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

[BasqueArch]

I have several "cover my azz" notes that I include on my drawings, developed over the years from the lessons learned by contractor games.

On one particular project (we were a 2 man firm at the time), the bid was won by a very large construction firm with a reputation for low ball bidding and then making it up on change orders and screwing sub contractors. The estimator even told me he was going to "bury me with change orders" My response was to remind him who did the punch list. I was a 5 million dollar contract. They walked away from the final 500k payment because it would have cost them over a million to complete the PL

The owner left most of the PL items as because they were not important and kept the 500k.

Nice!
The " government public bid law" ones are the worst. I don't take these jobs anymore.
We should trade "cover my azz" notes.


Do we know if NIST has more drawings they haven't released? They just recently released a second batch of drawings and correspondence.

 

[ozeco41]

Nice!
The " government public bid law" ones are the worst. I don't take these jobs anymore.
We should trade "cover my azz" notes..

Totally different experience to mine and I needed to manage the situation. ("we" actually - I was a couple of rungs down the overall corporate ladder )

I was manager of operations of sewage and water supply systems which made me the "Owners Rep" for some big infrastructure contracts - Hundreds of millions up into 2-3 billion range. And we knew we were pretty naive in managing hard line contractors who were well practised in the art of manipulating "extras". So we engaged the hardest nosed b..... we could find as a consultant on our side of the fence. Objective to stiffen our back bone. Probably not as big a problem at that level of cost because the contractors were only the big name ones who relied on big infrastructure projects for their business and most of those are government. So they would not get up to a lot of mischief. Maybe!

In fact the biggest project was a BOOT - build own operate transfer - for water treatment - the total Sydney water supply and about $AU3 billion involved. On that one we were only engaging the owners - they had the infrastructure side contracts to manage. Ended up as two contracts run by French/UK joint ventures.

 

[tsig]

Thank you for that moment of honesty.

A child can see that WTC 7 was a CD.

1 Corinthians 13:11

When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.

 

[enik]

It is conceptually plausible. BUT I would always ask "Why do it?"

This is the fundamental difference between you and me. My first question would be, “Why wouldn’t you do it?”

There are two main reasons for using a tool - whether engineering or any other profession. Those are:
1) Using it as a tool to assist solve a problem; OR
2) Using it for the fun/pleasure of playing with the tool.

I am assuming you mean FEA as a tool. If so, then FEA is used for two purposes:
(i) Creating a new or revising an existing design before spending money
(ii) Failure analysis

As for using it for fun/pleasure, maybe this is a subtle insult directed at me, but then again, all modelers have to experiment with their software and do some very basic analysis that can be hand checked. This is the only way the modeler has confidence when presenting their results to management.

The two obvious reasons are either:
(A) Pre the event to help determine how a planned CD would work; OR
(B) post the event, to show why it actually happened the way it did.

I will focus on "(A)" - if you have a different scenario in mind respond and we can see whether it is of any value for us to pursue it.

How about focusing on (B) instead.

 

[funk de fino]

That's pretty much the bottom line. They will defend nearly any preposterous hypothesis, as long as it supports the official story, regardless if there's even a speck of physical evidence.

Just know that your measured responses and thorough analyses are appreciated.

You're defending a proven liar who has not fully read the NIST report he castigates.

 

[Sword_Of_Truth]

That's pretty much the bottom line. They will defend nearly any preposterous hypothesis, as long as it supports the official story, regardless if there's even a speck of physical evidence.

Just know that your measured responses and thorough analyses are appreciated.

You're defending a proven liar who has not fully read the NIST report he castigates.

Corrected free of charge.

 

[ozeco41]

This is the fundamental difference between you and me. My first question would be, “Why wouldn’t you do it?” ...

Not so. The fundamental difference which has been demonstrated over several recent interactions is:
I am prepared to engage in discussion including answering your questions with clearly stated reasoning. You consistently decline to address my reasoning OR to present reasoned arguments of your own.

On this occasion I answered your question and could legitimately have stopped there. However I posted some additional explanation. You have ignored my reasoned explanation, quote mined a couple of bits out of my post, misrepresented those bits and attempted to shift the goalposts to another sub issue which once again you decline to admit or support with reasoning. So you have two choices:
1) Respond to my post addressing the points I clearly stated; OR
2) Clearly state with reasoning your alternate scheme which I may choose to respond to if it is stated with sufficient clarity and enough reasoned argument to warrant a response.



PS For other members who may wonder why my patience is wearing a bit thin.
This is part of a sequence of interactions I have had with Enik - the latest starts here: http://www.internationalskeptics.com/forums/showthread.php?p=8355011#post8355011

 

[Robrob]

Corrected free of charge.

So, have you read the NIST report?

 

[BasqueArch]

This is the fundamental difference between you and me. My first question would be, “Why wouldn’t you do it?”


