I found the missing Jolt.

JSanderO said:
I did not say that.

I said it was designed to support the antenna and that the hat truss steel added stiffness which likely played a minor role in resisting some of the wind load.

What I wrote, which is what I read and cited I believe is correct.
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At best, it was not ORIGINALLY designed to resist sway and wind loads. But Glanz's article details where Robertson went to the architect with 3 DESIGN changes. REDESIGNING the hat truss was one of those 3 changes.

It was designed to help resist sway.

Get up to speed.
 
Seymour Butz said:
At best, it was not ORIGINALLY designed to resist sway and wind loads. But Glanz's article details where Robertson went to the architect with 3 DESIGN changes. REDESIGNING the hat truss was one of those 3 changes.

It was designed to help resist sway.

Get up to speed.
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OK sounds to me like you are looking to spin this. What was the design change to the hat truss?

I wrote that the INTENT of the design of the hat truss was to support the antenna. That is factually accurate.

So what was the "redesign" of the hat truss about? I'd like to have some more specifics.

More analysds which do mention the hat truss related to resisting wind:

http://fire.nist.gov/bfrlpubs/build04/PDF/b04045.pdf

http://global.ctbuh.org/resources/p...e-design-features-and-structural-modeling.pdf

More quotes:

http://architectuul.com/architecture/world-trade-center

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communication antenna on top of each building. Only 1 WTC (north tower) actually had an antenna fitted; it was added in 1978. The truss system consisted of six trusses along the long axis of the core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.

...

The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns.

The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses connected to the perimeter at alternate columns and were on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.

++++++


Please show a engineering report or statement that the design of the hat truss was anything but support of the antenna.

Absent an engineering analysis or report...the assertion stands.
 
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JSanderO said:
OK sounds to me like you are looking to spin this. What was the design change to the hat truss?

I wrote that the INTENT of the design of the hat truss was to support the antenna. That is factually accurate.

So what was the "redesign" of the hat truss about? I'd like to have some more specifics.

More analysds which do mention the hat truss related to resisting wind:

http://fire.nist.gov/bfrlpubs/build04/PDF/b04045.pdf

http://global.ctbuh.org/resources/p...e-design-features-and-structural-modeling.pdf

More quotes:

http://architectuul.com/architecture/world-trade-center

Hat trusses (or "outrigger truss") located from the 107th floor to the top of the buildings were designed to support a tall communication antenna on top of each building. Only 1 WTC (north tower) actually had an antenna fitted; it was added in 1978. The truss system consisted of six trusses along the long axis of the core and four along the short axis. This truss system allowed some load redistribution between the perimeter and core columns and supported the transmission tower.

...

The World Trade Center towers used high-strength, load-bearing perimeter steel columns called Vierendeel trusses that were spaced closely together to form a strong, rigid wall structure, supporting virtually all lateral loads such as wind loads, and sharing the gravity load with the core columns.

The floors consisted of 4 inches (10 cm) thick lightweight concrete slabs laid on a fluted steel deck. A grid of lightweight bridging trusses and main trusses supported the floors. The trusses connected to the perimeter at alternate columns and were on 6 foot 8 inch (2.03 m) centers. The top chords of the trusses were bolted to seats welded to the spandrels on the exterior side and a channel welded to the core columns on the interior side. The floors were connected to the perimeter spandrel plates with viscoelastic dampers that helped reduce the amount of sway felt by building occupants.

++++++


Please show a engineering report or statement that the design of the hat truss was anything but support of the antenna.

Absent an engineering analysis or report...the assertion stands.
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So then you reject Glanz's article as evidence?

If so, then everyone can equally reject your evidence, for it is of No better quality.

What you're doing here is very twoofer-like. You have your belief, based on some evidence, but won't even entertain the possibility that you're only half right because you require counter evidence to be of a higher standard. And even then I suspect it will be rejected as evidence even then if it makes a single mention of supporting the antenna.

Cuz that's what twoofers and people with broken thought processes do
 
Of course the truss hat stabilized the structure and would be , imho, an essential part of the design. SOMETHING has to be done at rooftop level to tie the exterior walls to each other, and in this case to the core.
You cannot have four walls and the core all dancing to different beats so to speak.

So, how much did the hat truss contribute to resisting collapse?
Not much apparently as WTC 2 which fell first did not have the added weight and stress of an antenna that WTC 1 did.
 
