WTC: Rate of Fall (rate of crush)

If it was planned IF They tried to help it come down big ifs here they would only need to help take out one or two floors not some crazy rig every floor type deal here
 

Jazzy

Closed Account
The buckling argument does not explain simultaneous synchronized collapse of the floors to allow the freefall or close to freefall speed during the first few seconds. we all understand it explains the collapse just not in the way It actually happened
The collapsing floors allowed the buckling to occur. Not the other way round.

The floors depended on their trusses to remain flat, but the trusses were exposed to the fire. Once the bar work of the trusses was up to fire temperature, and under constant load, it crept, and the floors began to hang like curtains. They then exerted considerable side forces on the columns which supported them, and once they were pulled far enough off their vertical centerlines, they buckled en masse.
 
The collapsing floors allowed the buckling to occur. Not the other way round.

The floors depended on their trusses to remain flat, but the trusses were exposed to the fire. Once the bar work of the trusses was up to fire temperature, and under constant load, it crept, and the floors began to hang like curtains. They then exerted considerable side forces on the columns which supported them, and once they were pulled far enough off their vertical centerlines, they buckled en masse.
Well this is good thanks for clarifying this makes it easier for people to understand how impossible a synchronized collapse would be
 

Jazzy

Closed Account
Well this is good thanks for clarifying this makes it easier for people to understand how impossible a synchronized collapse would be
The collapse wasn't "synchronized". Your use of the word implies someone's overall control and is misleading.

It initiated when the very first column buckled. The loaded column wouldn't stand either if unsupported by the floor, or if pulled so far inside its centerline.

When it buckled, its loading was transferred to the columns either side of it. If they too were close to failure, then the additional loading would cause them to fail.

The failing column acted exactly like a trigger, but exactly like a trigger, there was a small delay before anything occurred. This delay would be too short to observe, because "the message" traveled at five miles per second - the speed of sound in steel.

Mick's demo, with the three drink cans and a golf club, shows this handover of loading very well.
 
Last edited:

Pete Tar

Senior Member.
A failure of a structure where each part is supported by another part will always appear synchronised to a certain extent, as each failure synchronises with the failure of the next.
 

Ron J

Active Member
Just started reading this thread but I see a fundamental error in this response. The way to think of a collapse is in terms of kinetic energy and equal and opposite reactions. The falling object strikes the entire structure bellow it. That structure is designed to resist this force, plus some safety margin, typically about 100% including wind, snow and occupancy loads. The week point will be at the buildings highest intact point due to the tapering of columns towards the top. So a large amount of energy is absorbed by any flex that occurs in the remaining intact areas. That expenditure of energy will result in a loss of speed in the falling mass, or masses as the collapsing segment will not all strike the area bellow at the same time. Simultaneously there will be some deflection in the falling mass as it attempt to follow the path of least resistance, there will also be some deflection at the weakest points in the remaining structure which will/may lead to catastrophic failure of individual members. These members, in the case of WTC towers can be seen to eject horizontally from the structure. An equal and opposite energy must be considered to both the falling mass above and the remaining structure bellow. There's a collision, the structure fails but the but the acceleration of the falling mass is deflected and diminished by the act of expending energy to damage otherwise intact components bellow it. The energy of the falling mass should have been either deflected laterally into the path of least resistance or gradually halted as the kinetic energy of it originally having only collapsed one or two stories was gradually expended on a building designed to handle likely 2x its expected loading. The collapse should have decelerated and/or destabilized into the path of least resistance.




Another fundamental flaw is the structural steel doesn't like to shatter, it bends, it actually bends a lot before it even begins to reach any critical point. This bending absorbs energy, which again must be subtracted from the kinetic energy of the falling debris. This fundamental error can be found in a huge number of arguments about the falling block hypothesis.

