Failure mode in WTC towers

[GregoryUrich]

Major Tom has, after a review of 100s and 100s of photos, pointed out that columns (both external annd internal) showing member failure (rupture or buckling) represent a very small minority compared to columns failing at their connections (i.e. welds amd bolts). If there was consensus on this issue it would greatly help further the discussion.

I think it would be useful to split the discussion between collapse initiation and the rest of the collapse. Collapse initiation involved less than 3% of the total number of column members (i.e 3 story, whole pieces of steel or external panels with which the vertical supporting structure was assembled during construction). The rest of the collapse involves the other (more than 97%) column members.

For the 97% question:

If member buckling is an important failure mode then I suggest at least half of the photos should show this. We have seen a number of buckled columns but they are still seem to be a very small minority. If the available photos cover only 10% of the members, we should be able to find 75 different buckled core columns and at least 200 buckled external panels.

Personally I have looked at 100s and 100s of photos, essentially randomly on many different sites and in Joel Myerowitz's book. I haven't seen very many examples of member failure either. Is this really an issue? Or are we just not understanding one another?

My suggestion is that, if there are people opposing this conclusion, to do an honest random sample of 50-100 photos and report back with numbers and sources. We will need to agree on what member failure as opposed to connection failure looks like.

 

[R.Mackey]

Major Tom has been pestering us with this nonsense for some time. Please don't be an enabler.

In answer to your question, however, it does appear that the majority of structural members suffered relatively little deformation. "Appear" is a weasel word, however. NIST reported that they had difficulty finding any members at all that didn't exhibit at least some deformation.

This is entirely consistent with buckling failure of steel members, fracturing or separating at the connections, and thus entirely consistent with any standard model of collapse.

 

[Myriad]

For the 97% question:

If member buckling is an important failure mode then I suggest at least half of the photos should show this.

Can you show the calculations that lead you to suspect this? Specifically, why is buckling in the form of elastic bending followed by weld failure ruled out? Why is buckling in the form of a small degree of inelastic bending, not readily apparent in photographs, followed by weld failure, ruled out?

No one answered my question about this column before (probably because the link I used for it didn't work correctly; it was redirected by an anti-hotlinking measure even though it was an ordinary link, not a hotlink):

Referring to the huge horizontal box column behind the workman (and ignoring the obviously buckled I-beams): is it straight? What does a straightedge placed over the image show?

Respectfully,
Myriad

 

[Reality Believer]

This sounds like a conversation for a civil / structural engineering board. Where is the conspiracy topic?

 

[Major_Tom]

Myriad, we see a slight bending. No need for a straight-edge.

NIST reported that they had difficulty finding any members at all that didn't exhibit at least some deformation.

I find that claim interesting.

It doesn't take a genius to see that this is not true.

 

[GregoryUrich]

Can you show the calculations that lead you to suspect this? Specifically, why is buckling in the form of elastic bending followed by weld failure ruled out? Why is buckling in the form of a small degree of inelastic bending, not readily apparent in photographs, followed by weld failure, ruled out?

No one answered my question about this column before (probably because the link I used for it didn't work correctly; it was redirected by an anti-hotlinking measure even though it was an ordinary link, not a hotlink):

[qimg]http://www.internationalskeptics.com/forums/imagehosting/13012479bb6d0c17d5.jpg[/qimg]

Referring to the huge horizontal box column behind the workman (and ignoring the obviously buckled I-beams): is it straight? What does a straightedge placed over the image show?

Respectfully,
Myriad

When I think of member failure, I think of member ruptures, fractures or bending 30 degress or more, which should be fairly easy to see. I'm not really sure if this is standard terminology. Maybe Mackey can comment on this.

I am not ruling out buckling in the form of elastic bending or even some inelastic bending followed by weld or bolt connection failure. I think we can safely say though that there is a very small proportion of member failure in the columns as opposed to connection failure. This can be contrasted with a higher proportion of member failure in horizontal members as opposed to connection failure. I think this is an important piece of the puzzle in understanding how this building failed.

I don't think the column you point to in the photo appears to have member failure. Is it bent? I don't know. I think cameras will play tricks on us if we try to use a straight edge because of depth of field and foreshortening effects.

 

[GregoryUrich]

This sounds like a conversation for a civil / structural engineering board. Where is the conspiracy topic?

As this has bearing on the collapse of the WTC towers I think it is clearly under the correct topic. Not every thread is for everyone.

 

[GregoryUrich]

Major Tom has been pestering us with this nonsense for some time. Please don't be an enabler.

