Critical Errors and Omissions in WTC7 Report Uncovered

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gerrycan

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What was that exactly? Just the "beams would not expand enough", or a more general "NIST were wrong" of "collapse is impossible" point?

Not trying to be snarky, but it would be best to simply state what assertion you think has been proven.

I believe they heated the concrete in the full sized simulations. This was just a mode-of-failure simulation to see what would happen in detail with the steel heating.
I wasn't being snarky, honestly. I was trying to be humerous. I think we're done here anyway. May start another thread at some point. Nice debate though. Thank you.
 

Mick West

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Hmm, doesn't feel done to me. What about pivoting at C44? Uneven heating order? Turning moment from those two things? Girder Expansion?

And why wouldn't the girder heat slower? It's not in the same spot, and it's bigger.
 

gerrycan

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Just quickly on that, I think i saw you post somewhere that these were not moment resisting connections, which they are of course. I may be thinking of someone else,apologies if i am. Also, interesting when you do the calculation on the expansion of the girder at 500C it looks like it will go into compression and expand into the gap at column 79 and be stuck there with the sideplates (not stiffeners) that are attached to the column preventing lateral shift. I think the inaccuracy of NISTs analysis has been illustrated well throughout this thread. As for the column 44 connection, that is one tight connection. It isn't going anywhere. Look at the shape of the girder. The wind girders (which are the cross braced members from your earlier post re pics of shear studs in the rubble) are not going to shift, and as NIST said, these are taken to be infinately strong in their analysis, hence our allowance for expansion only toward the inside of the building, and not outward.
 

Mick West

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As I understood it pretty much all connections are moment resisting to a degree, unless it's a hinge. But wouldn't that mean they had some significant non-shear resistance to twisting in the horizontal plane? Like:


The interior connections of the WTC would not really be considered a moment frame, would they?
 
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gerrycan

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As I understood it pretty much all connections are moment resisting to a degree, unless it's a hinge. But wouldn't that mean they had some significant non-shear resistance to twisting in the horizontal plane? Like:


The interior connections of the WTC would not really be considered a moment frame, would they?

Absolutely they would. Apart from anything else the welding marks should tell you that. Best way to think of a moment connection is like 2 planks of wood joined with one nail initially, They will still move independently of each other. Put another nail in and they won't. Over simplification, but I think you will see what I mean in terms of axial shift.
 
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MÆST

New Member
Absolutely they would. Apart from anything else the welding marks should tell you that. Best way to think of a moment connection is like 2 planks of wood joined with one nail initially, They will still move independently of each other. Put another nail in and they won't. Over simplification, but I think you will see what I mean in terms of axial shift.

Mick West is correct here. The connections from beam to girder or girder to to column are typically shear connections. Now just about all connections, even so called shear connections, will resist some moment, but we engineers have specific connection details in mind when we refer to moment connections. The seated connection was designed only for shear and modern analysis techniques should assume no ability to resist moments. Moment connections are used to resist lateral loads (wind/earthquake). There are steel moment frame options, but in this building, the concrete core was likely used to resist lateral loads.

I don't know about all the specifics of this controversy, but I'd be happy to answer any specific questions from a structural engineer's perspective. Feel free to PM me and draw attention to relevant posts.
 
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Jazzy

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when you do the calculation on the expansion of the girder at 500C it looks like it will go into compression and expand into the gap at column 79 and be stuck there with the sideplates (not stiffeners) that are attached to the column preventing lateral shift.
It depends what movements preceded it. It may have been pulled outward from its fixings by a particularly intense fire diametrically opposite on that floor causing the beams there to buckle and sag, and then start pulling. Until you consider the timeline and course of the fire you cannot say.

I think the inaccuracy of NISTs analysis has been illustrated well throughout this thread.
Throughout this thread you have neither fully appreciated what NIST was saying, not have you provided so full an evaluation of what occurred.

As for the column 44 connection, that is one tight connection. It isn't going anywhere. Look at the shape of the girder.
The shape of the column 44 may remain the same, yet its centerline may well no longer be where it should. Bulk expansion of that local volume of the structure may well have caused it to travel. But you don't consider it.

The wind girders (which are the cross braced members from your earlier post re pics of shear studs in the rubble) are not going to shift, and as NIST said, these are taken to be infinitely strong in their analysis, hence our allowance for expansion only toward the inside of the building, and not outward.
The whole shell of the building was relatively cold for most of the fire. It would have been tensioned by the expansion within it. It would therefore have put most of the structure bound within it in compression.