If we modify Jazzy's hypothesis with his Newtons swing we find that energies are dissipated in many directions but only under manufactured conditions does it travel through the path of most resistance. In Jazzy's model he'd have the energy going straight down through the structural steel and melting the base of each column. Not likely. But there is some truth to the principal he's misunderstanding. The energy does transfer, but not all of it goes into breaking a single bond at a time, just as not all of it would go in a single direction. Its transferred to the entire remaining structure, which will respond as its designed and spread that load out as much as possible and bending when the loads get to some critical stage. Somewhere in there something breaks. But what broke isn't the only resistive force involved. Shock loading and bending strain must also be considered along with the individual elements of catastrophic failure. IE each beam that gets broken away from the remaining structure and its energy of ejection (IE acceleration ) from a position of resistance to a position of less resistance.

In the end, no I'm not going to calculate out the exact numbers, I'd need a free month or two and a set of print which we all know aren't available. But the towers should never have reacted the way they did and completely collapsed. At worst some significant portion of the towers should have survived and at best I don't think fire or the damage they received should have been sufficient to cause any major collapse.


The Towers did react the way they did and completely collapsed. Both of them. It seems wishful thinking that they shouldn't have.

The top 15 floors of WTC1 collapsed down on the remaining 95. I don't see how the rest of the building could have stood up to that, just from a common sense point of view. A semi truck is no match for locomotive.

I watched some of the anniversary shows last week and i could see the intensity of the fire, where it was pouring out the windows. I don't see how the fire shouldn't have been sufficient to cause a major collapse. The fire was wide spread. Severe fire damage occurred on the east side of WTC2 and the top of the building tipped over to the east as it began to collapse. The fire in WTC1 was more global and the top 15 floors fell straight down. Collapse was consistent with the fire damage in both Towers.

A friend of Rick Rescorla called him in WTC2 and told him to get out of the building because it was going to collapse. The friend was not an engineer, but he could see what the fire was generally doing to the building.
 

Ron J

Active Member
I wouldn't want to overstate things. What this does prove is that the theory proffered by NIST is flawed, and that the gravitational loading and subsequent momentum that it would transfer would cause enough of a reduction in velocity for the perceived collapse to be arrested at quite an early stage. It should be considered more of a critique of NISTs lack of explanation, after all, they did not address the actual collapse itself in their report. Only the events leading up to it. Bazant did do an analysis early on and then revised it but did not take the shortening of the bottom block into account. Also, it is worth remembering that we are presuming that a whole floor (3.7m) of the tower just disappears and allows the block to drop at g.


I don't see how the collapse could have been arrested once it began. Once the top 15 floors fell down upon the 94th floor, the building began tearing itself apart. Once that began, it just kept going, all the way down to the ground. It never ran out of momentum. Floor after floor, debris flew out windows as the floor slabs were struck from above. As i recall from a video of the construction, i saw years ago, the floor trusses were attached to the outer columns by flanges. With floors crashing down from above, it seemed as if the trusses would have been ripped from their connection to the columns, crashing down to the next floor. The rapidity with which debris flew out each floor on down the Tower, indicated that each floor truss offered little resistance to the mass of debris that was landing on it.
 

Ron J

Active Member
It proves that there should be a more thorough investigation into the whole event. The fact that controlled demolition was not considered in the report is counter intuitive as this is the only cause ever of high rise steel framed building collapses like these. Fire does not have form for dong this to buildings made of steel, so the fact that NIST discarded the most likely cause, but clung to the least likely historically speaking should be a red flag to anyone. The implication that every highrise on the planet is now liable to collapse from fire should be disturbing to us all, whether it is true or not.


It is not counter intuitive, considering the circumstances unique to 9/11. A near fully fuel laden jetliner was flown into each Tower. The result was extensive fire damage. Damage in WTC2 was largely on the east side, which resulted in the top of the building tipping over to the east when it collapsed. NIST did not disregard the most likely cause, they discarded the least likely cause, controlled demolition.

Neither of the Tower fires was fought by NYFD. They burned uncontrolled. WTC7 also burned uncontrolled.

Be careful about implications. Most high rise buildings are not struck by near fully fuel laden jetliners while not not being fought afterward by the fire department. Details matter.
 

Carlito Jax

New Member
Let's do some maths: The outer collumns of the twin tower bore 40% of the load and they were designed to hold 5 times the load which they bore. The core collumns bore 60% of the load and they were designed to hold 3 times the load which they bore.

