'What about building 7'?

[DGM]

So why does the connection not match with the drawing for either of their models. LSDYNA has the connection modelled to match C81, and the ANSYS one doesn't account for some elements.

Your question is really arse backwards for this sub forum. If you showed they did this to accomplish a goal (conspiracy) and then showed proof then it would fit.

You need to show they did this as a deception not as an engineering choice. Get this?

 

[gerrycan]

We haven't started to discuss LSDYNA. The link I posted shows the reasons for the ANSYS simulation to omit the element in question you are referring to.

I'll admit to start discussing LSDYNA, as soon as you admit the seat moved east and therefore the distance the beams needed to push the girder in order to cause walk-off is reduced.

Do you admit this?

If so, we can move on to the next chapter.

If not, I won't admit to this gish-gallop.

According to NIST the column did not become laterally unstable until the girder had failed and the floors had began to fail. It would follow that in NISTs initiating event that any lateral movement that they supposed in the column could not contribute to the failure of the C79-44 girder.

 

[Ziggi]

... Actually, and just to nitpick, they don't. They say that, but for the beams, not for the girder

This is exactly NIST´s girder walk off story: Once the girder had been somehow displaced 6.25 inches its web was past the seat plate so that the girder was resting on the flange alone, which lacked "flexural stiffness" and consequently folded.

...At no point in the report do they say that any beam expanded by 5.5" or 6.25". That claim doesn't exist in the report. That distance is indicated as "the distance for walk-off", not "the distance by which the beams expanded".

I never said the beams expanded 6.25 inches but especially noted that: "NIST says that once the girder had been displaced 6.25 inches the flange would fold." I am giving you the benefit of doubt and assuming for now that NIST is talking about the walk off distance = 6.25 inches, not the amount of beam expansion. It is up to you to prove your point.

...So, that's primarily what NIST is saying here: that the simulation showed the girder walking off the seat. They don't point to exact reasons.


...Note how they mention column 79 displacing east.

So after all, within that long post of yours you seem to admit that NIST does not actually explain how the girder could be displaced 6.25 inches. If this is not the case I invite again to demonstrate where NIST explains this little "detail", for those of us that do not wish to accept this story on faith alone.

You also seem to make a big deal of supposed displacement of the column itself as an additional factor to the expansion of the beams, and that this would somehow absolve NIST.

But you seem shy about bringing forth some calculations, numbers. So again, giving you the benefit of doubt and assuming that NIST says the column displacement did in fact occur in time to help the walk off event, what are NIST´s numbers here. How much did the beams expand at what temperature, and how great was this alleged displacement of the column?

 

[Reactor drone]

But you seem shy about bringing forth some calculations, numbers. So again, giving you the benefit of doubt and assuming that NIST says the column displacement did in fact occur in time to help the walk off event, what are NIST´s numbers here. How much did the beams expand at what temperature, and how great was this alleged displacement of the column?

You specifically asked only for NISTs explanation, not anyone else's interpretation or calculations. If you're unhappy with the details given in the report maybe you should be talking directly to people at the NIST.

So my question to you is, how exactly did this happen according to NIST. That is, how is this explained in NIST´s little final report? I am not interested in what you or others think may have happened, I am asking how this event happened acoording to NIST? So just refer to the relevant chapter of the final report, figures and page numbers etc.

 

[DGM]

You specifically asked only for NISTs explanation, not anyone else's interpretation or calculations. If you're unhappy with the details given in the report maybe you should be talking directly to people at the NIST.

Judging from his history, I think he feels he is.

 

[pgimeno]

This is exactly NIST´s girder walk off story: Once the girder had been somehow displaced 6.25 inches its web was past the seat plate so that the girder was resting on the flange alone, which lacked "flexural stiffness" and consequently folded.

Reference, please?

So after all, within that long post of yours you seem to admit that NIST does not actually explain how the girder could be displaced 6.25 inches.

Nor do they say it was. That's the distance for walk-off. Walk-off is affected by the relative distance between girder and seat, not by the displacement of the girder alone.

