WTC7 and the girder walk-off between column 79 and 44

[tfk]

Tony,

Tom, you are talking a lot of smack here but not much substance.

The girder between columns 76 and 79 would buckle by the time it pushed column 79 just 1.6 inches to the east if it were unrestrained by the 12 beams framing into it with shear studs.

You go from one FALSE assumption (building in "as built, pristine condition") to another FALSE assumption ("all 12 beams removed").

Typical.

Why don't you try doing it with the RIGHT number of beams in place & removed.

Then publish your methods, not just unreliable results.

I did the calculation and that is at room temperature. If it is hot it buckles earlier. There is no way you can get 4.5 inches of eastward movement the way you envision.

I've seen your calculations, Tony.

They are about as reliable as your assurance that the concrete could not possibly fail before the studs shear.

That was wrong, too.

There is no way you can get 4.5 inches of eastward movement the way you envision.

"No way?"

Inept assertion for a building that is in the process of massively failing. Based on the idiocy of quoting the "as built" dimensions & constraints of components.

The reality is that, both the original NIST scenario and your alternative, for the girder failure at column 79, are impossible.

Write up & publish your nonsense.

You can just chalk it up to not looking hard enough before saying it. Sort of like what you did with your claim that the concrete would fail before the shear studs on girder G1 before the beams to the east of girder G1 buckled.

Nice lie, Tony.

I never said anything of the sort (in the bold).

I said that the whole question of shear studs failing on that girder was meaningless, because there were no shear studs on that girder.

I said that, if there had been shear studs on that girder, then the failure mode for the shear stud & concrete composite would have been the concrete fracturing.

And my last post proves it. As does NIST's calculations.

It's pointless arguing with you, Tony.
Like everyone else who knows what they are talking about, I've reached the end of my patience with your idiocy.
I'm not likely to waste any more time on you.

You are simply incompetent at big-picture, mature, experienced mechanical engineering judgment.

 

[leftysergeant]

I cannot make head or tails of the maths on this, but I have to wonder whether either of you are arguing for a constant movement and resistance on all axes.

This could, quite simply, not have been the case, given that the fires were moving from place to place, changing the dimensions of the steel members in all directions.Once a steel member has expanded, it can retreat if heat is removed, possibly to surge again when it is heated again. As windows break, as the fire moves from one floor to another or migrates through a fissure in a cracked floor slab, heat distribution becomes chaotic.

It would be logical to assume that this increases the possibility of a cascading failure.

It has always been my impression that buildings are more likely to remain standing when loads are distributed in a predictable manner. That, I thought, was why we pay engineers such enormous sums of money to design buildings. They are describing how the weight of a building is to be distributed.

Now we have a building that no longer distributes the weight and stresses as designed because a few members have been chopped up by multi-ton hatchets falling at free-fall acceleration. That alone is going to change the equations that predict how the surviving members hold hands to keep from falling. Add to that the random pushing and pulling that must occur in a major fire and we have a condition that is probably not going to be predictable based on normal engineering formulae.

Real answers might have to wait until somebody turns chaos theory into a workable engineering tool.

 

[Christopher7]

I've reached the end of my patience with your idiocy.
I'm not likely to waste any more time on you.

You are simply incompetent at big-picture, mature, experienced mechanical engineering judgment.

So much for Rule #12 being enforced.

The NIST hypothesis of the beams expanding and pushing the girder off its seat is impossible.

Your unsupported speculation about eastward movement of column 79 was not mentioned by NIST because it did not happen. If it had, they would have included it.

You ignore the fact that column 79 was surrounded by slabs that would expand with the beams and girders at ~85% of the beams and girders. At 5:00 p.m., the slab on the east side of column 79 was expanding and the west side was not. The 5:30 and 6:00 p.m. are irrelevant because the building had already imploded. NIST including them is very strange and very unprofessional. However, we can deduce that at 5:20 p.m. the slab to the east of column 79 was pushing west more that the the slab on the west was pushing east so your theory is not valid.
http://www.internationalskeptics.com/forums/picture.php?albumid=638&pictureid=5836

 

[Tony Szamboti]

I cannot make head or tails of the maths on this, but I have to wonder whether either of you are arguing for a constant movement and resistance on all axes.

