Moderated Steel structures cannot globally collapse due to gravity alone

[tfk]

Chris,

The mathematical analysis was done a couple pages back. The 'flicker factor' [buckling] is silly. Structural steel is not spring steel and cannot store very much 'spring energy' before it deforms and does not return to its original shape.

This is just a desperate childish attempt to deny the obvious.

Care to QUANTIFY "very much", chris. You might find it instructional.

It ain't hard. This'll help.
http://en.wikipedia.org/wiki/Yield_Strength#Definition

As an approximation, you can use:
Young's modulus: 29 million psi (for all steels)
Yield strength:
A36: 36 KSI
Spring steel: 100 KSI

Ultimate strength:
A36: 60 KSI
Spring steel: 200 KSI (this is widely variable, 150 - 300 KSI)

Give us the difference if you stay linear.
Give us the difference if you allow residual deformations.

tk

 

[bill smith]

This is an insult to all the firefighters who reported explosions.

If I screen the firefighter tetimonny video I wil make sure that the people get to see that rebuttal in the interests of fairness.

I'm approving this as a reply to another post, but any further discussion on the firemen should be taken to another thread.

Replying to this modbox in thread will be off topic  Posted By: chillzero

 

[funk de fino]

They have all the floors above the first intact floor to be impacted arriving at the same time. That is not what happened.

Not true, they have the load. Not the actual floors square on.

 

[Christopher7]

Edited by chillzero: 

Moderated thread

The fact that you don't understand something does make it "double talk".

I specifically did not get into "how to release" it.

Until you do you haven't shown that it is possible to use this stored energy to eject a beam laterally.

This is the type of specious argument that you've been bringing up constantly. The SPECIFIC question that ole bill was jabbering about (it turns out incorrectly) was that there was "only enough energy storage capability in a steel box column, without kinking, to be thrown a couple dozen feet. But never 200, 400 or 500 feet."

I am not an engineer or mathematician but excuse me if I don't accept your analysis without some verifiable conformation.

As I calculated, if one were to intentionally devise anchoring system that would allow you to pull back on the beam & arc it like a bow, and then cut the string, then it WOULD fly out at about 75 mph (remember that 54 mph was for a cantilever beam. You can get twice as much energy stored in a uniformly arced beam, for 41% more speed. Remember, energy goes as speed squared.

What kind of lateral force do you get when neither end is attached?

As a direct result of this horizontal speed, if you fling this from an altitude of 1000', it'll travel about 800' horizontally.

Hold on there cowboy, before you discuss how far it will travel, establish the conditions that could bend a 3 beam section to maximum energy storage, rip it loose and still use that stored energy to propel it laterally. Seems to me you can't get all these conditions to occur.

 

[tfk]

bill,

Beachnut shifted the burden the burden of proof unto himself by saying that a scientifically carried out analysis was 'a fraud' without giving adequate reason.or examples of same.

You have a consistent pattern of concluding that the "burden of proof" is on ANYone except yourself. You & I both realize that this is because you are incapable of performing the most rudimentary of calculations, such as calculating geometric volumes or converting from English to SI units.

Therefore if he cannot motivate his claim with evidence it will point to the analysis being correct and by extension that 9/11 was an inside job. With me so far.....?

No, bill, not "with you" in the slightest. You have a consistent, and ludicrous, delusion that the default conclusion is "an inside job".

<snip>

As you can see in the video the sounds of explosions were beautifully recorded

In order to take down the towers as the CT movement claimed (the supports had to be removed), approximately 12,000 "cut columns" would have been required per tower.

Please provide your evidence that anything CLOSE to this number of explosions were heard in ANY video, immediately before & during the collapse of the towers.

I am NOT interested in statements. I am interested in hearing this number of explosions for myself in any of the enormous number of videos that were produced that day.

I am also interested in HEARING (rather than your usual evading) an explanation of how those severed columns were magically absent in the debris pile at Ground Zero.

tk

 

[bill smith]

chris,

Edited by chillzero: 

Moderated thread

The fact that you don't understand something does make it "double talk".

To anyone who is knowledgeable about physics, my statement in clear. And is make more clear by the following discussion about rotational energy. The total energy represented by a moving, rotating object is the combination of the linear kinetic energy (1/2 m v²) plus the rotational kinetic energy (1/2 Ixx ω²), where Ixx = the rotational moment of inertia about the x axis, and ω is the rotational speed.

