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

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tfk said:
Animal,

Creep is not just temp & time dependent, but also extremely stress level dependent.
___

From Journal of Engineering Mechanics ASCE , Vol. 134 (2008)
What Did and Did not Cause Collapse of WTC Twin Towers in New York
Zdenek P. Bazant, Jia-Liang Le, Frank R. Greening and David B. Benson

Page 2:



This effect (accelerated creep due to high stress levels) was crucial in the towers because of the stress redistribution due to physical damage.

Less important in WTC7, because the stress levels didn't increase all that much over their design levels.


tom
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I know it is far more complex than the wiki explanation. I was just trying to give a basic explanatio to the non technical people here.
 
Christopher7 said:
No, I'm assuming that everything is about the same temp, as would be the case.

Thermal expansion of the girder would put more of it over the support plate.

But all that ignores the point:

Thermal expansion cannot result in 5.5" of axial elongation because sag would shorten the beams more than they expanded before then.

At 600oC the beams would expand 4.68" and lose 0.27" to sagging for a net elongation of 4.41"

At700oC the beams would expand 5.63" and lose 3.495" to sagging for a net elongation of 2.135".

The NIST theory of the beams pushing the girder off its seat is not possible.
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The response to this has been childish remarks and questions to divert the subject but no one has even attempted to refute the math that clearly shows that thermal expansion could not push the girder off its seat as NIST proposes. Alternate theories are irrelevant. The point is:

The NIST theory is in not possible and therefore they did not explain the collapse.

Someone said something about a single point. Although there are several points that show the NIST theory does not work, one is enough.
 
Christopher7 said:
The response to this has been childish remarks and questions to divert the subject but no one has even attempted to refute the math that clearly shows that thermal expansion could not push the girder off its seat as NIST proposes.
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No it doesn't.
Christopher7 said:
Alternate theories are irrelevant.
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What alternate theories? Why are they irrelevant? Do you mean CD, which still hasn't been proven, mathematically, computationally, or with any evidence?
Christopher7 said:
The point is:

The NIST theory is in not possible and therefore they did not explain the collapse.
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Yes it is and yes it does. A building can collapse from a fire.

Christopher7 said:
Someone said something about a single point. Although there are several points that show the NIST theory does not work, one is enough.
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A chorus of voices said that. And a single point cannot show the theory doesn't work, it may just lead to another point of failure that proves their theory. Do you know what a system is?
 
Hmmm. The NIST theory doesn't explain the collapse to Christopher7's satisfaction. What significance exactly is THAT supposed to have in the grand scheme of things?
 
ozeco41 said:
It is probably a good indication that NIST got it mostly right. ;)
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As I had stated in the past.

A box with 1000 toothpick falls off the shelf and spills all over the floor. Troofers insist on knowing why each individual toothpick landed where it did.
NIST type and normal people insist on knowing why the box fell in the first place.
 
Gamolon said:
Christopher7,

Have you actually ever presented your claims, with the calculations included, to NIST and asked them for further explanations?

It seems to me that your only objective is to come here and get into pissing contests with folks, who in all honesty, have nothing to do with NIST whatsoever. The only ones who can really address these issues of yours is NIST.

You have no desire to get your questions or claims answered. If you did, you'd be asking/confronting the correct people.

So back to my beginning question. Have you contacted NIST yet?
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I use this forum to "test drive" data and arguments that refute the NIST report on WTC 7. No one here can refute the fact that shortening due to sagging would exceed axial elongation at ~624oC, which equals 4.67". The NIST model was entirely built on data giving the strength of the various components that was derived from tests like the data on expansion and sagging so using this data to refute the NIST conclusion is appropriate.

sagvexpansion.jpg


The NIST theory does not work and their model does not look anything like the actual implosion.

I plan to forward these results and I will apprise you all if I get a response.
 