During the "collapse" the towers fell at roughly 0.6G. Using Newtons 3rd law we can derive that the upward force must have been 0.4 times the weight of the towers. Let's assume that due to the weakening of the trusses the outer collumns literally turned into spaghetti and lost all their supporting force. In this case The core collumns below the plane crash which do not rely on any tension from the trusses to maintain their supporting force and being below the plane crash had not undergone any weakening (using 0.6 x 3) would still be able to support 1.8 times the weight of the towers. However we know that the upward force was only 0.4 times the weight of the towers so the core collumns must have literally turned into spaghetti also.

The truth is that anyone with a background in newtonian physics and structural engineering that has researched 9/11 either knows that it is incontrovertible that all 3 towers under went a controlled demolition or they are lying to themselves. Tower 7 fell at freefall acceleration for almost half of it's descent. Freefall is impossible during a building collapse and can only be acheived via controlled demolition
 

Mick West

Administrator
Staff member
Let's do some maths: The outer collumns of the twin tower bore 40% of the load and they were designed to hold 5 times the load which they bore. The core collumns bore 60% of the load and they were designed to hold 3 times the load which they bore.

During the "collapse" the towers fell at roughly 0.6G. Using Newtons 3rd law we can derive that the upward force must have been 0.4 times the weight of the towers. Let's assume that due to the weakening of the trusses the outer collumns literally turned into spaghetti and lost all their supporting force. In this case The core collumns below the plane crash which do not rely on any tension from the trusses to maintain their supporting force and being below the plane crash had not undergone any weakening (using 0.6 x 3) would still be able to support 1.8 times the weight of the towers. However we know that the upward force was only 0.4 times the weight of the towers so the core collumns must have literally turned into spaghetti also.

The truth is that anyone with a background in newtonian physics and structural engineering that has researched 9/11 either knows that it is incontrovertible that all 3 towers under went a controlled demolition or they are lying to themselves. Tower 7 fell at freefall acceleration for almost half of it's descent. Freefall is impossible during a building collapse and can only be acheived via controlled demolition
Incorrect. You are confusing static and dynamic loads.
 

Carlito Jax

New Member
Incorrect. In order for collumn to completely fail the load must exceed it's maximum load capacity. So during the collapse the uprward supporting force of the collumns would have been at their maximum. Freefall is not possible during a building collapse. Mick West you are a deluded chronic debunker who works from preconceived conclusions to use any and all evidence to support your notion and try to downplay all the incontrovertible proof that shows otherwise.
 

Mick West

Administrator
Staff member
Incorrect. In order for collumn to completely fail the load must exceed it's maximum load capacity. So during the collapse the uprward supporting force of the collumns would have been at their maximum. Freefall is not possible during a building collapse. Mick West you are a deluded chronic debunker who works from preconceived conclusions to use any and all evidence to support your notion and try to downplay all the incontrovertible proof that shows otherwise.

There is a difference between a weight resting on something and a weight falling on something.
 

Carlito Jax

New Member
There is a difference between a weight resting on something and a weight falling on something as far as calculating kinetic energy. Kinetic energy is a function of speed. Force is a function of acceleration. Force is not a function of speed.
 

Hama Neggs

Senior Member.
Let's do some maths: The outer collumns of the twin tower bore 40% of the load and they were designed to hold 5 times the load which they bore. The core collumns bore 60% of the load and they were designed to hold 3 times the load which they bore.

During the "collapse" the towers fell at roughly 0.6G. Using Newtons 3rd law we can derive that the upward force must have been 0.4 times the weight of the towers. Let's assume that due to the weakening of the trusses the outer collumns literally turned into spaghetti and lost all their supporting force. In this case The core collumns below the plane crash which do not rely on any tension from the trusses to maintain their supporting force and being below the plane crash had not undergone any weakening (using 0.6 x 3) would still be able to support 1.8 times the weight of the towers. However we know that the upward force was only 0.4 times the weight of the towers so the core collumns must have literally turned into spaghetti also.

The truth is that anyone with a background in newtonian physics and structural engineering that has researched 9/11 either knows that it is incontrovertible that all 3 towers under went a controlled demolition or they are lying to themselves. Tower 7 fell at freefall acceleration for almost half of it's descent. Freefall is impossible during a building collapse and can only be acheived via controlled demolition

I'm sure it's been asked a thousand times, but how could explosives have been rigged(and how could they have survived the impacts and fires) to cause the collapse to begin precisely where the plane impacts occurred?
 

