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Merged Discussion of ARUP and Colin Bailey's analyses used in court case

pgimeno

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pgimeno
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So I finally was able to download and examine the FEA that gerrycan wanted to discuss but didn't want to provide.

At the time of writing, the document is available here:
https://kkkb6g.dm2303.livefilestore...-qQ/11_4403_Doc_76_Appendix_Bailey.pdf?psid=1

Should that link cease to work, I may be able to provide it if requested.

I'm still examining it, but a number of things came to my immediate attention:

1. The FEA covers only 1 floor and does not consider movement of column 79 as pushed by the girder on in the floor below it, which is something that NIST noted in their own FEA.

2. The simulation only covers about half a floor of WTC7, not the whole extent that NIST tested. It does include column 79 and the girders bracing to it, though.

3. The heat distribution differs substantially from that NIST used. It seems to be uniformly applied to all members, which is unrealistic for a real fire. Order matters when determining failure.

My preliminary conclusion before looking at it in more thorough detail is, therefore, that it does nothing to support or refute NIST's hypothesis.

Additional link: https://www.sendspace.com/file/uu4053


Edited by Loss Leader: 
Edited to add a working link at the request of the OP
 
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pgimeno said:
So I finally was able to download and examine the FEA that gerrycan wanted to discuss but didn't want to provide.

At the time of writing, the document is available here:
https://kkkb6g.dm2303.livefilestore...-qQ/11_4403_Doc_76_Appendix_Bailey.pdf?psid=1

Should that link cease to work, I may be able to provide it if requested.

I'm still examining it, but a number of things came to my immediate attention:

1. The FEA covers only 1 floor and does not consider movement of column 79 as pushed by the girder on the floor below it, which is something that NIST noted in their own FEA.

2. The simulation only covers about half a floor of WTC7, not the whole extent that NIST tested. It does include column 79 and the girders bracing to it, though.

3. The heat distribution differs substantially from that NIST used. It seems to be uniformly applied to all members, which is unrealistic for a real fire. Order matters when determining failure.

My preliminary conclusion before looking at it in more thorough detail is, therefore, that it does nothing to support or refute NIST's hypothesis.
Click to expand...

Agreed... they make a case that the girder could fail. They base this on design flaws such as failure to install fire stopping in the flutes.

They do not detail how the building would collapse. That seems to be a leap no one wants to take.
 
After a quick skim the main difference in conclusion seems to be that the girder between columns 79 and 44 walks off during the cooling phase rather than the heating phase. End result seems to be the same, lack of restraint on column 79 leading to a buckling failure of that column and building collapse.
 
pgimeno said:
So I finally was able to download and examine the FEA that gerrycan wanted to discuss but didn't want to provide.
Click to expand...

Except you did get it from me. Yes that's the document from the link that I emailed when requested. I had the document and not the link. When I got the link I sent it as requested right away. I wasn't sure when I only had the file.
You're welcome.
 
gerrycan said:
Except you did get it from me. Yes that's the document from the link that I emailed when requested. I had the document and not the link. When I got the link I sent it as requested right away. I wasn't sure when I only had the file.
You're welcome.
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I provided the link. I stated that you and Tony both provided it.

I wonder why you didn't just post it here. The document is public.

Now that that's done. Where do you want to start discussing?
 
DGM said:
I provided the link. I stated that you and Tony both provided it.

I wonder why you didn't just post it here. The document is public.

Now that that's done. Where do you want to start discussing?
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I had the pdf not the link. Did you not read my comment ?
 
DGM said:
I provided the link. I stated that you and Tony both provided it.

I wonder why you didn't just post it here. The document is public.

Now that that's done. Where do you want to start discussing?
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What do you think about the 30 shear studs being on girder A2001?
 
While gerrycan calls for backup, I'll comment on Bailey's assessment, because it's priceless. For link see the OP.

The first five points are mostly irrelevant.

Colin Gareth Bailey said:
6. Based on my work to date, including computer modeling at the University of Edinburgh in which many columns were removed in the model to see the effect on the structure of the building, it is my opinion that any structural damage caused by debris from the collapse ofWTC I or WTC2 played no part in the collapse of 7WTC.
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So he agrees with NIST on this one.