Gerrycan said:
The steel would conduct the heat away over time, and i also think that 100 degree of difference between the beams and the girder is unrealistic. As is the failure to heat up the concrete, which sets up a differential thermal expansion, putting an unrealistic force on the studs. Also, the failure to include the floor pan is just preposterous. The difference that heating the steel up gradually, as would happen in the real world is that the steel, being highly conductive would wick the heat away, as it conducts.
Answered by:
Heat can hardly "wick away" to regions already up to the same temperature.

The title you chose for the thread: "Critical Errors and Omissions in WTC7 Report Uncovered" is false on all counts.

a) You claimed NIST's beam expansion figure was critical. But it was never critical. NIST claimed that it was a COMBINATION (of that expansion and the movement of other parts of the structure) that was critical, and THEY NEVER CLAIMED OTHERWISE.

b) The corrections to the "omissions" arrived at a later date, apparently. Were you going to mention that if it hadn't been mentioned first?

c) Also FALSE because it was a vehicle for all the false claims you have made, both about NIST, and also about me. (But you couldn't do it with Mick because he didn't allow you the purchase, so-to-speak). But you would have done so had he done so.

But this finished you off:

Mick said:


So where is the long expansion needed?

And it's no wonder you want to finish this thread...

But I'm still looking for your answers to my questions.
 
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gerrycan

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Sure, I would welcome that, and also your opinion as to the topic of this thread generally, as every structural engineer I know agrees with me on this once they look at the detail. Here is the connection detail here :-

9114rr.jpg
Here is the detail to the column :-
1091.jpg

And this is a wind girder connection to compare, this is from the K3004 beam at column 38 which runs from there to 79.
E12/13 is the relevant frame plan and is on the thread already. I presume there isn't any dispute over the moment resisting issue at the wind girder, I say this is moment resisting also at 79.
 

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gerrycan

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Feel free to PM me and draw attention to relevant posts.
Would you be willing to discuss this on a conference call? We will make ourselves available whenever you like. Thank you for your input on this topic. As I said before, most debunkers won't touch this issue, let alone SE's. If you do not have enough of an interest to want to do this, let me know how much your time would cost, and I will arrange that.
 

Jazzy

Closed Account
Sure, I would welcome that
Then I suggest you begin answering.

and also your opinion as to the topic of this thread generally
I have already just given you that.

as every structural engineer I know agrees with me on this once they look at the detail.
Well, I'm an industrial designer, prior to that an aeronautical engineer, and I would agree with you too, on the information you offer. It's just that that isn't all the information that one needs.

One needs to know the rest of the structure that surrounded it, where and when the fire was in that area (and the floors above and below it).

One also needs to read for oneself the NIST Report because you have consistently misrepresented it.

I presume there isn't any dispute over the moment resisting issue at the wind girder, I say this is moment resisting also at 79.
Wind girders surrounded the area. They would resist the expansion due to fire wherever they were forced to, adding to the compressive forces forcing slab sagging, stud failures, and beam buckling.
 

gerrycan

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Jazzy, I looked at the page before I logged in and see you are typing responses to me. I have you on ignore. Just don't want you wasting your time. Not interested in your input. Sorry
 

Jazzy

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Jazzy, I looked at the page before I logged in and see you are typing responses to me. I have you on ignore. Just don't want you wasting your time. Not interested in your input. Sorry
That's a match for my interest in your output, then. Ignore all you like. I'll tot up the questions you don't answer (Forty so far, but maybe a few repeats in there). We'll both be happy. There's no need to be sorry.
 
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Cairenn

Senior Member.
Well, I think that means that I can do the same to Gerrycan, since it seems that he wants to pontificate and not discuss his points with someone that can demolish them.

Gerrycan, Jazzy has a professional background in this area, I can not understand why anyone interested in the facts would put him on ignore.
 

gerrycan

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Well, I think that means that I can do the same to Gerrycan, since it seems that he wants to pontificate and not discuss his points with someone that can demolish them.

Gerrycan, Jazzy has a professional background in this area, I can not understand why anyone interested in the facts would put him on ignore.
Cairenn, the thread has kind of run its course to be honest, the point has been made that NISTs explanation of thermal expansion of beams to the east of column 79 is not credible. I will happily engage Jazzy in other threads. He just wasn't adding anything meaningful to this one. All respect to Mick though, he did.
 

MÆST

New Member
Would you be willing to discuss this on a conference call? We will make ourselves available whenever you like. Thank you for your input on this topic. As I said before, most debunkers won't touch this issue, let alone SE's. If you do not have enough of an interest to want to do this, let me know how much your time would cost, and I will arrange that.

Sure, I would welcome that, and also your opinion as to the topic of this thread generally, as every structural engineer I know agrees with me on this once they look at the detail. Here is the connection detail here :-

9114rr.jpg
Here is the detail to the column :-
1091.jpg

And this is a wind girder connection to compare, this is from the K3004 beam at column 38 which runs from there to 79.
E12/13 is the relevant frame plan and is on the thread already. I presume there isn't any dispute over the moment resisting issue at the wind girder, I say this is moment resisting also at 79.