They do say that "when the girder end at Column 79 had been pushed laterally at least 5.5 in., it was no longer supported by the bearing seat". That misses focus on the displacement of the seat, but it's obvious that it's a factor to the walk-off displacement. Isn't it obvious for you?

What's more, they mention they used a local coordinate system in the column seat. What do you think that local coordinate system could be used for? What would it be measuring?

But you seem shy about bringing forth some calculations, numbers. So again, giving you the benefit of doubt and assuming that NIST says the column displacement did in fact occur in time to help the walk off event, what are NIST´s numbers here. How much did the beams expand at what temperature, and how great was this alleged displacement of the column?

They don't say either of them. They just report that the simulation indicated it happened. Why don't you ask them?

 

[pgimeno]

According to NIST the column did not become laterally unstable until the girder had failed and the floors had began to fail. It would follow that in NISTs initiating event that any lateral movement that they supposed in the column could not contribute to the failure of the C79-44 girder.

Two or three inches would not make the column unstable. Remember the connections resisted.

 

[Ziggi]

Nor do they say it was. That's the distance for walk-off. Walk-off is affected by the relative distance between girder and seat, not by the displacement of the girder alone.

Yes, why repeat this? The girder gets displaced to the west, relative to the seat plate, whenever the beams expand and push it to the west, or when the column is displaced to the east. You have implied that the sum of both actions is 6.25 inches.

They don't say either of them. They just report that the simulation indicated it happened. Why don't you ask them?

That´s right, NIST does never actually give any numbers or calculations or any scientific explanation for how the 6.25 inch displacement could be possible or plausible. That little step is simply skipped. And then there was light, AMEN.

Why don't you ask them?

WHAT? And dare to question NIST, and become a "conspiracy theorist"? No, no, us good skeptics would never do that. But this is exactly what AE911Truth is trying to do.

But have you done any sort of analysis yourself to check if NIST´s 6.25 inch displacement number is backed by its data?

Again, what was the beam temperature and expansion displacement? And how many additional inches would be needed from the alleged column displacement to add up to 6.25 inches?

 

[pgimeno]

Reference, please?

I'll have to ask again.

 

[JayUtah]

That´s right, NIST does never actually give any numbers or calculations or any scientific explanation for how the 6.25 inch displacement could be possible or plausible.-

Because the number and values of the unknowns in that model are indiscernible. Achieving a particular determination within a particular epsilon is industry standard, which is why the industry accepts NIST's methods and generally ignores under-informed conspiracy theorists.

 

[JayUtah]

I'll have to ask again.

I found the reference. It refers to beams, not to girders. Let's see if the conspiracy theorists can find one that refers to girders.

 

[pgimeno]

I found the reference. It refers to beams, not to girders. Let's see if the conspiracy theorists can find one that refers to girders.

That's exactly why I am asking.

Besides, I won't play "you're the only one who can ask". A debate is a two-sided exchange.

 

[DGM]

WHAT? And dare to question NIST, and become a "conspiracy theorist"? No, no, us good skeptics would never do that. But this is exactly what AE911Truth is trying to do.

But have you done any sort of analysis yourself to check if NIST´s 6.25 inch displacement number is backed by its data?

Again, what was the beam temperature and expansion displacement? And how many additional inches would be needed from the alleged column displacement to add up to 6.25 inches?

And the melt down begins...................

Why did you ask for the NIST explanation if you already dismissed it?

Tell you what, You give us a better explanation. I won't hold my breath.

 

[Ziggi]

I'll have to ask again.

I am surprised to see you ask about such a basic thing. The reference is in chapter 11, page 488, in a paragraph that begins under Figure 11-19, and the heading is "Criteria to remove locally unstable members..", ending in the words that "When a girder failed in this manner, the floor beams that it supported were removed at the same time."

IF this is not crystal clear enough for you, you can go back to something gerrycan has probably showed you numerous times, that is NIST´s omission of the stiffener plates, which would prevent the failure of that flange according to gerry´s team!

