Challenge: Demonstrate Sagging floor Trusses Pulling in Perimeter Columns

[DGM]

Huh, what?

.

You didn't use your real name so, anything said by someone that does "trounces" you.

Did you forget how to speak "truther"?

 

[Newtons Bit]

You didn't use your real name so, anything said by someone that does "trounces" you.

Did you forget how to speak "truther"?

If that's what he meant, then yea...

 

[Newtons Bit]

That's nearly up there with Christopher7's "you can't find something if you don't look for it." When discussing diffy q, if someone can't use plain language it means there is no answer?

Two Rules for Maximally Moronic Truthseeking:

Rule 1: Ask technical questions.
Rule 2: Ignore technical answers because they involve math.

 

[beachnut]

ergo says... "I'm not sure."

NB, who doesn't use his real name, has been trounced numerous times here and elsewhere for his technical "prowess". Other engineers who he has tried to engage no longer bother with him.

...

ergo, who doesn't use her real name... lol, seriously? Do you think before you post?
What a load of lies and BS.

I think you understand physics better than most, and don't be worried you don't have a clue what differential equation are. Use your special physics to feed your fantasy.

http://www.internationalskeptics.com/forums/showpost.php?p=6263596&postcount=621

I'm not sure even a moon-sized field or mountain of rubble, dropped from a height of 12 feet would entirely crush the WTC. No. If you had it coming down from a higher height, in a steady stream over a long period of time, we would certainly see some major damage. Total collapse? I'm not sure. (ergo)

ergo physics used on 911 issues: Because the buildings had inherent load-absorbing capacity, like any modern high-rise. When force is coming from above, it is referring ultimately through the entire structure. It would take a much greater force, from a much greater height to "crush" the building. Gravity cannot do it, because the building's design prevents it, as do all modern highrise designs.

Can you put this in laypeople terms?

I think you can apply this same stuff to this issue and keep your idiotic claims and failed fantasy safe in your mind. Wait, you forgot to use your real name.

 

[jaydeehess]

I don't get it! The Usmani paper clearly demonstrates a mode of perimeter column failure that satisfies the OP by eliminating tensile forces in the trusses as the main cause of perimeter inward bowing and reduces the role of heating wrt floor sag by showing that the floors would lose membrane strength at lower temperatures which cause compressive forces within the constrained membrane.

NB, otoh has done math to show heat sag in the trusses is sufficient to pull the columns in.

They are in some respects contradictory but that is due to differing initial assumptions, but the main point is that whether heat sag or compressive forces led to perimeter inward bowing, the fact of that bowing stands as just that, FACT!

The detail of what exact mechanism caused it is rather irrellevant given the existance of multifloor large area office fires that progressed around the building. Fire induced damage is expected to increase and accumulate over time and that is what is observed in the perimeter bowing, a relatively slow increase in that bowing.

Such a slow effect is anathema certainly to explosive use and even therm?te acts faster than the observed bowing.

Therefore one must logically conclude that the fires caused the inward bowing and exact mechanism is at best a concern only for future design considerations and at worst, of strictly academic interest.
ergo demonstrates little or no concern towards better future design and directly demonstrates no academic curiosity by outright refusal to concern himself with da math.

 

[ergo]

Two Rules for Maximally Moronic Truthseeking:

Rule 1: Ask technical questions.
Rule 2: Ignore technical answers because they involve math.

Here's my "technical" question:

Does that thread answer anywhere the question of how the truss-to-column connections can be so robust that the floor trusses, while sagging something like 40" (a feat in itself, without breaking) can pull in 14" steel box columns, causing them to break, but simultaneously be so flimsy as to then be unable to prevent rapid progressive floor collapse? Just curious.

PS: DGM, are you having trouble with the word "trounce" too?

 

[thedopefishlives]

Here's my "technical" question:






PS: DGM, are you having trouble with the word "trounce" too?

