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NIST North Tower ANSYS model -- floor trusses

gerrycan

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I thought that this issue deserved a thread of it's own. It looks as if NIST have applied short span cnnections to the long span floor trusses at the core column connection end.
short long span.jpg

I feel that I must be getting something wrong here, because this would invalidate NIST's whole model if it were the case, and is not something that would get past the scrutiny of any competent investigative engineer that had access to the drawings.
 
I thought that this issue deserved a thread of it's own. It looks as if NIST have applied short span cnnections to the long span floor trusses at the core column connection end.
View attachment 67228574

I feel that I must be getting something wrong here, because this would invalidate NIST's whole model if it were the case, and is not something that would get past the scrutiny of any competent investigative engineer that had access to the drawings.
From what I can see, you are wrong and here's why I think that.

1. You are using drawings from a document published in 1964 and NOT using the actual engineer stamped structural drawings for the trusses. They probably had made MANY changes to their designs since that 1964 publication due to having to use a draft of the newly revised codes in 1968.
https://en.wikipedia.org/wiki/Construction_of_the_World_Trade_Center
As an interstate agency, the Port Authority was not subject to local laws and regulations of the City of New York, including building codes. Nonetheless, the Port Authority required architects and structural engineers to follow the New York City building codes. At the time when the World Trade Center was planned, new building codes were being devised to replace the 1938 version that was still in place. The structural engineers ended up following draft versions of the new 1968 building codes, which incorporated "advanced techniques" in building design.[53]

2. The photos of the actual floor trusses not look anything shown in the details within your 1964 publication drawings. In your detail of the short span truss below, the component I circled in red is not round bar. Round bar is what is seen seen going between the angles of the the trusses. below is the side view.
short span core end conn.jpg

Next is the long span trusses from your publication. It also does not show the component I circled in red to be round bar.
longspantruss.jpg

Below is a cross section of the trusses. The component I circled in red is not round bar. Also in this section, there is no "round bar knuckle" shown coming through the decking at the top.
trusscrosssection.jpg

Below is a photo showing the "round bar knuckle" (circled in red) coming through the decking.
vlc 2011-08-19 14-18-36-50.jpg

Bottom line is that you need the proper drawings from the engineer stamped structural construction set showing how the trusses were design and put together and not use some drawings from a document published in 1964, especially when the engineers had to use newly revised codes from 1968 for their designs.
 
From what I can see, you are wrong and here's why I think that.

1. You are using drawings from a document published in 1964 and NOT using the actual engineer stamped structural drawings for the trusses. They probably had made MANY changes to their designs since that 1964 publication due to having to use a draft of the newly revised codes in 1968.
https://en.wikipedia.org/wiki/Construction_of_the_World_Trade_Center


2. The photos of the actual floor trusses not look anything shown in the details within your 1964 publication drawings. In your detail of the short span truss below, the component I circled in red is not round bar. Round bar is what is seen seen going between the angles of the the trusses. below is the side view.
View attachment 67228581

Next is the long span trusses from your publication. It also does not show the component I circled in red to be round bar.
View attachment 67228583

Below is a cross section of the trusses. The component I circled in red is not round bar. Also in this section, there is no "round bar knuckle" shown coming through the decking at the top.
View attachment 67228584

Below is a photo showing the "round bar knuckle" (circled in red) coming through the decking.
View attachment 67228585

Bottom line is that you need the proper drawings from the engineer stamped structural construction set showing how the trusses were design and put together and not use some drawings from a document published in 1964, especially when the engineers had to use newly revised codes from 1968 for their designs.

Bottom line is here is a video of a long span floor truss being lifted into place at about the 100th floor and it is EXACTLY as set out in the publication that I directed you to, which incidentally used the original drawings to lift the figures from.

@ 2:03 you can see the core end of the truss quite clearly. It is exactly as set out in the publication.

Try again Gamelon.

ADD - I am actually prepared to be wrong on this, and will accept a reasonable explanation for what looks like a howling error by NIST if there is one, but trying to say that a booklet which was published beore ground was broken came from anything other than the structural drawings makes zero sense.

Keep in mind that this document is so accurate as to have the (hypothetical) differential floor shortenings down to 1/100th of an inch. Where do you think they got the info for this publication if not from the drawings ??
 
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ADD - I am actually prepared to be wrong on this, and will accept a reasonable explanation for what looks like a howling error by NIST if there is one, but trying to say that a booklet which was published beore ground was broken came from anything other than the structural drawings makes zero sense.
You can't read can you? The publication you are citing came out in 1964. The structural engineers were using a draft of the newly revised codes from 1968! How can you say that those drawings from the 1964 publication is what went out in the final, approved construction set? They don't even match what was actually seen! I've pointed out that the diagonal members of the trusses shown in your details from 1964 are not round bar going between the angles.
 
