Heiwa's Pizza Box Experiment

[Heiwa]

Except where the floor is. Or is the floor also 99.86% air?

I also wonder if you know where I'm going with this...

It is Bazant, not me, that includes the total floor area as a parameter, where the solid columns being impacted only occupy 0.14 %.

The floors (and their masses) are just hanging 3.7 m apart on the columns, while the 260+ columns are impacting each other, repeatedly.

To continue the example above with only one column of 212 cm² (or 0.0212 m²) cross area being impacted by a similar column + mass 127 tons, we can assume for simplicity that each column supports on average a floor area of 4000/260 = 15.4 m².

So the 127 tons are spread on 15.4 m², or 8.2 ton/m².

So we have now a hammer with a head of 15.4 m² loaded with 8.2 ton/m² or total 127 tons! This hammer then impacts a lower column (nail) that has only 0.0212 m² cross area. What happens?

I assume the lower column punches a hole through the big hammer head dropping from above.

Alternatively, we make the hammer head 0.0212 m² large to mirror exactly the column below! But then we have to make this hammer head 55.5 metres tall and attach, say, 15 weights (floors) of 8.5 tons each to it every 3.7 metres to make up the total 127 tons.

OK - the 55.5 m tall hammer now impacts the column below. What happens?

Well, first of all it is no longer one mass (127 tons) as per Bazant's simple assumption but 15 masses of 8.5 tons (all attached/bolted to the hammer head) that are involved in the action.

These masses do not really know that they have impacted a column below because it is the column they are attached/bolted to that is impacting the column below.

Now, the question is - does the contraption hammer/upper part with 15 masses bolted to a 55.5 m tall column remain intact? According Bazant, yes. According common sense (and laws of physic), no.

Reason is that the 15 weights, in order to transmit their kinetic energies to the poor column below, must first transmit their kinetic energies to the column of the upper part that they are attached to, which in turn transmits the total kinetic energy to the column below. This takes time and there is an interesting flow of energies in the upper part at alleged impact that Bazant ignores. It is much simpler to assume the upper part being just one, solid, rigid mass that remains intact.

But if an impact really takes place, it is probable that the bolted connections of the weights (floors) of the upper part shear off and the floors and the upper column, free of weights, drop down. It never happened ... because there was no impact.

Read http://heiwaco.tripod.com/nist.htm and you understand why!

 

[GreyICE]

It is Bazant, not me, that includes the total floor area as a parameter, where the solid columns being impacted only occupy 0.14 %.

The floors (and their masses) are just hanging 3.7 m apart on the columns, while the 260+ columns are impacting each other, repeatedly.

No.

To continue the example above with only one column of 212 cm² (or 0.212 m²) cross area being impacted by a similar column + mass 127 tons, we can assume for simplicity that each column supports on average a floor area of 4000/260 = 15.4 m².

So the 127 tons are spread on 15.4 m², or 8.2 ton/m².

You are not an engineer. We tar and feather engineers who assume best-case scenario distributions on single occurrence random events. Pollyanna couldn't be excused for that.

Then you fail to calculate force absorbed/time of impact to determine how much energy they absorbed in an instant

So we have now a hammer with a head of 15.4 m² loaded with 8.2 ton/m² or total 127 tons! This hammer then impacts a lower column (nail) that has only 0.212 m² cross area. What happens?

Given the quality of this version of the model, stick to pizza. It's about as accurate and twice as tasty.
I assume the lower column punches a hole through the big hammer head dropping from above.

Alternatively, we make the hammer head 0.212 m² large to mirror exactly the column below! But then we have to make this hammer head 55.5 metres tall and attach, say, 15 weights (floors) of 8.5 tons each to it every 3.7 metres to make up the total 127 tons.

No.

OK - the 55.5 m tall hammer now impacts the column below. What happens?

Nothing resembling this.

No seriously, do you have any idea of how torque compares to compression stresses in loading problems? ANY IDEA? Do you have the least little clue what the ratio of magnitudes of torque resultant forces: compression forces due to gravity are in your typical loading?