It's simple, if you could do the math. The 6 kips force exerted as they were pulling the columns in is nothing compared to the force exerted by the collapsing top block. But then, you knew that already, you just choose to deny it, Mr. Moon-sized-field-of-rubble.

 

[Newtons Bit]

Here's my "technical" question:

I already answered you and said yes, the thread does answer that question. Go read the main post. Its all there.

 

[ozeco41]

I already answered you and said yes, the thread does answer that question....

I like it.
Moral: Make sure that you ask the right question.

One of my favourite examples of the same structure is:

Q: "Was the baby a boy or a girl?"
A: "Yes."

(at that point you either smile or duck - depending on your audience.)

 

[ozeco41]

Two Rules for Maximally Moronic Truthseeking:

Rule 1: Ask technical questions.
Rule 2: Ignore technical answers because they involve math.
Rule 3: Ignore technical answers which don't require maths.

FTFY.

Don't let them off too easy.

I see more engineering technical stuff ignored which does not require maths than the ones that actually do need quantitative support.

Take as an example ergo's technical question:

Does that thread answer anywhere the question of how the truss-to-column connections can be so robust that the floor trusses, while sagging something like 40" (a feat in itself, without breaking) can pull in 14" steel box columns, causing them to break, but simultaneously be so flimsy as to then be unable to prevent rapid progressive floor collapse? Just curious.

The main apparent "misunderstandings" (yes, I'm being gentle ) are:
A) "while sagging something like 40"... can pull in 14" steel box columns" Three sub issues of "misunderstanding" here are:

• The start of column failure doesn't need the 40" sag so there is a false implication here;
• "can pull in" implies that floor joist sag is the only pull in mechanism. It isn't. It is only needed to start inwards bowing. Once started and progressed beyond the critical point it will self propagate until load shedding/redistribution reduces the applied load. (Working out where that critical point occurs needs maths. Knowing that there is such a critical point doesn't.)
• The pull in direction is the weakest axis of the perimeter columns.

B) "causing them to break," False causation. The process of inwards bowing which floor joist pull in could have initiated would progress with no further help from the floor joists - column failure would result from vertical loads causing excessive bending leading to column failure or rather "folding or breaking" - it had already "failed". Most likely by breaking at the bolted joints if they were near enough to the maximum flexure point. (A bit of non maths explanation would help there but I won't derail at this stage.)

C) "simultaneously be so flimsy" I doubt he meant "simultaneously" but let's move on.

D) "...then be unable to prevent rapid progressive floor collapse?" A simple orders of magnitude avoidance. Pull in would require at least one order magnitude less force than joist attachment shear off. There was probably two surplus orders of magnitude - or more - available from the descending mass. I don't need to employ the maths because the gap is so wide.

So of the five issues identified in ergo's "technical question" none of them directly required maths.

 

[enik]

I created a thread about it back in 2008. Calculations are done. What's my prize?

The OP states to show, using FEA or in your case hand calculations, how the perimeter columns of WTC 1 were pulled in by up to 54” by sagging floor trusses. However, you already assumed the sagging floor trusses were pulling in the exterior column, with 6 kips per column no less, in your analysis. I don’t recall ever seeing the NIST use second order effects from combined bending and axial forces in their report.

The answer is simple: the pull-in force was small…

By how much? 1 kips, .5 kips, 1 lb?

In any event, I worked through your math some time ago and it had some issues. You used the wrong values for the 14x14x5/16 column (I mentioned this before to you). You also used a value of E (Modulus of Elasticity) much smaller than what the NIST used (I also mentioned this to you). But mostly, you had an incorrect equation relating moment to deflection that was critical to your analysis.

Instead of going into detail here, Here is a step by step analysis of your analysis. It should be easy enough to follow for any layperson.

I also ran your analysis through an FEA. It still didn’t work. In fact, it requires much more than 6 kips to get the column to buckle.

 

[Newtons Bit]

The OP states to show, using FEA or in your case hand calculations, how the perimeter columns of WTC 1 were pulled in by up to 54” by sagging floor trusses. However, you already assumed the sagging floor trusses were pulling in the exterior column, with 6 kips per column no less, in your analysis. I don’t recall ever seeing the NIST use second order effects from combined bending and axial forces in their report.