It turns out that 56 mph is the linear velocity that one would get if you turned ALL of the internal energy into LINEAR velocity. That means the speed of the CG (center of gravity) of the beam. There is a relationship between the linear velocity and the rotational velocity of anything that is thrown as proposed. The tip moves twice as fast as the CG. It turns out that when you input that constraint for the dimensions of a thin walled tube, the rotational energy is trivial compared to the linear energy. (I was surprised by this, so I double checked.)

Allowing for the rotational energy is PRECISELY why I dropped the linear speed from 56 mph to 54 mph.

I specifically did not get into "how to release" it. This is the type of specious argument that you've been bringing up constantly. The SPECIFIC question that ole bill was jabbering about (it turns out incorrectly) was that there was "only enough energy storage capability in a steel box column, without kinking, to be thrown a couple dozen feet. But never 200, 400 or 500 feet."

It turns out that he was dead wrong. (How unsurprising.) As I calculated, if one were to intentionally devise anchoring system that would allow you to pull back on the beam & arc it like a bow, and then cut the string, then it WOULD fly out at about 75 mph (remember that 54 mph was for a cantilever beam. You can get twice as much energy stored in a uniformly arced beam, for 41% more speed. Remember, energy goes as speed squared.

As a direct result of this horizontal speed, if you fling this from an altitude of 1000', it'll travel about 800' horizontally. I don't know why this is surprising to you. Go get a 1" x 1" x 36" long steel box channel from Home Depot. Put it on a short stumpy post. Make sure that it can rotate onto and off of the post easily from one direction only. Put it on the post, pull back really hard on the top until it bends into a serious arc, and then let it go. See how far you can throw it. Now scale everything up enormously, and stick the beam 1000' in the air. There is NOTHING surprising about this phenomenon.

BTW, I have not seen your response to my illustration of this effect using a credit card. Are the principles of mechanically converting slow motion to fast motion & of mechanically converting vertical motion to horizontal motion getting thru to you? Or are you really not interested in the truth?

tom

Hello Hello,
So let's take a 15 foot long slender cardboard box column and now lets bend it into a full arc for maximum stored energy. Oh look....it kinked almost immediately. See this cardboard box in your mind' eye and onserve two people compressing it into an arc. Will the front side go into tension ? will the back side go into comprsson ? And who wants to say what happens to the side plates that are both in tension and in compression ?

In the case of a canitiever. of course the fact that the columns is fixed at the bottom will cause t to head downwards when you release it from the pull-back and it's forward motion is arrested by the botom fixing.. So it pushed into hinging downward and snaps off.

No flying pigs available for this one.

 

[A W Smith]

you see, on numerous times I have had the opportunity to visit the steel milss where the wtc steel originated from, where it was poured, where it was rolled, what the chemistry and metallurgical make-up of what the steel was, for the center support beams and other steel used...so you may want to call this inside information, an insider advantage if you will, but, furnaces-blast furnaces-electric arc or gas

Ok. name the mills you have visited that supplied WTC steel. And no, Kobe in Cleveland was not one of them.

Also What grade or grades of steel were used at the impact zones of the towers? You should know this.

 

[Disbelief]

what was the temperature strength of the wtc steel when it was casted? how many times have you been to Kobe steel in Cleveland?

Can you tell me where Kobe Steel is in Cleveland?

 

[tfk]

is this like one of those self stroage bins?

I think that you need to look at the big field here, not a shed like structure, we're talking massive steel beams and girders of immenses size and strength,

... says the person who keeps bringing up his wood stove.

steel specifically designed and tested to withstand forces 10 times greater in heat and energy that the steel faced in the wtc.

"... forces 10 times greater in heat and energy ..."

Force, measured in pounds.
Energy, measured in foot-pounds, BTUs or Joules
Heat, measured in flow of foot-pounds, BTUs or Joules

To explain how stupid this statement is, equate it to "... distances that are 10 times heavier and hotter ..."

Bob the Analyst: "setting new standards in scientific ignorance"

tk

 

[Christopher7]

Can that same hypothetical child just as readily "see" that any explosion (or series of explosions) capable of bringing down (for instance) WTC 7 would leave incontrovertible evidence of their occurrence in the seismographic record for that place and time, as well?

A child can see WTC 7 fall straight down at near free fall [actual free fall for the first 105 feet]. Buildings don't do that unless they are CD's. It is not necessary to have any other information. There is no other explanation for a building falling the way WTC 7 did.

