Total Building Collapse from a Single Column Failure

[ozeco41]

...It is hard to understand why some here simply can't accept that the NIST WTC 7 report has been shown to be in serious error.

It's not hard.

1) There is nothing to "accept";
2) The report has not been shown to be in error;
3) It follows that it cannot be "in serious error".

BTW if you ever do show that it is in error how do you propose to show that the error is serious?

A minor detail that has zero effect on the main findings?

 

[LSSBB]

It's not hard.

1) There is nothing to "accept";
2) The report has not been shown to be in error;
3) It follows that it cannot be "in serious error".

BTW if you ever do show that it is in error how do you propose to show that the error is serious?

A minor detail that has zero effect on the main findings?

It's the missing inch, don't you see???? And the stiffeners, the stiffeners! (for some reason...)

My calculations! Prove something wrong with my calculations! I bet you can't! I have defeated the mighty NIST! Why aren't you listening??

What's that? Something about as built, other forces, unknown internal state, test results contrary to my calculations, this is all just a computer simulation to determine a likely mechanism? Blah blah blah blah blah. I have calculations and numbers, why are you ignoring them? Why?????

 

[ozeco41]

It's the missing inch, don't you see????

Actually no I don't see:

I have a box in front of me on my table. It is 11" wide. If I push it a smidgen over 5.5" over the edge of the table it will fall off.

Do you understand that? Great.

Now the hard bit. If the box was 13" wide how far would I need to push it so it fell off? You say 6.5" - great. Well done!!!

Do you understand that 5.5" wouldn't make it fall off?

Even better - go to the head of the class.

And the stiffeners, the stiffeners! (for some reason...)....

I run my own mail server - historic reasons. Means I have to tune my own spam filter - no ISP behind me doing the bulk filtering.

So I've just about eliminated all the spam mail offering stiffeners.

Its amazing how many different ways you can spell "viagra" and still leave the word recognisable.

 

[Tony Szamboti]

Actually no I don't see:

I have a box in front of me on my table. It is 11" wide. If I push it a smidgen over 5.5" over the edge of the table it will fall off.

Do you understand that? Great.

Now the hard bit. If the box was 13" wide how far would I need to push it so it fell off? You say 6.5" - great. Well done!!!

Do you understand that 5.5" wouldn't make it fall off?

Even better - go to the head of the class.

If you believe what you are saying here then you actually don't understand, as you are still thinking in roll-off of the girder terms with your box analogy, where the box would tilt and fall when its Cg was beyond the edge of the table.

In the case of the beam and girder assembly, in the northeast corner of WTC 7, it has been shown that the girder would not tilt and fall when its Cg is beyond the edge of the seat because the beams restrain it. There it is the Cg of that assembly which is operative, and it is in the middle of the floor area under the beams, and far from the edge of the bearing seat, so this is not about a gravity caused drop in the sense of an unsupported Cg.

The above is why NIST claimed structural failure of the girder's flange when the web was past the seat, not because the girder's Cg was past the seat. However, with the stiffeners on the girder the flange does not fail and the walk-off distance is much greater than half the width of the bearing seat. So it is not an inch we are talking about here, but more like four to five inches or nearly double the possible distance the girder could be pushed by the beams.

Why do you think the stiffeners on the girder were omitted from the NIST WTC 7 analysis? Do you really think it was just an oversight or minor error?

 

[NoahFence]

In the case of the beam and girder assembly, in the northeast corner of WTC 7, it has been shown that the girder would not tilt and fall when its Cg is beyond the edge of the seat because the beams restrain it. There it is the Cg of that assembly which is operative, and it is in the middle of the floor area under the beams, and far from the edge of the bearing seat, so this is not about a gravity caused drop in the sense of an unsupported Cg.

And if those beams were compromised as well?

 

[Animal]

If you believe what you are saying here then you actually don't understand, as you are still thinking in roll-off of the girder terms with your box analogy, where the box would tilt and fall when its Cg was beyond the edge of the table.

In the case of the beam and girder assembly, in the northeast corner of WTC 7, it has been shown that the girder would not tilt and fall when its Cg is beyond the edge of the seat because the beams restrain it. There it is the Cg of that assembly which is operative, and it is in the middle of the floor area under the beams, and far from the edge of the bearing seat, so this is not about a gravity caused drop in the sense of an unsupported Cg.

