So Just Fire Brought Down WTC7 In A Perfect Free Fall Collapse ?

Originally posted by Akareyon

Originally posted by wmd_2008
Now as the collapse started ANY of the falling mass which fell onto the floor slabs COULD ONLY BE RESISTED BY THE CONNECTIONS (ANGLE IRON/CLEATS) that held that floor slab in position, those connection were the same for floor 90 or floor 60 or floor 25 they were designed to resist a set loading plus a safety factor.

If that were the case, a hollow tower would be the result. However, the connections were strong enough to transfer the force to the core and perimeter columns and pull them down in the process as well.

Please rethink your argument.

I suggest you look at how the wall columns lined up during construction.

This image shows it quite well



Care to explain to everyone how physics works in your world for say the South Tower collapse and how no falling mass impacts the walls or core

Originally posted by Akareyon
Yeah, right. And I'm Napoleon, the Emperor of China, the inventor of the Bussard collector and Penicillin and in my leisure time I change water into wine and resurrect the dead.

Your alleged school career has no power on the internet. Your arguments need to be sound and valid. But they are not; you're so stuck on your "but the dynamic load was soooo huge" loop that you don't even understand anyone else's arguments. Just like you refuse to answer my simple question. Why is that? Because you don't really have a clue how the towers collapsed, you're happy with your "dynamic load" explanation and fail to see that it doesn't explain anything that happened on 9/11.

Your dynamic load must be great enough to accelerate the 9- to 10-fold of its own mass. How are you going to do that?

Although like you said you can claim to be anyone or do anything on the net, well I don't need
to lie . Here are some pictures I have taken over a few years of different types of projects I have been on up and down the UK.
Pictures edited and resized to protect peoples indentities.
Rain screen check on a large shopping centre project.

Road support system

Roof top steelwork anchor install for testing.

Road bridge site visit for inspection platform system design to allow repairs on bearing system under bridge deck.

Inspection platform installed

Hydro Electric scheme site visit to help with the design for tunnel lining system. Other end a few miles up through the mountain.


I can be 20,30 or 40 floors up, inside and outside buildings, I can be on the roof or in a basement at the next contract or on a bridge or in a power station or hydro electric scheme the next day so having seen your ahem video I know that I have a few more years LIFE experience and WORK experience than you!

PS Guess what Napoleon most people I know turn wine into water

The answer is in the new movie Man of Steel.

Superman and General Zod were ripping through concrete and steel cutting inner support columns and the buildings actually fell correctly....
they toppled over like a tree being cut down.

Movies are very interesting about exposing certain truths.

reply to post by wmd_2008


Sorry, does not prove much. You could be the Union photographer who takes photos of screw ups. You could be the guy that drills the holes. Your knowledge of how buildings fail is simply not up to scratch.

A little knowledge is dangerous. The problem is an unwillingness to understand your own limitations.

P

Originally posted by pheonix358
reply to post by wmd_2008

 

Sorry, does not prove much. You could be the Union photographer who takes photos of screw ups. You could be the guy that drills the holes. Your knowledge of how buildings fail is simply not up to scratch.

A little knowledge is dangerous. The problem is an unwillingness to understand your own limitations.

P

Union photographer NO not in a union never have been and never will be at this stage.

Have I drilled holes yes someone has got to show people how to do things right!

My kowledge about how buildings fall, actually I am more concerned in keeping them in position
but if your thoughts on my knoweldge give you a warm snug feeling and keeps you happy about
what you think of yourself fill your boots

So as you have brought the subject up please tell everyone your knowledge I can't wait.

Originally posted by -PLB-
And flawed inductive reasoning: A has not happened before therefor A can not happen.

As you have stated before, you have a hard time understanding what I am saying. I believe you said what I say is "cryptic" to you. Sadly, you put statements into my mouth I never made instead of asking for clarification - which I was always happy to provide; posting examples of buildings that were meant to be demolished but survived although they dropped through the height of several floors with all their weight; showing even a house of cards doesn't progressively collapse from top to bottom; showing how a domino effect only works if the pieces are intelligently aligned. I never said "A has not happened before therefor A can not happen", for instance. Because, as a saying goes in my language: "one time is always the first time".