 

[Christopher7]

Not true, they have the load. Not the actual floors square on.

funk,

We have been over this. Almost all of the load above the impact zone was on the core and exterior columns.

It would be physically impossible to put this load on the floor truss connections.

 

[DGM]

Can you tell me where Kobe Steel is in Cleveland?

I'd like to see know this too. Kobe is a Japanese company with an office in NY. I don't believe they have a plant in the US. They defiantly had nothing to do with the WTC.

 

[tfk]

What part of "more or less horizontal" don't you understand?

You are ignoring the point which is:

The object was traveling away from the tower at 72 mph.

The 'flicker factor' is fatally flawed. tfk's analysis does not provide a way for the potential stored energy to be applied to hurling a frame section away from the building.

chris,

It's not "fatally flawed" because it was not intended to be provided as a way that some particular beam was thrown that far. It demonstrate a way that some beam could have been thrown that far.

I know that may seem like splitting a hair, but it is not. You guys are claiming that it was impossible for the beams to get thrown that far. This shows that it is not impossible. There is an enormous difference between "impossible" and "improbable".

I assume that your problem is "how do you disconnect the beam from the restraints". Again, there are several possible ways. The most likely one is that the whole assembly is completely fractured free, and then parts drop on either end, bending it over a central support. As the parts fall off, it is thrown. This exactly mimics the thrown "credit card between the fingers" trick.

Again, you are putting forth a hypothesis that it was impossible for these beams to have been thrown this far thru a gravity collapse. What my analysis does is to "falsifies your hypothesis".

That's all it was intended to do. That's all it has to do.

tk

 

[Christopher7]

Please provide your evidence that anything CLOSE to this number of explosions were heard in ANY video, immediately before & during the collapse of the towers.

If the government would release the 7,000 video clips they are keeping from the public we could better assess all aspects of the collapses.

I am NOT interested in statements. I am interested in hearing this number of explosions for myself in any of the enormous number of videos that were produced that day.

You glibly discount all the witness statements about explosions and molten metal. That is just denial.

I am also interested in HEARING (rather than your usual evading) an explanation of how those severed columns were magically absent in the debris pile at Ground Zero.

tk

The vital evidence was removed and destroyed as fast as possible.

NFPA (National Fire Protection Association) 921, which is the National Standard for Fire and Explosion Investigations, very clearly indicates in numerous sections that the possibility of explosives should have been thoroughly investigated. Specifically in NFPA 921 18.3.2 High Order Damage - “High-order damage is characterized by shattering of the structure, producing small, pulverized debris. Walls, roofs, and structural members are splintered or shattered, with the building completely demolished. Debris is thrown great distances, possibly hundreds of feet. High-order damage is the result of rapid rates of pressure rise.” World Trade Center’s 1, 2, and 7 all clearly met this definition; therefore they should have been thoroughly investigated and analyzed for explosives. Specifically, the use of “exotic accelerants” should have been investigated. In NFPA 921 19.2.4 -”Exotic Accelerants,” three indicators were clearly met that should have led to a thorough investigation in to the possible use of “exotic accelerants,” specifically as stated in the guideline, “Thermite mixtures.”

NFPA 9.3.6 covers Spoliation of Evidence. Specifically, 9.3.6.7 reads as follows: “Once evidence has been removed from the scene, it should be maintained and not be destroyed or altered until others who have a reasonable interest in the matter have been notified. Any destructive testing or destructive examination of the evidence that may be necessary should occur only after all reasonably known parties have been notified in advance and given the opportunity to participate in or observe the testing.”

 

[tfk]

you see, on numerous times I have had the opportunity to visit the steel milss where the wtc steel originated from, where it was poured, where it was rolled, what the chemistry and metallurgical make-up of what the steel was, for the center support beams and other steel used...so you may want to call this inside information, an insider advantage if you will, but, furnaces-blast furnaces-electric arc or gas--

run well over 4000 degrees F. I realized that you have never been in a steel mill in your life or will ever have the chance to visit a steel mill, what it takes to produce steel..so untill you get the opportunity to go to a steel mill, you can just take my advice on this

Where were these mills, bob?

 

[tfk]

bill

So let's take a 15 foot long slender cardboard box column and now lets bend it into a full arc for maximum stored energy. Oh look....it kinked almost immediately.

And Even after having it explained to you, you don't seem to comprehend the difference between cardboard and steel. They make springs out of steel. They don't make 'em out of cardboard.

