Split Thread henryco's new paper

[Newtons Bit]

It's a joke a suppose! sound or any deformation of the steel will not pulverize concrete projecting massive debris at 160km/h several floors in advance! simply ridiculous...

No, but it could wreck both interior and exterior finishes that aren't detailed to accommodate such a large vertical deflection of the supporting columns.

 

[DGM]

.

2) I see no other really convincing explanation for such speeds here

F H-C

Thanks for clearing this up.

Now is it because you don't want to see them.

 

[henryco]

You're getting lost in translation here. I don't know what you mean? It's pressure, exactly like you've said that is responsible. Not shockwaves. The overpressure in the building blew out fresh air intake ducts. These ducts have been shown to be in the exact location of these alleged "squibs".

edit: nevermind Dave explained. waves propagating in a medium etc.

The ducts can drive material debris not over pressure! overpressure propagates everywhere in an opened area as is a WTC floor: il would blow out all windows on multifoors at the same time.

F

 

[R.Mackey]

45 meters per second works out to a dynamic pressure of about a sixth of a PSI. Easily achievable through non-explosive means, such as motion of the upper structure. In fact, utterly consistent with that motion.

See this thread. Old. Debunked. Over.

 

[Newtons Bit]

45 meters per second works out to a dynamic pressure of about a sixth of a PSI. Easily achievable through non-explosive means, such as motion of the upper structure. In fact, utterly consistent with that motion.

See this thread. Old. Debunked. Over.

1/6 of a PSI translates to 24 PSF. Interior partition walls are only designed for lateral loads of about 5 PSF.

 

[henryco]

Wrong. Consider an impact on the upper end of a vertical steel column. How fast does the effect of that impact propagate down the column? The answer is, at the speed of sound in steel, rather than at a velocity/time profile determined by the acceleration due to gravity. Therefore, a succession of collisions between extended objects can propagate downwards faster than a 1G acceleration velocity profile.
Dave

In case the two objects were already in contact before i'm not calling this a collision.

 

[henryco]

45 meters per second works out to a dynamic pressure of about a sixth of a PSI. Easily achievable through non-explosive means, such as motion of the upper structure. In fact, utterly consistent with that motion.

See this thread. Old. Debunked. Over.

Except that the motion of the upper structure here has not reached the level where we observe these ejections except through sound waves if you want!

 

[Sam.I.Am]

No problem since
1) its also a typical velocity for squibs in controlled demolition...
remember that any jet is decelerated thery fast in the air and here might be up to 20 meters away from its source.

2) I see no other really convincing explanation for such speeds here

F H-C

1) The "Squibs" you cite are a natural result of gravity forcing rubble downwards compressing the air inside the structure, The compressed air will always seek the path of least resistance just like any other fluid or gas will do. I hope that you are aware that all buildings have air in them. If you observes the "Squibs" at the WTC you will see that they start slow and then speed up, the exact opposite of what you would see in an explosion where the energy is released instantaneously and the pressure lowers as you get farther from the source.

2) If the airflow is restricted it will speed up at the exit point(s). the tighter the restriction the faster the airflow. This is why you can blow out a candle over a foot away from your mouth if you purse your lips like for a whistle and can't do so with your mouth open like you were saying "Ha". The collapses are just large scale examples of this simple phenomena. Is that convincing enough for you?

 

[R.Mackey]

Except that the motion of the upper structure here has not reached the level where we observe these ejections except through sound waves if you want!

Bare assertion fallacy. Yes it has. Do a simple conservation of volume calculation (the air is subsonic, so this holds).

ETA: Never mind, I misunderstood you -- I thought "reached the level" meant "moved fast enough." If instead you mean "this happens at a different floor," so what? Pressure can travel through the structure. Dumb argument either way.

---

What you're proposing is an explosive so large that it generated many thousands of cubic meters of gas, yet so small that the shock wave of its destruction was inaudible and insufficient to break windows. This is impossible. Give it up.

 

[Sam.I.Am]

The ducts can drive material debris not over pressure! overpressure propagates everywhere in an opened area as is a WTC floor: il would blow out all windows on multifoors at the same time.

F

The windows were designed to withstand hurricane force winds. Granted that wind was expected to push the glass against the frames from the outside inwards but it does demonstrate that the glass wasn't going to blow out at the pressures we are talking here. Otherwise the sidewalks below the towers would be a death trap during the decades preceding 9/11. I don't recall that being the case.

