I need all debunkers I can get!

[Heiwa]

Absolutely astonishing.

[qimg]http://wtc7lies.googlepages.com/Ronan.jpg[/qimg]

Why did this progressive collapse proceed to the ground? Why did the mass above not know to transport itself laterally, using no energy, so that it could take the "path of least resistance" through the air? What a stupid mass!

Jeebus, I have to get away from this insanity.

Nice picture that proves my point. I assume the wall failed at the bottom (not seen on photo) and that the 'mass above' the wall then dropped down thorugh air (least resistance of course - not much support by air) with a few pieces hanging from the roof that didn't drop (support provided by the roof).
Thus not some progressive collapse from top down.

 

[Heiwa]

Why should we read the work of an incompetent? You have no idea how often your errors have been corrected on this forum.

OK, you haven't read it.

Let's do a model test to prove my point! It is not too difficult.

You need a diameter 20 mm steel pipe with 1 mm wall thickness, thus cross area 6.28 mm², radius of gyration evidently 10 mm. Let's make it 185 mm long. It has slenderness ratio 18.5. Actually it looks like a WTC1 core column in scale 1/20 and that's the whole idea. Let's assume the steel has yield stress 23.5 kgs/mm².

Fix the pipe upright on a suitable table* to represent a floor and then put about 45 kgs of suitable weight* on the other, upper pipe end. It is 360 tons full scale but we are playing in 1/20! Ensure that the weight is properly aligned right above the pipe during the test.

Now the compressive stress in the pipe is 7.16 kgs/mm², which is 30.5 % of the yield stress of the steel of the pipe. No problem if the table can resist it. Exactly like WTC1. There is no bending of the pipe.

Now start to heat the pipe with a suitable device to 500° C (or 800°C). *The table and weight above must be suitable because the heat applied to the pipe will of course spread to them. Let's assume the table does not catch fire, etc. be careful!

The purpose of the model test is of course to establish the stiffness of the pipe (and why not, the table) and to see if suddenly, at, e.g. temperature 500°C, the weight* drops down at a significant speed and with an enormous kinetic energy and impacts on the table* or the pipe (?) with an enormous dynamic load (and destroys the table?) = no stiffness of the pipe, i.e. the column.

Or does nothing of that sort happen? Maybe the pipe will just bulge. You will find out.

Good luck!

BTW - The potential energy of 45 kgs falling 0.185 m is only 83.25 Joule so you don't really have to worry too much in scale 1/20.

BTW 2 - 83.25 Joule will light up a 100W bulb for 0.8325 seconds if it were electricity.

 

[uk_dave]

I assume the wall failed at the bottom (not seen on photo) and that the 'mass above' the wall then dropped down thorugh air (least resistance of course - not much support by air) with a few pieces hanging from the roof that didn't drop (support provided by the roof).
Thus not some progressive collapse from top down.

Nope. Ronan Point

ETA: The details of which you should already be fully aware of, if you were a structural engineer of any worth.

 

[LashL]

Nice picture that proves my point. I assume the wall failed at the bottom (not seen on photo) and that the 'mass above' the wall then dropped down thorugh air (least resistance of course - not much support by air) with a few pieces hanging from the roof that didn't drop (support provided by the roof).
Thus not some progressive collapse from top down.

You know what happens when you assume.

You're wrong, on all counts, genius.

 

[Gravy]

Nice picture that proves my point. I assume the wall failed at the bottom (not seen on photo) and that the 'mass above' the wall then dropped down thorugh air (least resistance of course - not much support by air) with a few pieces hanging from the roof that didn't drop (support provided by the roof).
Thus not some progressive collapse from top down.

The failure progressed downward from the 18th floor after a gas explosion there. The mass falls through the path of least energy change, capisce? Does this change your mind about the very real phenomenon of progressive collapse, Heiwa?

NISTIR 7396 "Best Practices for Reducing the Potential for Progressive Collapse in Buildings," February 2007

Above report based on NIST/SEI workshops. Workshop presentation materials are here.

Abolhassan Astaneh-Asl: Progressive collapse prevention in new and existing buildings (Includes use of catenary action of cables to resist collapse. 2003. pdf).

