Controlled Demolition Was Not Needed To Bring Down The Towers

Originally posted by DrEugeneFixer
My point about the towers not being a homogeneous solid is that falling columns and floor assemblies can overload the connection between the floor trusses and the perimeter columns with relative ease.

That is an illogical conclusion.

What about the connection to the core columns?

The thing that you are not understanding though, is regardless of whether the connections failed the floors would still stack up creating resistance and slowing down the collapse, leaving a stack of floors still visible in the footprint.

It takes time and energy for the floors to impact, and break connections (Ke is lost, not gained, momentum is slowed as that quote I presented tells you). Resistance would build as the floors stacked up. The more floors that fell the more resistance there would be until eventually the collapse would stop. Lightweight concrete does not have enough energy to destroy itself, and overcome the connections holding them up.

I told you how to test this yourself, until you do and prove your hypothesis then I will go with what has already been established in physics, and is well explained by the laws of motion.



What energy hurled large perimeter columns hundreds of feet into other buildings (gravity lol)?

reply to post by ANOK

Lightweight concrete does not have enough energy to destroy itself, and overcome the connections holding them up....

Huh? It was concrete, not styrofoam. Using the word lighweight is meaningless in this situation, the concrete was light compared to structural concrete.

reply to post by ANOK


Let me get this straight, what you are saying is that floors that failed, as in floors that are no longer supported, offer resistance? And with each floor that is added to the falling mass the resistance increases?

If I interpret you correctly, can you explain what force exactly causes floors that already failed to offer resistance?

Originally posted by -PLB-
reply to post by ANOK

 

Let me get this straight, what you are saying is that floors that failed, as in floors that are no longer supported, offer resistance? And with each floor that is added to the falling mass the resistance increases?

If I interpret you correctly, can you explain what force exactly causes floors that already failed to offer resistance?

Go try and drop concrete slabs on each other, they will stack up, not all break and eject themselves out. Add rebar to those concrete slabs, and you'll have an even harder time reproducing your claims.

Of course they will cause resistance as the floors, still in one piece or broken up, stack up (if not ejected as you claim). What crushed the very last floor to land? Can you tell me how many floors it would take to completely crush, or eject, another floor? How did the top falling mass stay in one piece while crushing the lower floors, and not be crushed itself during the collapse? How did the core collapse through an increasing path of most resistance? Where did all the steel floor pans go?

Sorry you can't get your head around this. Physics can be confusing I understand.

reply to post by ANOK


The stacked floors as you call them, are no longer supported. The connections to the columns failed. The are a falling mass with their own momentum. When these stacked floors hit the next floor, this next floor will also fail, and is added to the falling stacked floors. The top section is pretty much irrelevant in the collapse after a couple of floors failed. It can as well just disappear in thin air and the collapse would still continue because of the mass of the floors that failed. And you claim that the stacked floor offer resistance? Explain.

If you disagree with anything I just typed, point out what exactly it is you disagree with and why.

Originally posted by hooper

Huh? It was concrete, not styrofoam. Using the word lighweight is meaningless in this situation, the concrete was light compared to structural concrete.

It's lightweight compared to all the steel it was attached to.

You do realise that the concrete was not directly attached to the columns, but sat in steel pans that were connected to the columns? Those steel pans would not break up when they fell on each other. The mass of 15 floors is not enough to overcome the mass of 95 floors. Forget about how they were connected, even if they were connected with toothpicks the floors could not completely collapse themselves.

You are a laugh hooper, you OSers used to love to stress the trusses were lightweight, thus making the assumption that lightweight meant not very strong. You fail to understand that steel has a high strength to weight ratio, meaning it is light but very strong. That is the nature of steel. Concrete has a low strength to wait ratio in comparison.

Originally posted by -PLB-
reply to post by ANOK

 

The stacked floors as you call them, are no longer supported.