More importantly, NIST´s reply to gerry´s team, its excuse for not including the stiffener plates on that flange on that girder, is that they were designed to stiffen to web of that girder, not the flange! The stifferener plates are irrelevant according to NIST because it claims the stiffeners would have no strengthening effect on the flange that failed.

 

[pgimeno]

I am surprised to see you ask about such a basic thing. The reference is in chapter 11, page 488, in a paragraph that begins under Figure 11-19, and the heading is "Criteria to remove locally unstable members..", ending in the words that "When a girder failed in this manner, the floor beams that it supported were removed at the same time."

Thanks, let me paste the complete quote for reference:

Gravity shear loads in a beam were transferred to the bearing seat primarily in the proximity of the web on the bottom flange. Therefore, when the web was no longer supported by the bearing seat, the beam was assumed to have lost support, as the flexural stiffness of the bottom flange was assumed to be insufficient for transferring the gravity loads. Under such conditions, the beam would fall to the floor below under its self weight. When this occurred in the ANSYS analysis, the beam was removed. When a girder failed in this manner, the floor beams that it supported were removed at the same time.
​

That is exactly what I was referring to when I said this:

Actually, and just to nitpick, they don't. They say that, but for the beams, not for the girder, though they mention girders failing "in this manner" (which may be interpreted as the failure of the flange as described for beams, but it may also refer generically to a displacement by a distance of half the seat width).

So, it actually admits more than one interpretation. You can't attribute to them the meaning that interests you and disregard the other possibility without knowing which of these interpretations they actually meant.

Or in other words, you're shooting first and asking later. Jumping the gun. Choose your preferred saying.

More importantly, NIST´s reply to gerry´s team, its excuse for not including the stiffener plates on that flange on that girder, is that they were designed to stiffen to web of that girder, not the flange! The stifferener plates are irrelevant according to NIST because it claims the stiffeners would have no strengthening effect on the flange that failed.

I have read what they replied to Cole, and they don't say the part I've highlighted. Can you provide the citation where they said it would not have any strengthening effect? Or are you making up words that NIST never said?

WHAT? And dare to question NIST, and become a "conspiracy theorist"? No, no, us good skeptics would never do that. But this is exactly what AE911Truth is trying to do.

Oh, on that subject, in another thread I asked about the monthly technical briefings that AE911T says they were going to do. Do you have a link to the technical briefings for the past two months?

But have you done any sort of analysis yourself to check if NIST´s 6.25 inch displacement number is backed by its data?

Again, what was the beam temperature and expansion displacement? And how many additional inches would be needed from the alleged column displacement to add up to 6.25 inches?

Having read NIST's report, I saw that the attacks to it by "truthers" fail to consider too many factors and do the same you did above: shoot before asking. They have already decided that it must be wrong because if it was right, then it would prove that the building could have failed because of fire, which is against their (your) faith and thus interests, so they are walking backwards from that premise, rather than look for a reasonable explanation for the displacement or the omissions.

You have the conclusions, and are trying to walk backwards from there. All I did was contemplate the possibility that NIST didn't have any nefarious purpose with what they reported, and see what they did say and where it led, then point out what I found.

As forum member LSSBB succinctly summarized it, your premise is that the report must be completely thrown away because "they were off by an inch".

****, I don't even think that things happened the way they describe! They did what they could with what they knew, but the amount of unknowns they (or anyone, including any potential "new investigation") could not have access to, that could have had a far worse effect than what they describe, is so overwhelming, that the probability that it happened as they say is comparatively too small. But I'm satisfied because they identified one kind of vulnerability in buildings with long-span beams, that can help improve codes. Nothing wrong with that.

Structures do collapse due to fire, that's fact. Steel structures are no exception. Let me remind you what happened to the Windsor building in Madrid, which had a concrete core and a steel perimeter. This is what happened to the perimeter:

So, it's a fact that steel structures are vulnerable to fire, and codes are designed to protect them for long enough as to permit evacuation. It was the case of WTC7, and it met the expectations in that respect. Nist-picking on the significance of an inch leads nowhere.

 

[beachnut]

...t. Nist-picking on the significance of an inch leads nowhere.