Engineer my arse.

Well, first of all it is no longer one mass (127 tons) as per Bazant's simple assumption but 15 masses of 8.5 tons (all attached/bolted to the hammer head) that are involved in the action.

These masses do not really know that they have impacted a column below because it is the column they are attached/bolted to that is impacting the column below.

Now, the question is - does the contraption hammer/upper part with 15 masses bolted to a 55.5 m tall column remain intact? According Bazant, yes. According common sense (and laws of physic), no.

Oh where oh where do the forces go?

Reason is that the 15 weights, in order to transmit their kinetic energies to the poor column below, must first transmit their kinetic energies to the column of the upper part that they are attached to, which in turn transmits the total kinetic energy to the column below. This takes time and there is an interesting flow of energies in the upper part at alleged impact that Bazant ignores. It is much simpler to assume the upper part being just one, solid, rigid mass that remains intact.

What? You seem to think that these forces are transmitted below the speed of sound, or that the speed of sound in concrete isn't measured in kilometers/second.

But if an impact really takes place, it is probable that the bolted connections of the weights (floors) of the upper part shear off and the floors and the upper column, free of weights, drop down. It never happened ... because there was no impact.

No.

Read http://heiwaco.tripod.com/nist.htm and you understand why!

Well this link creates a totally new set of problems - you obviously have not the least little clue how a building is built.

Quick quiz - does a 110 story building have 110 story continuous columns? This will be on the test.

 

[Heiwa]

No. You are not an engineer. We tar and feather engineers who assume best-case scenario distributions on single occurrence random events. Pollyanna couldn't be excused for that.


No seriously, do you have any idea of how torque compares to compression stresses in loading problems? ANY IDEA? Do you have the least little clue what the ratio of magnitudes of torque resultant forces: compression forces due to gravity are in your typical loading?

Engineer my arse.

Oh where oh where do the forces go?

What? You seem to think that these forces are transmitted below the speed of sound, or that the speed of sound in concrete isn't measured in kilometers/second.

Oh yes, I am an engineer and I know a lot about 3-D structural analysis incl. all forces and moments. And re forces:

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. - Bazant

So my latest experiment is exactly as per Bazant's assumtions.

PS - Pls use proper language in your posts.

 

[Dave Rogers]

It is very easy to check full scale if 260+ WTC 1 tower structure columns collapse, if you drop an upper part on them from 3.7 m height above it. You just need to check one column! Easy for NIST to do!

Each WTC1 column has average cross area say 5.5/260 = 0.0212 m² or 212 cm². Quite solid - abt. 15 x 15 cms solid, square column. In reality it is a box shaped column, say 50 x 50 cms with 1.1 cm thickness (220 cm²).

The weight that impacts it is average 33000/260 = 127 tons or 127000 kgs. The original compressive stress in the column was then 600 kgs/cm² or 25% of yield. This is typical of WTC1. The column could easily carry that!

So here we have Heiwa's big deception: pretending that all the lower structure has to do is hold the weight of the top block. The column needs to do a little more than simply carry the static weight; it has to decelerate the weight to stationary, and that requires a force. What's the force required? Let's take Heiwa's numbers, and see what we get.

We've got 127000kg falling through 3.7m. The acceleration is 9.81ms-2, so the final velocity is 8.5ms-1. We need, therefore, to decelerate this to zero before the steel reaches its elastic limit for the lower column to survive. If the top block is still moving when the steel reaches its elastic limit - around 0.2% compression for steel - then the column will fail.

Let's assume that Heiwa is right about the yield strength of the column being 2400kg/cm2. That means that the greatest force it can exert is 220 x 2400 x 9.81 N, or just under 5.2 meganewtons. That force, acting on a mass of 127,000kg, will decelerate it at 40.8ms-2. Gravity is still acting on the mass, of course, so the net deceleration is only 31ms-2. That means that, with the column exerting its maximum force, the falling weight comes to a stop after it has compressed the lower structure by 1.17m.