<snip> And who wants to say what happens to the side plates that are both in tension and in compression ?

"Who wants to say what happens..." Well, so much for your understanding of mechanics 101.

The points that I am making are two fold.

1. You know almost nothing about mechanics. You know almost nothing about materials, as your cardboard/steel confusion shows. And yet, you continue to make pronouncements about mechanics and think that they carry some significance.
2. Your gut feelings about how much energy can be stored in a member is meaningless. You have to figure it out with calculations.


tk

 

[BenBurch]

OK, back to locomotive boilers.

If none of you truthers think that a hydrocarbon fire can weaken steel to the point of failure, why do oil burning steam locomotives explode when you allow the crown sheet to become dry? Why do you guys think that is, eh? Or are you going to go on record saying that a steam locomotive boiler is perfectly safe with a dry crown sheet if it is oil-fired?

And if you accept the fact that it will absolutely explode (unless the fusible plugs blow out, but nobody ever TRUSTS that safety mechanism) then how is that case different from the case that doomed those building and their trapped occupants?

Illuminate me, please?

But when you do, bear in mind that I know more about how steel works under such conditions than any of you appear to...

 

[Architect]

Now, B, I don't like to cut and paste previous posts en-masse but you've completely ignored the fact that you've been challenged on your assertion that steel is fireproof. Such response as we have seems to be limited to a claim that the steel for the towers was "cast" specifically to withstand temperatures up to 4000F and you've since hand-waved away everything else.

On that basis, and with the sufference of the Mods if they are so minded, I'm afraid I'm going to draw your oft-wandering attention back to this one:

Oh Bob, I'm afraid it's not your day. I hope you weren't supporting the Italians at the rugby. Anyway, let's look at fire performance of steel. I'd like you to tell me if there are any errors that I make. And be specific.

Testing Criteria

Firstly, the lay reader may be interested to learn that there are, of course, formal standards to test the fire performance of structural steelwork.

The general procedures used for determining the fire resistance of load-bearing elements of structure are specified in BS476 series. In assessing the performance of fire protection materials the relevant parts are:

Part 20 Method of determination of the fire resistance of elements of construction (general principles)

Part 21 Method of determination of the fire resistance of load-bearing elements of construction

Whilst BS 476 Part 20 is concerned with general principles and covers requirements which are common to the other parts of BS 476, the BS 476 Part 21 fire resistance testing covers load-bearing elements of construction, such as steel beams, columns or walls, whilst BS 476 Part 22 fire resistance tests are intended for non load-bearing elements of construction.

European fire testing standards have also been published. In assessing the performance of fire protection materials the relevant part is presently ENV 13381-4 “Test methods for determining the contribution to the fire resistance of structural members Part 4: Applied protection to steel members”. This standard makes reference to the EN 1363 Series of standards which contain general information about conducting fire resistance tests. However, as all the procedures for assessing fire protection are currently specified in ENV13381-4, it is this standard which is generally referred to.

Performance of Steel in Fires

Hot finished carbon steel begins to lose strength at temperatures above 300°C and reduces in strength at steady rate up to 800°C. The small residual strength then reduces more gradually until the melting temperature at around 1500°C. This behaviour is similar for hot rolled reinforcing steels. For cold worked steels including reinforcement, there is a more rapid decrease of strength after 300°C (Lawson & Newman 1990). In addition to the reduction of material strength and stiffness, steel displays a significant creep phenomena at temperatures over 450°C. The phenomena of creep results in an increase of deformation (strain) with time, even if the temperature and applied stress remain unchanged (Twilt 1988).

High temperature creep is dependent on the stress level and heating rate. The occurrence of creep indicates that the stress and the temperature history have to be taken into account in estimating the strength and deformation behaviour of steel structures in fire. Including creep explicitly within analytical models, is complex. For simple design methods, it is widely accepted that the effect of creep is implicitly considered in the stress-strain-temperature relationships.

For those who require further information or, as the case may be, persuasion regarding the actual performance of steelwork under such conditions we are fortunate that a predictably large numbers of leading bodies have looked at the issue in depth.

http://www.shef.ac.uk/fire-research/..._meetings.html (http://www.shef.ac.uk/fire-research/..._meetings.html)

http://www.corusconstruction.com/page_1416.htm (http://www.corusconstruction.com/page_1416.htm)

http://www.bfrl.nist.gov/866/CIB_W14/workprog.htm (http://www.bfrl.nist.gov/866/CIB_W14/workprog.htm)

http://www.civil.canterbury.ac.nz/fi...rts/KLewis.pdf (http://www.civil.canterbury.ac.nz/fire/pdfreports/KLewis.pdf)

Note in particular the strength/temperature/yield grading charts in the final link, which have obvious implications for the structure of any steel framed building exposed to fire conditions.