Mick West

Administrator
Staff member
There is a difference between a weight resting on something and a weight falling on something as far as calculating kinetic energy. Kinetic energy is a function of speed. Force is a function of acceleration. Force is not a function of speed.

Indeed, there's an old saying "it's not the fall that kills you, it's the sudden stop at the end"

Consider the force acting on your legs when you are just standing still. Legs straight.

Now consider the force acting on your legs when you jump from ten feet up and land without bending your knees.

Same weight. Different forces.
 

Cairenn

Senior Member.
You can easily pick up a 10 lb object, but if a hard 10 lb object falls off the shelf in your closet and hits your shoulder, it is going to hurt you.
 

Carlito Jax

New Member
how could explosives have been rigged? Using charges placed around the core collumns during the multiple power outs using the cover story of updating internet cables in the weeks leading up to 9/11 and also in the numerous empty floors where peculiar sounds of construction work was reported. how could they have survived the impacts and fires? Thermite has an ignition temperature of over 3,000 degrees C.
 

Carlito Jax

New Member
It is wrong to assume that an object traveling at a high speed will exert a bigger force onto the object it hits. It will have higher kinetic energy so if the object it hits brings it to rest then it will have transfered more momentum. However if the first object continues to accelerate while it crushes through the 2nd object then the force on the first object is greater than the force of the 2nd object pushing against the 2nd object. During a building collapse or during the verinage technique as the top half of the building drives into the bottom half, the bottom half exerts a greater force onto the top half than the weight of the top half driving it into the bottom half. This results in a deceleration. You can observe a deceleration in the videos you posted in the earlier part of this thread on the verinage technique, it has also been measured by phycisist David Chandler. The fact is that during every observed collapse and in coordinance with Newtons universal laws of motion when the top section of a building drives into the bottom section of a building it decelereates. The twin towers accelerated all the way to the ground meaning that there was another force present other than gravity to weaken the structure during the collapse.
 

Carlito Jax

New Member
Ah ok, well you can rig a building with explosives in a certain way so as to define where the collapse will occur. In most cases buildings are rigged to fail at the bottom but they can be rigged to fail at any specific point. Considering the counter argument that no explosives were needed at all to make the building fail at the precise point where the plane impacted it doesn't seem like a very good rebuttal. Also in the video of the collapse of wtc 1 you can see the spire of the building start to fall a fraction of a second before the outer structure starts to fall showing that it was the core collumns that failed first and not the precise point where the plane hit or the trusses holding the floors in place.
 

Mick West

Administrator
Staff member
It is wrong to assume that an object traveling at a high speed will exert a bigger force onto the object it hits. It will have higher kinetic energy so if the object it hits brings it to rest then it will have transfered more momentum. However if the first object continues to accelerate while it crushes through the 2nd object then the force on the first object is greater than the force of the 2nd object pushing against the 2nd object. During a building collapse or during the verinage technique as the top half of the building drives into the bottom half, the bottom half exerts a greater force onto the top half than the weight of the top half driving it into the bottom half. This results in a deceleration. You can observe a deceleration in the videos you posted in the earlier part of this thread on the verinage technique, it has also been measured by phycisist David Chandler. The fact is that during every observed collapse and in coordinance with Newtons universal laws of motion when the top section of a building drives into the bottom section of a building it decelereates. The twin towers accelerated all the way to the ground meaning that there was another force present other than gravity to weaken the structure during the collapse.

No. It mean that the net force was still a downward acceleration, less than gravity. Still an acceleration.
 

Carlito Jax

New Member
The net force resulted in a downward acceleration. During a building collapse there is an initial acceleration followed by a deceleration as the gravitational force (weight) is less than the upward force of the bottom part of the building pushing up against it. During the verinage technique the supports in the middle of the building all fail simultaneously causing an acceleration due to gravity then as the top half of the building crushes through the bottom half it decelerates. If the bottom section of the towers failed due to the top section of the towers crushing down on them then the top section would decelerate as it crushed through the bottom section.
 