This could, quite simply, not have been the case, given that the fires were moving from place to place, changing the dimensions of the steel members in all directions.Once a steel member has expanded, it can retreat if heat is removed, possibly to surge again when it is heated again. As windows break, as the fire moves from one floor to another or migrates through a fissure in a cracked floor slab, heat distribution becomes chaotic.

It would be logical to assume that this increases the possibility of a cascading failure.

It has always been my impression that buildings are more likely to remain standing when loads are distributed in a predictable manner. That, I thought, was why we pay engineers such enormous sums of money to design buildings. They are describing how the weight of a building is to be distributed.

Now we have a building that no longer distributes the weight and stresses as designed because a few members have been chopped up by multi-ton hatchets falling at free-fall acceleration. That alone is going to change the equations that predict how the surviving members hold hands to keep from falling. Add to that the random pushing and pulling that must occur in a major fire and we have a condition that is probably not going to be predictable based on normal engineering formulae.

Real answers might have to wait until somebody turns chaos theory into a workable engineering tool.

The reason there has never been a steel framed building that collapsed due to fire is because random interactions cannot defeat the heavy redunandcy in these buildings and things cannot get to the point of complete collapse.

Claiming that WTC 7 came down due to fire is an extraordinary claim and that requires extraordinary proof. NIST and those who support their explanation have failed to provide that proof, and in fact have been shown to claim completely impossible individual situations in their explanations.

The hand waving of complete chaos is not valid here and the thoroughly impossible situations claimed by the NIST, some of which have been discussed in this thread, need to be corrected.

 

[leftysergeant]

The reason there has never been a steel framed building that collapsed due to fire is because random interactions cannot defeat the heavy redunandcy in these buildings and things cannot get to the point of complete collapse.

Hogwash. Titanic.

 

[Tony Szamboti]

Shear studs

NIST provides a detailed description for the failure of these studs, and focuses completely on the concrete failure. It's results are:

The loads for a weak fracture of the concrete is about 17 kip.
For a strong way failure of the concrete, it's about 21.5 kip.

On aggregate, NIST used the average strength of 19.4 kip.

[See fig 11-8, NCSTAR 1-9 vol 2, pg 468, pdf pg. 130]
___


NIST NCSTAR 1-9 vol , pg 15, pdf 59

It doesn't say what alloy the studs are made from, but it is safe to assume that it would be made from a low carbon, mild steel alloy. This gives excellent weldability and toughness, which is why it is used for structural steel. It is also one of the weakest steels available, so any other alloy will have a higher shear load.

Using standard rule of thumb for steel: the ultimate shear strength (USS) is approximately 0.75 * ultimate tensile strength (UTS).

According to my trusty old Marks ME handbook (1978), UTS for mild steel ranges from 58 to 80 KSI. I'll use the average 69 KSI, which should be conservative for 3/4" studs.

This gives a USS of 52 ksi, and a shear load of about P = 52 ksi (π d²/4) = 23 kips.

This is higher than the value for both the weak & strong concrete failure modes.

I note that NIST later says the following:



NCSTAR 1-9 vol.1, pg 347, pdf pg. 391.

Note that this is the correct temp to use, because analysis shows that these shear studs fail at around 100 - 150°C.

This again puts the stud shear load (20 KSI) slightly higher than the average concrete failure load (19.4 KSI).

Again, Tony's assertion that "there is no chance of concrete failure" is shown to be simply wrong.


tk

PS. How adamantly, determinedly dumb are you, Tony?

There are NO shear studs on the girder between Col 79 & Col 44.

NIST was explicit about this.

But you think that they're lying, don't you?

Tom, what mathematical convention would allow you to get a 19.4 kip load on the concrete interface with the 30 shear studs when the five beams would buckle in even the most conservative estimate with a combined load of less than 60,000 lbs.?

60,000 lbs. of force from the five beams / 30 shear studs = 2 kips per shear stud interface with the concrete

Neither the concrete or the shear studs would fail on the girder between columns 44 and 79, before the five beams framing into the girder from the east buckled. The beams simply couldn't generate enough force.

I certainly don't think everyone at the NIST is lying about the shear studs on that girder, as most had nothing to do with that part of the report or the overall report, and only contributed to specific sections. The claim that John Salvarinas' paper doesn't show the as built condition is really weak.