I am patient with you, so I'll explain my line of reasoning again so you don't have to guess what I "mean to say".

Something vertical can sway, break, buckle, lean, tilt, topple or be compressed if a certain force acts upon it. These are the usual failure modes, they are witnessed on a daily basis and can easily be reproduced in experiment.

There is no reason not to compare these failure modes and the conditions that have to be met for each of these to happen to the three 9/11 skyscrapers. In doing so, it becomes clear why trees, domino buildings, card houses and buildings fail the way they do or don't.

It also becomes very obvious that the towers failed in a way that can only be compared to controlled demolitions. Claiming that there was no such controlled demolition is a statement so extraordinary it requires some extraordinary evidence. "But planes, but fires, but fireproofing, but inevitable, but dynamic load" does not qualify as extraordinary evidence for what is seen on the videos.

Why?

Because the three 9/11 skyscrapers were vertically, axially compressed. Although two of the "collapse sequences" started with what looked somewhat like a classic buckling, with the top tilting a few degrees to one side - comparable to a tree that has taken a few blows with an axe - it soon started to descend vertically, pushing everything - the rest of the intact structure - out of its way into the basement and all over the neighbourhood, comparable to a controlled demolition.

Let us assume no space laser beams, cutter charges, mini nukes or steel-eating microbes brought the towers down. Then these structures were designed to withstand massive lateral forces like storms and hurricanes. Their overall yield strength and stiffness against stresses like torsion, buckling and shearing allowed only a very narrow freedom of movement. Yet, weakening an arbitrary point within the structure to a certain degree would result in a jerk strong enough to propagate progressively, gravitationally and vertically.

Progressively is emphasized here because in a material like steel, such a "jerk" would usually propagate through the whole structure many times before the next floor has failed. In other words, the dynamic load of the falling section would have been distributed over (that is, dampened by) the rest of the intact structure within a few milliseconds.

But instead, the jerk was so great that the structure was unable to distribute the dynamic load force over the complete length of the structure; the segments were "shocked" out of the way one by one.

These are all extraordinary assumptions, yet there is no extraordinary evidence backing the official conspiracy theory. That forests can burn, dams can breach, balloons can pop and avalanches happen is not the sort of extraordinary evidence required to prove that skyscrapers just vertically and progressively self-compress within seconds if given the slightest excuse, whereas domino experiments and card houses clearly show how far out there the "inevitability theory" is - because it relies on the silent assumption that the structure was designed with built-in stress surpassing its capacity by a factor of three. So the next brain stretch necessary to somehow rationalize the official conspiracy theory is that many, if not all buildings are designed so that only a relatively small threshold needs to be overcome to induce progressive collapse, in other words, that the stress/weight ratio is similarly huge in all skyscrapers (why don't they lean on stormy days then?), and the only way to prevent these disasters is to strip search airplane passengers.

And somehow, deep inside, most "debunkers" know how silly that is and this is why they try to sidetrack and insult, resort to sophistry or claim to know better solely based on their alleged expertise when confronted with plain, simple logic and physical laws. After all, their world view stands, hangs and falls with the 3 9/11 skyscrapers.

reply to post by wmd_2008


Tall structures fall over! They do not fall down onto themselves. It is truly that simple!

P

Originally posted by pheonix358
Tall structures fall over! They do not fall down onto themselves. It is truly that simple!

So show us evidence of that happening in 100+ story buildings....

Originally posted by pheonix358
Tall structures fall over! They do not fall down onto themselves. It is truly that simple!

Yup. And I just spent exactly 5000 characters to say that

I also noticed in a few Hollywood productions how skyscrapers were not shown to be brittle things that dissolve upon the slightest touch but more like rigid stuff. Was it in "Despicable Me" where someone grabbed a tower and wielded it like a huge club? Also, Emmerichs CGI buildings in "2012" featured far more realistic failure modes than WTC 1, 2 & 7. And I remember how the theater audience went "Yeah, sure!" when one of the Minath Tirith watch towers was hit by a trebuchet missile fired by Saurons Army in "The Lord Of The Rings" and experienced an unbelievable disproportionate collapse.

