suppose it is the goal that I had in mind all along: get Heiwa to do an ACTUAL calculation and then use it to show that the collapse would progress behold, from section 7.0 (a new one!):

heiwa said:
It is quite simple to calculate the elastic strain energy that could be absorbed by the primary structure. It is a function of distance d of compression of the structure below after Teffect due to energy input from above starting at Tcause. Let's assume that the structure below with actual cross area 4 000 m² and 280+ columns spread around (with cross area 5.64 m² (it is less higher up and more lower down) behaves like a 'spring' with average stiffness or spring constant C = 2 GN/m. Note that only 0.141% of the total cross area of the 'spring' consists of steel (the columns) - the rest is air. It is like a mattress. And this compression also takes time (which is not considered here)!

As shown above the theoretical energy E input to compress the 'spring' is only 340 kWh or 1.22 GNm, when the top part hits the 'spring' instantaneously at Teffect. Let's assume only half this energy is used to compress the 'spring' and that the other half was lost destroying the columns in the initiation zone and sweeping them out of the way and that the upper part breaks up at impact absorbing energy. Let's assume the 'spring' below is suddenly compressed by E = 0.61 GNm at time Teffect.

The maximum compression d of the 'spring' due to energy E then becomes 78 centimeters (because d² = 2 E/C) and after that all the 0.61 GNm or 170 kWh of energy is absorbed as compression! And any motion has stopped! This is a good indication of the elastic strain energy that could be absorbed by a 'spring' without any permanent deformations. The total length (or depth) of the 'spring' is abt 370 meters all the way down to the basement and it is thus temporarily compressed 0.21%. In the basement the energy is also transmitted into the ground and will be recorded as such by any seismograph in the vicinity.

To compress the 'spring' d = 78 centimeters you need a force F corresponding to 1.56 GN (because F = d C) and as the spring cross area at the top is 5.64 m², the 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 a little at the top just below the initiation zone but hardly lower down, where the spring cross area is 20 - 35 m² and the yield stress is higher and thus the force in the spring will produce much smaller stresses
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Emphasis mine. Heiwa's own calculation here shows that the tower above collapses. Imagine that. He does this in two ways: the first is by stating that the tower compresses 0.21%. At this strain, a large amount of the steel (the core) will have failed. Secondly, he states that the stress in the columns is above the yield stress. The yield stress is important for two things:

a) It is the point in which the steel buckles, develops plastic hinges along it's length, and breaks at the splice points.

b) The Modulus of Elasticity, or the stiffness of the spring in his calculation, nearly flatlines after yield. The steel has much, much, much less stiffness and thus the tower moves a whole lot more.

I can argue about some of his assumptions, and how he takes out huge amounts of energy, but it's not even worth it. His own assumptions show that the collapse progresses. His own CALCULATION shows this. Why he doesn't see this, I don't know.
 
Heiwa said:
<1 -6 Snipped! Many words of nonsense>
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I gave you one more chance and you failed miserably to give a straight answer to a pretty straightforward question.

You can try again, but I will keep pointing it out every time you post junk instead of straight answers.

(if you forgot I can repeat the question, if we've established that the lower density of a plastic extension wouldn't have had any effect on the events, why do you keep insisting on using density in your descriptions? That is, before I can take any talk about hay bales or wood bales seriously I need a plausible explanation why density would be a factor, I thought the energy that impacted the lower parts only derived from speed and mass).

So, new try!
 
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Heiwa said:
You have apparently not read my article about why gravity force alone cannot globally collapse a multiparts steel structure? I do not speculate about what really caused the WTC collapses, only conclude gravity force alone (PE=KE>SE) cannot do it.
One mystery is the WTC1 upper block telescoping into itself prior any damage occurs in the structure below the fire/heat zone. The upper block and its PE is supposed to be intact before, during and after the complete collapse. The collapse is supposed to start with the lower structure being crumpled due to gravity force.
Another mystery is that the wall columns in the fire/heat zone (except those cut earlier where you can see two persons looking out) are intact, when smoke and dust are ejected some seconds later. Very strange! Was only the core collapsing? Why?
One thing is certain. The vertical core columns were massive and very strong. To just bend one (I have not seen any) and then cut it off (many examples seen) requires plenty of force, work and energy applied at the right locations. Gravity force does not work like that. It slips off. So you need something else. And it need not cause a massive explosion. There are many ways to cut steel without noise.

BTW - many odd things occurred on 911. But topic is tower collapse issues and gravity alone could not do it.
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Once more you are avoiding the question and using option f as a cope out.

You have stated that massive explosions not only started the collapse but actually disintegrated the massive upper portion of the towers. The massive upper portion weighed in at some 33000 tons.

Now again, what caused 33000 tons of building to totally disintegrate. You are now stating that other things cut steel but the upper section, if your theory is to work was totally disintegrate. So what caused it?

Explosives? Space beams? Thermite? Guys with angle grinders? What?

What caused 33000 tons of steal framed building to totally disintegrate in mid air and completely miss the lower section?

There is only one thing that will cause such massive damage , so why are you trying to avoid stating it?
 