 

[Alferd_Packer]

The ducts can drive material debris not over pressure! overpressure propagates everywhere in an opened area as is a WTC floor: il would blow out all windows on multifoors at the same time.

F

do you understand how highrise HVAC systems are designed?

 

[leftysergeant]

Except that the motion of the upper structure here has not reached the level where we observe these ejections except through sound waves if you want!

The long and the short of it is that the "squibs" have nothing to do with explosives of any kind. It does not take much to blow dusty air back through ventilation systems. The floors where they appear are either mechanical floors or "sky lobbies." All ventilating duct work leads to a mechanical floor and all skylobbies are end-points for several elevator shafts. The greatest build-up of pressure on a sky lobby floor would be exactly opposite the elevator shafts from which an over-pressurization came. So, either way, it need not have been a very great over-pressurization. Simply put, when you drop TONS of crap around a hollw tube, squeezing out the air that had been separating the stuff you dropped, it will go down that tube.

That there is not an explosive charge behind any of the "squibs" is obvious in that they increase in energy and contain more particulate matter as the collapse zone approaches. Explosives would drive out a pecific volumn of matter and no more. The "squibs" were not a result of explosives. That simple.

The perimeter columns where shoved out of the way by a great weight of rubble and dust trying to go somewhere. They follow the same trajectory. No smaller pieces are seen following a different trajectory. The only objects that do not fall at the same speed as the dust plumes, or follow a different trajectory are pieces of the aluminum cladding, which go every which way because of air resistance.

You have balloon juice.

 

[Dave Rogers]

It's a joke a suppose! sound or any deformation of the steel will not pulverize concrete projecting massive debris at 160km/h several floors in advance! simply ridiculous...

Actual physical movement of steel components is easily capable of causing destruction of significant parts of the building. If a massive object strikes the top of a steel column, and the column fractures at a lower point, the free lower end can do enormous damage to the structure at a point well below the lowest point that could have been reached at that time by free-falling debris at the upper end of the column. A point that seems to me so patently obvious that a failure to concede it constitutes wilful ignorance. If you hammer in a nail, does the tip of the nail wait till the time the hammer would have got there before it penetrates further into the wood?

Dave

 

[Dave Rogers]

In case the two objects were already in contact before i'm not calling this a collision.

Pretending that there weren't any collisions in the early stages of the collapse is a bit pointless. It's inevitable that structural components failed at many different points, and that there were many collisions between elements of the upper and lower parts of the structure that had not previously been in contact. If you don't understand this, you haven't the basic knowledge to even participate in this discussion.

Dave

 

[leftysergeant]

Actual physical movement of steel components is easily capable of causing destruction of significant parts of the building. If a massive object strikes the top of a steel column, and the column fractures at a lower point, the free lower end can do enormous damage to the structure at a point well below the lowest point that could have been reached at that time by free-falling debris at the upper end of the column.

Which is irrelevant anyway, but founded in better science than any of henryco's comments so far.

The simple fact is that, in watching the collapses, I see no sign that any of the damage to the lower structure was done by stuff hitting the tops of the perimeter columns. All the damage seems to be from rubble and dust and air pushing uniformly over the entire inner surfaces of the columns. What happened to the core columns is irrelevant because they were obviously not involved in sustaining the collapses.

The floors drove all of it after initiation.

So, to prove anything other than progressive collapse, you have to prove that there was never a great enough load on any floor below the collapse zone to break it.

I shall make a point of taking all scheduled meals in the time it takes for you to prove that. I probably have time to become obese in the interval.

 

[henryco]

1) The "Squibs" you cite are a natural result of gravity forcing rubble downwards compressing the air inside the structure, The compressed air will always seek the path of least resistance just like any other fluid or gas will do. I hope that you are aware that all buildings have air in them. If you observes the "Squibs" at the WTC you will see that they start slow and then speed up, the exact opposite of what you would see in an explosion where the energy is released instantaneously and the pressure lowers as you get farther from the source.

The compressed air goes everywhere it can in an open structure and the pressure equalizes everywhere once it reaches a closed area.
So there is absolutely no way how you could get a very powerfull ejection
very localized on one floor and a few metrers away: absolutely nothing at all
and on many upper floors nothing again.