However, there's a problem with that. Let's pretend that the elastic strain is instantly transmitted through the entire tower, so that the entire structure below the impact can be treated as a single spring. We've got 97 storeys, of average 3.7m high, being compressed. That's a total height of 359 metres. So the overall compression is 1.17/359, or 0.32%.

Remember the elastic limit of steel? Well, we're well past that, by one and a half times. And let me point out, this is assuming that all the columns at 97th floor level were in perfect condition, and they all contricuted equally to slowing the falling block. It's also assuming that the columns take the load equally, all the way down to the ground, instantly. In real life, there's an elastic wave propagating down the building, and only the top part of the column is able to contract to take the load. By the time the load path has had time to get down to the ground, it's too late; the top of the column is already gone. But even in an idealised situation, where we give the columns an unrealistically high chance of survival, and even using Heiwa's own numbers they still fail.

Heiwa may now tell you that there's no drop, that the top gently and gracefully deforms to lower itself gently on to the next level. But if he really believes that, why is he trying to pull the wool over everyone's eyes by pretending that the tower will survive when there is a 3.7m drop? Because this is not difficult stuff; calculating dynamic loads is engineering 101 stuff, and if Heiwa is the practicing engineer he claims to be, he knows that, and knows his numbers were calculating the wrong loading. In short, why is he lying? I'll leave that to the reader to decide.

So, Heiwa's right that the columns could take the weight of the top of the building. Of course he's right; they were designed to do that. What they weren't designed to do was to catch a falling block, and that's what they had to try and do. Unsurprisingly, they failed.

Dave

 

[Heiwa]

So here we have Heiwa's big deception: pretending that all the lower structure has to do is hold the weight of the top block. The column needs to do a little more than simply carry the static weight; it has to decelerate the weight to stationary, and that requires a force. What's the force required? Let's take Heiwa's numbers, and see what we get.

We've got 127000kg falling through 3.7m. The acceleration is 9.81ms-2, so the final velocity is 8.5ms-1. We need, therefore, to decelerate this to zero before the steel reaches its elastic limit for the lower column to survive. If the top block is still moving when the steel reaches its elastic limit - around 0.2% compression for steel - then the column will fail.

Let's assume that Heiwa is right about the yield strength of the column being 2400kg/cm2. That means that the greatest force it can exert is 220 x 2400 x 9.81 N, or just under 5.2 meganewtons. That force, acting on a mass of 127,000kg, will decelerate it at 40.8ms-2. Gravity is still acting on the mass, of course, so the net deceleration is only 31ms-2. That means that, with the column exerting its maximum force, the falling weight comes to a stop after it has compressed the lower structure by 1.17m.

However, there's a problem with that. Let's pretend that the elastic strain is instantly transmitted through the entire tower, so that the entire structure below the impact can be treated as a single spring. We've got 97 storeys, of average 3.7m high, being compressed. That's a total height of 359 metres. So the overall compression is 1.17/359, or 0.32%.

Remember the elastic limit of steel? Well, we're well past that, by one and a half times. And let me point out, this is assuming that all the columns at 97th floor level were in perfect condition, and they all contricuted equally to slowing the falling block. It's also assuming that the columns take the load equally, all the way down to the ground, instantly. In real life, there's an elastic wave propagating down the building, and only the top part of the column is able to contract to take the load. By the time the load path has had time to get down to the ground, it's too late; the top of the column is already gone. But even in an idealised situation, where we give the columns an unrealistically high chance of survival, and even using Heiwa's own numbers they still fail.

Heiwa may now tell you that there's no drop, that the top gently and gracefully deforms to lower itself gently on to the next level. But if he really believes that, why is he trying to pull the wool over everyone's eyes by pretending that the tower will survive when there is a 3.7m drop? Because this is not difficult stuff; calculating dynamic loads is engineering 101 stuff, and if Heiwa is the practicing engineer he claims to be, he knows that, and knows his numbers were calculating the wrong loading. In short, why is he lying? I'll leave that to the reader to decide.