Christopher7 said:
I use this forum to "test drive" data and arguments that refute the NIST report on WTC 7. No one here can refute the fact that shortening due to sagging would exceed axial elongation at ~624oC, which equals 4.67". The NIST model was entirely built on data giving the strength of the various components that was derived from tests like the data on expansion and sagging so using this data to refute the NIST conclusion is appropriate.

[qimg]http://img29.imageshack.us/img29/5707/sagvexpansion.jpg[/qimg]

The NIST theory does not work and their model does not look anything like the actual implosion.

I plan to forward these results and I will apprise you all if I get a response.
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Chris.......

Your "questions" and issues have already been answered.

If you do not understand the answers then that is your problem....not ours.

This is why you should probably leave engineering to the engineers.
 
Chris7 & gerrycan,

I've asked both of you guys, at least 3 times now, to list the assumptions & equations that you used to generate these sag & shortening numbers.

You've both ignored that request completely.

gerrycan, you said that you wanted to discuss this so that you'd have "a better product" and you'd discuss this openly.

Your actions betray your statements.

What happened to your wide-eyed innocent routine?

Are you going to list your assumption & equations or not?

If not, why not?


tk
 
tfk said:
Chris7 & gerrycan,

I've asked both of you guys, at least 3 times now, to list the assumptions & equations that you used to generate these sag & shortening numbers.

You've both ignored that request completely.

gerrycan, you said that you wanted to discuss this so that you'd have "a better product" and you'd discuss this openly.

Your actions betray your statements.

What happened to your wide-eyed innocent routine?

Are you going to list your assumption & equations or not?

If not, why not?


tk
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I've been debating gerrycan over at the David Icke forums. He has made a number of incorrect statements and even contradicts himself.

1. His claim about the girder between columns 79 and 44 having shear studs is based on him looking at the Cantor drawings S-8-10, S-8-19, and S-8-20. He seems to think that since there were separate drawings for these floors (which show shear studs), there should be separate drawings for ALL floors and that these in turn would show shear studs also. He wants people to find, for example S-8-12 or S-8-13. The problem is, as I have explained to him a number of times, is that drawing S-8 is a typical floor framing drawing for floors 8 thru 20 and floors 24 thru 45. The three drawings he is looking at which show shear studs on the girder were created from drawing S-8 to reflect revisions on those three floors which add plates welded to the bottom of certain floor beams. Below is gerry's response to someone in the comments section of one of his videos which shoes he thinks there should be separate drawings for each floor:
No answer Geoff? The 'S-8 drawing is typical for over 30 floors. S-8-10 and 20 are specific to floors 10 and 20, and show studs. The right drawings to reference are S-8-12 or S-8-13. not a general drawing that covers 30 or so levels of the building like S8. I would have included s-8-12,and s-8-13 in an ideal world, maybe you could get me the link to either of those? Maybe not....Hope you get the msg, floor specific drawings have 3 figures NOT JUST 1. Happy hunting. Try again.
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2. He claims that John J Salvarinas was the design engineer for WTC7 when in fact he was the project manager. Irwin Cantor was the engineer. His seal is on the drawings

3. He claims that Salvarinas wrote his lecture/paper post construction, trying to give his drawings more credibility. The fact is, if he would have read the lecture, it was written DURING the construction of WTC7. That means changes could have occurred when this paper was written.

4. I asked him to explain why Salvarinas' drawings in his lecture/paper don't match the Cantor drawings. They both call out different numbers of shear studs and even different types of beams.