​

Practical Means for Energy-Based Analyses of Disproportionate Collapse Potential
Journal of Performance of Constructed Facilities, Volume 20, Issue 4, pp. 336-348 (November 2006)

Progressive Analysis Procedure for Progressive Collapse
Journal of Performance of Constructed Facilities, Volume 18, Issue 2, pp. 79-85 (May 2004)

Progressive Collapse of Structures: Annotated Bibliography and Comparison of Codes and Standards
Journal of Performance of Constructed Facilities, Volume 20, Issue 4, pp. 418-425 (November 2006)

 

[Gravy]

Nope. Ronan Point

ETA: The details of which you should already be fully aware of, if you were a structural engineer of any worth.

He's not a structural engineer.

 

[Myriad]

OK, you haven't read it.

Let's do a model test to prove my point! It is not too difficult.

You need a diameter 20 mm steel pipe with 1 mm wall thickness, thus cross area 6.28 mm², radius of gyration evidently 10 mm. Let's make it 185 mm long. It has slenderness ratio 18.5. Actually it looks like a WTC1 core column in scale 1/20 and that's the whole idea. Let's assume the steel has yield stress 23.5 kgs/mm².

Fix the pipe upright on a suitable table* to represent a floor and then put about 45 kgs of suitable weight* on the other, upper pipe end. It is 360 tons full scale but we are playing in 1/20! Ensure that the weight is properly aligned right above the pipe during the test.

Now the compressive stress in the pipe is 7.16 kgs/mm², which is 30.5 % of the yield stress of the steel of the pipe. No problem if the table can resist it. Exactly like WTC1. There is no bending of the pipe.

Now start to heat the pipe with a suitable device to 500° C (or 800°C). *The table and weight above must be suitable because the heat applied to the pipe will of course spread to them. Let's assume the table does not catch fire, etc. be careful!

The purpose of the model test is of course to establish the stiffness of the pipe (and why not, the table) and to see if suddenly, at, e.g. temperature 500°C, the weight* drops down at a significant speed and with an enormous kinetic energy and impacts on the table* or the pipe (?) with an enormous dynamic load (and destroys the table?) = no stiffness of the pipe, i.e. the column.

Or does nothing of that sort happen? Maybe the pipe will just bulge. You will find out.

Good luck!

BTW - The potential energy of 45 kgs falling 0.185 m is only 83.25 Joule so you don't really have to worry too much in scale 1/20.

BTW 2 - 83.25 Joule will light up a 100W bulb for 0.8325 seconds if it were electricity.

In making your 1/20th scale model, you have scaled down the cross section area of the "column" (and therefore the yield strength under a pure compressive load) by a factor of 1/400, but you have scaled down the mass of the load (and therefore the compressive force) by a factor of 1/8000.

In other words, you're cheating, by a factor of 20.

I assume the cheating is inadvertent, because you do not understand the complex issues involved in scaling. That's not surprising, nor is it any reflection on your intelligence. People have to study for a long time to understand such issues properly.

But, we can get a much closer approximation to a proper scale model (while keeping in mind that no scale model can be fully equivalent to the full scale situation in respects that are relevant to a complex phenomenon such as progressive collapse) by putting a scale-correct 900 kilograms on top of your pipe.

Hey, wait, that exceeds your yield stress before you even start your heating experiment! Perhaps your slender pipe needs some horizontal bracing to be able to bear the load you've intended it to bear. The columns in the WTC towers certainly did.

Respectfully,
Myriad

 

[Heiwa]

The failure progressed downward from the 18th floor after a gas explosion there.

So there was an explosion up at the 18th floor!! Changes of course the cause of accident - now known - and what followed.

In my article I show that WTC1 could not have collapsed due to local structural failure and slow compression of some steel columns due to heat at floor 94, so no potential energy would be released and transformed to enormous amount of kinetic energy that would impact the structure below at high velocity, etc. The structure is too strong and the influence of heat too small! That's the message. Based on sound structural analysis and correct info about heat influence on steel.

But an explosion up at floor 94-96 on WTC1 would in fact be able to initiate a more extensive collapse. That is obviously not part of my article that is just about what happens to the structure at floor 94, or rather not happens. But I have to admit that the sudden collapse and what followed - as shown on the photo in the article - indicate a large amount of energy released in all directions up at floor 94. But I do not speculate of the origin of that.

 

[Heiwa]

In making your 1/20th scale model, you have scaled down the cross section area of the "column" (and therefore the yield strength under a pure compressive load) by a factor of 1/400, but you have scaled down the mass of the load (and therefore the compressive force) by a factor of 1/8000.

In other words, you're cheating, by a factor of 20.

Not at all - lengths are scaled 1/20, areas 1/400 and volumes/loads 1/8000. Stresses and slenderless ratios are not affected by scale.