So, Heiwa's right that the columns could take the weight of the top of the building. Of course he's right; they were designed to do that. What they weren't designed to do was to catch a falling block, and that's what they had to try and do. Unsurprisingly, they failed.

Dave

Thanks. Your calculations are correct = more or less same as mine at http://heiwaco.tripod.com/nist1.htm#7 .

If something drops on an elastic structure, the latter will deform elastically and maybe plastically (destruction) at the top only - decelaration occurs - and that's it. No big deal, actually. After that the destruction is arrested.

But let's be fair. 50% of the energy is transmitted up into the part being dropped. It will also deform elastically and maybe plastically (destruction) at the bottom only - decelaration occurs - and that's it. No big deal, actually. Same thing happened to the structure below. After that the destruction is arrested.

But it is assuming the columns actually meet at impact. I doubt it. They miss each other. Too small. Like a needle in a hay stack.

So at contact lower columns impacts upper floors and upper columns lower floors ... unless the columns miss altogether and hit the air; the columns are displaced outside! And the lower structure will catch the upper loose parts. Destruction will be arrested. Why is explained in my papers.

Dave, you suggest that I am lying and ask why. What's your answer?

I am stunned! Why would I lie? I am just an independent engineer that was asked by some children, whether buildings really could collapse like WTC1,2. They were maybe afraid that it would happen to the buildings, where they live? A quick check showed that NIST and Bazant were lying. That's serious. No consideration for, e.g. children.

Heiwa

 

[GreyICE]

Oh yes, I am an engineer and I know a lot about 3-D structural analysis incl. all forces and moments. And re forces:

For our purpose, we may assume that all the impact forces go into the columns and are distributed among them equally. - Bazant

So my latest experiment is exactly as per Bazant's assumtions.

PS - Pls use proper language in your posts.

Denial, you are in it.

 

[NobbyNobbs]

You have missed the basic, as usual!

Newton's third law is a result of applying symmetry to situations where forces can be attributed to the presence of different objects. For any two objects (call them 1 (WTC lower structure) and 2 (WTC upper block), Newton's third law states that any force that is applied to object 1, the WTC lower structure, due to the action of object 2, WTC upper block dropping, is automatically accompanied by a force applied to object 2 due to the action of object 1.


This law implies that forces always occur in action-reaction pairs. If object 1 and object 2 are considered to be in the same system, then the net force on the system due to the interactions between objects 1 and 2 is zero.

This is a common mistake that high school students make when learning Newton's laws. For an "engineer" to make it, though, is reprehensible.

The action-reaction pair you mention is a reference to Newton's 3rd law. Fine so far. Then you talk about the net force on the system due to interactione between objects in the system. Fine.

But the system is also effected by outside forces as well. Gravity, for example. When you draw a force diagram for purposes of finding out how an object behaves, you don't draw the action-reaction pairs. You draw the forces on the particular object.

In this case, the object is the lower block of the building. The forces on it are the upper block pressing down, gravity pulling down, and the ground pressing up. This is the static case. In this case, the net force on it is

F₁ + F₂ + F₃=0

where

F₁=force of upper block on lower (assigned a negative value)
F₂=force of gravity on lower block (assigned a negative value)
F₃=ground pushing on lower block (assigned a positive value)

Again, this is for a static case. As others have pointed out, in a dynamic case, the upper block exerts more force than it did previously. In this case you have

F₁' + F₂ + F₃ =X

Where X is the net force.

When X> the rated strength of the lower block, the lower block fails.

I am not an engineer, but even with the little bit of physics I know, I can understand this.

 

[pomeroo]

Thanks. Your calculations are correct = more or less same as mine at http://heiwaco.tripod.com/nist1.htm#7 .

If something drops on an elastic structure, the latter will deform elastically and maybe plastically (destruction) at the top only - decelaration occurs - and that's it. No big deal, actually. After that the destruction is arrested.

But let's be fair. 50% of the energy is transmitted up into the part being dropped. It will also deform elastically and maybe plastically (destruction) at the bottom only - decelaration occurs - and that's it. No big deal, actually. Same thing happened to the structure below. After that the destruction is arrested.