And while we're talking about Hollywood... remember the scene in American Psycho where our hero fires his gun at a police car and it explodes - and the way he stares at his gun in disbelief? That's the expression Osama must have had on his face when he saw the towers collapse :-)

reply to post by Akareyon


But YOU keep failing to recognize that the MASS falling and impacting on a floor slab CAN only be resisted by the connections of that floor slab, that's the real problem with the WTC Towers design there is NO RESISTANCE provided by the rest of the structure to LOAD applied to the floor slab.

In a traditional 3d grid type of construction with columns in internal floor space and not open plan LIKE the towers then you would have some additional resistance to the falling mass impacting the floor slab that's what you IGNORE!

Originally posted by Akareyon
I never said "A has not happened before therefor A can not happen", for instance. Because, as a saying goes in my language: "one time is always the first time".

You didn't say it, but it is the way you reason here. Else the "the collapses of WTC 1, 2 and 7 are the result of careful planning, purpose, knowledge and intelligence" is not "Consequently" at all.

I am patient with you, so I'll explain my line of reasoning again so you don't have to guess what I "mean to say".

In this case I didn't had to guess as what you wrote was pretty clear. But apparently you never actually mean what you write.

It also becomes very obvious that the towers failed in a way that can only be compared to controlled demolitions. Claiming that there was no such controlled demolition is a statement so extraordinary it requires some extraordinary evidence. "But planes, but fires, but fireproofing, but inevitable, but dynamic load" does not qualify as extraordinary evidence for what is seen on the videos.

We can compare it to any building collapse, not just the controlled ones.

Because the three 9/11 skyscrapers were vertically, axially compressed. Although two of the "collapse sequences" started with what looked somewhat like a classic buckling, with the top tilting a few degrees to one side - comparable to a tree that has taken a few blows with an axe - it soon started to descend vertically, pushing everything - the rest of the intact structure - out of its way into the basement and all over the neighbourhood, comparable to a controlled demolition.

So we can conclude that buildings do not behave the same as trees.

Progressively is emphasized here because in a material like steel, such a "jerk" would usually propagate through the whole structure many times before the next floor has failed. In other words, the dynamic load of the falling section would have been distributed over (that is, dampened by) the rest of the intact structure within a few milliseconds.

No it would not. You are making this up.

But instead, the jerk was so great that the structure was unable to distribute the dynamic load force over the complete length of the structure; the segments were "shocked" out of the way one by one.

It's pretty simple to explain why this is incorrect. The forces have to be transfered down the structure. The first column length which is transferring the force to the column length below it is the part that will fail first.

So its impossible to "distribute the dynamic load force over the complete length of the structure". That statement doesn't even make too much sense. All the load will be on the first resisting column length meets, and it will only transfer the load it is capable of transferring down, until it fails for course. Which is where FoS comes in play again.

Besides, in the WTC it were not the columns that had to endure the impacts, but the floor connections. So nearly no force was transfered to the columns to begin with. Making your argument even more flawed.

These are all extraordinary assumptions, yet there is no extraordinary evidence backing the official conspiracy theory.

I don't see any extraordinary assumption, but rather a general lack of understanding with people rejecting the notion that gravity alone was enough. Can you list say 5 of these extraordinary assumptions?

So the next brain stretch necessary to somehow rationalize the official conspiracy theory is that many, if not all buildings are designed so that only a relatively small threshold needs to be overcome to induce progressive collapse, in other words, that the stress/weight ratio is similarly huge in all skyscrapers (why don't they lean on stormy days then?), and the only way to prevent these disasters is to strip search airplane passengers.

We already went over this. Its why controlled demolition works.

And no, not allowing passengers is not the only way to prevent it. The most obvious way to prevent this is to prevent collapse initiation after a plane impact. I think almost anyone would agree to this.

And somehow, deep inside, most "debunkers" know how silly that is and this is why they try to sidetrack and insult, resort to sophistry or claim to know better solely based on their alleged expertise when confronted with plain, simple logic and physical laws. After all, their world view stands, hangs and falls with the 3 9/11 skyscrapers.

It seems you are trying to rationalize why there are so many highly educated people on the subject at hand that disagree with you. Its because "deep inside" they actually do agree.