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Newtons Bit said:
This is hilarious, but I suppose it is the goal that I had in mind all along: get Heiwa to do an ACTUAL calculation and then use it to show that the collapse would progress behold, from section 7.0 (a new one!):



Emphasis mine. Heiwa's own calculation here shows that the tower above collapses. Imagine that. He does this in two ways: the first is by stating that the tower compresses 0.21%. At this strain, a large amount of the steel (the core) will have failed. Secondly, he states that the stress in the columns is above the yield stress. The yield stress is important for two things:

a) It is the point in which the steel buckles, develops plastic hinges along it's length, and breaks at the splice points.

b) The Modulus of Elasticity, or the stiffness of the spring in his calculation, nearly flatlines after yield. The steel has much, much, much less stiffness and thus the tower moves a whole lot more.

I can argue about some of his assumptions, and how he takes out huge amounts of energy, but it's not even worth it. His own assumptions show that the collapse progresses. His own CALCULATION shows this. Why he doesn't see this, I don't know.
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?? Assuming that a rigid, solid upper block actually impacts a flexible, elastic lower structure, it is shown that the lower structure, after the upper block bumps into it, actually compresses and then de-compresses = no global collapse. If the lower structure actually is overloaded, it will only break in one location, etc. Not splinter in 1000's of pieces.

But there is no impact after free fall, of course. No evidences for that And no huge amounts of energy. The amounts of energy evidently origin from the various parts of the the upper block (walls, floors, etc) and they are applied one after the other, get deflected by some locally failed, sloping floors in the lower structure and then just get jammed together at the top of the lower structure. No global collapse. Should not be to difficult to grasp.
 
Heiwa said:
?? Assuming that a rigid, solid upper block actually impacts a flexible, elastic lower structure, it is shown that the lower structure, after the upper block bumps into it, actually compresses and then de-compresses = no global collapse. If the lower structure actually is overloaded, it will only break in one location, etc. Not splinter in 1000's of pieces.
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Well to be frank that's a simply ludicrous proposition. However, there's a simple solution to this Heiwa. Produce calculations. Proper structural analysis. Tell us the imposed and design loads on the individual joints within the lower structure under the dynamic loading and then show us (haha!) that they have sufficient capacity. Show us a calculation proving that the floors can carry impact loads.

Put up, or shut up.

But there is no impact after free fall, of course.
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Remind us what happens to the 33,000t of upper tower again? Just bounces off, does it? Floats around?

...get deflected by some locally failed, sloping floors in the lower structure and then just get jammed together at the top of the lower structure. No global collapse. Should not be to difficult to grasp.
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Aha, that's right. The lower structure catches it gently. No impact....hmmm. Catches it very, very gently? Is there a big crash mat there or something?
 
Architect said:
Well to be frank that's a simply ludicrous proposition. However, there's a simple solution to this Heiwa. Produce calculations. Proper structural analysis. Tell us the imposed and design loads on the individual joints within the lower structure under the dynamic loading and then show us (haha!) that they have sufficient capacity. Show us a calculation proving that the floors can carry impact loads.

Put up, or shut up.



Remind us what happens to the 33,000t of upper tower again? Just bounces off, does it? Floats around?



Aha, that's right. The lower structure catches it gently. No impact....hmmm. Catches it very, very gently? Is there a big crash mat there or something?
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Yes, it is ludicrous to assume that the upper block is rigid, solid, of uniform density and can be regarded as ONE mass that free falls due to gravity and impacts something weak. Simple calculations in my article show what happens. Also provides ideas how to make proper calculations based on correct assumtions. Not too difficult.

And you are right about the upper block. The lower structure should catch it gently. I use other words of similar precise meaning and explain why in the article. No reason to get virulently passionate about it. I like to be neutral and, of course, cynical. In layman's terms.
 
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Heiwa said:
Yes, it is ludicrous to assume that the upper block is rigid, solid, of uniform density and can be regarded as ONE mass that free falls due to gravity and impacts something weak. Simple calculations in my article show what happens. Also provides ideas how to make proper calculations based on correct assumtions. Not too difficult.

And you are right about the upper block. The lower structure should catch it gently. I use other words of similar precise meaning and explain why in the article. No reason to get virulently passionate about it. I like to be neutral and, of course, cynical. In layman's terms.
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I think you missed the "put up or shut up" part...

I'd also like to know your definition of "gently".
 
Heiwa said:
And you are right about the upper block. The lower structure should catch it gently. I use other words of similar precise meaning and explain why in the article. No reason to get virulently passionate about it. I like to be neutral and, of course, cynical. In layman's terms.
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"Gently" is a precise word to describe something? You have strange definitions. By the way, how does something gently catch 33,000t? There is nothing gentle about it, at least in the real world where most of us are living.
 
Disbelief said:
"Gently" is a precise word to describe something? You have strange definitions. By the way, how does something gently catch 33,000t? There is nothing gentle about it, at least in the real world where most of us are living.
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You need a really big catcher's mitt.

Heiwa doesn't seem to grasp that the lower floors where the same density as the upper, not that density matters. I wonder what would happen if you just lifted the top floors off and then dropped 30,000 tons of water on the stub?

I suspect they would collapse.
 
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Heiwa said:
You have apparently not read my article about why gravity force alone cannot globally collapse a multiparts steel structure? I do not speculate about what really caused the WTC collapses, only conclude gravity force alone (PE=KE>SE) cannot do it.
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No you don´t. That makes the discussion so much easier for you. What happened to your theory about thousands of gallons of hidden gasoline cans cunningly sneaked into the WTC-complex? You used to promote that as a plausible cause for the explosion you claimed was not caused by the two planes.
 
Well, with a uniform density of 0.18 and all, it's a darned good thing that the building was bolted to the ground . . .
 
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