Practical Implications - Design Codes and Building Regulations

The fire design codes BS 5950-8, Eurocode 3 Part 1-2 and Eurocode 4 Part 1-2 provide the framework for designers to calculate the temperature at which a given steel member will fail in a fire situation. These design methods incorporate more realistic estimates of the applied load during a fire and include the effects of non-uniform heating through and along the member. The design methods are based on either fire
resistance, which is a measure of an element to withstand given criteria in a standard furnace test, or natural fires where the size of the fire compartment, available combustible material, characteristics of the compartment boundaries andair supply are considered.

The requirements and calculations so arising are necessarily complex.

As the reader might anticipate, because structural steelwork is at risk of failure in a fire building regulations also introduce fireproofing requirements.

The Scottish Regs, section D, are a bit detailed - http://www.scotland.gov.uk/build_regs/sect-d.pdf (http://www.scotland.gov.uk/build_regs/sect-d.pdf) - but you'll notice do flag up the need for fire protection in structural components and steelwork.

In England, Part B of the Regs flags up a similar position - its not available on-line free but Corus (who do know a thing about steel) have a useful and relatively non-technical summary at http://www.corusconstruction.com/leg...s_section1.pdf (http://www.corusconstruction.com/legacy/fire/images/fireres_section1.pdf) . Some of you will note on page 5 the admission that most unportected steel sections only have fire integrity for about 15 minutes.

The Canadian Regs aren't available on-line free either, but their national buildings institute flags up across all their documents the risk posed by fire and the need for protection - see, by way of example, http://irc.nrc-cnrc.gc.ca/cbd/cbd071e.html (http://irc.nrc-cnrc.gc.ca/cbd/cbd071e.html) .

The New Zealand and Australian steel codes, (SNZ, 1997 and SAA 1990) are very similar to each other. The NZ regs section C4 requires....wait for it......structural protection of steel in fire ( http://www.building.govt.nz (http://www.building.govt.nz/))

Summary

It is recognised through empirical analysis across a recognised series of standards that structural steelwork weakens significantly under normal fire conditions, and as a consequence codes require additional protection through (for example) the incorporation of passive fire protection systems.

There is no evidence that such tests are wrong, or that fire protection can be safely omitted due to (for example) the efects of heat conduction throughout the affected members.

 

[bill smith]

bill



And Even after having it explained to you, you don't seem to comprehend the difference between cardboard and steel. They make springs out of steel. They don't make 'em out of cardboard.



"Who wants to say what happens..." Well, so much for your understanding of mechanics 101.

The points that I am making are two fold.

1. You know almost nothing about mechanics. You know almost nothing about materials, as your cardboard/steel confusion shows. And yet, you continue to make pronouncements about mechanics and think that they carry some significance.
2. Your gut feelings about how much energy can be stored in a member is meaningless. You have to figure it out with calculations.







tk

Hello Helloo

As you helpfully pointed out yourself, structural steel does not lend itself well to'springing' and of course the structure of a hollow box column exacerbates that deficiency to the point of impossibility in terms of a column springing out several hundred feet from the building.

For the rest your comments are purely subjective and a waste of space.

 

[Christopher7]

chris,

It's not "fatally flawed" because it was not intended to be provided as a way that some particular beam was thrown that far. It demonstrate a way that some beam could have been thrown that far.

It does NOT show that.

I assume that your problem is "how do you disconnect the beam from the restraints". Again, there are several possible ways. The most likely one is that the whole assembly is completely fractured free, and then parts drop on either end, bending it over a central support. As the parts fall off, it is thrown. This exactly mimics the thrown "credit card between the fingers" trick.

That's quite a card trick. Problem is, the top section is coming down at 5 or more floors per second. Any section that got torn loose was being bombarded by so much so fast that it would not have time to do the card trick you propose.

Again, you are putting forth a hypothesis that it was impossible for these beams to have been thrown this far thru a gravity collapse. What my analysis does is to "falsifies your hypothesis".

Although very creative, your theory is not possible.