That makes no difference whatsoever. Try dropping unsupported concrete slabs, and see if you can reproduce the crushing floors. The unsupported floors would stack up, not crush and eject themselves.

reply to post by ANOK


If, lets say, 10 unsupported stacked floors fall 4 meter down onto an intact floor. I have heard claims of a safety factor of 3. So the floors were designed to carry at most 3 times their own weight. Now the weight is increased ten fold. What do you thing will happen? Will the floor be able to hold all that weight? Or will the connections fail? And why do you think that?

Originally posted by ANOK
How did the top falling mass stay in one piece while crushing the lower floors, and not be crushed itself during the collapse?

Where do you get this idea that the falling mass remained in one piece. even if it is "crushed" it has mass and velocity.?

reply to post by ANOK

It's lightweight compared to all the steel it was attached to.

All concrete is light compared to steel That's not why they refer to it as lightweight.

You do realise that the concrete was not directly attached to the columns, but sat in steel pans that were connected to the columns?

More than you do.

Those steel pans would not break up when they fell on each other.

Don't know what you mean by "break up", but yes they would break apart as they fell and were struck by other parts of the structure. The pans are attached to the top chords of the trusses with spot welds and in the case of the WTC the diagonal protruded above the top chord into the pans in order to turn the concrete filled pans and the trusses into a unit and reduce the amount of re-bar in the floor section. Strong, yes, but not meant to withstand dropping a couple of hundred feet.

The mass of 15 floors is not enough to overcome the mass of 95 floors. Forget about how they were connected, even if they were connected with toothpicks the floors could not completely collapse themselves.

Oh here we go with the "mass" crap. It was a building. Not a bowling ball. Complex systems comprised of millions of interlocked elements. Breach the interlockings and the system fails. Result, pile of rubble.

You are a laugh hooper, you OSers used to love to stress the trusses were lightweight, thus making the assumption that lightweight meant not very strong.

Not as funny as you guys trying to pretend the building was a solid block of steel.

You fail to understand that steel has a high strength to weight ratio, meaning it is light but very strong. That is the nature of steel. Concrete has a low strength to wait ratio in comparison.

And you fail to understand that the buildings were not just two masses of concrete and steel. Thanks for the entertainment.

reply to post by -PLB-


Let us not forget the truss seats. The paper I posted earlier speaks about how the seats were either bent, twisted, sheered, or completely torn off from the columns (bot interior and exterior). It just goes to show the unimaginable forces at work during that collapse. Also add in the eyewitness accounts of the workers that saw first hand, how 10-20 floors in some cases, were squished down into a fraction of the normal size. I dont know of any explosives tat can do that. Or thermites. Just good ol fashioned gravity.

ANOK thinks that somehow, the truss seat connections, and the welds holding them to the columns, got stronger the lower down you got. How does that happen?

Originally posted by ANOK

Originally posted by DrEugeneFixer
My point about the towers not being a homogeneous solid is that falling columns and floor assemblies can overload the connection between the floor trusses and the perimeter columns with relative ease.

That is an illogical conclusion.

What about the connection to the core columns?

No one forgot about them. In fact, they had even less attaching them as they didnt have a dampener attached to the bottom chord of the truss.

The thing that you are not understanding though, is regardless of whether the connections failed the floors would still stack up creating resistance and slowing down the collapse, leaving a stack of floors still visible in the footprint.

It takes time and energy for the floors to impact, and break connections (Ke is lost, not gained, momentum is slowed as that quote I presented tells you). Resistance would build as the floors stacked up. The more floors that fell the more resistance there would be until eventually the collapse would stop. Lightweight concrete does not have enough energy to destroy itself, and overcome the connections holding them up.

I told you how to test this yourself, until you do and prove your hypothesis then I will go with what has already been established in physics, and is well explained by the laws of motion.

Gravity was working just fine that day. The more floors joined in the mass falling down, the more momentum built and more mass, etc. Also, the top collapsing section helped push away the exterior columns, and I'm pretty sure that doesnt bode well for the truss seat connections.

