Acceleration of the falling top blocks.

[ergo]

No I don't doubt there were bridging trusses. I just know for a fact they don't do what you think they do.

What do you think they do?

BTW. If you want to challenge me on the details of the construction. You're way out of your league.

I look forward to your answer to the above question.

 

[Brass]

So how long have you been in construction there ergo?

 

[DGM]

What do you think they do?

The same thing as the long span trusses except they fill in the corners and where changes in truss connection directions are needed.

 

[ergo]

So how long have you been in construction there ergo?

?

I sincerely hope this isn't DGM's way of avoiding my question.

 

[thedopefishlives]

The core was not left standing. It fell a few seconds after it appeared. (Straight down, too, which is a different topic.) Do you have an explanation for how its top 40 or 50% was demolished before the remnant dropped? Keep to your floor failure model while explaining this, please.

Tell me, what other direction would you expect the core to fall? Gravity only works straight down, last time I checked.

As for an explanation of how the top "40 or 50%" was demolished, obviously I don't know exactly what happened - nobody does - but my best guess would be that as the collapse progressed, the joints between the top sections of the columns and the bottom sheared.

 

[ergo]

The same thing as the long span trusses except they fill in the corners and where changes in truss connection directions are needed.

What is that "same thing" ?

 

[Brass]

?

I sincerely hope this isn't DGM's way of avoiding my question.

Can't answer it, eh? (No pun intended).

 

[DGM]

?

I sincerely hope this isn't DGM's way of avoiding my question.

Nope, It's been over 35 years for me (in construction).

 

[DGM]

What is that "same thing" ?

Look at the pictures of the connection that you had issue with. You can see examples of them. Where are you going with this? You don't think that the floor system could have arrested the collapse, do you?

I'd still love to see the "cabling". I'm guessing you're confusing the sway dampers with something that provides structural strength.

 

[ergo]

As for an explanation of how the top "40 or 50%" was demolished, obviously I don't know exactly what happened - nobody does - but my best guess would be that as the collapse progressed, the joints between the top sections of the columns and the bottom sheared.

Why does nobody know exactly what happened? Why should this be mysterious for structural engineers for a gravity collapse of a steel-framed highrise? Aren't you folks always saying how "obvious" the collapse was? Why is this difficult for you?

And please tell us more how the floors were ripped from the columns, how that occurred at the average rate of 0.16 of a second per floor through 287 floor-to-column connections, and how all that ripping of connections (and concomitant pulverization of all building contents) only took an extra 0.047 of a second to occur per floor than if each floor fell through air. I'd be fascinated to hear this story.

 

[thedopefishlives]

Why does nobody know exactly what happened? Why should this be mysterious for structural engineers for a gravity collapse of a steel-framed highrise? Aren't you folks always saying how "obvious" the collapse was? Why is this difficult for you?

And please tell us more how the floors were ripped from the columns, how that occurred at the average rate of 0.16 of a second per floor through 287 floor-to-column connections, and how all that ripping of connections (and concomitant pulverization of all building contents) only took an extra 0.047 of a second to occur per floor than if the "upper block" fell through air? I'd be fascinated to hear this story.

You are adding to what I said. I said nothing about pulverization of ANYTHING. You are misinterpreting and twisting my BEST GUESS (remember, I am not a structural engineer, I am a computer scientist) of what happened in order to make me into a convenient strawman. If you want answers as to the how and why of the mechanics of collapse, I would refer you to an expert engineer who can explain to you how little time it takes for bolts to shear and welds to fail if the force is great enough.

As for why this should be "mysterious", I know that in your fantasy world, building collapses happen in a neat wrapped-up little package, but out here in reality, it's an extremely complex and chaotic occurrence that no one can predict beyond collapse initiation.

 

[ergo]

You are adding to what I said. I said nothing about pulverization of ANYTHING.

Unfortunately, your theory has to account for the reality of what occurred. What I'm adding is reality into your model. How well does your model work now?

 

[Brass]

Can't answer it, eh? (No pun intended).

I guess I'll answer it then.

"Well, now that you mention it, Brass, I don't have too much experience in construction. I don't know why exactly I doubt the work of real, respected experts in the field and instead believe in my heart of hearts that I have more knowledge of their fields of study than they do. Seems a little backwards. Perhaps I should go back to the drawing board and see if the stuff I say really makes sense...."

 

[thedopefishlives]

Unfortunately, your theory has to account for the reality of what occurred. What I'm adding is reality into your model. How well does your model work now?

I'm sure it works just fine. I would again defer to an actual structural engineer to get more accurate information, since I freely admit that this is not my area of expertise. Still, I'm sure you will find plenty to nitpick about in order to disassemble your neatly created strawman.

 

[DGM]

Why does nobody know exactly what happened? Why should this be mysterious for structural engineers for a gravity collapse of a steel-framed highrise? Aren't you folks always saying how "obvious" the collapse was? Why is this difficult for you?

It's not a mystery. The real world collapse are very well understood. We have shown you several times where to get this understanding. The problem is you throw in a condition that did not actually happen. The confusion is with you, If you want an education, maybe you could show a willingness to learn. Frankly, I don't think you give a damn.

 

[ergo]

Look at the pictures of the connection that you had issue with. You can see examples of them. Where are you going with this? You don't think that the floor system could have arrested the collapse, do you?

I'd still love to see the "cabling". I'm guessing you're confusing the sway dampers with something that provides structural strength.

Still not answering the question.

The floor system, which exists in both upper and lower building assemblies, is not tasked with arresting the collapse. The column structure, which exists in both upper and lower building assemblies, is.

No, the "cabling" I'm referring to is not the sway dampers, DGM.

 

[ergo]

It's not a mystery. The real world collapse are very well understood.

Then it should be no problem for you to explain mechanically how the core structure was demolished.

The problem is you throw in a condition that did not actually happen.

What condition have I thrown in that wasn't there?

 

[ergo]

I'm sure it works just fine. I would again defer to an actual structural engineer to get more accurate information, since I freely admit that this is not my area of expertise.

Well, I'm sorry, but I've already stated that no structural engineer currently endorses a floor failure model for the WTC. If you know otherwise, please correct me.

 

[NoahFence]

The core was not left standing. It fell a few seconds after it appeared. (Straight down, too, which is a different topic.) Do you have an explanation for how its top 40 or 50% was demolished before the remnant dropped? Keep to your floor failure model while explaining this, please.

Wait a minute...the CORE fell straight?

See, the thing about lying, then lying to cover up the previous lie, its that eventually they become way too obvious. And that comment was pretty damn obvious.

 

[tsig]

Anyone still defending the gravity collapse model at this point is a moron or a liar. We know who the liars are. This is pre- high-school level physics.

Kindergarten level even.