WTC 1 & 2. What happened after collapse initiation?

[pomeroo]

Good that we agree (pomeroo disagreeing) that when two objects collide the forces developing at contact are in equilibrium as postulated by Newton.

You really must stop. Nobody agrees with your insane garble of basic physics. It has been explained to you repeatedly that dropping the top third of a building onto the bottom two-thirds destroys the structure completely--reduces it to rubble. No "equilibrium" is established. Get it?

What happens then, the initiation = topic, is interesting. Both objects may remain intact and bounce - one object going one way, the other another, like billiard balls. Alternatively one object remains virtually intact, while the other is damaged. Or both objects are damaged by the contact forces. There are other possibilites.
Re WTC1 NIST and Bazant suggest that the upper block remains intact, while the lower structure is destroyed. Simple damage analysis in my articles shows that assumption is false. It is as simple as that.
Detailed observations then demonstrate that the objects involved in the collision consist of strong parts (columns) and weak parts (floors) and the logical conclusion is that the strong parts of the object destroy the weak parts.
NIST and Bazant suggest that one floor is superstrong and remains intact and as a piston top loaded with energy compresses and destroys the structure below due to lack of strain energy there. Simple damage analysis in my articles shows that assumption is also false. It is as simple as that.
Etc, etc.

Either you are a flagrant liar or you are obtuse beyond belief. What you have written here is utter nonsense. Absolutely nobody suggests that "one floor is superstrong" (why should it be?).

In my analysis it is shown that the energy involved in the collision is soon wasted as deformation of local failures and friction = the destruction is soon arrested.
NIST and Bazant suggest that there is no friction so that further destruction can proceed at free fall velocity. Simple damage analysis in my articles shows that assumption is also false. It is as simple as that.
I strongly support the efforts by relatives of victims of 9/11 that the investigations are redone by better qualified people.

You have performed no analysis, as you are incompetent. Your articles are worthless rubbish, written by someone who lacks a high-school student's understanding of physics.

 

[pomeroo]

Hm, according Bazant and NIST the upper block remains intact and destroys the lower structure after initiation = topic. When the lower structure is completely destroyed, the upper block finally decides to collapse in a push up, in spite of the fact that a fair amount of the core of the lower structure remains partly undamaged after the destruction as pointed out by somebody on this thread. Are NIST and Bazant idiots?
Using clear thinking, which seems to be lacking by many participants at this thread, I point out to children in my articles that it is only the weak components of both parts that are destroyed (due to lack of local strain energy) and that the strong parts remain intact (due to big built in strain energy exceeding any energy applied to them) when in contact with the weak parts. And contact only occurs locally up top. By including friction in the analysis (not done by NIST and Bazant) it is concluded that the local failures (of the floors) are soon arrested.

No big deal, actually. Happens all the time. Should have happened after initiations at WTC1/2.

There would appear to be two reasons why a person would address an article purporting to explain the mechanics of the collapses of the Twin Towers to children:

1) He is insane;

2) He understands that informed adults will discover that his explanations are total nonsense.


Physicists and engineers keep pointing out that your babble about friction is absurd.

 

[pomeroo]

-

Hm, according Bazant and NIST the upper block remains intact and destroys the lower structure after initiation = topic. When the lower structure is completely destroyed, the upper block finally decides to collapse in a push up, in spite of the fact that a fair amount of the core of the lower structure remains partly undamaged after the destruction as pointed out by somebody on this thread. Are NIST and Bazant idiots?
Using clear thinking, which seems to be lacking by many participants at this thread, I point out to children in my articles that it is only the weak components of both parts that are destroyed (due to lack of local strain energy) and that the strong parts remain intact (due to big built in strain energy exceeding any energy applied to them) when in contact with the weak parts. And contact only occurs locally up top. By including friction in the analysis (not done by NIST and Bazant) it is concluded that the local failures (of the floors) are soon arrested.

No big deal, actually. Happens all the time. Should have happened after initiations at WTC1/2.

YES OR NO:

Dropping the top third of building from a height of two miles onto the bottom two-thirds destroys the whole structure.

No lunatic discussions about when and where this hypothetical event occurred--it didn't. No invoking Sir Isaac Newton. Answer the question,

YES OR NO.

 

[Newtons Bit]

So I gave the answer for one bolt. Evidently an identical second bolt will shear off at the same load.

Anyway, bolted connections are inherently unsafe so designers use much bigger FoS for them than for a completely welded one. It seems bolts were only used in WTC1 to fix the floor to the column. Then they added a little steel bar below to support the connection (and to assist transmitting the vertical load on the floor to the column).

BTW & OT - why do you use such foul language. Did your mother teach you that or did you pick it up at university? Or are you only 10 years old?

Everyone needs to remember to attack the argument and not the arguer. This applies to all members and all those posting in this thread.

Replying to this modbox in thread will be off topic  Posted By: LibraryLady

You said one bolt had 40-50KN of capacity (or 9.0-11.2kips of capacity). You're off by a factor of two. The design strength of an A307 bolt is 5.52 kips (24.5KN).

