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

[Newtons Bit]

Section 8.8 does not say the girder failed due to lateral-torsional buckling. It says the northmost girder failed due to lateral-torsional buckling and that the remaining beams did also and that they rocked the girder off it's seats to the east.

Try looking at the pretty picture 8-27. That's classic lateral torsional buckling. Without such behavior, the "rocking off the seat" that NIST refers to would never happen.

Of course, they only show the north most two beams and the model is missing the three beam stubs from the north exterior to the northmost beam.

I did a finite element analysis with and without those beam stubs. Without them the northmost beam did fail in lateral-torsional buckling and the second beam was deformed some sideways but hadn't rotated. With the stubs the northmost beam did not fail in lateral-torsional buckling.

Normally I would ask for your input parameters. But at this point I'm just calling bull .

 

[Tony Szamboti]

Try looking at the pretty picture 8-27. That's classic lateral torsional buckling. Without such behavior, the "rocking off the seat" that NIST refers to would never happen.



Normally I would ask for your input parameters. But at this point I'm just calling bull .

Lateral-torsional behavior due to vertical loads occurs due to excessive compression flange stress. That isn't what the pretty picture 8-27 is showing. It is showing the girder being pulled to the east. If the beams hadn't failed they would have restrained the girder.

The real question here isn't the point you attempted to make, as far as lateral-torsional buckling of the girder, but rather whether or not those beams buckled in the lateral-torsional mode. My FEA analysis says they didn't and the NIST model is incomplete with those three beam stubs.

How you can sit there and support the present NIST report, when we are seeing that in multiple instances important details were left out, is beyond me.

 

[DGM]

My FEA analysis says they didn't and the NIST model is incomplete with those three beam stubs.

How you can sit there and support the present NIST report, when we are seeing that in multiple instances important details were left out, is beyond me.

Has NIST gotten back to you on this yet?

 

[Justin39640]

How you can sit there and support the present NIST report, when we are seeing that in multiple instances important details were left out, is beyond me.

You know... If you were just arguing that they were wrong about their collapse mechanism theory, that would be one thing. But, you're not. You're (wrongly) accusing them of covering up an intentional demolition of a building and ultimately being complicit in the murders of almost 3000 people.

 

[Christopher7]

Try looking at the pretty picture 8-27. That's classic lateral torsional buckling. Without such behavior, the "rocking off the seat" that NIST refers to would never happen.

This is a prime example of obfuscation by NIST.

This is NOT the collapse hypothesis as I once thought but was corrected by someone here. You have yet to catch on so I will post again:

"This analysis demonstrated possible failure mechanisms that were used to develop the leading collapse hypothesis further. The failure modes in this model were incorporated into the 16 story ANSYS and 47 story LS-DYNA analyses." 1-9 pg 353.

The Official Collapse Theory starts with the girder being pushed off its seat by the thermal expansion of the floor beams. It should be noted that NIST has the beams buckling in this simulation but expanding at least 5.5 inches and not buckling in the final analysis.

Perhaps you can explain how NIST got entirely different results when heating the beams and girder in these two simulations.

 

[Christopher7]

You know... If you were just arguing that they were wrong about their collapse mechanism theory, that would be one thing. But, you're not. You're (wrongly) accusing them of covering up an intentional demolition of a building and ultimately being complicit in the murders of almost 3000 people.

We are just pointing out the facts. You figured out the rest by yourself but you can't believe your government would do that so you reject the facts.

NIST lied about the width of the girder seat.
That is fraud.

NIST omitted the stiffeners.
That is fraud.

They lied to get their walk-off theory to work because if they told the truth, it does not.

 

[Clayton Moore]

You know... If you were just arguing that they were wrong about their collapse mechanism theory, that would be one thing. But, you're not. You're (wrongly) accusing them of covering up an intentional demolition of a building and ultimately being complicit in the murders of almost 3000 people.

That's the ticket. The rest of the world knows it. The only thing saving the perpetraitors is the MSM.

 

[Clayton Moore]

Lateral-torsional behavior due to vertical loads occurs due to excessive compression flange stress. That isn't what the pretty picture 8-27 is showing. It is showing the girder being pulled to the east. If the beams hadn't failed they would have restrained the girder.

The real question here isn't the point you attempted to make, as far as lateral-torsional buckling of the girder, but rather whether or not those beams buckled in the lateral-torsional mode. My FEA analysis says they didn't and the NIST model is incomplete with those three beam stubs.