Originally posted by -PLB-

Progressively is emphasized here because in a material like steel, such a "jerk" would usually propagate through the whole structure many times before the next floor has failed. In other words, the dynamic load of the falling section would have been distributed over (that is, dampened by) the rest of the intact structure within a few milliseconds.

No it would not. You are making this up.

Yes it would. No I'm not making this up.

I find this childish, you should at least back your claims somehow.

But instead, the jerk was so great that the structure was unable to distribute the dynamic load force over the complete length of the structure; the segments were "shocked" out of the way one by one.

It's pretty simple to explain why this is incorrect. The forces have to be transfered down the structure. The first column length which is transferring the force to the column length below it is the part that will fail first.

So its impossible to "distribute the dynamic load force over the complete length of the structure". That statement doesn't even make too much sense. All the load will be on the first resisting column length meets, and it will only transfer the load it is capable of transferring down, until it fails for course.

I have a small update for you.

Remember my tower made of vinyl records and paper loops?

Imagine I would slowly, gently apply a vertical force on the tower, by putting more vinyl records on top. The force of the weight would be transmitted through all the paper loops until the paper loop on the bottom fails.

Now imagine I would apply a sudden, vertical force on it, by dropping a bunch of vinyl records on top. Then the paper loops in the impact zone would fail while those below remain intact. Do you understand why that is? I do.

Because gravitation makes no distinction between the planet and the vinyl records.

So basically, the whole structure is squeezed tight between a planet and a few vinyl records moving towards each other. If that happens very slowly, the first paper loop to fail is that which has to sustain most of the weight.

Why would that change if it happens very fast? Because of inertia, of course - all the vinyl records in between would need to be accelerated, but they are "lazy" (really, the German word for inertia can be translated as "mass lazyness momentum"), so the energy of the impact is used to deform the paper loops in the impact zone first.

However, in my experiment, since I had designed the loops so each of them barely holds up the weight of all the records, some of the force was transmitted through the paper loops all the way to the one at the bottom, and this little surplus sufficed to crush it.

Obviously, the "impact shock" or "pressure wave" rippled through the structure, as each molecule "bounced" against the next one, accelerated it and "bounced" back to its previous position, if it could.

How fast that mechanical pressure transmission is depends on the material's properties. Steel exhibits a comparatively high velocity of propagation for mechanical forces, in rubber, this velocity is much smaller. In air, it determines how long it takes for a sound to reach your ears.

So no, it is not "impossible to distribute the dynamic load force over the complete length of the structure"; in fact, it is the most common phenomenon to be encountered in the universe.

As soon as the top section falls onto the rest of the structure, there is a planet with the base protuding from it in one state of inertia and the top section in another. These two collide. The pressure wave would usually run through both parts of the structure and cause deformation wherever the molecular bonds are too weak to bounce the respective molecules back to their previous position. Since the pressure wave hits in the impact zone first, the molecular bonds will fail here first. This energy will not be available to do anything anymore, so the pressure wave becomes weaker as it travels down the base and up the top and back again until all its energy has been converted.

So if you want to make the whole structure fail, you must make sure that one pressure wave sets off the next.

Probably I have not used the correct technical terms again, anyway, I hope you can guess what I mean to say and point me to the correct ones.

Can you list say 5 of these extraordinary assumptions?

First extraordinary assumption: a skyscraper compresses uniaxially under its own weight.

Ummm... that should suffice.

The most obvious way to prevent this is to prevent collapse initiation after a plane impact.

What about the buildings where collapse was initiated... but stopped?

Originally posted by Akareyon
So no, it is not "impossible to distribute the dynamic load force over the complete length of the structure"; in fact, it is the most common phenomenon to be encountered in the universe.

This only happens when the part of the columns or the floor that is impacted does not fail. If it does fail it can not transfer the forces to the lower part of the structure, as it loses its load capacity.

Obviously, the floors connections in the WTC failed way before they could transfer any significant load to the columns.

First extraordinary assumption: a skyscraper compresses uniaxially under its own weight.

Ummm... that should suffice.

If you change it to: Some skyscrapers can collapse uniaxially under their own weight given that 1 or more complete floors fail.

