Moderated Continuation - Why a one-way Crush down is not possible

[Ragnarok]

Now if that had been 100 storeys high, would it have just fell straight down, crushing everything below it?

 

[Dave Rogers]

Depends how it was built. Different structures, different collapse dynamics.

Dave

 

[bill smith]

Type : dl : (without spaces) to get a laughing dog.

 

[Dave Rogers]

Amazing! He shows capacity for learning!

Dave

 

[Bluesky]

BasqueArch,
You summarize Heiwa's arguments very nicely. I hope he doesn't charge you with breach of copyright!

 

[FineWine]

The safest assumption in the world is that if Bill can do something, anyone can:

 

[bill smith]

Amazing! He shows capacity for learning!

Dave

I was just 'avin' a laff at your previous post Dave. And killing two birds with one stone.

 

[Klimax]

[qimg]http://www.imagebeast.net/images/a5evebbc8nxjzobtoho2.gif[/qimg]

Now if that had been 100 storeys high, would it have just fell straight down, crushing everything below it?

Most probably it could at least topple partially. But ,you know, difference is not only materials,but position of charges. In this case you have charges very low and possible some of them failed leaving large hole,while back was "undamaged" causing quite bad situation. (The remaining material couldn't support rest of buidling)

Were it same construction material and height as WTC tower,then it would move in two directions. Down and rotating around the (virtual)axis.

And this is perfect example why would be demolishion of any high high-rise using demolish charges so tricky that it would be impossible without significant damage to nearby buildings.(Collapse of towers can be counted as very bad demolishion,so bad that it wasn't controlled at all and as a side effect. )

Notice:I am not expert.I may be corrected by professional in following posts!

 

[tfk]

LOL! Core columns supported by external floors!

.
You are starting to get positively "bill smith-ish" in the mixture of incompetence, arrogance and insult in your comments.

But you've got the LOL-ing down pat. You must be so proud...
__

It appears that the structural engineers at NIST, you know, the guys that actually have a clue what they are yammering about, seem to agree with me.

From NIST NCSTAR1-1, pg 11

Floor Framing System

The floor system of a framed-tube structure is designed for four main functions. First, it supports the vertical gravity loads on the floor and transfers these loads to the external and core columns. Second, as a diaphragm it distributes wind loads to the side walls of the framed tube structure. Third, it, together with the external frame, provides the stiffness to resist torsional motion of the building. Fourth, it provides lateral support to the columns, thereby, keeping the columns stable.
[Emphasis added]

C'mon, genius. LOL some more...

tk

 

[tfk]

Evidently the 'floors' do not support the core! The core is self supporting.

Evidently, you don't know what the #*&* you are talking about.

See previous post for pertinent excerpt from NIST report.

tk

 

[bill smith]

Evidently, you don't know what the #*&* you are talking about.

See previous post for pertinent excerpt from NIST report.

tk

Maybe we should post the NIST FAQ for Bad Boy so he can see how they go into detail about he core columns T ? What do you think ?

I mean that was the most important document NIST produced for informing the general public wasn't iit ? So obviously igreat care was taken to ensure that it was complete and without omission or underplaying of any factor. Stands to reason. Shall we do that ?

 

[funk de fino]

Maybe we should post the NIST FAQ for Bad Boy so he can see how they go into detail about he core columns T ? What do you think ?

I mean that was the most important document NIST produced for informing the general public wasn't iit ? So obviously igreat care was taken to ensure that it was complete and without omission or underplaying of any factor. Stands to reason. Shall we do that ?

No, it was a doucument to shut up the crazy TM nuts who asked stupid questions. The general public, who are not crazy TM nuts, did not need the FAQ's.

You dont even know why the FAQ's were released. That figures

 

[BadBoy]

Hi tfk

Would the strength of the central core have helped keep the collapse vertical - at least to some extent while the floors pancaked, perhaps upto the point it was exposed or damaged by the collapse itself. Im thinking of the building falling and rolling over in the previous post.

 

[tfk]

http://www.imagebeast.net/images/a5evebbc8nxjzobtoho2.gif

Now if that had been 100 storeys high, would it have just fell straight down, crushing everything below it?

.
Notice, before the fall starts, the HUGE gap that they'd chopped in 3 sides of the building. It's literally about 10 stories in the front & 2 stories on the sides. There is a small chance that it could have come down straight if the gap had been about 2 feet. Not 2 stories.

But, then again, that was one tough building. So, perhaps they thought that they needed more drop to get it to come apart.

What the hell did these bozos think would happen, starting on one side & then working their way continuously around the building, like they did??

If they wanted it to come straight down, they should have chiseled a bunch of narrow width gaps into it, (tall gaps, if they need "drop"), leaving interspersed supports all around. Very dangerous for the guy in the machine, tho.

If this building had been 100 stories high, yes, it would have fallen straight down. As they were adding about the 50th story.

If it had been 45 stories high, it also would have come straight down when it got to about 10 - 20° of lean. (And they never would have gotten very far, chiseling out the bottom before it all came down.)

Look at the height to width ratio of this building. 1.5:1 or so?

The tower were 1310/208 = 6.3:1.

Big difference.

Still, one tough building. And showing that, without modern engineering, you have to overbuild things. The WTC was weaker (overall) because the engineering was better, and you could accurately design closer to the failure stresses.

 

[BadBoy]

The 'external floors' are the pre-fabricated floor assemblies installed between core and perimeter columns. Installed? They are simply put on small angle bars at perimeter/core and then bolted at regular intervals to the angle bars on the perimeter columns and horizontal beams at the core; they are hanging on the angle bars and then bolted.
The weakest element here is the bolt and the angle bar. The bolt may provide some lateral support in shear. Evidently the 'floors' do not support the core! The core is self supporting.

ok, if the construction of the floors with the outside walls are not acting as support for the central core, then the central core cannot be acting as support for the outside walls. So both the outside structure and core structure are to all intense and purpose separate structures, self supporting.