But it is assuming the columns actually meet at impact. I doubt it. They miss each other. Too small. Like a needle in a hay stack.

So at contact lower columns impacts upper floors and upper columns lower floors ... unless the columns miss altogether and hit the air; the columns are displaced outside! And the lower structure will catch the upper loose parts. Destruction will be arrested. Why is explained in my papers.

Dave, you suggest that I am lying and ask why. What's your answer?

I am stunned! Why would I lie? I am just an independent engineer that was asked by some children, whether buildings really could collapse like WTC1,2. They were maybe afraid that it would happen to the buildings, where they live? A quick check showed that NIST and Bazant were lying. That's serious. No consideration for, e.g. children.

Heiwa

So, you were asked by your intellectual peers why the buildings collapsed and you gave them an inept, incorrect answer. Shouldn't you apologize to them for your incompetence. Don't "children" deserve an answer from someone capable of providing one?

Your stated opinion about the effects of dropping the top third of a building onto the bottom two-thirds is ludicrously wrong. You have yet to retract it.

 

[often mrunderstood]

Oh yes, I am an engineer and I know a lot about 3-D structural analysis incl.

PS - Pls use proper language in your posts.

Care to share your credentials so I know what institutions my child should avoid. Pizza box experiments....I'm speechless when I am not laughing.

 

[tanabear]

Very good.

Now: What kind of effect do you think a layer of compacted debris at the bottom of the upper layer will have when the upper layer impacts a floor of the lower layer?

Try looking at it this way: What happens when you catch a hardball bare-handed? What happens when you catch it with some hard leather (i.e. a baseball glove) between you and the ball?

Assume a baseball is hit into the air and someone runs under to catch it. According to Bazantian Physics, once the baseball hits the glove the catchers hand will began to crushed and will continue to be crushed until the hand is pulverized. Once their hand is pulverized, the baseball will be crushed by the now pulverized hand. If you doubt this, watch any baseball game. It will convince you otherwise.

You know that serious researchers are wrong, but you know nothing about physics or engineering. Here's a question your fellow liars always duck, and you will not be the exception: What do you know that real experts don't, and how did you learn it?

You define a "serious" researcher/real "expert" as someone who defends the official story. I know that explosive charges can destroy buildings. Bazant seems to believe that a building can self-destruct via crush-down and crush-up. I don't know this, as it has never been proven experimentally.

 

[X]

Assume a baseball is hit into the air and someone runs under to catch it. According to Bazantian Physics, once the baseball hits the glove the catchers hand will began to crushed and will continue to be crushed until the hand is pulverized. Once their hand is pulverized, the baseball will be crushed by the now pulverized hand. If you doubt this, watch any baseball game. It will convince you otherwise.

I'm not sure whether you missed the analogy on purpose (in a poor attempt at wit) or out of ignorance.


Either way, allow me to further my explanation: The hand is undamaged precisely because the glove forms a kind of "cushion" between the hard, high-momentum ball and the hand (generally optimized for static andf not dynamic loads).

 

[Zipster]

I'm not sure whether you missed the analogy on purpose (in a poor attempt at wit) or out of ignorance.


Either way, allow me to further my explanation: The hand is undamaged precisely because the glove forms a kind of "cushion" between the hard, high-momentum ball and the hand (generally optimized for static andf not dynamic loads).

To add to this, the baseball player is also able to move his hand in the direction of the ball travel to increase the "cushioning" effect. If you've ever seen a slow-motion capture of a baseball being caught or hitting something, you'd see that baseball indeed does compress and deform as it goes through the impact.

If the baseball drops from high enough, it can and will crush an unprotected hand under it. The reason it doesn't "pulverize" on impact is because the speed of impact (and thus the energy transferred) is less than what the material can handle. It's designed to compress on impact. If it didn't, it would be "pulverized".

I don't know about everyone else, but I've never seen a skyscrapers move into the ground to "catch" a portion of the building in the event it falls into itself.