Then I can live with it. Evidence of to support this so called "extraordinary" assumption is readily available. We see it happen in several controlled demolitions. The main difference is the method of making 1 or more floors fail.

What about the buildings where collapse was initiated... but stopped?

Its another possibility. We already been over this. You were unable to demonstrate the feasibility of it, and I do not have enough knowledge on the subject to form an educated opinion.

Originally posted by -PLB-

Originally posted by Akareyon
So no, it is not "impossible to distribute the dynamic load force over the complete length of the structure"; in fact, it is the most common phenomenon to be encountered in the universe.

This only happens when the part of the columns or the floor that is impacted does not fail. If it does fail it can not transfer the forces to the lower part of the structure, as it loses its load capacity.

Obviously, the floors connections in the WTC failed way before they could transfer any significant load to the columns.

This is where the part with the velocity of propagation comes in. It is so great that the pressure wave would run to the basement and back in the time one single floor needs to fail completely :-)

If you change it to: Some skyscrapers can collapse uniaxially under their own weight given that 1 or more complete floors fail.

Then I can live with it.

Now, what did you tell me about shifting the goalposts? ;-) I'm okay with that, though, under one little condition.

Evidence of to support this so called "extraordinary" assumption is readily available. We see it happen in several controlled demolitions.

So the towers were brought down by controlled demolitions?

Wait no:

The main difference is the method of making 1 or more floors fail.

One, or more, or all... so, here comes aforementioned condition.

If you change this to: the main difference is the relative amount of floors made to fail, I can see the dawning light of an agreement between the two of us.

Just to keep track, this is what it would look like now:

Extraordinary Assumption No. 1: skyscrapers can collapse uniaxially under their own weight given that less than X% of all floors completely fail.

For X, I would insert something around 10 or 15 or so, what do you think would be fair?

What about the buildings where collapse was initiated... but stopped?

Its another possibility. We already been over this. You were unable to demonstrate the feasibility of it,

Oh, sorry, I was pretty sure I had mentioned this and this one, as they are my favourites - the first one for the music and the other one for the huge "BOOM!" flag :-)

Originally posted by Akareyon
This is where the part with the velocity of propagation comes in. It is so great that the pressure wave would run to the basement and back in the time one single floor needs to fail completely :-)

Not sure what this means.

Now, what did you tell me about shifting the goalposts? ;-)

Shifting goal posts? I am correcting your straw man argument.

If you change this to: the main difference is the relative amount of floors made to fail, I can see the dawning light of an agreement between the two of us.

Sorry, no agreement. There are examples of controlled demolition that have a similar amount of floors as in the WTC that fail. You already know this though.

Extraordinary Assumption No. 1: skyscrapers can collapse uniaxially under their own weight given that less than X% of all floors completely fail.

For X, I would insert something around 10 or 15 or so, what do you think would be fair?

I think 2 would be fair, based on a) verinage demolition b) WTC tower collapses c) publications by Bazant.

Do you have anything to support your "15"? Or did you make that up on the spot?

Oh, sorry, I was pretty sure I had mentioned this and this one, as they are my favourites - the first one for the music and the other one for the huge "BOOM!" flag :-)

Sure you did. Now do a feasibility study to figure out the benefit to make all buildings with such a feature. Take in consideration that significant measure are already been taken to prevent collapse initiation as a result of plane impacts. And put your focus on skyscrapers. Or find a publication of such a study, which is also fine.

Originally posted by -PLB-

Originally posted by Akareyon
This is where the part with the velocity of propagation comes in. It is so great that the pressure wave would run to the basement and back in the time one single floor needs to fail completely :-)

Not sure what this means.

It means that the pressure wave travels at around 4512 m/s in steel, down the structure and back, whereas the speed of an object after free falling 3.7 meters at g=9.81 m/s² is merely 8.52 m/s. So during the time of one floor being crushed, a huge portion of the dynamic load force can easily distribute all over the structure of remaining intact floors, be partially absorbed into the ground and partially reflected back up many times over. It is far from "impossible", it is the most usual thing in the universe to occur.

If you change this to: the main difference is the relative amount of floors made to fail, I can see the dawning light of an agreement between the two of us.