5. He first says that WTC7 went from a building to a pile of debris in 6.6 seconds. He then later states that the NW corner dropped in 6.6 seconds. I asked him to clarify his contradiction, but as of yet, he has not.
 
gerrycan said:
CSA of W24 x 55 beam=15.986 sq. inches, the modulus of elasticity of steel is 29 million lbs./sq. inch, length is 52 feet x 12 inches/foot = 624 inches

force generated by beam for a 5 inch expansion is force = [5 inches x 15.986 sq. inches x 29,000,000 lbs./sq. inch] / 624 inches = 3,714,753 lbs, and for five beams would be 18,573,768 lbs buckling force = [Pi^2 x modulus of elasticity of steel x area moment of inertia] / [(effective length factor x unsupported length of beam)^2] = [9.8696 x 29,000,000 lbs/sq. inch x 29.1 in^4]/[(2 x 624 inches)^2] = 5,347 lbs, so the max force of the 5 beams is 26,738 lbs.30 x 3/4" diameter shear studs on the girder, so their total cross sectional area was Pi x R^2 x 30 = 13.25 sq. inches. The shear stress is just force/unit area and is thus 26,738 lbs. / 13.25 sq. inches = 2,018 psi
The shear studs would have had a tensile yield of 36,000 psi and a shear yield of 57.7% of that at 20,772 psi. The shear stress would only be 10% of what the shear studs could take.
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gerrycan, any response to TFK's criticisms below concerning your friend's calculation above?

tfk said:
There is virtually nothing about this calculation that is correct.

Here are his mistakes:

His biggest mistake is the most obvious one: there were no shear studs connecting the girder to the concrete floor. NIST was very explicit about that.

But if he were trying to figure out if the girder shear studs would have failed IF they were really there, then he screwed up a bunch of things.

1. He uses the wrong E value. He uses room temp E, instead of high temp E.

2. IF the girder shear studs would have survived, then the shear studs on the beams would also have survived. So he's got to figure out how much of the expansion load those studs would have supported. He didn't do this.

3. He has laid out the problem as though the lateral stiffness of the girder is essentially infinite. This is false. The lateral stiffness of the girder is significantly less than the axial stiffness of the beams. In this case the girder will flex laterally, and he must consider this in calculating the resultant loads on his (imaginary) studs.

3. As a result of the flex of the girder, the loads from each girder will be concentrated on the (imaginary) studs that are immediately adjacent to each beam connection, and not uniformly shared amongst the (imaginary) studs.

4. He is assuming that the failure mode of his (imaginary) studs is shearing of the studs. This is false. The failure mode is fracturing of the concrete, which happens at a significantly lower stress level than the shearing of the (imaginary) studs.

5. He forgot to include the portions of the loads taken up by the bolts on either end of the girder.

6. 5 digits of precision is absurd.

7. All in all, the right way to do this calculation is with a quick FEA.

Mr. Gerrycan should stay out of mechanical analysis.
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Gamolon said:
I've been debating gerrycan over at the David Icke forums. He has made a number of incorrect statements and even contradicts himself.

1. His claim about the girder between columns 79 and 44 having shear studs is based on ...[more details]... Below is gerry's response to someone in the comments section of one of his videos which shoes he thinks there should be separate drawings for each floor:


2. He claims that John J Salvarinas was the design engineer for WTC7 when in fact he was the project manager. Irwin Cantor was the engineer. His seal is on the drawings

3. He claims that Salvarinas wrote his lecture/paper post construction, trying to give his drawings more credibility. The fact is, if he would have read the lecture, it was written DURING the construction of WTC7. That means changes could have occurred when this paper was written.

4. I asked him to explain why Salvarinas' drawings in his lecture/paper don't match the Cantor drawings. They both call out different numbers of shear studs and even different types of beams.

5. He first says that WTC7 went from a building to a pile of debris in 6.6 seconds. He then later states that the NW corner dropped in 6.6 seconds. I asked him to clarify his contradiction, but as of yet, he has not.
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Take care that you do not fall for the tactical trick that gerrycan is attempting - whether by deliberate choice OR his own limited skill at reasoning.

It is the standard truther trick of forcing attention onto details whilst ensuring that they and you lose the plot of the broader picture.

In this thread ONE example of this tactic is all the discussion about length changes in the girder between Col79 and Col44. Originally in this thread C7 managed to keep the argument to discussion of details about the length change due to temperature expansion/contraction. That is by treating the problem as if it depended on a single factor. It doesn't and there are several key factors. After several rounds of criticism about this false setting C7 allowed sag to come into the picture then proceeded to play sag off against thermal expansion/contraction. But still keeping it to one factor really - shortening of the girder but now admitting two mechanisms.