What energy hurled large perimeter columns hundreds of feet into other buildings (gravity lol)?

Hows about, gravity? Why cant debris from a tower that is over 1,000ft high, fall over and impact something 100-500ft away? The exterior columns, once free from the floors that collapsed earlier, were freestanding. They then proceeded to tip over and fall, like a tree! And that caused some column spandrals to get "thrown" into other buildings nearby. But ANOK, what would have happened if the exterior columns stayed in one piece, and then fell over? They would have fallen a lot farther away, due to its height. The exterior columns practically peeled open like a banana peel.

But hey, laughs, give me a rough estimate as to the amount of explosives required to be even able to catapult 10 tons of steel 500 ft. Just give me a good ballpark guess. Dont give me this, "I dont know" nonsense. You think there is some sort of "extra energy" at play. Ok, so at least use some critical thinking skills, and the basic knowledge that is readily available online and at the library, and give us an idea of just how much explosive would have been required. Then tell us, how it got rigged, etc etc etc, oh, and also, how it was missed on detonation, and the other "side effects" of a large amount of high power explosives that were absent, ie, shattering every window in Lower Manhattan on detonation.

reply to post by DrEugeneFixer

What's your point RE the balls.

My point is that if your calculations show you that there is MORE momentum in the falling mass after each collision you are calculating wrong or are leaving something out.

The towers are a closed system including gravity. Gravity does not add any energy since it is always acting, so every collision must reduce the total amount of energy available to do work.

Since we know that the crush front is accelerating from observational evidence and from the total overall collapse time (I think the figure is a steady 60% of freefall) but we also know that in terms of the second law the total energy available to crush must be reducing we know that the total momentum of the crush front must be decreasing.

There are two components to the momentum of the crush: The mass and the velocity. We have established that the velocity is increasing so that means that in terms of the relation between momentum and energy
the total mass at the crush front must be decreasing at about the same rate (actually at least slightly more) as the velocity

But the mass available to crush is only around 10% of the total mass to be crushed. So even if the crushing mass is some magically compacted jackhammer and the crush mass is a flimsy cardboard house you have to run out of crushing mass before the process can complete.

Try it in an experiment yourself. Sorry if it conflicts with you worldview.

reply to post by Darkwing01


Gravity does not add energy, it transforms energy. From potential to kinetic. Any amount of kinetic energy that is reduced by crushing is added again from potential energy. Momentum increases. The fact that gravity is acting on the building means it is not a closed system. Gravity is an external force.

reply to post by -PLB-

Gravity does not add energy, it transforms energy. From potential to kinetic. Any amount of kinetic energy that is reduced by crushing is added again from potential energy. Momentum increases. The fact that gravity is acting on the building means it is not a closed system. Gravity is an external force.

Gravity was acting on the buildings at all times. It's action never changes, only the balance of forces change.

You cannot add to the total amount of energy available to do work by doing work, that is in direct violation of the second law of thermodynamics.

reply to post by Darkwing01


Gravity did not transform energy at all times, that only happened once the collapse was initiated. From that moment the amount of energy capable of doing work (kinetic energy) continued to increase, while the amount of potential energy decreased.

North Tower - 18 floors above impact zone vs 92 floors below impact zone. Note: impact zone was infact 92-98th floor. Must of been magic because 18 floors couldn't totally demolish 92 floors of intact building, especially in around the time it took. If you cant see and understand that then you're deluded and certainly not smart enough to comment on 9/11. how much of north tower was left standing? How long did it take to collapse? And what was the supposed weight of the 18 floors that totally demolished and imploded the 92 floors below it? ask yourself these questions?

reply to post by -PLB-

From that moment the amount of energy capable of doing work (kinetic energy) continued to increase, while the amount of potential energy decreased.