How you can sit there and support the present NIST report, when we are seeing that in multiple instances important details were left out, is beyond me.

I think they're hiding the truth in order to protect some guilty people.

Clayton Clouseau

 

[BasqueArch]

Lateral-torsional behavior due to vertical loads occurs due to excessive compression flange stress. That isn't what the pretty picture 8-27 is showing. It is showing the girder being pulled to the east. If the beams hadn't failed they would have restrained the girder.

The real question here isn't the point you attempted to make, as far as lateral-torsional buckling of the girder, but rather whether or not those beams buckled in the lateral-torsional mode. My FEA analysis says they didn't and the NIST model is incomplete with those three beam stubs.

How you can sit there and support the present NIST report, when we are seeing that in multiple instances important details were left out, is beyond me.

You've been repeatedly shown your deflection calculations are wrong and asked to provide and show the correct girder deflection calculations for review. Why haven't you.

 

[Tony Szamboti]

You've been repeatedly shown your deflection calculations are wrong and asked to provide and show the correct girder deflection calculations for review. Why haven't you.

They aren't wrong in the sense you imply. I used the distributed load equation for a simply supported beam of (5PL^3)/(384EI), with the full load of the east side floor at 100 psf on the girder for a rough order of magnitude check, since there are also loads from the west side on the girder. The load I used was 238,500 lbs. applied in a distributed way to the W33 x 130 girder at 500 degrees C, with a reduced modulus per the AISC retention factor of 0.630 at that temperature and considering the room temperature modulus of structural steel to be 29 x 10e6 psi. I subtracted room temperature deflection to find that due to temperature increase and reduced modulus.

The actual loads are point loads at the beam interfaces to the girder from both sides. The difference in deflection with multiple point loads vs. a distributed load would be minimal, if any at all.

So I did a rough calculation to back up the 1.5 inch girder vertical deflection caused by the 500 degrees C temperature that I stated. In your case you show 37" of vertical deflection in your drawing, but provide no calculations whasoever. I think it is actually you who should be asked to provide your calculation supporting your claim.

If you want a copy of my spreadsheet send me your e-mail address by PM.

 

[BasqueArch]

They aren't wrong in the sense you imply. I used a distributed load on the girder for a rough order of magnitude check. The actual loading is five point loads at the beams. The difference in deflection would be minimal.

The girder would not fail by lateral-torsional buckling.

I did a rough calculation to back up the girder deflections I stated. In your case you show 37" of deflection, but no calculations whasoever. I think it is actually you who should be asked to provide your calculation supporting your claim.

I show a 20" deflection not 37". The CAD program told me the angle was 8 deg.
Your calculations assumed fixed ends (bolted). The girder ends were not fixed ( not bolted). You've pretended not to notice or mention this significant difference for deflection although I've said this a number of times.

I've also said that I can't do the calculations. I've asked an SE to do this for me but he has no appetite for it because to him this whole conspiracy thing has the stink of failure.

 

[Tony Szamboti]

I show a 20" deflection not 37". The CAD program told me the angle was 8 deg.
Your calculations assumed fixed ends (bolted). The girder ends were not fixed ( not bolted). You've pretended not to notice or mention this significant difference for deflection although I've said this a number of times.

I've also said that I can't do the calculations. I've asked an SE to do this for me but he has no appetite for it because to him this whole conspiracy thing has the stink of failure.

The 8 degree angle of the deflection you show would require 37" of defelection on a 45 foot long beam. If you want to say it was 20" that is fine, just explain how you did the calculation to arrive at that figure like I did for my claim.

My calculation was not done with fixed/bolted ends. It was done for a simply supported beam.

Since you say you can't do the calculations you have no basis for the deflection and angle of sag you show. The CAD program told you what it did based on your inputs and if the inputs aren't right then the output won't be. It sounds like you made a guess of some sort on your input. The actual calculations show that guess to be incorrect by a very large degree.

I will do a FEA of the girder with point loads at the beam interfaces to prove my point again.

You keep bringing up this SE you approached who doesn't want to be bothered because he thinks it is stupid. Since he doesn't say why, all this proves is the guy hasn't looked into it and has accepted the present official story uncritically. So your point here is meaningless in this discussion.

 

[BasqueArch]

Girder length 547"
Load 293 lb/inch
MOI W33x130 6995 in(4)
MOE 15,000,000 psi
Neutral axis 16.5"
Max deflection 3.26"
But this is for fixed ends Not ends not fixed.