7. Based on my work to date, inclnding computer models by the University of Edinburgh, it is my opinion that if there had been a diesel fuel fire on September 11 involving between 7,350 and 9,300 gallons of diesel fuel on the fifth floor of 7WTC in the area of the transfer trusses, such a fire would have compromised the strength of the transfer trusses, and could have caused them to fail, resulting in the collapse of columns 79 and/or 80.
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NIST ruled out this case. I think JSanderO disagrees with NIST's assessment and thinks that it's likely that that diesel fuel played a part.

8. The computer modeling completed to date supports the conclusion that 7WTC would have collapsed as a result of typical office contents fires because of several design/construction failures, including the failure to adequately fireproof the flutes of the metal floor decking for 7WTC and the failure to ensure that a restrained floor system was constructed.
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This bears repeating. The computer modeling supports the conclusion that 7WTC would have collapsed as a result of typical office contents fires because of several design/construction failures. NIST happened to say the same thing.

9. When a steel beam supports a composite deck, comprising a fluted (trapezoidal shaped) steel deck, concrete and mesh reinforcement, a cavity (or void) is formed between the top flange of the beam and the fluted deck. For fluted decks, such as those used on 7WTC, this cavity (or void) is large. Leaving the cavities between the fluted deck and top flange of the beam unfilled or inadequately filled with fire protection material results in:

a. an increase in temperature of the top flange and web;
b. an increase in temperature of the shear studs;
c. reduction in load capacity of beams during a fire; and
d. reduction in overall fire resistance.
​
In the UL Fire Resistance Directory for 1983 and 1985 the need to fill the voids is covered by the following statement: “€œCavities, if any, between the upper beam flange and floor or roof units shall be filled with the fire protection material applied to the beam, unless stated otherwise on an individual design.”

10. The photographic evidence shows that the cavities were either not filled with fire protection at all, or were so inadequately filled as to have been unfilled for all practical purposes. See Exhibit A. An example of flutes in the process of being filled with fire protection on a different building is shown in Exhibit B. Exhibit C, which appears in the American Institute of Steel Construction Design Guide, shows another example where the flutes have been filled with fire protection.1 Failure to construct the building with adequate fire protection by filling the voids reduced the fire resistance below building code requirements.
_______________
1 Steel Design Guide 19: Fire Resistance of Structural Steel Framing. American Institute of Steel Construction, December 2003
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That's something that NIST failed to take into account in their analysis. Only for this reason I have to agree now that their probable collapse sequence is less probable: the building was likely to have failed before they said due to that problem.

More discussion later.
 
DGM said:
No. I agree that the amount was ineffective in preventing collapse but would help with floor load capacity. I think that's what Mr Bailey states.

Do you disagree?
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Quote him so that everybody has the context of the specific simulation that he was speaking about.
 
gerrycan said:
Quote him so that everybody has the context of the specific simulation that he was speaking about.
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Evidence discovered after June 15, 2009 revealed that, contrary to the information I had
reviewed prior to that date, some shear studs were ultimately installed on each floor on the girder
running between columns 79 and 44. This was done to increase the ability of this part of the structure to support an additional 10 psf load above the original design load. As a result, only 30 shear studs were installed, which, in my opinion, was not sufficient to transfer thermal thrusts. For a fully composite girder a total of 96 shear studs would be required, which would have transferred the thermal thrusts.
Click to expand...

I think you've seen this before.
 
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DGM said:
I wasn't going to comment on this but, what the hell do you mean by this? A composite floor is a floor containing multiple elements. The studs don't make it "composite".
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Well let's see your quote from Mr Bailey and we can talk about composite in context of your assertion and his statement.
 
DGM said:
He's arguing about statements made by experts in the document he provided.

Nothing will surprise me.........
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So now you have the full document can you find me one sentence that endorses NISTs walk off theory ?
 
gerrycan said:
So now you have the full document can you find me one sentence that endorses NISTs walk off theory ?
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It doesn't have to. It's not set up to endorse it. It doesn't refute it either. As noted in the OP.

