Legge/Szamboti: Sudden Collapse Initiation was Impossible

[A W Smith]

Quintierre would apparently like to see a new investigation himself, given the entire context of his remarks. Are you going to argue that?

http://www.opednews.com/articles/1/genera_alan_mil_070820_former_chief_of_nist.htm

[FONT=arial,helvetica,sans-serif]Although Dr. Quintiere was strongly critical of NIST’s conclusions and its investigatory process, he made it clear he was not a supporter of theories that the Twin Towers were brought down by pre-planted explosives. “If you go to World Trade Center One, nine minutes before its collapse, there was a line of smoke that puffed out. This is one of the basis of the ‘conspiracy theories’ that says the smoke puffing out all around the building is due to somebody setting off an explosive charge. Well, I think, more likely, it’s one of the floors falling down.”[/FONT]
[FONT=arial,helvetica,sans-serif]Dr. Quintiere summarized the NIST conclusion about the cause of the collapses of the Twin Towers. “It says that the core columns, uninsulated due to the fact that the aircraft stripped off that insulation; they softened in the heat of the fire and shortened and that led to the collapse. They pulled in the external columns and it caused it to buckle. They went on further to say that there would be no collapse if the insulation remained in place.”

[FONT=arial,helvetica,sans-serif]Dr. Quintiere then presented his and his students’ research that contradicts the NIST report and points to a different cause for the collapses; the application of insufficient fire-proofing insulation on the truss rods in the Twin Towers. “I suggest that there’s an equally justifiable theory and that’s the trusses fail as they are heated by the fire with the insulation intact. These are two different conclusions and the accountability for each is dramatically different,” he said.[/FONT]
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[LashL]

What is really funny is the obvious fact that you said nothing here. Did you take a course in ad hominem tactics?

What is even funnier is that you ignored everything I said, and pretended that it was an ad hom instead of addressing what I wrote. No, that's not "funny", actually, just typical.

You are, apparently, not only uneducated on the subject matters upon which you purport to opine, but you are also obviously uneducated on the subject of logical fallacies.

Gee, why am I not surprised?

 

[beachnut]

There is no "plausible" demolition theory. That is why everyone in the demolition industry rejects the codswallop shoveled by you and your fellow liars. There isn't a shred of evidence that any columns were cut. The collapses proceeded--obviously--from the impact floors. When is it time to pull down the curtain on this truly rotten show?

You are correct it is a delusional demolition theory based on nothing.

 

[LashL]

I'd actually agree to such an investigation if the kooks paid for it.

As would I.

It would be such a gross embarrassment to them, though, that they will never put their money where their mouths are.

 

[cmcaulif]

The collapse would not have continued as there would not have been enough of a dynamic load. NIST's recent FAQ talks of a sudden load amplification factor of 2.00 and the central core had a 3:00 to 1 factor of safety and the perimeter columns a 5:00 to 1 factor of safety.

too bad they are talking about the nominal strength of the connections, not any kind of design capacity, making your point worthless.

 

[cmcaulif]

Additionally slow heating by fire would have had a problem causing a catastrophic collapse due to strain hardening.

Why would this be a problem when the members are undergoing an inelastic buckling mechanism at relatively low strains?

The WTC columns would not undergo compressive failures, as you sem to think.

 

[Tony Szamboti]

Why would this be a problem when the members are undergoing an inelastic buckling mechanism at relatively low strains?

The WTC columns would not undergo compressive failures, as you sem to think.

What does the slenderness ratio of a structural steel column need to be to be in the inelastic buckling range?

What were the slenderness ratios of the central core columns at the collapse initiation sites of the 98th floor in the North Tower and 82nd floor in the South Tower?

 

[Newtons Bit]

What does the slenderness ratio of a structural steel column need to be to be in the inelastic buckling range?

What were the slenderness ratios of the central core columns at the collapse initiation sites of the 98th floor in the North Tower and 82nd floor in the South Tower?

Inelastic buckling occurs for all slenderness ratios under the Euler limit. That's 4.71 * SQRT(E/Fy). Of course extremely stout members won't buckle inelastically, however none of the columns in the upper floors of the WTC were that stout.

Do you have any clue as to what you're talking about? I recommend picking up an AISC Manual of Steel Construction and see exactly how steel is designed these days. We're not in the 1940's, we know how steel fails now. Maybe you should update you knowledge to modern information.

 

[TjW]

Inelastic buckling occurs for all slenderness ratios under the Euler limit. That's 4.71 * SQRT(E/Fy). Of course extremely stout members won't buckle inelastically, however none of the columns in the upper floors of the WTC were that stout.

Do you have any clue as to what you're talking about? I recommend picking up an AISC Manual of Steel Construction and see exactly how steel is designed these days. We're not in the 1940's, we know how steel fails now. Maybe you should update you knowledge to modern information.