Sorry, no agreement. There are examples of controlled demolition that have a similar amount of floors as in the WTC that fail. You already know this though.

Wow, no, I really didn't know that. I'm quite sure that a large percentage of floors need to be made to fail in a controlled demolition, not just a few.

(Which, If I may add this little side note, has once been one of the favourite arguments proponents of the official conspiracy theory used against the controlled demolition theory - it would be one hell of a work to rig a 110 story building, it wouldn't go unnoticed. It is a strong argument, by and large I agree with it)

Extraordinary Assumption No. 1: skyscrapers can collapse uniaxially under their own weight given that less than X% of all floors completely fail.

For X, I would insert something around 10 or 15 or so, what do you think would be fair?

I think 2 would be fair, based on a) verinage demolition b) WTC tower collapses c) publications by Bazant.

a) vérinage demolition utilizes hydraulic cylinders and pulleys and removes load-bearing walls beforehand, b) WTC tower is the extraordinary thing we're discussing and c) Bazant clearly says it can best be explained with a controlled demolition.

Do you have anything to support your "15"? Or did you make that up on the spot?

I was trying to be generous, that's all, but I'll agree with 2, of course, or we could meet in the middle, let's say 8:

Extraordinary Assumption No. 1: skyscrapers can collapse uniaxially under their own weight given that less than 8% of all floors completely fail.

Now do a feasibility study to figure out the benefit to make all buildings with such a feature. Take in consideration that significant measure are already been taken to prevent collapse initiation as a result of plane impacts. And put your focus on skyscrapers. Or find a publication of such a study, which is also fine.

:-) Nice try. Please allow me to stress that the evidence I had the honour to present - two totally unrelated and different buildings - clearly shows that the interruption of a progressing collapse is nothing out of the ordinary and even common if the charges don't go off as planned, which in turn backs my not-so-extraordinary claim that the floors have to be weakened just in time in order to facilitate the uniaxial collapse of a tall building. You, on the other hand, are the one defending the extraordinary assumption that once collapse is initiated, progression is inevitable, so you are the one to come up with extraordinary evidence - other than the subject of the debate. For whether it happened or not is not the question, the question is how and why it could happen. Planned demolition is the ordinary assumption. Failure of 2%-15% of the floors (for example because of fires and some localized structural damage due to a plane crash or a suitcase bomb or a gas leak) and inevitability after initiation is the extraordinary assumption. The assumption is not the evidence.

Originally posted by Akareyon

I was trying to be generous, that's all, but I'll agree with 2, of course, or we could meet in the middle, let's say 8:

To be fair NIST calculated a safety factor of 12, that is 11 extra floors could be placed ever ever ever so gently on an existing floor and it would support the weight. Note that is the weight of the floors only and not the extra weight of exterior and core columns. By adding ANY inertia at all, the safety factor drops to 7. The falling mass of the upper floors grossly exceeded this safety factor.

Consider a typical floor immediately below the level of collapse initiation and conservatively assume that the floor is still supported on all columns (i.e., the columns below the intact floor did not buckle or peel off due to the failure of the columns above). Consider further the truss seat connections between the primary floor trusses and the exterior wall columns or core columns. The individual connection capacities ranged from 94,000 pounds to 395,000 pounds, with a total vertical load capacity for the connections on a typical floor of 29,000,000 pounds (see Section 5.2.4 of NIST NCSTAR 1-6C). The total floor area outside the core was approximately 31,000 square feet, and the average load on a floor under service conditions on Sept. 11, 2001, was 80 pounds per square foot. Thus, the total vertical load on a floor outside the core can be estimated by multiplying the floor area (31,000 square feet) by the gravitational load (80 pounds per square foot), which yields 2,500,000 pounds (this is a conservative load estimate since it ignores the weight contribution of the heavier mechanical floors at the top of each WTC tower). By dividing the total vertical connection capacity (29,000,000 pounds) of a floor by the total vertical load applied to the connections (2,500,000 pounds), the number of floors that can be supported by an intact floor is calculated to be a total of 12 floors or 11 additional floors.