Once the Squibs are out of the building they cannot accelerate except if there is an extra source of energy acting there propelling them like a Rocket: if your observations are correct they are interesting from a conspirationist point of view

2) If the airflow is restricted it will speed up at the exit point(s). the tighter the restriction the faster the airflow. This is why you can blow out a candle over a foot away from your mouth if you purse your lips like for a whistle and can't do so with your mouth open like you were saying "Ha". The collapses are just large scale examples of this simple phenomena. Is that convincing enough for you?

But here you are only able to see a squib when it is out of the building where there is nothing to restrict the flow thus no way how it could accelerate anymore.

Again neither is there such restricting paths inside the building on any floor at the WTC because these are open structures between the core and exterior columns: the compressed air getting in through an elevator shaft could flow everywhere and it would have no reason to run particularly along the ducts you mention.

Moreover a piston effect needs hermiticity. What you call a piston here several floors above is just a sieve.

On the other hand the ducts can stop all projected debris (by explosions) except the ones running in the direction of the ducts thus producing a very localized Squib.

 

[henryco]

The windows were designed to withstand hurricane force winds. Granted that wind was expected to push the glass against the frames from the outside inwards but it does demonstrate that the glass wasn't going to blow out at the pressures we are talking here. Otherwise the sidewalks below the towers would be a death trap during the decades preceding 9/11. I don't recall that being the case.

I do agree, i 'm just arguing that if overpressure was responsible for the localized ejections we see (i'm just trying to follow this absurd scenario some other people seem to believe in) then it would do exactly the same several meters away because overpressure would be the same there: pressure equalizes when entering a closed area.

 

[Alferd_Packer]

Again neither is there such restricting paths inside the building on any floor at the WTC because these are open structures between the core and exterior columns: the compressed air getting in through an elevator shaft could flow everywhere and it would have no reason to run particularly along the ducts you mention.

I was right, you do not appear to understand how high rise HVAC systems are designed.

 

[Furcifer]

I do agree, i 'm just arguing that if overpressure was responsible for the localized ejections we see (i'm just trying to follow this absurd scenario some other people seem to believe in) then it would do exactly the same several meters away because overpressure would be the same there: pressure equalizes when entering a closed area.

The collapse of a hotel in China resulted in the clothes being stripped off of people. Consistent with wind in excess of 160 Km/h. There would be decreasing pressure as you move away from the collapse front, but overpressure was felt through the entire building. This happened when the planes hit, why not when they began to collapse?

 

[henryco]

The long and the short of it is that the "squibs" have nothing to do with explosives of any kind. It does not take much to blow dusty air back through ventilation systems. The floors where they appear are either mechanical floors or "sky lobbies."

Not at all ! many of those squibs appear at floors which are neither mechanical floors nor "sky lobbies."

All ventilating duct work leads to a mechanical floor and all skylobbies are end-points for several elevator shafts. The greatest build-up of pressure on a sky lobby floor would be exactly opposite the elevator shafts from which an over-pressurization came. So, either way, it need not have been a very great over-pressurization. Simply put, when you drop TONS of crap around a hollw tube, squeezing out the air that had been separating the stuff you dropped, it will go down that tube.
The long and the short of it is that the "squibs" have nothing to do with explosives of any kind. It does not take much to blow dusty air back through ventilation systems. The floors where they appear are either mechanical floors or "sky lobbies."

Wrong!

That there is not an explosive charge behind any of the "squibs" is obvious in that they increase in energy and contain more particulate matter as the collapse zone approaches. Explosives would drive out a pecific volumn of matter and no more.

I have seen nowhere such a correlation. the very massive ejections i discuss in the article are far away from the collapse zone as predicted by Greening and Bazant.

The "squibs" were not a result of explosives. That simple.
The perimeter columns where shoved out of the way by a great weight of rubble and dust trying to go somewhere. They follow the same trajectory. No smaller pieces are seen following a different trajectory. The only objects that do not fall at the same speed as the dust plumes, or follow a different trajectory are pieces of the aluminum cladding, which go every which way because of air resistance.

You have balloon juice.

pressure cannot carry by itself a great weight of rubble faster than gravity : neither can it carry air and dust. However once a window opens, a flow of air can well carry dust out of the building through this opening, but the first flow of air has to be the air present at those floors, a clean air...and later only when all the clean air has been evacuated should we start to see the flow of the dirty air: this would take much time since the column of clean air is huge, before seeing the dust!
What we see instead is Several seconds ahead of the collapse front and almost at the same level of freely falling debris a huge and localized ejection of pulverized concrete...
How can you defend this piston theory! incredible!