Congratulations! If you were a real engineer you would have just gotten a bunch of people killed! And you wonder why no one takes you seriously: you have no clue.

Now then, the correct total design capacity of two bolts is 11.0kips. Can this force be significant in damaging the columns?

 

[Heiwa]

You said one bolt had 40-50KN of capacity (or 9.0-11.2kips of capacity). You're off by a factor of two. The design strength of an A307 bolt is 5.52 kips (24.5KN).

Congratulations! If you were a real engineer you would have just gotten a bunch of people killed! And you wonder why no one takes you seriously: you have no clue.

Now then, the correct total design capacity of two bolts is 11.0kips. Can this force be significant in damaging the columns?

Thanks for not using foul language. A little politeness costs nothing. Design strength? I work with design stresses as % of max stress (generally yield or buckling stress, if the latter occurs before) and the design (static + dynamic) combined stress (x% shear + y% bending + z% axial) in welded steel construction is usually 0.3 yield or FoS = 3. Your bolt design strength (sic) may very well be 5.52 kips if you are using some old tables but it will shear off at 9-11.2 kips, i.e. the table use a FoS of 2 to get 'design strength'. Better use direct calculations of stress only.
Bolts are very unsafe, particularly in shear. The hole in which the bolt is fitted must provide a perfect fit = no clearances anywhere. If the bolt can move in the hole, it (and the hole) will wear very quickly and soon shear off at 1 kips or just drop out. All OT of course. T is what happened after initiation.

 

[pomeroo]

Thanks for not using foul language. A little politeness costs nothing. Design strength? I work with design stresses as % of max stress (generally yield or buckling stress, if the latter occurs before) and the design (static + dynamic) combined stress (x% shear + y% bending + z% axial) in welded steel construction is usually 0.3 yield or FoS = 3. Your bolt design strength (sic) may very well be 5.52 kips if you are using some old tables but it will shear off at 9-11.2 kips, i.e. the table use a FoS of 2 to get 'design strength'. Better use direct calculations of stress only.
Bolts are very unsafe, particularly in shear. The hole in which the bolt is fitted must provide a perfect fit = no clearances anywhere. If the bolt can move in the hole, it (and the hole) will wear very quickly and soon shear off at 1 kips or just drop out. All OT of course. T is what happened after initiation.

See post # 563.

 

[Heiwa]

-


YES OR NO:

Dropping the top third of building from a height of two miles onto the bottom two-thirds destroys the whole structure.

No lunatic discussions about when and where this hypothetical event occurred--it didn't. No invoking Sir Isaac Newton. Answer the question,

YES OR NO.

??? Why would anyone drop a top third of a building from a height of two miles onto the bottom two thirds? How do you do that? How do you ensure that you hit the bottom two thirds? Aren't you a little OT? Two miles?

 

[pomeroo]

??? Why would anyone drop a top third of a building from a height of two miles onto the bottom two thirds? How do you do that? How do you ensure that you hit the bottom two thirds? Aren't you a little OT? Two miles?

ANSWER THE QUESTION IN POST # 563,

YES OR NO

Are you capable of reading?

 

[Heiwa]

You really must stop. Nobody agrees with your insane garble of basic physics. It has been explained to you repeatedly that dropping the top third of a building onto the bottom two-thirds destroys the structure completely--reduces it to rubble. No "equilibrium" is established. Get it?

Either you are a flagrant liar or you are obtuse beyond belief. What you have written here is utter nonsense. Absolutely nobody suggests that "one floor is superstrong" (why should it be?).

You have performed no analysis, as you are incompetent. Your articles are worthless rubbish, written by someone who lacks a high-school student's understanding of physics.

Everyone needs to remember to attack the argument and not the arguer. This applies to all members and all those posting in this thread.

 

[Newtons Bit]

Thanks for not using foul language. A little politeness costs nothing. Design strength? I work with design stresses as % of max stress (generally yield or buckling stress, if the latter occurs before) and the design (static + dynamic) combined stress (x% shear + y% bending + z% axial) in welded steel construction is usually 0.3 yield or FoS = 3. Your bolt design strength (sic) may very well be 5.52 kips if you are using some old tables but it will shear off at 9-11.2 kips, i.e. the table use a FoS of 2 to get 'design strength'. Better use direct calculations of stress only.
Bolts are very unsafe, particularly in shear. The hole in which the bolt is fitted must provide a perfect fit = no clearances anywhere. If the bolt can move in the hole, it (and the hole) will wear very quickly and soon shear off at 1 kips or just drop out. All OT of course. T is what happened after initiation.

Don't kid yourself Heiwa. This is based on LRFD methodology. That's the actual value that an 3/4"Ø A307 bolt will break with a reasonable confidence level. No one uses large material factor of safeties anymore. We factor the load up to ensure that the design is adequate.

And no, if bolts move around they won't just shear off and fall away, assuming the bolt is actually installed correctly. You do know that bolts are pre-tensioned beyond their yield strength and thus form a bond through friction with the connecting surface right? This is the slip resistance of the bolt. It is less than the bearing capacity (direct shear on the bolt shank) but much, much greater than 1 kip.