I prefer the forum format but thanks for the interest. I don't have experience in structural forensics or fire engineering, but I do have a structural background and deal with steel structures at high temperatures so I may be of some limited usefulness. I'm inclined towards skepticism, but most of the 9/11 skeptics I have come across on the internet just don't have the technical background to make their case persuasively and they do more harm to their cause in the eyes of those with relevant expertise. I came across your concerns after seeing that Ben Swann video and was impressed with the quality and research that went into the questions raised ... not to mention and open dialog and mind.

That said, I'll look at detail 79. First, may I ask, what is the importance of the classification of this detail as moment resisting? I have read this thread, but may have skimmed past the discussion.

If you ask a structural engineer to classify the connection as either a shear or moment connection, they will say shear. If you get access to the AISC steel construction manual, there's a tab for shear connections and there's a section for unstiffened seated shear connections that looks very similar (standards may have changed since the mid-80's.) Another hint that the connection was designed and analyzed only for shear is that the detail gives only the reaction and capacity in kips and no moments are given. If inclined, I found a design example here - Example II.A-13.

That said, even shear connections resist some moment. You see that angle bolted to the top and say, yeah, if they cantilever that beam off a column, and you walked to the end, it'd hold your weight. That may be true, but connections classified as shear connections are detailed in a way to allow rotation and the moment capacity is so small as to be taken as zero in analysis. A true moment connection can be partially or fully restrained and frequently have the flanges of the beam complete joint penetration welded to the column. The top angle is for stability only and is not designed for any load. It is simply to keep the beam from having its top flange want to topple to the side in a behavior known as lateral torsional buckling. when a gravity load is loaded on the span

The 5 1/2" x 3/4" stiffener welded to the beam web is either there to prevent local failures in the web or bottom flange due to the high concentrated reaction load or again for rotational stability at the beam end. In summary, when the original engineer was designing this, he was not thinking about fires whatsoever and was just thinking about a beam sitting on a seat. All the other things going on here are standard practice for stability under normal gravity loading.
 

gerrycan

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I prefer the forum format but thanks for the interest. I don't have experience in structural forensics or fire engineering, but I do have a structural background and deal with steel structures at high temperatures so I may be of some limited usefulness. I'm inclined towards skepticism, but most of the 9/11 skeptics I have come across on the internet just don't have the technical background to make their case persuasively and they do more harm to their cause in the eyes of those with relevant expertise. I came across your concerns after seeing that Ben Swann video and was impressed with the quality and research that went into the questions raised ... not to mention and open dialog and mind.

That said, I'll look at detail 79. First, may I ask, what is the importance of the classification of this detail as moment resisting? I have read this thread, but may have skimmed past the discussion.

If you ask a structural engineer to classify the connection as either a shear or moment connection, they will say shear. If you get access to the AISC steel construction manual, there's a tab for shear connections and there's a section for unstiffened seated shear connections that looks very similar (standards may have changed since the mid-80's.) Another hint that the connection was designed and analyzed only for shear is that the detail gives only the reaction and capacity in kips and no moments are given. If inclined, I found a design example here - Example II.A-13.

That said, even shear connections resist some moment. You see that angle bolted to the top and say, yeah, if they cantilever that beam off a column, and you walked to the end, it'd hold your weight. That may be true, but connections classified as shear connections are detailed in a way to allow rotation and the moment capacity is so small as to be taken as zero in analysis. A true moment connection can be partially or fully restrained and frequently have the flanges of the beam complete joint penetration welded to the column. The top angle is for stability only and is not designed for any load. It is simply to keep the beam from having its top flange want to topple to the side in a behavior known as lateral torsional buckling. when a gravity load is loaded on the span

The 5 1/2" x 3/4" stiffener welded to the beam web is either there to prevent local failures in the web or bottom flange due to the high concentrated reaction load or again for rotational stability at the beam end. In summary, when the original engineer was designing this, he was not thinking about fires whatsoever and was just thinking about a beam sitting on a seat. All the other things going on here are standard practice for stability under normal gravity loading.