Keep in mind that this document is so accurate as to have the (hypothetical) differential floor shortenings down to 1/100th of an inch. Where do you think they got the info for this publication if not from the drawings ??
Reading comprehension for the win gerrycan.

I'm not saying they didn't get them from drawings. I am saying that they may have gotten them from EARLY drawings that were changed later. The engineers were using a draft of the newly revised codes from 1968! Do you understand that?

Your publication: 1964
Newly revised codes being used in design: 1968

How do you know the drawings from your publication in 1964 were not modified because of the newly revised codes to go out in the final construction set? You need to get the actual drawings from the stamped set gerrycan!
 
You can't read can you? The publication you are citing came out in 1964. The structural engineers were using a draft of the newly revised codes from 1968! How can you say that those drawings from the 1964 publication is what went out in the final, approved construction set? They don't even match what was actually seen! I've pointed out that the diagonal members of the trusses shown in your details from 1964 are not round bar going between the angles.

The knuckles are formed by the top of the inverted V from the underside of the truss.
This is from WTC2, but you can quite clearly see what's happening as far as the truss knuckles are concerned.
 
Try again Gamelon.
I will.

See your drawing below. See the component circled in red? That is not "round bar". That is a "T" shaped cross member that is cut so the vertical leg of the "T" fits between the angles.
trusscrosssection.jpg

If this is wrong then show me a photograph or and actual stamped construction drawing from the final set of drawings that show this. If I am wrong, then I will say I'm wrong.
 
I tihink this should clear up which type of truss was actually used in the construction at the long span ends at the core.
LS truss define.jpg

The publication from 1964 corresponds with the construction footage.
 
I will.

See your drawing below. See the component circled in red? That is not "round bar". That is a "T" shaped cross member that is cut so the vertical leg of the "T" fits between the angles.
View attachment 67228595

If this is wrong then show me a photograph or and actual stamped construction drawing from the final set of drawings that show this. If I am wrong, then I will say I'm wrong.

Point it out on this....
Figure-E-2-Mock-up-of-office-floor-framing-system-Photograph-from-about-1967-provided-b.ppm.jpg
 
See your drawing below. See the component circled in red? That is not "round bar". That is a "T" shaped cross member that is cut so the vertical leg of.
(my emphasis)

You're looking for the wrong thing in the wrong place.
This is round bar...
WTCrebarfloorsetup.jpg

Do you see it ? It's that sort of round shaped steel stuff lying around in precut lengths eady to be installed. :2wave:
 
(my emphasis)

You're looking for the wrong thing in the wrong place.
This is round bar...
View attachment 67228615

Do you see it ? It's that sort of round shaped steel stuff lying around in precut lengths eady to be installed. :2wave:
You are completely wrong!
WTCrebarfloorsetup.jpg

The stuff lying around in precut lengths is #4 rebar as noted in my picture. Here is a link to the rebar, #4 Rebar - #4 Reinforcing Bar | Harris Supply Solutions. That is the same #4 bar that is called out in your detail below. Do you see the "#4 Bar" callout just below the word "Telephone"? That #4 rebar is what lies HORIZONTALLY across the top of the decking and is what will sit inside the concrete.
short span core end conn.jpg

The "knuckles" are formed by the bending of the "round bar" (different from rebar) that comes up through the decking and form a kind of shear stud for the concrete to be poured. That round bar that forms the knuckles continues in a "W" pattern to form the truss. Your details from the 1964 booklet show "T" shaped components for the "W" pattern of the trusses and not "round bar".

Your Detail "X" below proves this. The #4 bar callout in this detail shows a cross section of the #4 bar that runs HORIZONTALLY across the top of the decking. That #4 bar does NOT go through the decking to form the "W" shape pattern below.
detail x.jpg
 
You are completely wrong!
View attachment 67228616

The stuff lying around in precut lengths is #4 rebar as noted in my picture. Here is a link to the rebar, #4 Rebar - #4 Reinforcing Bar | Harris Supply Solutions. That is the same #4 bar that is called out in your detail below. Do you see the "#4 Bar" callout just below the word "Telephone"? That #4 rebar is what lies HORIZONTALLY across the top of the decking and is what will sit inside the concrete.
View attachment 67228617

The "knuckles" are formed by the bending of the "round bar" (different from rebar) that comes up through the decking and form a kind of shear stud for the concrete to be poured. That round bar that forms the knuckles continues in a "W" pattern to form the truss. Your details from the 1964 booklet show "T" shaped components for the "W" pattern of the trusses and not "round bar".