Potential energy IS the propensity of a system to do work.

I am glad that we at least agree on one thing, Pe must decrease whenever any work is done in a closed system.

Once the collapse initiated the Ke did increase. But you have to reconcile this with the fact that the total propensity to do work is decreasing. That only means one thing: The driver must be shedding mass at a greater rate than it is gaining speed.

The equation itself is fairly straightforward.

I think people think of this as if it was a cup falling through air, it appears that as it falls it increases speed and therefore becomes more and more likely to do work (i.e. shatter the cup) at the bottom. This is a difficult image to banish in this context. You must remember that the total propensity to do work is not represented only by the speed, but also by its position in the field. In other words if I put my hand under the cup to stop it falling all the way the cup will not shatter, even though the system at that point still has a greater propensity to do work than at the moment the cup hits the ground in the first scenario.

What you must bear in mind is that A) Each floor was capable of sustaining the full weight of all the above floors and B) to be adding to the mass the floors must be broken up almost completely. That means that for every successive floor drop the above floor must be doing more work than its position in relation to the gravitational field alone would allow. That extra work comes from the Ke that has been accumulated from the drop.

That means that it should be slowing down. The fact that it is not slowing down means that there is only one place where the missing work can be coming from: Shedding mass.

The correct analogy is not a cup falling through, but a clump of feathers shedding as it goes, or a car that keeps the the engine producing the same amount of power accelerating as the gas tank runs dry, reducing the overall weight.

Originally posted by Darkwing01
A) Each floor was capable of sustaining the full weight of all the above floors

No it wasn't. Only the support columns, to which the floors are connected, carry the full weight of all floors above. Floors themselves were only designed to carry their own weight.

B) to be adding to the mass the floors must be broken up almost completely. That means that for every successive floor drop the above floor must be doing more work than its position in relation to the gravitational field alone would allow. That extra work comes from the Ke that has been accumulated from the drop.

Where did you get all this from? Why must a floor be broken up completely and what do you even mean by that? And how did you come to "That means that for every successive floor drop the above floor must be doing more work than its position in relation to the gravitational field alone would allow".

reply to post by -PLB-

No it wasn't. Only the support columns, to which the floors are connected, carry the full weight of all floors above. Floors themselves were only designed to carry their own weight.

I take it you have never heard of live loads.

Woe betide he who keep a filing cabinet in his office, or, heaven forbid, jump for joy.

In any event it is fairly irrelevant since both the floors and the columns were destroyed, so both must have been giving resistance.

Where did you get all this from? Why must a floor be broken up completely and what do you even mean by that?

The floors, and much of the core and perimeter structure, must be completely broken up because there is no visible intact floor elements after the collapse and few intact perimeter and core elements. (There were some, but I doubt that they are even the majority, so complete was the destruction)

And how did you come to "That means that for every successive floor drop the above floor must be doing more work than its position in relation to the gravitational field alone would allow".

If you take one floor element and drop it on the floor element below one of two things can happen:

1) The lower element can be unseated, in which case it offers little or no resistance. In this scenario the speed increases but there is no mechanism for producing the damage to the floors, since the only place that the energy to cause the damage can come from is the speed of the collapse.

2) The collapse could be halted momentarily as the lower element gives resistance, this allows the upper element to become broken up and even possibly compacted, but it requires the speed to decrease significantly in relation to the new mass added to the process, as is visible in Verinage demolitions.

OS'ers want 1) and 2) to happen simultaneously. This is magical thinking with no empirical support behind it.

If you dropped unattached floor element from the height of one story onto another floor element on the ground, neither would be completely destroyed (or even badly damaged I would venture, OS'ers are so fond of pointing out how lightweight the reinforced concrete was). So the energy to destroy the floors must be taken from elsewhere in the process, specifically the structure and integrity of the upper falling body.

By that I am implying that with each subsequent crush the ability of the remaining upper structure to do further work is reduced.