Heat input evidently is - the model wall thickness is only 1 mm and should be 20 mm full scale which requires much more heat, longer times, etc.

I assume the actual deformation due heat is not affected by scale - 1 mm is evidently much easier to deform than 20 mm but the load is only 1/8000. But nothing happens at 500° C.

Why would I cheat? Did you get burnt? I warned you. This is a hot subject. No Pulitzer prices, etc. Media, etc. do not dare to touch it.

 

[Gravy]

So there was an explosion up at the 18th floor!! Changes of course the cause of accident - now known - and what followed.

You continue to be deliberately ignorant. The failure occurred on the 18th floor, and the falling mass broke through each successive floor, to the ground. The mass did not defy the laws of physics by magically transporting itself laterally to seek the air to fall through.

What is preventing you from understanding this very simple concept, Heiwa?

 

[Myriad]

Not at all - lengths are scaled 1/20, areas 1/400 and volumes/loads 1/8000.

Exactly. You've scaled the strength (which is proportional to area) and the load (which is proportional to volume) by different factors.

Why, after doing that, would you believe (let alone attempt to convince others) that the results of your experiment would be any indication of what would happen full-scale?

Respectfully,
Myriad

 

[Heiwa]

Exactly. You've scaled the strength (which is proportional to area) and the load (which is proportional to volume) by different factors.

Why, after doing that, would you believe (let alone attempt to convince others) that the results of your experiment would be any indication of what would happen full-scale?

Respectfully,
Myriad

This is the way model tests are done.

Actually the objective of the test is to show that a steel pipe or column with slenderness ratio <20 (or 40 if you like that) and under compression at stress 0.3Xyield does not buckle at 500°C.

BTW - http://journalof911studies.com/volume/200703/Sudden_collapse_initiation_impossible.pdf explains my findings in a much simpler way.

 

[Myriad]

This is the way model tests are done.

You mean, in erroneous ignorance of the physical effects of scaling?

What model tests are you referring to?

Respectfully,
Myriad

 

[Heiwa]

You continue to be deliberately ignorant. The failure occurred on the 18th floor, and the falling mass broke through each successive floor, to the ground. The mass did not defy the laws of physics by magically transporting itself laterally to seek the air to fall through.

What is preventing you from understanding this very simple concept, Heiwa?

Come on - the cause of accident was a gas explosion that blow out the walls on the 18th floor and we don't know if the gas (heavier than air) had leaked down to lower floors and contributed to the damages there. Also, a gas explosion really causes a shock wave that affects structure remote from the origin of explosion.

I have experience of gas explosions on sea going oil tankers!! On one of our tankers (M/T Cam Etinde abt 1995) there was an explosion in a tank! The deck top part) lifted but also several bulkheads (walls) - weaker than the deck - were damaged (remote from the tank).

 

[Heiwa]

You mean, in erroneous ignorance of the physical effects of scaling?

What model tests are you referring to?

Respectfully,
Myriad

The one described above.

Kind regards

Heiwa

 

[Heiwa]

Gents,

come on! You are supposed to debunk me. Come up with some scientific data that shows that my article is wrong.

 

[Heiwa]

You mean, in erroneous ignorance of the physical effects of scaling?

What model tests are you referring to?

Respectfully,
Myriad

If you do not like model tests, do it full scale with a 3.7 m long, dia 400 mm upright pipe with wall thickness 20 mm and load/compress it with 360 tons (or what corresponds to 30% yield stress) and then start to heat the pipe to 500°C. You need plenty of heat and it will dissipate in the support below and the weight above. It will be very hot.

There is no risk that the 360 tons suddenly drop down on you, though.

But easier with a proper model test (as outlined above).

 

[Gravy]

Come on - the cause of accident was a gas explosion that blow out the walls on the 18th floor and we don't know if the gas (heavier than air) had leaked down to lower floors and contributed to the damages there.

Yes, we do. The failure occurred only on the 18th floor. The woman who lit the match that caused the explosion in her kitchen survived.

Are you going to insist, in the face of hundreds of historical incidents and studies, experiments, calculations and papers by structural engineers, that progressive collapse is a myth?

Are you that ignorant?


Fire Induced Progressive Collapse
David Scott, Barbara Lane, Craig Gibbons,
Arup, 155 Ave of the Americas, NY, NY10013
contact: david.scott@arup.com ; www.arup.com

"This paper considers issues related to fire induced progressive collapse of tall buildings in extreme events."