It's just not complete enough.
 
gerrycan said:
So now you have the full document can you find me one sentence that endorses NISTs walk off theory ?
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Why? Nothing changed. Nothing in this document supports you outside of the NIST's probable initiation. It does not refute it, it only adds another layer of complexity.
 
Originally Posted by gerrycan View Post
So now you have the full document can you find me one sentence that endorses NISTs walk off theory ?

pgimeno said:
It doesn't have to. It's not set up to endorse it. It doesn't refute it either. As noted in the OP.

It's just not complete enough.
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That was a long way to get to "NO"
It runs an lots of FEA analysis that go beyond NISTs temperatures and there is no walk off.
That's why you can't find a sentence to endorse it. Cos it's horse****.
 
pgimeno said:
It doesn't have to. It's not set up to endorse it. It doesn't refute it either. As noted in the OP.

It's just not complete enough.
Click to expand...

EVERY single analysis contradicts NISTs walk off theory. Every one refutes it by seeing the girder trapped in the side plates.
 
DGM said:
I wasn't going to comment on this but, what the hell do you mean by this? A composite floor is a floor containing multiple elements. The studs don't make it "composite".
Click to expand...

Shear studs welded to a beam or girder and embedded in the concrete slab on top of that beam or girder are precisely what creates the composite floor behavior. They cause the steel and slab beams to act in unison and this increases their stiffness and bending resistance.

It is the same thing if you nail two planks together and apply a force in the center. The total bending deflection of the two joined beams will be less than it would be if they weren't nailed together but were only stacked together.
 
gerrycan said:
That was a long way to get to "NO"
It runs an lots of FEA analysis that go beyond NISTs temperatures and there is no walk off.
That's why you can't find a sentence to endorse it. Cos it's horse****.
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I explain why it's not comparable in the OP. Go read it again.

One thing that I don't mention is that column 79 was fixed during the analysis. In NIST's analysis it was allowed to move. And it did.
 
pgimeno said:
I explain why it's not comparable in the OP. Go read it again.

One thing that I don't mention is that column 79 was fixed during the analysis. In NIST's analysis it was allowed to move. And it did.
Click to expand...

It is a series of FEA analysis on the exact same part of the exact same building and you describe it as "not comparable". Pathetic.
you're struggling.
Careful what you wish for DGM eh.
 
gerrycan said:
EVERY single analysis contradicts NISTs walk off theory. Every one refutes it by seeing the girder trapped in the side plates.
Click to expand...
As I already said, that's because there hasn't been a complete enough analysis yet. You said you have; I challenged you to present it. You haven't, and you know it was false.
 
pgimeno said:
I explain why it's not comparable in the OP. Go read it again.

One thing that I don't mention is that column 79 was fixed during the analysis. In NIST's analysis it was allowed to move. And it did.
Click to expand...

How far did column 79 move in NIST's analysis?
 
Tony Szamboti said:
Shear studs welded to a beam or girder and embedded in the concrete slab on top of that beam or girder are precisely what creates the composite floor behavior. They cause the steel and slab beams to act in unison and this increases their stiffness and bending resistance.

It is the same thing if you nail two planks together and apply a force in the center. The total bending deflection of the two joined beams will be less than it would be if they weren't nailed together but were only stacked together.
Click to expand...
No kidding.......Is there a number needed for a given length to be effective in thermal shear?

The expert in the document linked seams to think so, Do you disagree?
 
DGM said:
No kidding.......Is there a number needed for a given length to be effective in thermal shear?

The expert in the document linked seams to think so, Do you disagree?
Click to expand...

My calculation shows the 30 shear studs on girder A2001 would stop any walk-off by causing the thermally expanding beams to the east to buckle before the girder would move.

This does not involve composite bending resistance. The failure modes needed for the girder to move is shearing of the studs or compressive bearing failure of the concrete. The forces needed for either of those situations to occur for thirty (30) 3/4" diameter x 5" high shear studs in 3,500 psi concrete are a lot higher than the force needed to buckle the five beams.
 
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