However, the shear studs on the girder issue is moot because it can be emphatically shown in other ways that there was no way to produce the amount of movement needed to push that girder off its seats. This is especially true in light of the recent revelation of web to flange stiffeners at the column 79 end of the girder. I guess you think that was just an oversight to not include those stiffeners in the models.

The reality, is that the girder between columns 44 and 79 could not have fallen off its seat the way NIST or anyone here has explained. It is an impossibility and its use in the explanation for the collapse needs to be removed.

 

[twinstead]

The reason there has never been a steel framed building that collapsed due to fire is because random interactions cannot defeat the heavy redunandcy in these buildings and things cannot get to the point of complete collapse.

Isn't "there has never been a steel framed building that collapsed due to fire" both false, because it has happened, and irrelevant to this discussion because you forgot to add "and massive damage from parts of another huge skyscraper falling on it"?

 

[Christopher7]

I cannot make head or tails of the maths on this, but I have to wonder whether either of you are arguing for a constant movement and resistance on all axes.

NIST simply argued that the beams expanded and pushed the girder off its seat so refuting their theory using the method they used is valid. The principle is easy enough for you and I to understand. The beams will expand when heated but will also sag. The maximum lengthening of a 53' 4" beam is 4.75" before the loss to sagging is greater than the elongation due to thermal expansion so the NIST theory of the beams pushing the girder 5.5" is not valid. Other theories as to how the girder may have come off the seat are meaningless because we are refuting the NIST theory, not the anonymous JREFer theory.

ETA: http://img404.imageshack.us/img404/739/expansionvsag2.jpg

This could, quite simply, not have been the case, given that the fires were moving from place to place, changing the dimensions of the steel members in all directions.Once a steel member has expanded, it can retreat if heat is removed, possibly to surge again when it is heated again. As windows break, as the fire moves from one floor to another or migrates through a fissure in a cracked floor slab, heat distribution becomes chaotic.

The fires on floors 12 and 13 burned in a counter clockwise direction with the fire on floor 13 about 1/2 hour behind the fire on floor 12. Once an area has burned for 20 to 30 minutes, the fuel is exhausted and the fire moves on.

The fire on floor 12 had burned out in the NE corner by about 3:45 p.m. and the fire on floor 13 by about 4:15 p.m. so none of this took place at 5:20 p.m. as NIST requires for their theory. The non-walk-off is just another fatal flaw in the NIST theory.

 

[Tony Szamboti]

Hogwash. Titanic.

The Titanic is not comparable in the least. Historically there were ships sunk by collisions with icebergs prior to that.

What you are saying would be comparable to buildings having collapsed due to fire in the past and a claim that a new building couldn't and then it does. It isn't the same at all.

There are very sound reasons which show why superstructure type grids of steel don't collapse down through themselves due to fire.

 

[Animal]

The reason there has never been a steel framed building that collapsed due to fire is because random interactions cannot defeat the heavy redunandcy in these buildings and things cannot get to the point of complete collapse.

Except for the fact that the list of steel framed buildings that have collapsed due to fire is quite long. (Cue the goal post moving in 5.....4.......3.....2.....1.)

Claiming that WTC 7 came down due to fire is an extraordinary claim and that requires extraordinary proof.

Given the above, the claim is quite ordinary

NIST and those who support their explanation have failed to provide that proof, and in fact have been shown to claim completely impossible individual situations in their explanations.

The hand waving of complete chaos is not valid here and the thoroughly impossible situations claimed by the NIST, some of which have been discussed in this thread, need to be corrected.

The "hand waving of complete chaos" is very valid in response to troofer claims that the simulation does not EXACTLY match the collapse. No one except troofers expect such an exact match.

Speaking of extraordinary proof for extraordinary events........The WTC 7 far exceeds the largest building every demolished with explosives, and that buildiing took months of prep work and pre demolition. TO date, the amount of proof provide by troofers to prove their claim of CD is ZILCH. Isn't it about time that troofers provide the extraordinary proof for their extraordinary events like they demand?

 

[cjnewson88]

Claiming that WTC 7 came down due to fire is an extraordinary claim and that requires extraordinary proof.

Claiming that WTC 7 came down in a controlled demolition is an extraordinary claim and that requires extraordinary proof.