I agree with some of what you have said here re people doing more harm than good. I thought that the Ben Swan thing did a fair job generally for the time that he had, but didn't quite get the points across in the way I would have. That said, I would have probably still been there now prattling on about stiffeners and plates if it had been me, so given the time, and the average technical awareness of his target audience, I love what he did, and salute Tony for getting this info out there.
I am sure that given the chance Tony would have blown NIST even further out of the water, and i am sure he did off camera. I am well aware of what connection is what and do have access to the info that you cite above. And yes, things have changed a lot since the 80s.
As to the relevance of whether this is moment or not, it is going to resist anything that is getting thrown at it from expansion of beams to the east, and in that sense it is. I think to labour this point is not required for the purposes of this thread, or NISTs analysis, or indeed ours.
As far as the stiffeners are concerned, I have no interest as to intent on the original designers part, what matters here is the function that they would have served within NISTs sequence of events, and that function, hypothetical as it is, is as follows. As the girder is pushed just over 6" to the west the gravity load is no longer over the web and the full load then exerts onto the flange of the girder. This potential overstress is then redistributed from the flange, through the stiffener, back to the web, and in this way the 'walk off' distance is extended and the beam would not fail at 6.25" movement to the west, this figure originally being 5.5", and both being impossible from the thermal expansion of the floor system to the east. NIST could not have got this analysis from an FEA model as it just wouldn't happen in ANSYS or elsewhere. They deemed the element to have failed once it had moved to the halfway point, which is a howler of an error.
In our own analysis we estimated the walk off distance required for failure to be in excess of 9" which is about double that which would be possible. Also we allowed it to expand unrestrained. As for NIST seeing stud failure at 103C in the beam as per table 8-2 at 1.44s (Micks post#354), clarification of this will have to be sought from NIST, and i suspect another erratum and 'typo' confession will result from that, if there indeed is any reply, as such an occurrence is beyond the realms of reality, even for Mr Sunder. If this were possible, I would advise wearing a hard hat next time you boil a kettle inside a steel framed high rise, in case studs start to fall from above. ;)
Also, the stiffener plate is not just welded to the web, it is welded to the flange at 3/8", that flange also being clipped to the lower plate (pf).

It is great that you are looking at this also, and given that the info is somewhat new to you, if I can help at all in saving you the legwork of trawling through the drawings to find those relevant to the particulars of your research, please just ask, and I will do my best to help.
 

Grieves

Senior Member
That's a match for my interest in your output, then. Ignore all you like. I'll tot up the questions you don't answer (Forty so far, but maybe a few repeats in there). We'll both be happy. There's no need to be sorry.
Jazzy, you might want to revise your list a little. A fair deal of them aren't questions at all.
 

gerrycan

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WTC7 - The Stiffener Plates Explained
A brief explanation of the relevance and consequences of NISTs failure to include these elements in their analysis of the WTC7 collapse. This is designed to be a brief introduction to the issue.
 

Mick West

Administrator
Staff member
WTC7 - The Stiffener Plates Explained
A brief explanation of the relevance and consequences of NISTs failure to include these elements in their analysis of the WTC7 collapse. This is designed to be a brief introduction to the issue.

It's not complicated. You say that the stiffener plates mean that the beams don't fail if they are half way off the seat. So you claim the fail criteria used by NIST was incorrect.
 

gerrycan

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It's not complicated. You say that the stiffener plates mean that the beams don't fail if they are half way off the seat. So you claim the fail criteria used by NIST was incorrect.
Yeah, it's not complicated. Obviously because NIST referred directly to Frankel 1091 in their erratum statement, that means that they must have looked at the bill of materials on that sheet, which refers directly above to Frankel 9114 which has the side detail showing the stiffeners, so NIST can no longer claim ignorance to these elements and have no excuse for not using them in the LSDYNA. Actually it is kinda complicated. Bottom line, they presented a false report, which is a serious offense, and would have trouble reasonably claiming incompetence rather than negligence. This isn't new to you Mick?
Oh, and we now have done an FEA on the set up with the stiffeners added and that proves that they do make the difference that I said.
 

Mick West

Administrator
Staff member
Yeah, it's not complicated. Obviously because NIST referred directly to Frankel 1091 in their erratum statement, that means that they must have looked at the bill of materials on that sheet, which refers directly above to Frankel 9114 which has the side detail showing the stiffeners, so NIST can no longer claim ignorance to these elements and have no excuse for not using them in the LSDYNA. Actually it is kinda complicated. Bottom line, they presented a false report, which is a serious offense, and would have trouble reasonably claiming incompetence rather than negligence. This isn't new to you Mick?
Oh, and we now have done an FEA on the set up with the stiffeners added and that proves that they do make the difference that I said.

It was new to me at the start of this thread.

So are you going to release your FEA data?
 

gerrycan

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It was new to me at the start of this thread.

So are you going to release your FEA data?
Waiting on NIST responding to FOIA requests first. Looks like the courts are the only option though because the drawing references mean that this is not just incompetent. The very fact that you feel this is not complicated make the fact that NIST got it so wrong all the worse doesn't it. I'll let you know when the FEA is out.
 