 

[Myriad]

If you do not like model tests, do it full scale with a 3.7 m long, dia 400 mm upright pipe with wall thickness 20 mm and load/compress it with 360 tons (or what corresponds to 30% yield stress) and then start to heat the pipe to 500°C. You need plenty of heat and it will dissipate in the support below and the weight above. It will be very hot.

There is no risk that the 360 tons suddenly drop down on you, though.

But easier with a proper model test (as outlined above).

"Or what corresponds to 30% yield stress?" Is this some kind of joke or parody? If so, congratulations on fooling me for so long.

Dude, you either know what the stress on the column was, or you don't. What kind of test is it that starts out with the assumption that the actual condition is only 30% the magnitude of the failure condition?

This is a great way to "prove" all kinds of stuff. Here's my proof that a car can't knock over a road sign: start with a car moving at what corresponds to 30% of the speed needed to knock over the sign, double the car's speed, crash it into the sign, and the sign stays intact! (You can do this with a scale model test, too.)

Or here's proof that cyanide is harmless: get an amount of cynaide that's 30% of the amount needed to harm a person, double the dose, and swallow it. You won't be harmed!

But these are just pale reflections of the genius of your thesis. Start with steel under 30% of the load needed to cause failure, heat the steel to a temperature that weakens the steel by a factor of .5, and the steel won't fail! Who'd have thought? (Too bad you had to add all those complications about slenderness ratios and temperature-stress-strain curves and stuff. Why obfuscate the marvelous insight that your argument is really based on, which is that steel under a load specified in advance to be less than the load needed to cause it to fail, won't fail?)

Now I see why you're so confident that no one will be able to prove your paper wrong with scientific data. Because what little scientific data it contains (basically, that .6 is less than 1) is irrelevant, and the error is in the logic.

Fortunately, I have a counter-argument. The moon orbits the earth, and therefore 9/11 could not have been an inside job. Can you show me some scientific data that proves me wrong?

Respectfully,
Myriad

 

[Heiwa]

Yes, we do. The failure occurred only on the 18th floor. The woman who lit the match that caused the explosion in her kitchen survived.

Are you going to insist, in the face of hundreds of historical incidents and studies, experiments, calculations and papers by structural engineers, that progressive collapse is a myth?

Are you that ignorant?


Fire Induced Progressive Collapse
David Scott, Barbara Lane, Craig Gibbons,
Arup, 155 Ave of the Americas, NY, NY10013
contact: david.scott@arup.com ; www.arup.com

"This paper considers issues related to fire induced progressive collapse of tall buildings in extreme events."

Not at all! We are not talking about progressive collapse or global collapse of structures. They occur.

The subject is what happens before that and IF local collapse of any structural part can take place to initiate what follows, e.g. local deformation, load transfer to other structural parts, etc. And the example is WTC1.

Very strong steel structure to say the least. Why not admit it. Very low static stresses in it! And the total mass is only 10% steel columns and the rest is the rest (floors, glass, etc), most of it concrete in the floors.
There is also plenty of redundancy. The core columns are really heavy - 30 - 60 mm thick plates. Strong stuff. And plenty of spandrels (brackets) to keep them together.

And then ... it is a well known fact that steel structures with low static stresses are not materially affected by heat at 500° C. The yield stress will be reduced a little but it does not affact the strengt as the stresses are low! Why not admit that? Why exagerate temperatures 3X, suggest that steel melts in office fires, etc. Why ignore the basics?

Yes, you are right that a wall may fall down/collapse it there is a gas explosion inside a steel structure. Why that happens depends on how the explosive load is applied on the structure. I gave you an example above that happened to my ship.

But WTC1 is officially no explosion. Only normal fire - most jet fuel burn out. What is burning is office furniture, decorations, paper, carpets, etc. But it looks like one (or more) explosions prior to and during the global collapse! Things are blowing out sideways through the windows.

NIST suggest the floors are falling down, but come on. Each floor is attached to the columns with 700 bolts.

Etc, etc. Professors are talking about that big masses in the WTC1 building are first suddenly falling down due to simultaneous collaps of 100's of columns and second, impact other structure at high velocity. No evidence of any kind, of course! A fairy tale or a simple invention. A myth! Then they come up with funny analysis about impacts, shock waves, etc. that breaks up very strong structure in 1000's of pieces. All nonsense, of course. Twisted science.

I know why! They are afraid. They will lose their jobs if they say something else ... or even shut up. Their colleagues just nod ... (and probably suffer). But it is the easiest solution for them. Support official policy.

Like DDR 1949 - 1989. Terrible times there and then.