As it stands, we know fire was in WTC 7.
As it also stands, no one has proven the existence of explosives in building 7.

So unless someone cares to provide evidence that there were bombs in building 7, then I'm afraid that you're just gonna have to accept that building 7 fell due to fires Tony. Deal with it.

 

[erwinl]

The Titanic is not comparable in the least. Historically there were ships sunk by collisions with icebergs prior to that.

What you are saying would be comparable to buildings having collapsed due to fire in the past and a claim that a new building couldn't and then it does. It isn't the same at all.

There are very sound reasons which show why superstructure type grids of steel don't collapse down through themselves due to fire.

Doesn't that mean that the first ship to sink from a collision with an iceberg couldn't have sunk from it?
At least that is how I read this logic.

 

[Christopher7]

Claiming that WTC 7 came down in a controlled demolition is an extraordinary claim and that requires extraordinary proof.

As it stands, we know fire was in WTC 7.

We also know that the fire on floor 12 had burned out over an hour before the collapse.

As it also stands, no one has proven the existence of explosives in building 7.

That is a subject for another thread.

So unless someone cares to provide evidence that there were bombs in building 7, then I'm afraid that you're just gonna have to accept that building 7 fell due to fires

No,

This thread is about walk-off and we have shown that that is impossible.

 

[Christopher7]

Except for the fact that the list of steel framed buildings that have collapsed due to fire is quite long. (Cue the goal post moving in 5.....4.......3.....2.....1.)

He forgot to use the qualifiers "high rise" and "completely" to satisfy the JREF semantics nitpickers.

The "hand waving of complete chaos" is very valid in response to troofer claims that the simulation does not EXACTLY match the collapse. No one except troofers expect such an exact match.

The NIST theory does not work for a number of reasons and their model doesn't look anything like the actual collapse.

Speaking of extraordinary proof for extraordinary events........The WTC 7 far exceeds the largest building every demolished with explosives, and that buildiing took months of prep work and pre demolition. TO date, the amount of proof provide by troofers to prove their claim of CD is ZILCH. Isn't it about time that troofers provide the extraordinary proof for their extraordinary events like they demand?

The evidence has been given but y'all just go into denial mode and claim that there is no evidence.

 

[MarkLindeman]

This thread is about walk-off and we have shown that that is impossible.

Nonsense. You've barely even argued that, as much as you've asserted it. You've argued that the girder can't have been pushed off in one particular way.

It's basically a Zod-of-the-gaps argument, a veiled appeal to malevolent design (or maybe I should say intelligent anti-design). Tony's bizarre assertion that "random interactions cannot defeat the heavy redun[dan]cy in these buildings" underscores the point. You can wish that we wouldn't notice, but we do.

 

[twinstead]

The evidence has been given but y'all just go into denial mode and claim that there is no evidence.

If your "evidence" was as compelling as you think it is, it wouldn't exist solely on relatively obscure internet sites. When I turn off my computer, your "evidence" disappears. Nobody who actually can DO something about it and nobody whose opinion actually MATTERS in the real world is saying much about your "evidence" at all. After a freakin' decade.

As a layman, this speaks volumes.

 

[Christopher7]

Nonsense. You've barely even argued that, as much as you've asserted it. You've argued that the girder can't have been pushed off in one particular way.

Correct - the way NIST theorizes that it failed. i.e. The NIST theory does not work.

 

[tsig]

The Titanic is not comparable in the least. Historically there were ships sunk by collisions with icebergs prior to that.

What you are saying would be comparable to buildings having collapsed due to fire in the past and a claim that a new building couldn't and then it does. It isn't the same at all.

There are very sound reasons which show why superstructure type grids of steel don't collapse down through themselves due to fire.

If a steel building can't collapse due to fire why do they put fire proofing insulation on the steel?

 

[GlennB]

If a steel building can't collapse due to fire why do they put fire proofing insulation on the steel?

So that it can last long enough for fire-fighting efforts to save the building. Wait .... I'm missing the point here, aren't I ?

 

[twinstead]

Correct - the way NIST theorizes that it failed. i.e. The NIST theory does not work.

This is what confuses me. Nobody who matters from anywhere in the world is saying that the "NIST theory does not work". All I have is a few people on some internet forums declaring NIST invalid.

To me, this is suspicious. I have absolutely NO reason to believe you.