Mick West

Administrator
Staff member
Waiting on NIST responding to FOIA requests first. Looks like the courts are the only option though because the drawing references mean that this is not just incompetent. The very fact that you feel this is not complicated make the fact that NIST got it so wrong all the worse doesn't it. I'll let you know when the FEA is out.

I mean what you are claiming is not complicated. However the validity and significance are not entirely obvious.
 

Mick West

Administrator
Staff member
Waiting on NIST responding to FOIA requests first. Looks like the courts are the only option though because the drawing references mean that this is not just incompetent. The very fact that you feel this is not complicated make the fact that NIST got it so wrong all the worse doesn't it. I'll let you know when the FEA is out.

Why are you waiting? What exactly are you waiting for?
 

Boodles

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WTC7 - The Stiffener Plates Explained
A brief explanation of the relevance and consequences of NISTs failure to include these elements in their analysis of the WTC7 collapse. This is designed to be a brief introduction to the issue.
Thanks for the video.
 

Jazzy

Closed Account
WTC5 had much more serious fires than 7.
Seeing that WTC7 fell completely down, after having no fires fought by firefighters, that statement appears fraught with difficulty.

The video says that the building was reduced to a smoking debris pile in 6.6s, this is true, regardless of what was happening internally.
This too. AT first you pay great attention to a minute spot within WTC7, then you wish us to dismiss preceding events entirely.

No time frame accounts for a period of 2.25s freefall acceleration
The failure of a structure by buckling DOES, actually, perfectly account for free fall. It is in the nature of buckling that that does indeed happen.

the initiating event being impossible from thermal expansion of the beams to the east of column 79
Ignoring the thermal expansion of the beams to the west of column 79 which you never care to mention or acknowledge.

especially once the stiffener plates are brought into the analysis
Not even when they are brought into your "analysis".

We can deal with freefall and 6.6s once you have addressed the initiating event, which is the topic of this thread and the series of videos.
The initiating event was WTC1's collapse.

'For a few floors' is the big logical fallacy there.
WTC5 wasn't a long-span beam skyscraper.

not even NIST is claiming that the fires did the same thing to7 as it did to the towers. Steel sagging in the towers was blamed and steel expanding in 7 due to fire was blamed.
Destabilized columns were common to both.

These are 2 different things
Not really. Destabilized columns were common to both.

the latter is what this thread is about
You wouldn't know. You are concentrating on one end of a beam. The rest of us prefer to consider what happened to the whole of WTC7.

As for credibility, you need to get yourself some of that
.

This is about engineering and physics, not about fantasies and secret agents. Address the issues.
.
 

gerrycan

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Seeing that WTC7 fell completely down, after having no fires fought by firefighters, that statement appears fraught with difficulty.
The fires and the results are plain to see in both buildings. You need to make an estimate of what % of each building was on fire to quantify this assertion.
This too. AT first you pay great attention to a minute spot within WTC7, then you wish us to dismiss preceding events entirely
The initiating event, according to NIST happened at the 'minute spot' you are alluding to, and you are saying that the internal collapse preceded this. You have the effect before the cause, and the sequence of events the wrong way round. You need to stop putting the cart before the horse. NIST failed to pay enough attention to this 'minute spot' to get the elements and dimensions correct. You are similarly mistaken. Maybe you can explain how the internal collapse could possibly happen before the initiating event in your opinion.
The failure of a structure by buckling DOES, actually, perfectly account for free fall. It is in the nature of buckling that that does indeed happen.
You need to explain this. Steel is weakened by heat, not removed by it.
Ignoring the thermal expansion of the beams to the west of column 79 which you never care to mention or acknowledge.
Which beams and how do they connect with the girder and what difference do they make? Did NIST include them in their analysis, which is the topic of this thread?
Not even when they (the stiffeners) are brought into your "analysis"
The stiffeners were there, they made a difference, NIST did not include them in their analysis. Again, you need to come up with something to back up your assertions. I have drawings, facts, and figures. You have rhetoric.
The initiating event was WTC1's collapse.
You need to READ the official account if you want to defend it. You can read NIST saying that the collapse of the towers did not initiate the collapse of WTC7 at their site FAQ (when it is back up).
WTC5 wasn't a long-span beam skyscraper
Have you seen the structural drawings?
Destabilized columns were common to both.
....and were the initiating event in neither. Again, read the account that you are trying to defend.
You wouldn't know. You are concentrating on one end of a beam. The rest of us prefer to consider what happened to the whole of WTC7.
The initiating event happened, according to NIST, in one place. That place was the end of a girder, not a beam, and without that initiating event the rest of their explanation is meaningless. Let's discuss the initiating event that NIST cite, then we can get onto the rest of the building, which I have also studied. Do you have the drawings for WTC7?