EDIT: http://www.youtube.com/watch?v=mOLp4doE51Q

I believe this video is a good illustration of physics at play. In slow-motion, you can clearly see how the concrete block is broken, but at the same time, how it exerts a force back onto the hand. The hand deforms into an unshapely mass onto the top of the block, but yet, still breaks the block. If this was done improperly, there is a high chance that the bones in the hand could have been broken too.

 

[GreyICE]

Ah, nevermind...

 

[pomeroo]

Assume a baseball is hit into the air and someone runs under to catch it. According to Bazantian Physics, once the baseball hits the glove the catchers hand will began to crushed and will continue to be crushed until the hand is pulverized. Once their hand is pulverized, the baseball will be crushed by the now pulverized hand. If you doubt this, watch any baseball game. It will convince you otherwise.

Basic physics indicates the source of your error--the same error made by so many conspiracy liars. The mass of the baseball is very small and so is its acceleration. Consequently, the force impacting the glove is very small.
Nothing gets crushed or pulverized. There is nothing difficult about any of this.

You define a "serious" researcher/real "expert" as someone who defends the official story. I know that explosive charges can destroy buildings. Bazant seems to believe that a building can self-destruct via crush-down and crush-up. I don't know this, as it has never been proven experimentally.

There is, as you know, no "official" story. All of the serious researchers have reached similar conclusions. You, by contrast, know absolutely nothing about the science and practice of demolition. That doesn't stop you from making foolish, uninformed comments about the subject. Nobody who works in demolition thinks that the Towers were brought down by explosives--nobody. The evidence for your fantasy is nonexistent.

 

[Heiwa]

This is a common mistake that high school students make when learning Newton's laws. For an "engineer" to make it, though, is reprehensible.

The action-reaction pair you mention is a reference to Newton's 3rd law. Fine so far. Then you talk about the net force on the system due to interactione between objects in the system. Fine.

But the system is also effected by outside forces as well. Gravity, for example. When you draw a force diagram for purposes of finding out how an object behaves, you don't draw the action-reaction pairs. You draw the forces on the particular object.

In this case, the object is the lower block of the building. The forces on it are the upper block pressing down, gravity pulling down, and the ground pressing up. This is the static case. In this case, the net force on it is

F₁ + F₂ + F₃=0

where

F₁=force of upper block on lower (assigned a negative value)
F₂=force of gravity on lower block (assigned a negative value)
F₃=ground pushing on lower block (assigned a positive value)

Again, this is for a static case. As others have pointed out, in a dynamic case, the upper block exerts more force than it did previously. In this case you have

F₁' + F₂ + F₃ =X

Where X is the net force.

When X> the rated strength of the lower block, the lower block fails.

I am not an engineer, but even with the little bit of physics I know, I can understand this.

??? The force of upper block on lower block is only caused by gravity, actually gravity acting on the mass of the upper block. This force can either be static (upper block is fixed to the lower block) or dynamic (upper block is moving and impacting lower block).

The lower block always apply a reaction force on the upper block that equals that force. This is Newton's third law.

In the static case the forces involved produce static compression of the columns in both the upper and lower blocks.

Same in the dynamic case; the forces involved produce dynamic compression (shock waves?) of the columns in both the upper and lower blocks and that's where Bazant goes wrong. Bazant assumes that only the lower block is affected by the dynamic force applied by the upper block.

That the lower block applies a force of equal value on the upper block is conveniently ignored. To make things worse Bazant assumes that the upper block is rigid, so that even if a force is applied to it, the upper block structure will remain unchanged = undamaged. Regardless, a force applied to a rigid body will accelerate it. As the rigid body in this case is moving at a certain velocity, a force applied on it will decelerate it, which Bazant forgets. Etc, etc.

Not too difficult to grasp.

Evidently the upper block is not one solid mass as assumed by Bazant. It consists of plenty of sub-parts/masses and you have to look at all of them when analyzing the problem.

Some of these upper block parts are in contact with the lower block at alleged impact, some not. The result would be, as in all collisions/impacts, that the upper block would be locally damaged at points of contact and where the forces applied to it produce local failures. Same applies to the lower block.