What, and give up show business?

 

[Tony Szamboti]

Inelastic buckling occurs for all slenderness ratios under the Euler limit. That's 4.71 * SQRT(E/Fy). Of course extremely stout members won't buckle inelastically, however none of the columns in the upper floors of the WTC were that stout.

Do you have any clue as to what you're talking about? I recommend picking up an AISC Manual of Steel Construction and see exactly how steel is designed these days. We're not in the 1940's, we know how steel fails now. Maybe you should update you knowledge to modern information.

How did I know you would come on.

You used an effective length factor of 1.0 in your letter to Gordon Ross, which is for a pinned connection, when you should have used .5 to .65 for fixed both ends connections for the tower columns. The 1.0 gave you larger slenderness ratios and they still weren't greater than 40. Now you are going to say the tower columns weren't in the short column category and would have been subject to inelastic buckling. The AISC equations you show here and which you used in your paper are conservative for design.

You want to say the tower columns would fail due to buckling. Well how about a test case were an I beam with a slenderness ratio of 20 or lower failed due to inelastic buckling. Do you have any test cases? I have an AISC manual right here. I am familiar with the equations and monograph. You want to go around asking others if they have a clue and you seem to be the one who should be asked that question Mr. Smarty pants.

 

[Newtons Bit]

How did I know you would come on.

Hey, you've already figured out that when someone flings BS regarding structural engineering on this forum I pipe in.

You used a pinned connection instead of a fixed one for the tower columns and raised the slenderness ratio.

No, I used a connection as part of a moment frame.



Notice the lowest value of the effective length factor (that's the K, as in KL/r) is 1.0. That only occurs for an infinitely stiff girder, or spandrel compared to the column. The prevailing idea at the time was strong column - weak beam, so I REALLY doubt that's the case.

Now you are going to say any the tower columns weren't in the short column category.

Were they? An effective length of 26 to 52 (the probable range that the exterior columns were at) is definitely not "short".

The AISC equations you show here and which you used in your paper are conservative for design.

No, they're not, they're pretty much exact on. There's a reason why we tack on a 0.9 phi factor (aka factor of safety for material) and factor the loads up.

You want to say they would fail well how about a test case were an I beam with a slenderness ratio of 20 or lower failed due to inelastic buckling.

Show me the columns in the tower that have a slenderness ratio of less than 20 and then show me test results that a 12' tall column fails compressively rather than buckling. I'll change my calculations to reflect that if true.

Do you have any test cases? I have an AISC manual right here.

I'm sure there's some out there, one of my textbooks has a large graph that shows the equations are fairly predictive of actual results. Though it's at work.

I am familiar with the equations and monograph. You still used the wrong effective length factor for the fixed situation in the tower columns.

It's NOMOgraph table. A monograph is a scholarly book or a treatise on a single subject or a group of related subjects, usually written by one person. It is a one-time publication that is complete in itself. It may refer to a detailed, well-documented work on a limited subject or a person.

 

[Newtons Bit]

How did I know you would come on.

You used an effective length factor of 1.0 in your letter to Gordon Ross, which is for a pinned connection, when you should have used .5 to .65 for fixed both ends connections for the tower columns. The 1.0 gave you larger slenderness ratios and they still weren't greater than 40. Now you are going to say the tower columns weren't in the short column category and would have been subject to inelastic buckling. The AISC equations you show here and which you used in your paper are conservative for design.

You want to say the tower columns would fail due to buckling. Well how about a test case were an I beam with a slenderness ratio of 20 or lower failed due to inelastic buckling. Do you have any test cases? I have an AISC manual right here. I am familiar with the equations and monograph. You want to go around asking others if they have a clue and you seem to be the one who should be asked that question Mr. Smarty pants.

Hey, you completely edited your post and you still spelled nomograph wrong. Isn't that interesting.

I also find it interesting that you call out a K of 0.65. I'm assuming you're referring to this table:



And you'd be wrong. Notice how in Fig C-C2.4 it's called an "alignment chart - sidesway uninhibited (moment frame)". They're actually talking about columns in "moment frames". I assume you know what that word means. It's the type of frame that the exterior columns were a part of.

Table C2.2 is a table for more idealized conditions. Like for instance a compression member in between two very large and very stiff concrete walls. In that case it would have a K of approximately 0.65.

Here's the quote from the commentary (AISC-360, p239): "These range from simple idealizations of single columns such as shown in Table C-C2.2 to complex buckling solutions for specific frames and loading conditions"

That may have been a good idea for you to read.

Reading comprehension is important. Either actually study AISC-360 and learn about it and the research behind the recommendations, or stop talking about something you obviously know nothing about.

 

[Max Photon]

Creepy strain hardening

I thought this post of Apollo's would look great riiiiiiiiight.....
here.

No...here.