Jazzy, you still have not offered anything technical to this thread in terms of figures or physics. Strange for a man who claims to be a highly qualified engineer. Could you explain the above thermal expansion question that I posed to representative? If not, I won't be responding to you. I will wait for representatives answer.

cheers.
 

Mick West

Administrator
Staff member
You need to explain this. Steel is weakened by heat, not removed by it.

This seems to be the crux of the AE911 argument. The need to have all the structure somehow "removed" to account for what was observer. This focus is exemplified by Gage's disingenuous cardboard box demonstration.

Is this really what you think Gerry? Can't you see that buckling essentially removes the steel as a support? It's still there. It's just not supporting anything. Because it has buckled.

How much resistance would it take to be measurable in the videos? How much resistance does several floors of buckled steel column around the 8th floor give to the floors of the exterior above it? Once it's buckled, wouldn't it essentially just hinge for a while, letting the upper portion of the building descend in what is (as near as is measurable from video free fall?
 

gerrycan

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This seems to be the crux of the AE911 argument. The need to have all the structure somehow "removed" to account for what was observer. This focus is exemplified by Gage's disingenuous cardboard box demonstration.
I am not talking for AE911, I am not talking about cardboard boxes, I am talking about 108ft of no resistance across the entire face of a building. You need to explain how fire would do that.
Is this really what you think Gerry? Can't you see that buckling essentially removes the steel as a support? It's still there. It's just not supporting anything. Because it has buckled.
That buckling lessens resistance is hardly breaking news. You are describing a gradual deformation that wouldn't result in 108 feet of resistance being removed across the entire face of a building.
You know what I might start doing here. Instead of dealing with the whole statement that you make, I think i might just pick ONE sentence out of it and construct an entire strawman argument about organisations that you are not representing, and people that that you are not talking about. Does that sound fair Mick?
 
I am talking about 108ft of no resistance across the entire face of a building. You need to explain how fire would do that.

Because the collapse starts before Chandler (who blocks comments on his videos so people can't see the simple rebuttal to his garbage) and other ignorant people say it does. Look at the computer model on the left of the screen, you can see an internal collapse starting around floors 8 to 14: "floors to fail around column 79 on Floors 8 to 14." NIST NCSTAR1-A: Final Report on the Collapse of World Trade Center Building 7 (PDF). NIST. November 2008.Archived from the original on 21 July 2011. Retrieved July 11, 2011. See the model here:

You don't understand the internal collapse was already underway BEFORE the point you are looking at on the exterior
"initial downward movement of the N face from the NE corner to the east side of the screenwall was observed at 6.9 s AFTER the initial downward motion of the E penthouse." So the part you are looking at that falls faster than you expect is ATTACHED to part of the building that already started to collapse and is yanking on that part. As is explained here:
"It's easy for a falling object to accelerate faster than g if it's attached to something else that started falling first." - (source:
The outer frame of wtc7 was attached to the inner structures which began falling first (as demonstrated by the initial motion of the penthouse). By the time the outer walls began falling, they were being accelerated not only by their own weight, but also by momentum transfer (via torque and tension through linkages) from internal structures that were already falling. All the forces involved, essentially weight + transferred dynamic forces - resistance, netted out to approximately mg for a brief period of time.

As an illustration of the general principle, imagine parking two similar cars next to each other on the edge of a cliff. Connect the two cars by 100 meters of 30mm steel cable. Roll one car off the cliff. Once that car clears the cliff it will accelerate at about g ("free fall speed"). But when the cable tightens, the second car will accelerate faster than g at first, for a brief period. It's easy for a falling object to accelerate faster than g if it's attached to something else that started falling first.

NIST's justification is in a way far simpler (though far more complex to actually perform, and far more authoritative): they modeled the entire collapse (which really just means, they did the calculations for what would happen to each piece of the building moment by moment throughout the event based on the laws of physics) and that's what the model shows happening.

Respectfully,
Myriad
http://www.internationalskeptics.com/forums/showthread.php?postid=5683547#post5683547 )


Footage that kills the conspiracy theories: Unseen 9/11 footage shows WTC Building 7 consumed by fire
http://www.dailymail.co.uk/news/art...s-Rare-footage-shows-WTC-7-consumed-fire.html
 
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Jazzy

Closed Account
You need to make an estimate of what % of each building was on fire to quantify this assertion.
Nothing of that sort is necessary. WTC7 collapsed completely. WTC5 remained standing.

The initiating event, according to NIST happened at the 'minute spot' you are alluding to, and you are saying that the internal collapse preceded this. You have the effect before the cause, and the sequence of events the wrong way round. You need to stop putting the cart before the horse. NIST failed to pay enough attention to this 'minute spot' to get the elements and dimensions correct. You are similarly mistaken. Maybe you can explain how the internal collapse could possibly happen before the initiating event in your opinion.
The initiation was being struck by WTC1. Seven hours of worsening events preceded the collapse, but without them there would have been no collapse at all.