Read http://heiwaco.tripod.com/nist.htm for further info (and try to debunk any information given there).

 

[Quad4_72]

May I make a suggestion? Stop talking to Heiwa. The fallacies of his "theory" have been explained countless times to him in this thread. He chooses to ignore this. Let him keep playing with his pizza boxes.

 

[GreyICE]

??? The force of upper block on lower block is only caused by gravity, actually gravity acting on the mass of the upper block. This force can either be static (upper block is fixed to the lower block) or dynamic (upper block is moving and impacting lower block).

The lower block always apply a reaction force on the upper block that equals that force. This is Newton's third law.

*Thud*

To understand how absurd this statement is, reword it slightly.

"The barstool always applies a reaction force to the elephant landing on it equal to the force of the Elephant's landing. This is Nuttown's third law."

In the static case the forces involved produce static compression of the columns in both the upper and lower blocks.

Same in the dynamic case; the forces involved produce dynamic compression (shock waves?) of the columns in both the upper and lower blocks and that's where Bazant goes wrong. Bazant assumes that only the lower block is affected by the dynamic force applied by the upper block.

*Blink*

So he goes wrong when considering the effect on the lower block, he considers the forces on the lower block?

The upper block IS FALLING. I think we can safely determine that very little is going to keep it structurally sound.

That the lower block applies a force of equal value on the upper block is conveniently ignored. To make things worse Bazant assumes that the upper block is rigid, so that even if a force is applied to it, the upper block structure will remain unchanged = undamaged. Regardless, a force applied to a rigid body will accelerate it. As the rigid body in this case is moving at a certain velocity, a force applied on it will decelerate it, which Bazant forgets. Etc, etc.

Not too difficult to grasp.

Yes. All you have to have to grasp it is a complete lack of anything resembling an engineering education.

What is this? A bunch of people tearing the truthers to shreds have engineering degrees so you assume its some magical club that immediately makes you right if you join it?

Evidently the upper block is not one solid mass as assumed by Bazant. It consists of plenty of sub-parts/masses and you have to look at all of them when analyzing the problem.

Not really...

Some of these upper block parts are in contact with the lower block at alleged impact, some not. The result would be, as in all collisions/impacts, that the upper block would be locally damaged at points of contact and where the forces applied to it produce local failures. Same applies to the lower block.

Show me where anyone who wasn't you assumed a single point of collision.

Read http://heiwaco.tripod.com/nist.htm for further info (and try to debunk any information given there).

Okay. Once again, that stupid picture you drew in MS Paint STILL isn't how buildings are constructed. Again.

I won't even start on the rest. I'll just say its amazingly obvious you have no idea how a building is built from that one picture, so you would obviously have not the least little idea of how one might or might not fall down.

 

[Dr Adequate]

"The gravity-driven progressive collapse of a tower consists of two phases—the crush-down, followed by crush-up each of which is governed by a different differential equation. During the crush-down, the falling upper part of tower having a compacted layer of debris at its bottom is crushing the lower part...with negligible damage to itself. During the crush-up, the moving upper part C of tower is being crushed at bottom by the compacted debris B resting on the ground.

The fact that the crush-up of entire stories cannot occur simultaneously with the crush-down is demonstrated by the condition of dynamic equilibrium of compacted layer B, along with an estimate of the inertia force of this layer due to vertical deceleration or acceleration

...the hypothesis that the crush-down and crush-up cannot occur simultaneously is almost exact."

"What Did and Did not Cause Collapse of WTC Twin Towers in New York"
Zdenek P. Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson

So Bazant has the upper block crushing the lower block(Crush-down). Then once this upper block finishes crushing the lower block it hits the rubble pile and is destroyed via a crush-up. Yes, I know it is complete nonsense, but this is the best nonsense the defenders of the official 9/11 fairy tale can come up with.

Don't you ever think about your fantasy world?

Look, if this was "complete nonsense", then Bazant et al would know it was nonsense; and if crush-down simultaneous with crush-up made sense, then they would see that that made sense, and if, as you imply, Bazant was just pulling stuff out of his ass, then that is what he would have pulled out of his ass.