I am assuming you mean FEA as a tool. If so, then FEA is used for two purposes:
(i) Creating a new or revising an existing design before spending money
(ii) Failure analysis

As for using it for fun/pleasure, maybe this is a subtle insult directed at me, but then again, all modelers have to experiment with their software and do some very basic analysis that can be hand checked. This is the only way the modeler has confidence when presenting their results to management.

How about focusing on (B) instead.

The last time I looked, your starting model showed the stiffener plates were not over the bearing plate. They should be. You may want to check my drawings for additional details at
http://www.internationalskeptics.com/forums/showthread.php?postid=8336945#post8336945

 

[tfk]

WTC 7 is NOT leaning.

Hello? Look at the pretty pictures with the straight red lines.

No, it fell straight down for about 100 feet and fell a little to one side when it hit uneven resistance. It did not "topple".

No lean of any building can be measured by someone who doesn't know the difference between "straight" & "vertical".

It's kinda damning to your claim to being a carpenter that you think that those two adjectives mean the same thing.

Big hint: all 4 edge of a poorly-hung picture frame are still traight.

Your "pretty pictures & straight red lines" prove zippo.

It's also kinda cute that the one line that compares the building to a fixed, known reference - the horizontal line along the roof of the BNY/Mellon building (the white building in front, below and to the left of WTC7) - shows the tops of the windows of the lower floor of WTC7 NOT parallel to the straight line.

To the extent that the west walls of WTC7 & BNY/Mellon are parallel to each other (& they look pretty darn close in aerial views), this divergence would indicate that WTC7 is leaning at this point slightly to the south.

Way to go, champ.

tk

PS. The meaningful question is not "is it leaning?"

Of course it's leaning.

The meaningful question is "how much?"

That doesn't seem to be anything that you are capable of measuring.

However, it most certainly is leaning by amounts measurable by transits & NIST's Moire´ techniques

 

[tfk]

A couple of quick sketches for those who'd like to see how the column splices work.

This was in response to Tony's assurance that the splice joints would provide just as much stiffness & resistance to buckling (i.e., equivalent MoI) as would a continuous, unbroken beam. An assumption that was integral to his calculations about how much the column would deflect in response to side load, and to his calculation as to how many stories of column 79 would have to be unsupported before it went unstable.

Tony's assurances turn out to be false. Numbers below.

First sketches:
Note: all components drawn to scale.

Isometric view of splice joints & seats.

[Note: bolts exploded for clarity]

Top view of splice joints & seats

[Note: seat on south side of column not shown.]

Calculation of Moment of Inertia of built-up column versus bolts

Component|I|A|d|n|Itot
||(in^2)|in||(in^4)
Column|4715|214.5|0|1|4715
Side plates|16.3|48.8|9.95|2|9679
Total|||||14394
|||||
Bolts|0.05|0.7854|17.45|8|1913
|||||
|Values verified|||Ratio (beam/bolt)|7.5

MoI calculated for deflections in east-west direction, i.e., "about vertical axis of top view thru center of column"


Observations

1. The splice plates are incredibly thin. The MOI calculation assumes that they will stay straight & untorqued when side load applied. This assumption seems wildly optimistic to me.

2. From the table: The MoI's of the various components are calculated using the standard "parallel axis theorem". From the table, one can see that the MoI of the column is about 7.5x greater than the MoI of the 8 bolts.

3. MoI of joint to deflections in north south direction (about horizontal axis in top view) is pretty darn close to zero. The splice plates are simply going to torque, and the alignment plates, not being welded to upper column, provides zero recoverable strain, and therefore do not contribute to MoI.

4. The bolts are thermally isolated from the heat sinking mass of the columns. They are going to heat up & lose strength in a fire far faster than the columns themselves.

 

[enik]

You edited your post from when I first saw it. You wanted me to comment about (A) Pre the event to help determine how a planned CD would work. But I see you have changed your mind. Therefore:

What benefits would FEA give in assessing "overkill" which would warrant the complexity and cost of an FEA? Remember that the person considering using a tool to achieve some benefit in a task will be thinking "cost benefit" - "What do I gain and is it worth it?"

So, to answer the question of “Why do it”, if an FEA is too expensive, you would not pursue one for a proposed demolition of a "structure" where there isn't a history of one done before in the past?

I assume you are speaking from experience. Can you provide some details on some of your military demolition projects?

The last time I looked, your starting model showed the stiffener plates were not over the bearing plate. They should be. You may want to check my drawings for additional details at
http://www.internationalskeptics.com/forums/showthread.php?postid=8336945#post8336945

Those are pretty good drawings, where did they come from? They would have helped me when I initially built my model. Even though these drawings show the stiffener plates, did the NIST include the stiffener plates in their analysis? And if I do move my stiffener plates over the bearing plate, would you expect a change in the results?