You have no handle on that moment of collapse because you have never acknowledged that the whole of that floor area in that particular place was compromised, and none of the points in question was accurately locatable by anyone, including you. NIST paid plenty of attention to that spot.

You need to explain this. Steel is weakened by heat, not removed by it.
It has very little to do with heat, and everything to do with stability. You have consistently ignored my recommendations to do with buckling instability. Namely study it until you understand it. You really don't...

Which beams and how do they connect with the girder and what difference do they make? Did NIST include them in their analysis?
The rest of the floor NIST dealt with. I have drawn this to your attention before, so I shall not repeat myself further.

The stiffeners were there, they made a difference, NIST did not include them in their analysis.
I will agree with you. They did not bother because they weren't essential to the argument.

Again, you need to come up with something to back up your assertions. I have drawings, facts, and figures. You have rhetoric.
You have fifth-grade figures dealing with an insubstantial event. My "rhetoric" is about your total failure to comprehend the situation as a whole. You are rearranging the deck chairs while the boat sinks.

You need to READ the official account if you want to defend it.
I'm not defending it. I'm attacking your argument and demonstrating its unsuitability.

You can read NIST saying that the collapse of the towers did not initiate the collapse of WTC7 at their site FAQ (when it is back up). Have you seen the structural drawings?
I know what NIST says and have seen the drawings. Neither are necessary to demonstrate how unsuitable your argument is. WTC7 was FIVE TIMES TALLER than WTC5.

....and were the initiating event in neither. Again, read the account that you are trying to defend.
I'm not defending it. I'm attacking your argument and demonstrating its unsuitability. The initiating event was the impact of an aircraft (ITCO towers) and WTC1 (ITCO WTC7).

The initiating event happened, according to NIST, in one place. That place was the end of a girder, not a beam, and without that initiating event the rest of their explanation is meaningless. Let's discuss the initiating event that NIST cite, then we can get onto the rest of the building, which I have also studied. Do you have the drawings for WTC7?
NIST indicated a probability of that position being the source of final collapse, but did not fix a position for the other end of that beam, as you prefer, probably because they knew it wasn't in its original position.

Your use of drawings merely confirms you don't know what you're talking about. As I have said before, your analysis is meaningless if you do not consider the progression of the fires, particularly in the floor beneath, over a timeline, and quantify all the forces generated, and discover the lateral movements of all the columns of that floor - because, in the end column 79 went unstable.

Jazzy, you still have not offered anything technical to this thread in terms of figures or physics. Strange for a man who claims to be a highly qualified engineer. Could you explain the above thermal expansion question that I posed to representative? If not, I won't be responding to you. I will wait for representatives answer.
There is nothing to offer in that respect. There is nothing adult or demanding about your presentation. It is simply wrong, for the reasons I have given above, and many times previously.
 

gerrycan

Banned
Banned
rep, you're not talking to chandler, you're not talking to gage, you are talking to me. Address what I am saying. YOU say "You don't understand the internal collapse was already underway BEFORE the point you are looking at on the exterior", but you do not understand that I am addressing the initiating event that NIST cite for the collapse. This is the thermal expansion of floor beams to the east of column 79. We are talking about their explanation, and my rebuttal of it, and you seem incapable of addressing that. Talk about where you disagree with my analysis in terms of the initiating event. And I think you mean freefall acceleration, not speed. Give me some figures so I can check your math.
 

MichaelStox

Member
Rep you might want to review the politeness policy before calling people crazy and ignorant just because they don't share your narrow view of the world. And instead of resorting to ad hominem and straw mans, refer to this when constructing your posts:

 
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Mick West

Administrator
Staff member
I am not talking for AE911, I am not talking about cardboard boxes, I am talking about 108ft of no resistance across the entire face of a building. You need to explain how fire would do that.
That buckling lessens resistance is hardly breaking news. You are describing a gradual deformation that wouldn't result in 108 feet of resistance being removed across the entire face of a building.
You know what I might start doing here. Instead of dealing with the whole statement that you make, I think i might just pick ONE sentence out of it and construct an entire strawman argument about organisations that you are not representing, and people that that you are not talking about. Does that sound fair Mick?

Strawman? I think it's a key point. Perhaps a little OT, but I was responding to something you claimed. It also happens to be something that AE911 repeat over and over, and it's incredibly misleading. And "108 feet of resistance being removed" IS essentially the same argument Gage makes with his boxes.

You seem to like focussing on details (like the stiffener plates, and the 11 vs. 12 inch seat, and the temperature, and the thermal expansion coefficients of steel) so why then phrase your subsequent arguments in such inexactitudes? How much does buckling of the exterior columns "lessen resistance"? How "gradual" is the subsequent deformation?