Your Detail "X" below proves this. The #4 bar callout in this detail shows a cross section of the #4 bar that runs HORIZONTALLY across the top of the decking. That #4 bar does NOT go through the decking to form the "W" shape pattern below.
View attachment 67228618

Hang on a bit - we are in agreement there. Look at what I said again.
The only thing I would mention is that the short span sides had runs in the same direction, as you can see here. The knuckles being formed by the short span truss lateral open web trusses.
4061836605_80ddxxd7663_b.jpg

I think you are maybe disagreeing with me on the basis of terminology, which is fine.

ADD round bar is just a generic name for rounded steel - as opposed to flat bar for example, which is also just a generic term. I used to buy shedloads of the stuff every week.
 
I am not saying that AT ALL. The bit you circled in the top pic - what is it YOU think that is ?
I'm trying to explain to you that the drawings you are using from the 1964 publication are NOT what was installed. Look at the drawings you provided and match them to pictures. It's YOUR turn to match components and try and explain what you think matches.
 
Okay - I will try ONE MORE TIME.

The bit that you are pointing to in the 1964 publication. It is a HALF detail.

it is showing on the left a floor truss running at 90 degrees to the one illustrated on the right.

The one on the LEFT forms the knuckle on the short span trusses, and the one on the RIGHT forms the knuckle on the long span trusses.

The bit you circled is an open web truss running at 90 degrees to the Core - Perimeter direction on the short span sides.

If you still disagree with that - ket's just leave it.

ADD - I even gave you the pic of it doing that - here it is again in case you missed it.
4061836605_80ddxxd7663_b.jpg
 
Okay - I will try ONE MORE TIME.
I'll make this easy for you.

Using the picture below, please match both the area in the green and red boxes...
halfdetail.jpg

...with their matching areas in the photo below.
Figure-E-2-Mock-up-of-office-floor-framing-system-Photograph-from-about-1967-provided-b.ppm (2).jpg

If you think both or just one don't match the photo, just say so.
 
Gamolon - you thought that the truss was a "T" piece - You wrote it on this thread.

Here.
Long span dir.jpg

For a long span truss it's obvious because of the direction of the knuckles that are formed. That's the whole point.

You though it was a "T" piece of some sort 5 minutes ago - you need to start being honest here..
 
Gamolon - you thought that the truss was a "T" piece - You wrote it on this thread.

Here.
View attachment 67228632

For a long span truss it's obvious because of the direction of the knuckles that are formed. That's the whole point.

You though it was a "T" piece of some sort 5 minutes ago - you need to start being honest here..
No, that's not what I "thought".

I am saying that the "web diagonal" (your term in the picture above) is shown as a "T" piece (or the more I look at it, some may be an angle piece also) in the drawing from your 1964 publication. That does not match what was actually installed. The "web diagonals" in the photos we have been throwing around are made of "round bar".
 
I will.

See your drawing below. See the component circled in red? That is not "round bar". That is a "T" shaped cross member that is cut so the vertical leg of the "T" fits between the angles.
View attachment 67228595

If this is wrong then show me a photograph or and actual stamped construction drawing from the final set of drawings that show this. If I am wrong, then I will say I'm wrong.

What you thought was a " T shaped cross member" is a truss at 90 degrees.

You also said "If I am wrong, then I will say I am wrong".

Let's see.....
 
Answered your pic question already - you need to do some 'fessing up - You thought that the truss at 90 degrees was a T piece.

Now let's move on please.
 
What you thought was a " T shaped cross member" is a truss at 90 degrees.
No.

What I said was a "T" shaped member was the "web diagonal" (again, the term used in your picture just recently). I am saying that is what your 1964 publication drawings show it to be. I am saying that all the pictures show not a "T" shaped "web diagonal" (like your drawings show), but "round bar" as seen in the pictures.
 
Answered your pic question already - you need to do some 'fessing up - You thought that the truss at 90 degrees was a T piece.

Now let's move on please.
No, you just can't read drawings which is why you want to "move on" so quickly now.
 
No.

What I said was a "T" shaped member was the "web diagonal" (again, the term used in your picture just recently). I am saying that is what your 1964 publication drawings show it to be. I am saying that all the pictures show not a "T" shaped "web diagonal" (like your drawings show), but "round bar" as seen in the pictures.

What forms the knuckles ? - The open web trusses that form the floor truss.

What does your "alleged" T piece do ? - it forms the knuckles.

What is your alleged "T piece" - A floor truss at 90 degrees.
 
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