Only when you hand wave away so much additional information that has been shown to refute this absurd claim.
Such as.....


The temperature of the girder between Columns 76 and 79 on Floor 13 was sufficient to displace Column 76 to the west and Column 79to the east
(pg 527 NIST NCSTAR 1-9)

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 welds to the column. (pg 527 NIST NCSTAR 1-9)

"Connection damage was typically gradual, with bolts and/or welds failing sequentially over time."
(pg 490 NIST NCSTAR 1-9)

The above is why NIST claimed structural failure of the girder's flange when the web was past the seat, not because the girder's Cg was past the seat. However, with the stiffeners on the girder the flange does not fail and the walk-off distance is much greater than half the width of the bearing seat. So it is not an inch we are talking about here, but more like four to five inches or nearly double the possible distance the girder could be pushed by the beams.

Why do you think the stiffeners on the girder were omitted from the NIST WTC 7 analysis? Do you really think it was just an oversight or minor error?

IT is neither.....it is the same reason why they added a stiffener plate to the girder seat.

 

[Newtons Bit]

The full 130 kip load on the girder is not on the column 79 side, only half of it (65 kips). The girder has to fall before the column 44 side can be pulled from between the flanges of the column and that side is supported at that point.

Even if it were the full 130 kips it wouldn't matter as the factors of safety are well above 2 in all cases at 600 degrees C.

Additionally, I would hope you realize it is only one beam which shows a roll-off is a non-starter even at elevated temperature. At least several beams would have been involved, so the margin of safety against it, even at elevated temperature, is quite large.

It is the gravity load of the girder which would be involved in generating the moments and the failure modes. Any pushing by the beam is not involved in shear tearout of the upper bolt hole, or shear of that bolt, or the top welds on the fin plate, once the girder's Cg is past the edge of the bearing seat as the loads are in the opposite direction.

Now that the notion of a roll-off has been shown to be so far removed as to be ridiculous, it is the omitted stiffeners which give the NIST report its problems. Why don't you try to address that instead of bringing things up which aren't even feasible?

It is hard to understand why some here simply can't accept that the NIST WTC 7 report has been shown to be in serious error.

And why aren't you including the reaction from the beams in your calc? You're treating it as a fixed-end-reaction, yet neither the moment nor the shear from the beam is in your calc. Why is that?

 

[ozeco41]

If you believe what you are saying here then you actually don't understand, as you are still thinking in roll-off of the girder terms with your box analogy, where the box would tilt and fall when its Cg was beyond the edge of the table....

Tony my post was directed at LSSBB - I know from experience that he can process analogies. I'm well aware that you do not process analogies nor engage in reasoning. Your trademark response to reasoned argument is "blah blah blah" or similar. Hence you show no comprehension of my analogy of what NIST actually said about the half of 11" or 12" issue.

That is one of the key reasons why your arguing of details is either in error or does not prove what you claim.

Why do you think the stiffeners on the girder were omitted from the NIST WTC 7 analysis? Do you really think it was just an oversight or minor error?

You should know by now that I will not fall for reversed burden of proof. YOU are the one claiming NIST is wrong - not me. YOUR claim - you prove it. So far you haven't and it is a long while since I showed you why.

What I think is irrelevant. I am under no obligation to do your homework for you. Nor is my opinion of the technical issue under debate. I have once again shown that your claims are not legitimately supported. Ball in your court as ever.

 

[tsig]

The full 130 kip load on the girder is not on the column 79 side, only half of it (65 kips). The girder has to fall before the column 44 side can be pulled from between the flanges of the column and that side is supported at that point.

Even if it were the full 130 kips it wouldn't matter as the factors of safety are well above 2 in all cases at 600 degrees C.

Additionally, I would hope you realize it is only one beam which shows a roll-off is a non-starter even at elevated temperature. At least several beams would have been involved, so the margin of safety against it, even at elevated temperature, is quite large.

It is the gravity load of the girder which would be involved in generating the moments and the failure modes. Any pushing by the beam is not involved in shear tearout of the upper bolt hole, or shear of that bolt, or the top welds on the fin plate, once the girder's Cg is past the edge of the bearing seat as the loads are in the opposite direction.