By how much? 1 kips, .5 kips, 1 lb?

In any event, I worked through your math some time ago and it had some issues. You used the wrong values for the 14x14x5/16 column (I mentioned this before to you). You also used a value of E (Modulus of Elasticity) much smaller than what the NIST used (I also mentioned this to you). But mostly, you had an incorrect equation relating moment to deflection that was critical to your analysis.

Instead of going into detail here, Here is a step by step analysis of your analysis. It should be easy enough to follow for any layperson.

I also ran your analysis through an FEA. It still didn’t work. In fact, it requires much more than 6 kips to get the column to buckle.

Hi enik, I don't have time at the moment to go through your analysis, but I want to point out two things.

1) You are correct on my mistaken column section, I used a moment of intertia values of a 16x16 instead of a 14x14 too large.
2) I did not assume a simple span beam with a single point load. I used a simple span beam with two equal concentrated loads symmetrically placed, as the diagram depicts. If you have an AISC Manual of Steel Construction 13th, you'll find the equation on page 3-213.

 

[enik]

...2) I did not assume a simple span beam with a single point load. I used a simple span beam with two equal concentrated loads symmetrically placed, as the diagram depicts. If you have an AISC Manual of Steel Construction 13th, you'll find the equation on page 3-213.

I do not have the manual. Maybe you can copy the pertinent pages and email them?

 

[Newtons Bit]

I do not have the manual. Maybe you can copy the pertinent pages and email them?

Try this page.

The condition is "Twin loads on beam with two simple supports"

 

[jaydeehess]

Yee gads!
The whole arguement is moot.

The columns DID bow inwards
There WAS large area multifloor office fires that began within seconds of aircraft impact and continued throughout the time period between that event and collapse.
Therefore it is quite logical to assume that some mechanism driven by or initiated by the heat of those fires, with possible contribution from impact damage, is responsible for the inward bowing and eventual failure of the perimeter columns.

There is no evidence to support anything other than office fire heat being the driver of this bowing.

There are two reasons to make a determination as to exact initiating forces that were developed by this heat;
- to aid in future contruction techniques for safer buildings
- a purely academic curiosity

Yet it appears that neither of these reasoned and logical paths is what causes ergo or enik to ask these questions.
In fact it is a given among those who understand technology, even if they do not possess an engineering degree, that any study that seeks to make such a determination of the detail of the mechanism by which the bowing occured WILL REQUIRE some understanding of the math involved.

The Usmani paper is written after development and running of an FEA in which MATH is what the computer is doing!
Lo and behold, the NIST did the same thing. They developed and ran FEAs which had the computer crunching numbers and formulae.

Any discussion that seeks to reconcile differences bewteen the conclusions of each FEA would REQUIRE an in depth examination of the math, that is to say the initial conditions assumed in the structure, the force formulae used at each node, etc.

Ergo for one is on record as rejecting any such investigation because he is not capable of following the math.
Too bad so sad, Nancy, that's the way its done!

 

[beachnut]

I do not have the manual. Maybe you can copy the pertinent pages and email them?

Are you a debunker, or a truther? Can you debunk 911 truth who say it was an inside job, with respect to this challenge?

Debunkers are not smart. They have taken just enough engineering courses to sound like they know what they are talking about, however, I haven't found one yet that can prove they are a mechanical engineer or do an FEA.

Did the bad guys in in your inside job fantasy used military to set the secret stuff to destroy the WTC? The old chain of command, soldiers don't rat out lies and corruption because of the old chain of command? lol, I guess the chain of command looks different at the bottom to the paranoid mind. http://s1.zetaboards.com/LooseChangeForums/topic/4660006/1/
Did the military plant the stuff, from secret military grade explosives, or is your fantasy based on the idiotic thermite scam?