 

[BasqueArch]

The 8 degree angle of the deflection you show would require 37" of defelection on a 45 foot long beam. If you want to say it was 20" that is fine, just explain how you did the calculation to arrive at that figure like I did for my claim.

My calculation was not done with fixed/bolted ends. It was done for a simply supported beam.

Since you say you can't do the calculations you have no basis for the deflection and angle of sag you show. It sounds like you made a guess of some sort. The actual calculations show that guess to be incorrect by a very large degree.

You keep bringing up this SE you approached who doesn't want to be bothered because he thinks it is stupid. Since he doesn't say why, all this proves is the guy hasn't looked into it and has accepted the present official story uncritically. So your point here is meaningless in this discussion.

So you don't believe there is a difference in the deflection between a beam that is not restrained at the ends with one that is restrained at the ends

 

[twinstead]

That's the ticket. The rest of the world knows it. The only thing saving the perpetraitors is the MSM.

Please Mr Ideolog, let the grownups talk. Go out and play.

 

[Tony Szamboti]

Girder length 547"
Load 293 lb/inch
MOI W33x130 6995 in(4)
MOE 15,000,000 psi
Neutral axis 16.5"
Max deflection 3.26"
But this is for fixed ends Not ends not fixed.

The 3.26" result is not for fixed ends. It is what you get using your input from the simply supported beam with a distributed load deflection equation of (5PL^3)/(384EI). This also doesn't subtract the room temperature deflection to find what the elevation in temperature effect was on the deflection.

The MOE you used is lower than what the AISC says for structural steel at 500 degrees C. They say it has a retention factor of 0.630 at that temperature, giving a MOE of 18,270,000 psi.

The MOI that I used for the W33 x 130 in the vertical axis was 6,710 in^4. So here you were conservative.

 

[Tony Szamboti]

So you don't believe there is a difference in the deflection between a beam that is not restrained at the ends with one that is restrained at the ends

That isn't what I am saying. I am saying that the 3.26" deflection you got was for a beam that was not restrained at the ends. That is what simply supported means.

I did the room temperature deflection calculation using your inputs and it is 1.68". Subtracting that from your calculation with the lower MOE of 3.26" gives a deflection due to increased temperature of 1.58". Very close to what I got. Surprise, surprise! The slight difference would only be because you used a little lower MOE than I did at 500 degrees C.

I hope you see that the large deflection you somehow got from the CAD was not correct and there had to be something else going on there.

 

[BasqueArch]

That isn't what I am saying. I am saying that the 3.26" deflection you got was for a beam that was not restrained at the ends. That is what simply supported means.

I did the room temperature deflection calculation using your inputs and it is 1.68". Subtracting that from your calculation with the lower MOE of 3.26" gives a deflection due to increased temperature of 1.58". Very close to what I got. Surprise, surprise! The slight difference would only be because you used a little lower MOE than I did at 500 degrees C.

I hope you see that the large deflection you somehow got from the CAD was not correct and there had to be something else going on there.

I will rephrase the question.
Do you believe there is a difference in the amount of deflection between a beam heated at 500C bolted to its seat at the ends, and a beam heated at 500C not bolted to its seat at the ends.

 

[Tony Szamboti]

I will rephrase the question.
Do you believe there is a difference in the amount of deflection between a beam heated at 500C bolted to its seat at the ends, and a beam heated at 500C not bolted to its seat at the ends.

It isn't a question of belief. There is a slight difference, as the ends do not rotate on the bolted beam.

The same relative effect between fixed and simply supported is true regardless of temperature. With a higher temperature there is greater deflection in both cases, due to a lower modulus.

 

[BasqueArch]

Your calculations show that the girder has buckled, which results in your deflection calculations being completely wrong. Now I haven't been following this sub-forum that closely. Maybe you've run some numbers that take this into consideration. Perhaps you'd like to show this revised calculation?

Per NB - It looks like the buckling of the girder is the real reason the deflection > couple of inches and/or that it failed. NIST describes torsional buckling where if the tilting angle displaces the flange > ½ of the flange width from vertical then it would fail.

Once the girder buckled the web was no longer plumb and the flanges no longer parallel to each other or the ground. Once the optimum geometry was lost this would reduce its strength and cause excessive sagging (for flange relative displacement < than ½ of flange width) or failure (for flange relative displacement > ½ of flange width).