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jaydeehess said:
Of course the truss hat stabilized the structure and would be , imho, an essential part of the design. SOMETHING has to be done at rooftop level to tie the exterior walls to each other, and in this case to the core.
You cannot have four walls and the core all dancing to different beats so to speak.

So, how much did the hat truss contribute to resisting collapse?
Not much apparently as WTC 2 which fell first did not have the added weight and stress of an antenna that WTC 1 did.
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That's not the point.... the floor plates tied the facade moment frame to the core from floor 6 to the roof. But the plates could not support the antenna... and the columns in the center under the tower were very small and carried little floor loads... most the area under the antenna was a full ht freight shaft... They designed the truss to move antenna axial loads to multiple core columns.
 
JSanderO said:
That's not the point.... the floor plates tied the facade moment frame to the core from floor 6 to the roof. But the plates could not support the antenna... and the columns in the center under the tower were very small and carried little floor loads... most the area under the antenna was a full ht freight shaft... They designed the truss to move antenna axial loads to multiple core columns.
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Yes, but....

Would floor plates work as a roof? I think not. Obviously something different must be done at the roof level(not top floor, but the roof).

I may be mistaken. I am neither an architect or an engineer, but ALL roofs serve to tie walls together to keep them braced to each other (and a core, if present), and resistant to wind loads (as I said they cannot be allowed to all dance to a different 'tune' in the wind) even if its only for one (top) storey.



In the case of the towers, there was added, the requirement to carry a large tower.

Point being that the roof(operative word) hat truss was designed to do both jobs.

Its ridiculous to claim it was designed for one or the other.
 
jaydeehess said:
In the case of the towers, there was added, the requirement to carry a large tower.

Point being that the roof(operative word) hat truss was designed to do both jobs.

Its ridiculous to claim it was designed for one or the other.
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That is reality jaydeehess. And "requirement" (or "need") is a more appropriate word than "design".

A combination of two factors:

1) A need ("requirement") to support antennae - which led to the decision to use the form of the hat trusses - only one of which ended up serving the original layout deciding need: THEN

2) the reality that whatever was included in the structure at that location would take part in the functioning of the structure - including balancing or distributing or resisting wind loadings.

How much it contributed to each function a matter of structural element size and layout BUT no way could the Hat Truss be told "Don't resist wind loads". Once there it would do what a bit of structure at that location and in that layout would do. Take part in all the force interactions.

And Sander isn't saying it wasn't involved - he identifies both aspects but not clearly enough to prevent other members disagreeing with what he says.
 
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ozeco41 said:
That is reality jaydeehess. And "requirement" (or "need") is a more appropriate word than "design".

A combination of two factors:

1) A need ("requirement") to support antennae - which led to the decision to use the form of the hat trusses - only one of which ended up serving the original layout deciding need: THEN

2) the reality that whatever was included in the structure at that location would take part in the functioning of the structure - including balancing or distributing or resisting wind loadings.

How much it contributed to each function a matter of structural element size and layout BUT no way could the Hat Truss be told "Don't resist wind loads". Once there it would do what a bit of structure at that location and in that layout would do. Take part in all the force interactions.

And Sander isn't saying it wasn't involved - he identifies both aspects but not clearly enough to prevent other members disagreeing with what he says.
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This is essentially what I wrote about the hat truss.

The roof is just another floor except the load may be a bit more or even less... snow load as opposed to office use live load. There were other antennas which required support as concentrated loads....probably located above a perimeter core column with guys to the steel frame of the roof...as there were no bar trusses on mech floors.

All floors provided stiffness and held the tubes square and each resisted wind load.

Duly noted who piled on to attack me with the usual ad homs and insults for conveying the original intent for the hat truss...and the additional strength it provided...It did little to resist wind loads... but little is not nothing.
 
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Sander - some bits of the analogy need reversing in phase but...

....remember the little bird and the cow poop.

There often comes a time when it is best to ignore and shut up. :)





...and don't go jumping back into the poop when friends dig you out. << That bit needs both "sides" of the "bird in poop" analogy reversing in phase.
 
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JSanderO said:
This is essentially what I wrote about the hat truss.

.
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I find the whole exercise a bit odd. Arguing a point of minutia, imho.
Does it make any particular difference when discussing the demise of the towers?
Would not matter a whit how strong or stiff the hat truss was when enough columns have lost strength or had loads shifted off axis.

Only Wile E. Cayote doesn't fall unless he can see he has no support.
https://campustocareer.files.wordpress.com/2011/06/wile-e-coyote-2.jpg
 
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