What happens if the outside structure moves (with the wind) if the inside core structure is not integral to the whole. wont the floors buckle?

 

[A W Smith]

Anders Bjorkman debunks himself.

I generally just scroll past your ignorant repetitive posts. but this caught my eye.

The 'external floors' are the pre-fabricated floor assemblies installed between core and perimeter columns. Installed? They are simply put on small angle bars at perimeter/core and then bolted at regular intervals to the angle bars on the perimeter columns and horizontal beams at the core; they are hanging on the angle bars and then bolted. The weakest element here is the bolt and the angle bar. The bolt may provide some lateral support in shear. Evidently the 'floors' do not support the core! The core is self supporting.

Yet you have claimed in hundreds of previous posts. That these very same floors which you now say are too fragile to support the core. Were somehow strong enough to arrest this collapse due to entanglement?

 

[BadBoy]

.
Notice, before the fall starts, the HUGE gap that they'd chopped in 3 sides of the building. It's literally about 10 stories in the front & 2 stories on the sides. There is a small chance that it could have come down straight if the gap had been about 2 feet. Not 2 stories.

But, then again, that was one tough building. So, perhaps they thought that they needed more drop to get it to come apart.

What the hell did these bozos think would happen, starting on one side & then working their way continuously around the building, like they did??

If they wanted it to come straight down, they should have chiseled a bunch of narrow width gaps into it, (tall gaps, if they need "drop"), leaving interspersed supports all around. Very dangerous for the guy in the machine, tho.

If this building had been 100 stories high, yes, it would have fallen straight down. As they were adding about the 50th story.

If it had been 45 stories high, it also would have come straight down when it got to about 10 - 20° of lean. (And they never would have gotten very far, chiseling out the bottom before it all came down.)

Look at the height to width ratio of this building. 1.5:1 or so?

The tower were 1310/208 = 6.3:1.

Big difference.

Still, one tough building. And showing that, without modern engineering, you have to overbuild things. The WTC was weaker (overall) because the engineering was better, and you could accurately design closer to the failure stresses.

I saw a CD documentary about a firm blowing up buildings and other structures (sinking large ships for example). In one case they had a large (3-4 stories I think) reinforced concrete sructure and they actuall failed to demolish it. Best they managed was to blow the structure in half, but it never collapsed. That rolling building reminded my of it.

 

[tfk]

Hi tfk

Would the strength of the central core have helped keep the collapse vertical - at least to some extent while the floors pancaked, perhaps upto the point it was exposed or damaged by the collapse itself. Im thinking of the building falling and rolling over in the previous post.

.
Tim,

Now you've impressed me.

It doesn't matter that others have suggested this before. You came up with it yourself.

I think "absolutely". People have compared this to records dropping on a spindle.

And I think that components in the floors that were toughest were the rebar in the concrete. That rebar, interwoven & tied together, is incredibly tough stuff. The cross trusses too, of course.

But those concrete floors were incredibly thin.

As a very interesting exercise, go out into a football field some day with 3 of your buddies. Pace off a square about 200' (67 yards) on a side. (Just approximately) Now imagine a slab of concrete stretching between all of you, with the rectangular core cut-out, just 5.5" thick (with 1.5" deep Vee channels).

Now stack 110 of them on top of each other...

To me, what is amazing about that building is not "what is there". It is how much they were able to pare it back to the absolute essentials, and still have a terrific, robust building that took as much punishment as it did.

Tom.

 

[Heiwa]

.
You are starting to get positively "bill smith-ish" in the mixture of incompetence, arrogance and insult in your comments.

But you've got the LOL-ing down pat. You must be so proud...
__

It appears that the structural engineers at NIST, you know, the guys that actually have a clue what they are yammering about, seem to agree with me.

From NIST NCSTAR1-1, pg 11

Floor Framing System

The floor system of a framed-tube structure is designed for four main functions. First, it supports the vertical gravity loads on the floor and transfers these loads to the external and core columns. Second, as a diaphragm it distributes wind loads to the side walls of the framed tube structure. Third, it, together with the external frame, provides the stiffness to resist torsional motion of the building. Fourth, it provides lateral support to the columns, thereby, keeping the columns stable.
[Emphasis added]

C'mon, genius. LOL some more...

tk

NIST seems to have missed the angle bars/bolts that connect the pre-fab floor assemblies to the perimeter columns and the core beams. Without them the floors would simply drop down.
Evidently these floors - read bolts - do not provide lateral support of the core that is self-supporting.

 

[Heiwa]

ok, if the construction of the floors with the outside walls are not acting as support for the central core, then the central core cannot be acting as support for the outside walls. AA. So both the outside structure and core structure are to all intense and purpose separate structures, self supporting.

BB. What happens if the outside structure moves (with the wind) if the inside core structure is not integral to the whole. wont the floors buckle?

AA. In principle yes. The core is self-supporting and so are also the four walls of perimeter columns/spandrels assemblies just bolted together around the core. The pre-fab floors are simply hanging on angle bars between core and perimeter and fixed by bolts. All described in my papers.

BB. Wind loads on one perimeter wall are evidently transmitted via the perimeter columns, the bolts, the prefab floor assemblies, more bolts, core, more bolts, floor assemblies and bolts to the other three walls and their columns. No risk that the pre-fab floors would buckle. The weakest element here is the bolts and they would not shear off due to wind loads. There are much too many bolts.

But, wind loads will really deform/displace the upper part relative ground. The whole structure was very flexible ... thus not rigid at all ... and the roof could displace several meters laterally in really stormy weather. You could feel it.