Your main point here is that you don't think the initiating event happened exactly as NIST described, and you raise some reasonable sounding technical objections to this very narrow point. But after that you seem to just resort to appeals to incredulity.

Let's say the initiating event was a bit different to the beams simply pushing the column directly off it's seat in one dimension. Do you then claim that this lack of precision in the description renders everything else irrelevant and not worth discussing?
 
Rep you might want to review the politeness policy before calling people crazy and ignorant just because they don't share your narrow view of the world. And instead of resorting to ad hominem and straw mans, refer to this when constructing your posts:


Quote specifically where I do that in my above reply to gerrycan. Saying Chandler and others who keep insisting the start of the collapse is after when it actually started is ignorant. Some of them may be ignorant because some people have intentionally misled them but that doesn't mean they are not ignorant of when the collapse started.
 
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rep, you're not talking to chandler, you're not talking to gage, you are talking to me. Address what I am saying. YOU say "You don't understand the internal collapse was already underway BEFORE the point you are looking at on the exterior", but you do not understand that I am addressing the initiating event that NIST cite for the collapse. This is the thermal expansion of floor beams to the east of column 79. We are talking about their explanation, and my rebuttal of it, and you seem incapable of addressing that. Talk about where you disagree with my analysis in terms of the initiating event. And I think you mean freefall acceleration, not speed. Give me some figures so I can check your math.

I quoted you: "I am talking about 108ft of no resistance across the entire face of a building. You need to explain how fire would do that."

And I explained that: #233

So what are you complaining about? You complain, "but you do not understand that I am addressing the initiating event that NIST cite for the collapse." Then don't write: "I am talking about 108ft of no resistance across the entire face of a building. You need to explain how fire would do that" and waste people's time. Is this a game to you?

As for you nitpicking about "free fall acceleration," I am citing someone called Myriad and I think it is clear what they are saying when they wrote "it will accelerate"

So what I posted addressed the specific thing you told us we need to explain. And now you you claim you weren't talking about that! That was rude and it was rude to ignore the explanation I went to the trouble of putting together.

If I have 2 weights tied by a rope together on a table & I push one off the side of the table, it is not strange to think that the second weight might be accelerated by the first one faster for a few seconds as the initial jerking motion of the first weight tied to the rope pulls on the second. Did that help you understand?

Truthers have been omitting the penthouse collapse which occurs 1st but it is part of the collapse! The structure is connected so internal movement can pull the exterior.

NIST was responding to a specific inquiry about a specific video that focused on a time period AFTER the penthouse collapse and truthers dishonesty twisted NIST's response (NIST went to the trouble of doing a detailed analysis of the video they were asked about and designated the roofline as t=0 yet truthers then acted like t=0 is the start of the collapse, they acted like the roofline decent is the beginning of the collapse sequence. As I keep explaining, the collapse was already underway and part of the structure that had already started to move downward yanked on the exterior which is the part of the building and time frame you fixate on (or at least posed a specific question about then acted like you weren't even talking about.))

There were about 6.9 s BEFORE the t=0, About 6.9 s BEFORE the initial downward motion of the north face roofline at the eastern section of the building the START of the descent of east penthouse occurred.

"The buckling of Column 79 led to a vertical progression of floor failures up to the east penthouse and to the buckling of Columns 80 and 81. An east-to-west horizontal progression of interior column buckling followed, due to loss of lateral support to adjacent columns, forces exerted by falling debris, and load redistribution from other buckled columns. The exterior columns then buckled as the failed building core moved downward, redistributing its loads to the exterior columns. " NIST NCSTAR 1-9 Vol 2 pp617-618 WTC Investigation

I think Myriad explained it well: "By the time the outer walls began falling, they were being accelerated not only by their own weight, but also by momentum transfer (via torque and tension through linkages) from internal structures that were already falling."

Don't play games claiming you didn't ask about the downward movement of those 108ft. You were given an explanation and you ignored it and falsely claimed you weren't talking about it when I quoted you saying, "I am talking about 108ft of no resistance across the entire face of a building."
 
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jomper

Inactive Member
NIST... modeled the entire collapse
Patently a lie. The NIST "model" doesn't come close to "modelling" the whole collapse as represented by the video evidence.

It simulates a hypothesis of internal collapse and then stops. It does not represent even 25% of the collapse of the "facade" as recorded in the video evidence, and even this 25% does not successfully model the features that make the video evidence so remarkable and controversial.

Added to this, it is unverifiable and would not be admissible as evidence in any court in the US. It's basically an expensive cartoon.

"Modeled the entire collapse"? Thanks for giving me a belly laugh. Roffle
 
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