The reason he says crush-down came before crush-up is that that's what the physics tells him:

The fact that the crush-up of entire stories cannot occur simultaneously with the crush-down is demonstrated by the condition of dynamic equilibrium of compacted layer B, along with an estimate of the inertia force of this layer due to vertical deceleration or acceleration.​

Y'see, being an actual engineer, he is constrained by the laws of physics and unconstrained by what random Truthers happen to find plausible; the two being, of course, incompatible.

 

[Dave Rogers]

Thanks. Your calculations are correct = more or less same as mine at http://heiwaco.tripod.com/nist1.htm#7 .

If something drops on an elastic structure, the latter will deform elastically and maybe plastically (destruction) at the top only - decelaration occurs - and that's it. No big deal, actually. After that the destruction is arrested.

That's a lie. Steel columns fail in buckling, and break after a certain amount of plastic deformation. If the mass falling on them has enough kinetic energy to fracture them, it will continue falling. The destruction continues. Your statement is equivalent to a statement that it is impossible to collapse an elastic structure under any circumstances. That is only true of a structure with an infinite elastic limit, and such a structure doesn't occur in nature.

But let's be fair. 50% of the energy is transmitted up into the part being dropped. It will also deform elastically and maybe plastically (destruction) at the bottom only - decelaration occurs - and that's it. No big deal, actually. Same thing happened to the structure below. After that the destruction is arrested.

Funnily enough, I didn't say anything about energy. Simple analysis of the forces on the lower block makes it clear that the columns reach the point of failure before the falling block has been arrested.

Oh, and the force calculation assumes a homogeneous column with no welds or bolt connections. In real life the perimeter columns were bolted together, and the core columns were welded. We've seen pictures. The welds and bolt connections are weak points where fracture will occur at a lower strain.

But it is assuming the columns actually meet at impact. I doubt it. They miss each other. Too small. Like a needle in a hay stack.

So at contact lower columns impacts upper floors and upper columns lower floors ... unless the columns miss altogether and hit the air; the columns are displaced outside! And the lower structure will catch the upper loose parts. Destruction will be arrested. Why is explained in my papers.

Which is insane. If the upper columns miss the lower ones - as, in fact, they must have from the geometry of the collapse - they will strike the floors, which will collapse after slowing them down much less than the columns would have. At some point some kind of impact will occur between the upper and lower block columns, but by this time the falling block will be falling faster, increasing the force exerted on the lower columns; the lower columns will no longer be braced by the floors, leaving them vulnerable to lateral forces; and the forces of the impact will be largely lateral. Your suggestion that the two column trees would somehow miss each other completely and fall interlaced is a geometrical impossibility that would be obvious to the smallest child among the ones you claim you wrote your paper for, and your assertion that the collapse would be arrested by friction is unsupported by even the vaguest attempt at calculation. And you know all this, but refuse to acknowledge it.

Dave, you suggest that I am lying and ask why. What's your answer?

I have no answer. You lie every time you post on this forum, and you gain nothing from it. Your behaviour makes no sense to me whatsoever. That doesn't change the fact that you lie.

Dave

 

[Dave Rogers]

Assume a baseball is hit into the air and someone runs under to catch it. According to Bazantian Physics, once the baseball hits the glove the catchers hand will began to crushed and will continue to be crushed until the hand is pulverized. Once their hand is pulverized, the baseball will be crushed by the now pulverized hand. If you doubt this, watch any baseball game. It will convince you otherwise.

According to Heiwa physics, when the baseball hits your glove, all you will feel is the static weight of the baseball as it settles gently into your hand. There's actually no point, in Heiwa's world, in wearing a glove at all. The baseball cannot do any damage to your hand, as your hand will elastically deform to absorb the impact. Simple! No damage. A child could understand it. In fact, though, it's unlikely that the baseball would hit your hand at all, it would slide past it doing no damage at all and being brought gently to a halt by the friction against your arm. No need for a baseball glove, and no damage!

Dave