Robertson the chief structural engineer of the WTC says NIST in general was right, and you say they were wrong? Is that the challenge, the purpose of the challenge to show, how do you put it, debunkers that NIST is wrong? What about the many other studies and papers, are they wrong too? Will the challenge silence them?

Why does 911 truth not understand models? Dismissing Bazant's model, and acting all superior? Is it their delusion of an inside job, and inability to understand models? What is the outcome goal of this challenge with respect to models? LOL, a model challenge, which 911 truth rants against models all the time, goal is what? Another model to ignore? http://s1.zetaboards.com/LooseChangeForums/single/?p=516896&t=4724858 Bazant was right, a building can collapse.

Who will this challenge silence the fact steel fails in fire?

http://s1.zetaboards.com/LooseChangeForums/topic/4724858/1/

"Inside Job Evidence is in the Physics of WTC #1"

Will your challenge make your failed claims of an Inside Job true? What is your goal? 11 years and you are stuck on this, your inside job fantasy.

"Inside Job Evidence is in the Physics of WTC #1"

How will the Challenge support your fantasy of an inside job?

 

[Newtons Bit]

The OP states to show, using FEA or in your case hand calculations, how the perimeter columns of WTC 1 were pulled in by up to 54” by sagging floor trusses. However, you already assumed the sagging floor trusses were pulling in the exterior column, with 6 kips per column no less, in your analysis. I don’t recall ever seeing the NIST use second order effects from combined bending and axial forces in their report.

By how much? 1 kips, .5 kips, 1 lb?

In any event, I worked through your math some time ago and it had some issues. You used the wrong values for the 14x14x5/16 column (I mentioned this before to you). You also used a value of E (Modulus of Elasticity) much smaller than what the NIST used (I also mentioned this to you). But mostly, you had an incorrect equation relating moment to deflection that was critical to your analysis.

Instead of going into detail here, Here is a step by step analysis of your analysis. It should be easy enough to follow for any layperson.

I also ran your analysis through an FEA. It still didn’t work. In fact, it requires much more than 6 kips to get the column to buckle.

It looks like you're not doing the p-delta iterations right

The 4th calculation in your chart results in a much too high deflection. Here's the correct calculation:

Mu4 = (0.435+0.184)in*139k = 86.04 kip*in

Deflection = Mu4*L^2 / (4*EI)
= 86.04kip*in*(37 * 12ft\in)^2 / (4*29000ksi*739in^3)
= 0.197in

If we go one more step:

Mu5 = (0.435+0.197)in*139k = 87.85 kip*in

Deflection = Mu5*L^2 / (4*EI)
= 87.85kip*in*(37 * 12ft\in)^2 / (4*29000ksi*739in^3)
= 0.202in

The second-order deflection for each iteration is:
0.140 -> 0.184 -> 0.197 -> 0.202
The change in second order deflection per iteration is
0.044, 0.013, 0.005

The total deflection thus stabilizes.

 

[alienentity]

I see Gamolon has issued a challenge in another thread. I will offer an even simpler one. Show with your own FEA or calculations how the perimeter columns of WTC 1 were pulled in by up to 54” by sagging floor trusses.

Bonus, demonstrate how this instability caused the initiation sequence for collapse of WTC 1.

Hi Enik,

Just curious about your understanding of the inward bowing of the columns. What do you think caused this?

I see that you may like to see a mathematical explanation, but for argument's sake let's assume nobody can produce one (I know they have, and ironically you seem awfully reluctant to accept these..) - does that mean the columns didn't bow inward?

Again, just curious.

 

[ozeco41]

^^^^

 

[enik]

Hi Enik,

Just curious about your understanding of the inward bowing of the columns. What do you think caused this?

I see that you may like to see a mathematical explanation, but for argument's sake let's assume nobody can produce one (I know they have, and ironically you seem awfully reluctant to accept these..) - does that mean the columns didn't bow inward?

Again, just curious.

The perimeter columns did bow inward. The mechanism that could cause this and is supported by FEA is a downward displacement of the core.