Carlito Jax

New Member
The analogy of someone jumping on the ground with their knees bent and their knees straight is a bit of an obfuscation. When the person is standing stationary on the ground, the ground is applying an equal force upwards as the weight of the person pushing down. When the person jumps and bends their knees the ground applies a force greater than the persons weight to cause a deceleration and bring them to rest. When the person lands with straight legs the ground exerts a greater force still to bring them to rest quicker. If we take this analogy and apply it to the twin towers, the person stands on the ground and the ground can hold their weight then the person jumps up and accelerates through the ground, the force that the ground was exerting on the person before they jumped has miraculously disapeared when they land back on the ground. "Same weight. Different forces." It's actually different weight and different forces as weight is a force. If the person jumped on a scale with straight legs the scale would measure higher than if the person jumped on the scale with bent legs as the net force is constantly being balanced by the rate of acceleration/deceleration.
 

Hama Neggs

Senior Member.
Also in the video of the collapse of wtc 1 you can see the spire of the building start to fall a fraction of a second before the outer structure starts to fall showing that it was the core collumns that failed first and not the precise point where the plane hit or the trusses holding the floors in place.

I think you mean you can look at that vid and wishful-think that into your own personal reality. I'm dropping the discussion of wiring and explosives as being off-topic.
 

Carlito Jax

New Member
To which I must assume that you have been carefully analysing different slow motion clips of the onset of collapse of wtc 1 for the last 3 hours. Either that or you decided that this information doesn't line up with your preconceived notion and therefore must be wrong.
 

Mick West

Administrator
Staff member
The analogy of someone jumping on the ground with their knees bent and their knees straight is a bit of an obfuscation. When the person is standing stationary on the ground, the ground is applying an equal force upwards as the weight of the person pushing down. When the person jumps and bends their knees the ground applies a force greater than the persons weight to cause a deceleration and bring them to rest. When the person lands with straight legs the ground exerts a greater force still to bring them to rest quicker. If we take this analogy and apply it to the twin towers, the person stands on the ground and the ground can hold their weight then the person jumps up and accelerates through the ground, the force that the ground was exerting on the person before they jumped has miraculously disapeared when they land back on the ground. "Same weight. Different forces." It's actually different weight and different forces as weight is a force. If the person jumped on a scale with straight legs the scale would measure higher than if the person jumped on the scale with bent legs as the net force is constantly being balanced by the rate of acceleration/deceleration.

It's not rocket science.

I think some diagrams might be helpful though.
 

Carlito Jax

New Member
Here's an accompanying explanation:

The twin towers and Newton's Universal laws of motion:
W=weight
F=supporting force
a=acceleration

In figure 1 we can see the situation just before the collapse of either of the towers, although there is damage to the area that the plane hit the bottom section of the tower is still holding the entire weight of the top of the tower. The tower is stationary therefore according to Newtons 3rd law the forces are balanced

In figure 2 we can see the moment of collapse. For the sake of argument let's assume that all of the supporting force in the area that the plane hit has been reduced to 0. In this case the top section of the tower will fall at freefall acceleration until it smashes into the bottom section of the tower which has not been damaged by fire and should still be able to support the entire weight of the top section

In figure 3 the top section of the tower smashes into the bottom section which has been designed to support at least 1.6 times the weight of the top section. In this case The supporting force should be 1.6 times the weight before it fails. The upward force should be greater than the downward force and therefore according to Newtons 2nd law the acceleration should be upwards meaning the top section of the tower should decelerate (slow down)

Conclusion: Both towers 1 and 2 fell at roughly 60% of freefall acceleration meaning that during the collapse the supporting force of the bottom section must have been compromised by an outside force as the weight of the top section was not enough to produce the acceleration observed.
 
Last edited:

Carlito Jax

New Member
It's not rocket science (although if you think about it, newtonian physics is actually rocket science, lol) and yet you cannot concede that the theory, the experimental data and the observations on 9/11 lead to only 1 possible conclusion.
 
Last edited:

Mick West

Administrator
Staff member
You diagram does not account for the fact that the upper block is moving. The key is what force is required to STOP it, not what is simply needed to support it from below.