The main trick??

The assumption that the two columns remain in their original location to within fractions of an inch. Technically that is a ludicrous suggestion. The idea that in a building affected by serious fires one structural element - the girder - would be temperature affected WHILST the columns it is attached to were not affected....no further comment needed. Sadly quite a few people fall for the deception. That one deliberately overlooked factor on it's own is sufficient to throw all the girder length arguments into doubt.

Think about it without letting the truthers set boundaries on the problem. The issue is "How could the girder have fallen off the seating?" There are two ways this could happen:
1) Because the girder becomes too short for the distance between the columns. That in turn becoming some combination of the girder gets shorter and the gap gets longer.
2) The girder goes off sideways. This likely in combination of "1)" above to overcome some concerns about flanges getting in the way.

So don't let the truthers limit the discussion to detail as they miss the plot and try to get you to miss it also.
 
Christopher7 said:
No one here can refute the fact that shortening due to sagging would exceed axial elongation at ~624oC, which equals 4.67". The NIST model was entirely built on data giving the strength of the various components that was derived from tests like the data on expansion and sagging so using this data to refute the NIST conclusion is appropriate.
Click to expand...

So then you're proposing that shortening due to sag, combined with thermal contraction due to the fact that the fires were burned out in the area of col 79 resulted in the girders being pulled of their seats, rather than being pushed off, per NIST.

This means that while you have indeed won against NIST, you have also proven that there is zero need for any kind of cd at 7.

This renders your statements of how cd is necessary.... etc.... absolutely false. It proves that it was indeed a natural event.

Are you comfortable with that?
 
Gamolon said:
gerrycan, any response to TFK's criticisms below concerning your friend's calculation above?
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TFK's response to the buckling calculations is less than impressive when he complains that the modulus of elasticity of steel used is that of room temperature.

We can see that the buckling calculations were indeed done using the room temperature modulus of elasticity of steel. However, what TFK either fails to realize or doesn't want to admit, is that the lower values of the modulus at higher temperatures will cause the buckling load to be lower. So the room temperature calculations are in essence an upper bound for the buckling load. If the beam buckles before breaking the shear studs at room temp it will certainly do so at higher temperatures.
 
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Seymour Butz said:
So then you're proposing that shortening due to sag, combined with thermal contraction due to the fact that the fires were burned out in the area of col 79 resulted in the girders being pulled of their seats, rather than being pushed off, per NIST.

This means that while you have indeed won against NIST, you have also proven that there is zero need for any kind of cd at 7.

This renders your statements of how cd is necessary.... etc.... absolutely false. It proves that it was indeed a natural event.

Are you comfortable with that?
Click to expand...

I have looked at this and the temperature at which the shortening overtakes the expansion of a 53'-4 11/16" long steel beam with a 100 psf load on it in the northeast corner of WTC 7 is 649 degrees C, with the maximum expansion being 4.753". Far short of the 6.00" needed.

The shortening of the beam at 700 degrees C is 1.747". This would hardly support the argument that the girder could be pulled off it's seat after the beams cooled down, as the girder would need to pulled at least 6.00".

The equation used to determine shortening is the same as that used by Zdenek Bazant in his 2002 paper where he uses u = L x (1 - COS of theta).

Here it would be Shortening = full length of beam x (1 - COS of the angle of sag).

Both of the above don't even consider the 3/4" thick flange to web stiffeners shown on drawing 9114 that we have recently learned about, which would require even more than 6.00" of horizontal movement in an east or west direction by the girder.

Simply put, the fall of the girder between columns 79 and 44 off its seat in an east or west direction at the 12th floor of WTC 7 is impossible due to fire. The NIST report is incorrect here and needs to be corrected.
 
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