It proves 911 truth has no valid engineering expertise, has no clue what probable, means, and fails to realize if NIST was wrong, it was still fire.

good work putting up with 13 years of BS, thank you, thank you very much

I doubt Ziggi realizes 19 terrorists did 911, and the Gish Gallop of WTC 7 BS is nonsense. If I was a 911 truther, I would have had a PhD in structural engineering, and then see my 911 truth days were a delusion. And in my case it would never happen, but I already finished my masters in engineering - but I find most lay people to be smarter than I... good luck

 

[Spanx]

Can anyone tell me if the ae911 engineers have asked their very specific questions yet ?

 

[Oystein]

I received a message saying that good old Oystein was promoting a real discussion about Building 7 on the forum that once belonged to the JREF, and what´s more, that he was actually asking the trolls to stay out.

Wrong.
As always, you are wrong.
Someone proposed a debate between myself and Jay Howard about the Harrit-paper. Jay said he'd be all for it. So I opened a thread for that:
http://www.internationalskeptics.com/forums/showthread.php?t=289588
So far, Jay hasn't reported in.
By the way: You'd be one of the trolls

So let´s test this and see what kind of discussion is possible, and let me focus on pgimeno since he has been the one responsible for debating gerrycan.

Responsible?
LOL
He simply IS debating gerrycan. Reasonably competent, I think. I sometimes interject a question to either gerrycan or pgimeno. I have enjoyed the debate so far. Hope it doesn't deteriorate now as more noise is introduced.

Before someone is tempted to flood the thread with trolling it should be known that all of my posts are sent directly your own frontman Chris Mohr and his buddy Rick Shaddock.

LOL
Frontman?
You're cute.
Buddy?
Even cuter.
Rick Shaddock's love for truth is by the displayed in this thread:
http://www.skepticforum.com/viewtopic.php?f=72&t=25149&sid=716cc6eb0d228fd9100f23b48bdd41f2
He (TruthMakesPeace) display wonderfully that he avoids facts and evidence whenever he can, and if pressured to face them, distorts them with shameless dishonesty.
Rick Shaddock is scared of truth.

And since Building 7 is gathering a LOT of interest, I have asked some potential recruits to 9/11Truth to observe this discussion (they are mostly engineers). They all have very specific questions and expect very specific answers.
...

Please present evidence those engineers exist.
What engineering disciplines do they practice?

*munching popcorn*

 

[Oystein]

NIST said in p.482 of NCSTAR 1-9 volume 2 (last sentence in the page) that "eam walk off in the lateral direction was monitored during the analysis". That sentence appears in the description of the analytical model, which also mentions that walk-off in the axial direction was monitored through a control element (I presume that they meant the COMBIN37 one in the illustration).

Then in section 11.3, titled "ANALYSIS RESULTS", they give more details on that monitoring:

The analysis of the structural response of WTC 7 to the effects of elevated temperatures produced a large volume of output data. Results for Floors 2 to 7 and Floors 15 and 16 are not presented as they were subject only to gravity loads and were not subjected to thermal loads. The analysis results for Floors 8 to 14 were first examined graphically for a selected response, such as vertical displacement or strains. Areas of interest were then examined in more detail by listing the results of interest.
​

(p.489).

Then in the same section, in subsection 11.3.2 (Case B temperatures), p.504, it says: "The following beam and girder failures occurred: [...] On Floor 13 (Figure 11-35), all four of the north-south girders attached to Columns 79, 80, and 81 had failed, due to either buckling or girder walk off of the bearing seat at Columns 79 and 81".

Note that they are not mentioning here the precise mechanism that caused the failure; in the context of a section that reports the results of the ANSYS analysis, the only possible meaning of their words is that they are saying that the FEA produced that result. Nothing more, nothing less. This necessarily means that by that time, the distance between the girder's center and the seat's center at the point where the girder and the seat were when the failure occurred, exceeded a certain predetermined distance, as that's the criterion for determining if that girder walks off the seat or not. And that distance was monitored from ANSYS output, as I've already established above.