These forces are radically different. It's like resting a hammer on a nail vs. hitting a hammer with a nail. Or:
 

Carlito Jax

New Member
"The key is what force is required to STOP it" The key isn't what force is required to stop it. The key is what effect should upward force that is capable of holding the objects weight have on it's rate of acceleration. I never stated that the bottom structure should stop the top structur so you are completely misrepresenting my argument.

In fact no there is no fixed force that is required to stop it. There is a fixed force to cause the object to decelerate at a fixed rate but the force required to stop it depends on how fast it is going and how long the force is being applied for.

If you measure the rate of acceleration of the 30lb weight in video you posted you will see that the force required to break through the bottom object slows the weight down as it breaks it, the weight does not continue to accelerate into the bottom object.
 
Last edited:

Carlito Jax

New Member
"The key is what effect should upward force that is capable of holding the objects weight have on it's rate of acceleration." Would you like to answer this question instead of more obfuscation.
 

Jazzy

Closed Account
"The key is what effect should upward force that is capable of holding the objects weight have on it's rate of acceleration." Would you like to answer this question instead of more obfuscation.
You have already obfuscated enough for the rest of us.

The effect of the "upward force" was to reduce the downward acceleration by about a third.

This "upward force" was already NOT the "designed" resistance because that resistance was aligned up the column axes, and the first move of the collapsing top was a move out of alignment.

So your argument, which could never possibly be correct, leads into an area of complete unpredictability, where it could never be proved to be either correct or incorrect. Well done, there.

Your diagram showing the "applied load" of the falling top is wrong by at least an order of magnitude. By the time the remnants of the tower top reached the ground, that "applied load" would be more like two orders of magnitude times its mass.

This would have been smoothed somewhat by having to deal with the increasing strength of the components it met.
 
Last edited:

Carlito Jax

New Member
"that resistance was aligned up the column axes, and the first move of the collapsing top was a move out of alignment." However it would still have taken up the load or it would still have been standing after the collapse. The core structure of the towers were a tower in their own right which did not rely on the floors or the outer structure to support them. If the core structure was not taking up the load then it should still be standing.

"Your diagram showing the "applied load" of the falling top is wrong by at least an order of magnitude. " How can something that doesn't have any numbers be wrong by at least an order of magnitude. That is totally retarded.

The fact remains that in every single case of the top section of a building collapsing onto the bottom section, the top section undergoes deceleration as it crushes through the rest of the building. You are trying to justify something that has no basis in scientific theory or experimental data.
 

Jazzy

Closed Account
However it would still have taken up the load or it would still have been standing after the collapse.
It never took up loads where it was expected to. Instead, individual parts of the intact tower were individually and separately subjected to the impact of the entire mass of the falling tower top. They failed uniquely and separately from each other.

The core structure of the towers were a tower in their own right which did not rely on the floors or the outer structure to support them. If the core structure was not taking up the load then it should still be standing.
The top was out of alignment and fell through the core. The same rules as above applied. Individually and separately the core elements met the full force of the falling tower top and failed instantly. As, of course, did parts of the tower top.

How can something that doesn't have any numbers be wrong by at least an order of magnitude. That is totally retarded.
Pardon me, but you show a "W". That represents the total downward loading. My point is that the impact loading at the collision speed was at least TEN TIMES "W" (rising to a HUNDRED TIMES "W"). You shouldn't argue in a language whose lexicon you aren't yet familiar with. Your diagram is wrong. False. A mistake.

The fact remains that in every single case of the top section of a building collapsing onto the bottom section, the top section undergoes deceleration as it crushes through the rest of the building. You are trying to justify something that has no basis in scientific theory or experimental data.
The fact remains that the reduction of downward acceleration (30%) exactly conforms with what you might expect with random collisions with the intact structure slowing the tower top's free fall. There is every justification in what I have written to you, and I haven't yet felt the need to be impolite.

Note the lack of apostrophe in the possessive of "it".
 
Last edited:

Carlito Jax

New Member
There is not 1 example you could point to of a building collapsing and not decelerating as it crushes through it's structure. There is no justification for what you have written and it is not supported by any experimental evidence.
 
Top