This simplified and conservative analysis indicates that the floor connections could have carried only a maximum of about 11 additional floors if the load from these floors were applied statically. Even this number is (conservatively) high, since the load from above the collapsing floor is being applied suddenly. Since the dynamic amplification factor for a suddenly applied load is 2, an intact floor below the level of collapse initiation could not have supported more than six floors. Since the number of floors above the level where the collapse initiated exceeded six for both towers (12 for WTC 1 and 29 for WTC 2), neither tower could have arrested the progression of collapse once collapse initiated. In reality, the highest intact floor was about three (WTC 2) to six (WTC 1) floors below the level of collapse initiation. Thus, more than the 12 to 29 floors reported above actually loaded the intact floor suddenly.

www.nist.gov...

Originally posted by Akareyon
Remember my tower made of vinyl records and paper loops?

Your tower fails under compression the WTC Towers failed under shear.

Originally posted by Akareyon
It means that the pressure wave travels at around 4512 m/s in steel, down the structure and back, whereas the speed of an object after free falling 3.7 meters at g=9.81 m/s² is merely 8.52 m/s. So during the time of one floor being crushed, a huge portion of the dynamic load force can easily distribute all over the structure of remaining intact floors, be partially absorbed into the ground and partially reflected back up many times over. It is far from "impossible", it is the most usual thing in the universe to occur.

You really fail at understanding that the floor connections fail before they can cause this whole "pressure wave". Do you believe in magic? If not, show your physics.

Wow, no, I really didn't know that. I'm quite sure that a large percentage of floors need to be made to fail in a controlled demolition, not just a few.

Well this would be a great moment to extend your knowledge.

a) vérinage demolition utilizes hydraulic cylinders and pulleys and removes load-bearing walls beforehand

Though you can not deny that the building is still standing strong after these preparations beforehand. Physics does not care about building codes.

c) Bazant clearly says it can best be explained with a controlled demolition.

I don't doubt it can be interpreted like this in some delusional interpretation. It has no relevance to reality though,

I was trying to be generous, that's all, but I'll agree with 2, of course, or we could meet in the middle, let's say 8:

Okido, you made it up based on nothing. Noted.

:-) Nice try. Please allow me to stress that the evidence I had the honour to prese and different buildings - clearly shows that the interruption of a progressing collapse is nothing out of the ordinary and even common if the charges don't go off as planned, which in turn backs my not-so-extraordinary claim that the floors have to be weakened just in time in order to facilitate the uniaxial collapse of a tall building.

Again the incorrect inductive reasoning. Get a logic course at your local university. Just because some buildings show some behavior does not mean all buildings do. Logic 101.

You, on the other hand, are the one defending the extraordinary assumption that once collapse is initiated, progression is inevitable, so you are the one to come up with extraordinary evidence - other than the subject of the debate.

Labeling something "extraordinary" does not make is so. A government conspiracy that deludes all experts in the world, how would you classify that?

For whether it happened or not is not the question, the question is how and why it could happen. Planned demolition is the ordinary assumption. Failure of 2%-15% of the floors (for example because of fires and some localized structural damage due to a plane crash or a suitcase bomb or a gas leak) and inevitability after initiation is the extraordinary assumption.

Its not. Physics does not care about what you call "extraordinary". If you want to make a case, show the physics.

Originally posted by hellobruce

Originally posted by pheonix358
Tall structures fall over! They do not fall down onto themselves. It is truly that simple!

So show us evidence of that happening in 100+ story buildings....

Well, I can't!

You see, in all of history, a building made from steel and concrete has never collapsed due to a fire, except three buildings that went down in one day. And since that time, there has never been another one.

Weird isn't it?

P

So WMD and PLB believe that 15% of the structure plowed its way through the remaining 85% with - and this is in your own words - "NO RESISTANCE"


again because this is just too rich... NO RESISTANCE!!!!

And come on WMD, wth are you doing posting rubber tire fires as an example of hot fires that burn black. Do you think everyone is retarded.? and the other one? with the tankers all lying about i can only speculate what they were filled with, I suppose you are going to say they were filled with office furniture?

I am going to pretend you just grabbed the first couple pictures you saw without giving it much thought. Otherwise i have to believe you are just trying to pull the wool over everyone's eyes.

Oh and I guess the current NSA revelations have shined a little light on how something of this magnitude could be covered up.