Now that the notion of a roll-off has been shown to be so far removed as to be ridiculous, it is the omitted stiffeners which give the NIST report its problems. Why don't you try to address that instead of bringing things up which aren't even feasible?

It is hard to understand why some here simply can't accept that the NIST WTC 7 report has been shown to be in serious error.

OK the NIST report is wrong, now you tell us what happened.

Give us your account of why the building collapsed.

 

[LSSBB]

Why do you think the stiffeners on the girder were omitted from the NIST WTC 7 analysis? Do you really think it was just an oversight or minor error?

Neither.

You are neglecting there are other, legitimate reasons, Tony. It has been mentioned time, and time again.

They were omitted for purposes of the simulation. Simplifying assumptions are often made for purposes of the simulation.

 

[Newtons Bit]

Tony Szamboti:

I think you should run a torsion calc on the wide-flange girder with 65kip*in on it and get back to us. It's non-trivial, but programs like Enercalc can do it for you.

 

[Porkpie Hat]

True.

The "big picture" is simple:

1) WTC7 did in fact collapse;
2) There was no CD.
3) NIST has suggested a plausible mechanism. Truthers disagree but cannot put forward plausible reasons.

It really is quite simple!

The model can only support the use of knowns to answer the question of what plausibly could have caused global collapse.

 

[Porkpie Hat]

That's a very interesting point, and one I hadn't twigged before.

TS claims the EP collapse was a separate issue, yet hasn't considered the falling debris and/or load transfers as having anything to do with the Col 79 issue here.

But then, we have to consider the fact that he once claimed the EP was *deliberately* dropped early, by CD, so that "It wouldn't fall off the side". It would be a breach of the MA to suggest we're debating a loon. You might very well think that, I couldn't possibly comment.

And perhaps it didn't have any impact on the failure of column 79 in the end, but we have no way of knowing that for sure which renders any absolutes regarding the possiblity mute.

 

[Porkpie Hat]

And if those beams were compromised as well?

Unpossible!

 

[Grizzly Bear]

OK the NIST report is wrong, now you tell us what happened.

Give us your account of why the building collapsed.

His conclusion is already known. He needs to tell us the relevance this has to it. He apparently has some mysterious insight on the relevance to CD that we lack.

 

[Newtons Bit]

Does anybody have the imposed dead and live loads for the floor in this area that NIST used?

 

[Tony Szamboti]

Tony Szamboti:

I think you should run a torsion calc on the wide-flange girder with 65kip*in on it and get back to us. It's non-trivial, but programs like Enercalc can do it for you.

Edited by kmortis: 

Removed personal comment

If you really think there is any possibility of a "roll-off" of the girder, I think you should show calculations to back that up. I don't see any possible way for the girder to "roll-off", as the beams and their connections to the girder would have restrained the girder.

 

[Tony Szamboti]

Does anybody have the imposed dead and live loads for the floor in this area that NIST used?

The floor loads for WTC 7 are given in NIST NCSTAR 1-9 Chapter 11.2.7.

 

[Tony Szamboti]

Neither.

You are neglecting there are other, legitimate reasons, Tony. It has been mentioned time, and time again.

They were omitted for purposes of the simulation. Simplifying assumptions are often made for purposes of the simulation.

Sure the stiffeners were omitted as a simplifying assumption, and there is a bridge in Brooklyn for sale.

When making simplifying assumptions in structural analyses you aren't supposed to omit anything that would have a significant effect on the results. The stiffeners certainly would have had a very large effect, as in a diametrically opposed conclusion regarding whether or not the girder could have walked off its seat.

It is also customary to sate what you have left out of the model and the stiffeners aren't mentioned anywhere in the report. How come?

Why doesn't Figure 8-21 in NCSTAR 1-9 show them?

 

[thedopefishlives]

Sure the stiffeners were omitted as a simplifying assumption, and there is a bridge in Brooklyn for sale.

When making simplifying assumptions in structural analyses you aren't supposed to omit anything that would have a significant effect on the results. The stiffeners certainly would have had a very large effect, as in a diametrically opposed conclusion regarding whether or not the girder could have walked off its seat.

You have yet to demonstrate this supposed "significant" effect. Nor can you demonstrate that the absence is due to anything other than a simplifying assumption, as was stated in the report. If you think NIST is lying, show your proof.