 

[Animal]

Those are pretty good drawings, where did they come from? They would have helped me when I initially built my model. Even though these drawings show the stiffener plates, did the NIST include the stiffener plates in their analysis? And if I do move my stiffener plates over the bearing plate, would you expect a change in the results?

The stiffeners would have prevented on one potential method of the initiating event (the failure of the girder) by preventing folding of the bottom flange if the web of the girder had moved past seat. However, that is one of several potential ways the NIST mentioned as possible failure modes.

Other potential methods-
The girder buckled from the floor beam expansion.
The girder rocked off by twisting from the failure of the floor beams at the exterior wall.
Combination of westward movement of the girder from thermal expansion of the floor beams and eastward movement of the column from thermal expansion of other girders.
Failure of the girder seat after the girder moved off the vertical seat support.

And the fact is that it could very well be a combination of all of the above.

The NIST summary report uses the term "walk off" which is what C7 so bitterly clings to.

 

[enik]

The stiffeners would have prevented on one potential method of the initiating event (the failure of the girder) by preventing folding of the bottom flange if the web of the girder had moved past seat. However, that is one of several potential ways the NIST mentioned as possible failure modes.

So the NIST did not include the stiffener plates in any of their analysis.

 

[Animal]

So the NIST did not include the stiffener plates in any of their analysis.

If you have read the NIST report, you would know that they did not include LOTS of things in their analysis, mostly to reduce the computer time required. If they had included everything......the computers would still be running, and troofers would be yammering about a "cover up"

 

[enik]

If you have read the NIST report, you would know that they did not include LOTS of things in their analysis..

So that would be a "no" to my question.

 

[Animal]

So that would be a "no" to my question.

Actually it is a maybe. Even the full volume report Parts 1 and 2 discuss most issues in generalities. There is no way to determine whether they did or not without specific information from NIST.

Why is it such a concern? It doesn't change the outcome.

 

[enik]

Why is it such a concern? It doesn't change the outcome.

My point exactly.

 

[femr2]

To the extent that the west walls of WTC7 & BNY/Mellon are parallel to each other (& they look pretty darn close in aerial views), this divergence would indicate that WTC7 is leaning at this point slightly to the south.

The building is already on its way down at that point. That says nowt about the condition prior to descent.

However, it most certainly is leaning by amounts measurable by transits & NIST's Moire´ techniques

How exactly would NIST use their crappy moire technique, which only measures the motion of a single "point" (sort of), to determine leaning ? And where would that study be in the report ?


You still haven't responded within the "NIST blew WTC7 Stage 1 analysis" thread you started.

 

[Tony Szamboti]

A couple of quick sketches for those who'd like to see how the column splices work.

This was in response to Tony's assurance that the splice joints would provide just as much stiffness & resistance to buckling (i.e., equivalent MoI) as would a continuous, unbroken beam. An assumption that was integral to his calculations about how much the column would deflect in response to side load, and to his calculation as to how many stories of column 79 would have to be unsupported before it went unstable.

Tony's assurances turn out to be false. Numbers below.

First sketches:
Note: all components drawn to scale.

Isometric view of splice joints & seats.
[qimg]http://www.internationalskeptics.com/forums/picture.php?albumid=553&pictureid=6214[/qimg]
[Note: bolts exploded for clarity]

Top view of splice joints & seats
[qimg]http://www.internationalskeptics.com/forums/picture.php?albumid=553&pictureid=6215[/qimg]
[Note: seat on south side of column not shown.]

Calculation of Moment of Inertia of built-up column versus bolts

Component|I|A|d|n|Itot
||(in^2)|in||(in^4)
Column|4715|214.5|0|1|4715
Side plates|16.3|48.8|9.95|2|9679
Total|||||14394
|||||
Bolts|0.05|0.7854|17.45|8|1913
|||||
|Values verified|||Ratio (beam/bolt)|7.5

MoI calculated for deflections in east-west direction, i.e., "about vertical axis of top view thru center of column"


Observations

1. The splice plates are incredibly thin. The MOI calculation assumes that they will stay straight & untorqued when side load applied. This assumption seems wildly optimistic to me.

2. From the table: The MoI's of the various components are calculated using the standard "parallel axis theorem". From the table, one can see that the MoI of the column is about 7.5x greater than the MoI of the 8 bolts.

3. MoI of joint to deflections in north south direction (about horizontal axis in top view) is pretty darn close to zero. The splice plates are simply going to torque, and the alignment plates, not being welded to upper column, provides zero recoverable strain, and therefore do not contribute to MoI.

4. The bolts are thermally isolated from the heat sinking mass of the columns. They are going to heat up & lose strength in a fire far faster than the columns themselves.

Where did you get the dimensions and configuration of the column splice you show? The NIST WTC 7 report doesn't give sizes and configurations of column splices.

However, the recently released drawings do, and the sizes and configuration you show aren't what is shown in the released drawings. The splice plates shown in the actual drawing are significantly larger than what you show.