Stop making things up. Be honest, at least to yourself and admit you don't have much of a clue when it comes to this stuff. I don't expect you to actually admit that to me, but maybe you'll grow as a person if you can admit it to yourself.

 

[Heiwa]

ANSWER THE QUESTION IN POST # 563,

YES OR NO

Are you capable of reading?

Yes, I can read +. The answer to your hypothetical question is NO! Surprise. Do you want an explanation?

 

[pomeroo]

Yes, I can read +. The answer to your hypothetical question is NO! Surprise. Do you want an explanation?

Your answer is insanely, spectacularly, stupendously, absurdly, preposterously, ridiculously, moronically, ignorantly, crazily, bizarrely, grotesquely, fatuously, cluelessly, bumptiously, flagrantly, laughably, staggeringly, eye-poppingly, outrageously, incompetently, foolishly

WRONG !!!!!!!!!!!!!

 

[pomeroo]

Yes, I can read +. The answer to your hypothetical question is NO! Surprise. Do you want an explanation?

If it's all the same to you, we'll pass on the explanation.

 

[Grizzly Bear]

Either you are a flagrant liar or you are obtuse beyond belief. What you have written here is utter nonsense. Absolutely nobody suggests that "one floor is superstrong" (why should it be?).

I keeping trying to tell him that he ignores details which a blatantly obvious to any non-engineer. He thinks he connections would be able to resist such immense lateral shear that they would be able to not only hold together and let the top section but also have core columns mincing floors to pieces.

If a plane can shear right through the columns and introduce enough lateral force to dislodge 30 some odd exterior columns eityher through breaking their connections or otherwise, then what are they to do to stop an entire 15 to 30 story section of building crashing down all at once on individual parts applying the same kid of forces?

 

[Heiwa]

Don't kid yourself Heiwa. This is based on LRFD methodology. That's the actual value that an 3/4"Ø A307 bolt will break with a reasonable confidence level. No one uses large material factor of safeties anymore. We factor the load up to ensure that the design is adequate.

And no, if bolts move around they won't just shear off and fall away, assuming the bolt is actually installed correctly. You do know that bolts are pre-tensioned beyond their yield strength and thus form a bond through friction with the connecting surface right? This is the slip resistance of the bolt. It is less than the bearing capacity (direct shear on the bolt shank) but much, much greater than 1 kip.

Stop making things up. Be honest, at least to yourself and admit you don't have much of a clue when it comes to this stuff. I don't expect you to actually admit that to me, but maybe you'll grow as a person if you can admit it to yourself.

I have seen many bolts dropping out causing local damage to my welded steel structures.

Reasonable confidence level! Can't you do better than that?

Better is first to establish the design loads involved. It can be tricky.

Then you apply these loads to the structure/component and establish the resulting stresses everywhere.

Then you adjust the structure/component so that the combined stress is, say, 1/3 of the maximum permissible stress (e.g. yield) to obtain a FoS of 3.
Then you have a nice safety margin and redundancy allowing for wear and tear, misalignment, manufacturing faults, errors in load estimations, fatigue, etc, etc. Oh yes, in my steel construction business we use FoSs like that - always based on stress calculations. Only 40+ years experience.

Of course I can slender down the structure allowing one static stress level and another dynamic (short term) stress level and permitting that some deformation will take place (due short term dynamic loads), etc, etc. There are many variations.

 

[pomeroo]

I keeping trying to tell him that he ignores details which a blatantly obvious to any non-engineer. He thinks he connections would be able to resist such immense lateral shear that they would be able to not only hold together and let the top section but also have core columns mincing floors to pieces.

If a plane can shear right through the columns and introduce enough lateral force to dislodge 30 some odd exterior columns eityher through breaking their connections or otherwise, then what are they to do to stop an entire 15 to 30 story section of building crashing down all at once on individual parts applying the same kid of forces?

He does not believe that dropping the top third of a building onto the bottom two-thirds from a height of two miles destroys the whole structure.

There is nothing to add. His response speaks for itself.

 

[Heiwa]

If it's all the same to you, we'll pass on the explanation.

The whole structure will not be destroyed! Only parts of it = the ones that fail due to contacts. Thus answer NO is therefore correct.

 

[pomeroo]

Everyone needs to remember to attack the argument and not the arguer. This applies to all members and all those posting in this thread.

Some of us have noticed that I am attacking your insane arguments.

 

[pomeroo]

The whole structure will not be destroyed! Only parts of it = the ones that fail due to contacts. Thus answer NO is therefore correct.

The result, as every sane human realizes, will be a pile of rubble.

You are quite mad.

 

[Heiwa]

Your answer is insanely, spectacularly, stupendously, absurdly, preposterously, ridiculously, moronically, ignorantly, crazily, bizarrely, grotesquely, fatuously, cluelessly, bumptiously, flagrantly, laughably, staggeringly, eye-poppingly, outrageously, incompetently, foolishly

WRONG !!!!!!!!!!!!!

I know you would be surprised. Doesn't change anything. You were in error. Happens all the time. That's why we discuss so you and other non-engineers and sect members will learn a little about the real world.