In answer to your question, however, it does appear that the majority of structural members suffered relatively little deformation. "Appear" is a weasel word, however. NIST reported that they had difficulty finding any members at all that didn't exhibit at least some deformation.

This is entirely consistent with buckling failure of steel members, fracturing or separating at the connections, and thus entirely consistent with any standard model of collapse.

When I think of member failure, I think of member ruptures, fractures or bending 30 degress or more, which should be fairly easy to see. I'm not really sure if this is standard terminology. Surely there is some accepted, more rigorous definition.

I am not ruling out buckling in the form of elastic bending or even some inelastic bending followed by weld or bolt connection failure. I think we can safely say though that there is a very small proportion of member failure in the columns as opposed to connection failure. This can be contrasted with a higher proportion of member failure in horizontal members as opposed to connection failure. I think this is an important piece of the puzzle in understanding how this building failed.

I still don't see how this is evidence of PNAC (Pre-planned Nefariously Assisted Collapse--coined by jhunter, refined by your's truly).

 

[Brainache]

I'm not sure I can see the argument here. Are you talking about a majority of the collumns from the floors where the collapse initiated, or a majority of collumns from the whole towers?

Don't the fires and sagging floor trusses only need to bend enough collumns so that the loads on the remaining ones exceed the strength of the welds to make them break at the weakest point? And once that top part starts falling, the only things stopping it from hitting the ground are the connections of the lower floors to the core and the outer shell.
Is there something significant here that I'm missing?(in case you haven't guessed, I'm not an engineer)

 

[Reality Believer]

As this has bearing on the collapse of the WTC towers I think it is clearly under the correct topic. Not every thread is for everyone.

What I don't understand is the point of this pedantic back and forth about how many seconds this, calculate that. What is the end game here? To prove CD? Seems kind of ridiculous to do this by proving the building fell down. We already know this happened.

Suppose you convince yourself and everyone here that the collapse is anomalous. Now what? What is the next question? Unless the next question can be proven plausible, then an anomalous collapse is just that and nothing more.

Cut to the chase man! Prove CD by showing direct evidence of CD materials, men, methods and opportunity.

 

[gumboot]

It seems to me there are numerous individuals who feel the NIST investigation is flawed, and are trying to pick holes in the tiny details. They don't appear to actually be willing to directly refute NIST's claim that fires and structural damage caused the collapse of the WTC.

Personally I don't see how such debates relate to 9/11 Conspiracy Theories. Frankly I'm sick and tired of this "if I pick enough holes the whole thing will be refuted" approach. And something like the NIST reports are so extensive and complex, there's ample space for hole picking. If you're discussions do not specifically relate to alternative explanations for the overall cause of the 9/11 attacks (rather than arguing over whether the buildings collapsed in 18 seconds or 17.5 seconds) then your discussion does not belong in this sub forum.

 

[R.Mackey]

When I think of member failure, I think of member ruptures, fractures or bending 30 degress or more, which should be fairly easy to see. I'm not really sure if this is standard terminology. Surely there is some accepted, more rigorous definition.

That terminology works for me... The majority of what we see have connection and weld failures, however the pieces left over are not actually undamaged, but are apparently bent a couple of percent out of true. Not enough to see in photographs but evident to investigators.

I am not ruling out buckling in the form of elastic bending or even some inelastic bending followed by weld or bolt connection failure. I think we can safely say though that there is a very small proportion of member failure in the columns as opposed to connection failure. This can be contrasted with a higher proportion of member failure in horizontal members as opposed to connection failure. I think this is an important piece of the puzzle in understanding how this building failed.

I still don't see how this is evidence of PNAC (Pre-planned Nefariously Assisted Collapse--coined by jhunter, refined by your's truly).

Me either. Far be it from me to inhibit discussion, I just want you to be aware of what you're getting into with Major Tom. He has a website where he claims this is proof of his own brand of explosives-planted-all-over-the-place, and that's just silly.

I tend to think this observation biases us towards fracture, shattering and shearing connections without dissipating much energy in the columns themselves -- not quite ala Cherepanov, since at least early in the collapse waves would have been torsional rather than planar, but not completely different from his proposal either. Seffen's paper gives some pretty good insights into the local mechanics with his own candidate mechanism.

I also think this is one of the reasons why the structure didn't generate full power in opposing the collapses, and that's why your revised calculation of ~20 seconds is a bit high compared to the observation of ~15 seconds for the "crush-down" portion.