At no point in the report do they say that any beam expanded by 5.5" or 6.25". That claim doesn't exist in the report. That distance is indicated as "the distance for walk-off", not "the distance by which the beams expanded".

What they do mention, however, is that "[o]n Floors 10, 11, and 12 (Figure 11-32, Figure 11-33, and Figure 11-34), the girder between Columns 76 and 79 failed due to a tensile weld failure in the knife connection on the west side of Column 79. Temperatures in this region were less than 100 °C on these floors. The tensile force in the connection was due to an eastward lateral displacement of Column 79, which was primarily caused by thermal expansion of the girder between Column 76 and Column 79 at Floor 13". This NECESSARILY indicates a displacement of the seat to the east in ANSYS. No way around it. The girder between 76 and 79 was next to the seat.

So, that's primarily what NIST is saying here: that the simulation showed the girder walking off the seat. They don't point to exact reasons.

They proceed to interpret the results in the next section, 11.4: "DISCUSSION OF RESULTS". They repeat this (p.525, top): "By 4.0 h of heating, there was substantially more damage in the WTC 7 structural system, particularly the loss of lateral support to Column 79 after the failure of girder connections at Floors 10, 11, 12, and 13. [...] The girder between Columns 44 and 79 had walked off the bearing seat at Column 79 on Floor 13, and all 4 bolts had failed on Floor 14 and two to three bolts had failed on Floor 12 at this seated connection".

Later in this section, in page 527, they say: "Walk off occurred when beams that framed into the girders from one side thermally expanded and the resulting compressive forces in the beams pushed laterally on the girder from one side, sheared the bolts at the seated connection, and then continued to push the girder laterally until it walked off the bearing seat". Note that it doesn't say what happened to the seat. That sentence is followed by: "A girder was considered to have lost vertical support when its web was no longer supported by the bearing seat. The bearing seat at Column 79 was 11 in. wide. Thus, when the girder end at Column 79 had been pushed laterally at least 5.5 in., it was no longer supported by the bearing seat". That distance was later corrected to 6.25 in.

Note that:
1. They don't say that the beams expanded that much. They only say that when that situation happened, the girder would no longer be supported.
2. This is an interpretation of the results, not the results themselves.
3. For discussion purposes, it's reasonable to consider that since the column displaced east, they are talking about the main factor that displaced the girder from the seat and not each and every factor.

The mention to the displacement of the column comes in the paragraph next to it: The temperature of the girder between Columns 76 and 79 on Floor 13 was sufficient to displace Column 76 to the west and Column 79 to the east. The forced displacements at Floors 10, 11, and 12 created a tensile load in the girder knife connections to the columns, and failed the connection fillet weld to the column". Note how they mention column 79 displacing east.

So, are they guilty of not being specific enough about the pushing of the column to the east, as they said happened in the simulation, in the fragment of the discussion related to the girder walk-off? Yes, definitely. That doesn't invalidate the report, however. That's focusing too much in the primary cause and forgetting about the secondary ones, that certainly happened. But they are not lying or misrepresenting the primary cause of the failure. That also does not invalidate the initiating event experienced in their FEA in any possible way.

Hope I have made the point clear enough to you.

Thanks for the well-structured and sourced summary!

#oysteinbookmark

 

[jaydeehess]

We haven't started to discuss LSDYNA. The link I posted shows the reasons for the ANSYS simulation to omit the element in question you are referring to.

I'll admit to start discussing LSDYNA, as soon as you admit the seat moved east and therefore the distance the beams needed to push the girder in order to cause walk-off is reduced. Do you admit this? If so, we can move on to the next chapter.

If not, I won't admit to this gish-gallop.

According to NIST the column did not become laterally unstable until the girder had failed and the floors had began to fail. It would follow that in NISTs initiating event that any lateral movement that they supposed in the column could not contribute to the failure of the C79-44 girder.

Did you somehow misunderstand the scenario?

Col79 displaced in one direction, the girder in the other. The combination of this results in the girder not being supported by the seat on col 79.
Do you or do you not acknowledge col 79 displacement?