 

[GregoryUrich]

What I don't understand is the point of this pedantic back and forth about how many seconds this, calculate that. What is the end game here? To prove CD? Seems kind of ridiculous to do this by proving the building fell down. We already know this happened.

Suppose you convince yourself and everyone here that the collapse is anomalous. Now what? What is the next question? Unless the next question can be proven plausible, then an anomalous collapse is just that and nothing more.

Cut to the chase man! Prove CD by showing direct evidence of CD materials, men, methods and opportunity.

I see your point, but I don't think there is any reason to investigate CD unless the collapse can be shown to be anomalous. Furthermore, I have no means of investigating or proving CD and I am not interested in fantasizing some conspiracy scenario. Since I am not satisfied with the explanations provided to date, I continue to investigate. Why do so many people seem to have a problem with that?

 

[gumboot]

I see your point, but I don't think there is any reason to investigate CD unless the collapse can be shown to be anomalous. Furthermore, I have no means of investigating or proving CD and I am not interested in fantasizing some conspiracy scenario. Since I am not satisfied with the explanations provided to date, I continue to investigate. Why do so many people seem to have a problem with that?

I don't think they have a problem with that. They simply have a problem with it being discussed in this sub forum. This is not a "September 11" sub forum. This is a Conspiracy Theory sub forum.

 

[GregoryUrich]

I don't think they have a problem with that. They simply have a problem with it being discussed in this sub forum. This is not a "September 11" sub forum. This is a Conspiracy Theory sub forum.

Does this topic have no bearing on conspiracy theories surrounding 9/11?

 

[Reality Believer]

I don't think they have a problem with that. They simply have a problem with it being discussed in this sub forum. This is not a "September 11" sub forum. This is a Conspiracy Theory sub forum.

What I really mean is there is no purpose to the minutia of structural analysis by amature investigators who have no access to the original evidence. Like I said before, what is the next question? If the next question is not plausible, then the first question is moot.

 

[Myriad]

When I think of member failure, I think of member ruptures, fractures or bending 30 degress or more, which should be fairly easy to see. I'm not really sure if this is standard terminology. Maybe Mackey can comment on this.

I am not ruling out buckling in the form of elastic bending or even some inelastic bending followed by weld or bolt connection failure. I think we can safely say though that there is a very small proportion of member failure in the columns as opposed to connection failure. This can be contrasted with a higher proportion of member failure in horizontal members as opposed to connection failure. I think this is an important piece of the puzzle in understanding how this building failed.

No disagreement there, because you're being careful to distinguish between member failure and connection failure, two very specific failure modes. Meanwhile, though, Major Tom (in the parent thread) was claiming, basically, "NIST must be lying about the structure having buckled because most columns look straight in photographs" and I was partially responding to that.

I don't think the column you point to in the photo appears to have member failure. Is it bent? I don't know. I think cameras will play tricks on us if we try to use a straight edge because of depth of field and foreshortening effects.

You mean, you can't just look at a photograph and tell for certain whether a column is straight or bent? Wow, you could knock me over with a feather! I had no idea!

Major Tom, are you paying attention?

Respectfully,
Myriad

 

[gumboot]

Does this topic have no bearing on conspiracy theories surrounding 9/11?

Well no. Not as far as I can tell. What do you think? If you feel it does have relevance perhaps you'd be so good as to explain what that relevance is?

 

[Major_Tom]

the structure couldn't have buckled because most columns look straight in photographs" and I was partially responding to that.

I believe Gregory started this thread because collapse initiation comments were taking his original thread in an ambiguous direction?

Myriad, I mentioned that buckling was obviously not the main collapse mechanism in the core or the perimeter.

This is because we aren't seeing many buckled columns in the rubble.


Collapse initiation may, and probably does, involve a different mechanism.

If allowed, I'd like to put forth and discuss certain curious phenomena witnessed during collapse initiation and just after these initial moments.

A collapse continuation mechanism involving "assisted weld failure" as opposed to weld failure may also be another parallel topic for this thread.

 

[GregoryUrich]

No disagreement there, because you're being careful to distinguish between member failure and connection failure, two very specific failure modes. Meanwhile, though, Major Tom (in the parent thread) was claiming, basically, "NIST must be lying about the structure having buckled because most columns look straight in photographs" and I was partially responding to that.

You mean, you can't just look at a photograph and tell for certain whether a column is straight or bent? Wow, you could knock me over with a feather! I had no idea!

Major Tom, are you paying attention?

Respectfully,
Myriad

You can tell member failure from connection failure though.