Derek,
Had to look up your idiotic acronym.
You're suggesting that "his name is only occasionally 'James Randi'"...??
LMAO. You're as illiterate as you are innumerate.
By all means, keep up the name-calling. Be my guest.
It's always better, somehow, when the completely clueless cop a 'tude, too.
There ain't no "Mexican standoff", junior. The entire world's engineering community made its judgment about events years ago. We decided that twoofers are a bunch of hapless bozos.
But we also have a far, far harsher judgment on the likes of you. And Szamboti. Incompetent punk engineers who are so brain-dead, and eager to betray the dignity of their own profession, as to tell the public that we are all frauds, liars & accessories to mass murder & treason. (LMAO, why do you think that, other than signing some nebulous petition, 98% of the ae911t engineers are absolutely, 100% silent.)
I invite you, I plead with you, to continue on your one-man exercise in public self-humiliation & self-aggrandizement. You're already the buffoon. As your role becomes known, you'll also become a pariah amongst all the local engineers. Why do you think that all the other engineers at ae911t keep their heads down & out of sight?
Do you remember this comment you made about the help I gave you when this all started?
Post 267
LoL. You aren't close to "done scrubbing".
I'll be the one laughing as I watch from the sidelines.
Are you completely brain-dead? "No tested physical evidence..."??
So, your considered opinion is that it isn't possible to do a meaningful analysis without "tested physical evidence"??
Gee, I guess it must be impossible to design anything, eh Derek? Ain't no physical evidence to do any analysis before you build the thing.
That must explain why all those planes (the F119, F22, F35, B2, A380, etc) all crashed the first several times they tried to fly 'em. Just no way to know what's gonna happen unless you have physical parts to test...?!!
Can't learn anything from videos, photos or seismic records, of course...
You really think that the only form of physical evidence is hunks of WTC7 metal?? Gee, I guess you must insist that your company do a couple hundred thousand dollars worth of testing on each shipment of raw material you use on each project. After all, what good are certs? They aren't "physical evidence".
I guess your conclusion is that there is no way for engineers to tell what happened to the Thresher. Or to the Spirit rover on Mars. After all, nobody has any of those parts either. Or, for that matter, any of the parts from WTC1 or 2 that initiated those collapses.
I guess that, without the actual parts that fail, all engineering forensic examinations are merely "guesswork", eh? With that attitude, it's comforting to know that you'll never lead any of those investigations.
I've already provided you with my answers. There ain't no need to do it pointless calculations. This is one of the things that you learn thru your career: don't take on tasks that you don't need to. It's just a waste of time.
I have ALL the evidence that I need to know that the collapse of WTC7 did not violate any CoE considerations. And not one of those pieces of evidence requires the tedious manual calculation of buckling loads in a latticework structure.
But, here, let me elaborate a little further on your silly, silly questions in your prized post#1152 questions ...
Your premise is wrong.
It's wrong for the core columns because you have zero information about how long it took those columns to collapse.
It's also wrong for the north wall columns. And NIST says it's wrong. And I agree with them.
Remember these graphs?
NIST's graph:
[qimg]http://img7.imageshack.us/img7/3748/nistwtc7velocityvstime.png[/qimg]
Do you see that curve during Stage 1? And during Stage 3?
Those curves say that your premise MUST BE wrong.
Those curves say "LOTS of energy was dissipated during those phases of the collapse of the building.
Do you see the lack of an error analysis in NIST's & Chandler's work for Stage 2? Do you see the regression coefficient of R^2 = .9906?
Those considerations say that your claim that "no energy" was dissipated during Stage 2" is unsupportable. And that the most that you can say is "little energy was dissipated during Stage 2".
Which is exactly what I've been saying all along to you: "Little energy was dissipated during Stage 2 because buckling of the main support columns was not the principle failure mode. Fracturing of connections (bolts & welds) was."
tfk's graph:
[qimg]http://img839.imageshack.us/img839/9636/ffavswtc7northwallaccel.png[/qimg]
See all that area above the red line & below the green line? All of that area represents energy that was dissipated during the collapse. Now, during my time equivalent of "Stage 2" (5.25 seconds < t < 7.50 seconds), the integrated sum of the difference between the red line & the green line shows a significant energy sink even during this stage.
You are invited to comment.
If you'd like to post your "Lagrangian energy dissipation" snake in the weeds, be my guest.
I've answered this question very simply: "Your premise is wrong."
If you want to dispute my answer, then it's your job to provide your own analysis.
Not my job.
Meaningless question.
This could be done pretty easily for an isolated column in the undamaged building, given accurate statements of the nature & stiffness of the various constraints, and some assumptions of the loading geometries.
But that answer is irrelevant to the critical buckling loads of any column as a component of the lattice structure. As the loads on any one column increase, they will be shifted thru the structure to adjacent columns. And therefore, what might have been a critical buckling load to the individual column becomes less than critical to the column within the structure. Just part of the redundancy of intact structures.
The "isolated, undamaged answer" is also irrelevant to the buckling loads of fire-weakened or support-damaged or load-conditions-massively-changed columns.
No answer can be given to your question without a clear assessment of the damage, the constraints and the load state.
Too bad you're so sloppy in crafting your arguments, Derek.
Please translate this question from Gibberish into English.
Same caveats above apply.
In principle, fairly straightforward to calculate. Made a bit tricky by the transfer trusses on the 7th (IIRC) floor.
But to get real buckling loads for the columns as part of the structure, that takes some FEA work.
As for the critical buckling loads WHEN THEY ACTUALLY BUCKLED ... well, that's a calculation of a very different order of magnitude. Especially when you're trying to define the actual loading conditions that caused the buckling.
Gibberish to English, please.
I can easily imagine how it could happen. But my imaginings are irrelevant, because they would be speculation.
NIST's imaginings wouldn't be speculation in the slightest, tho. It would be the direct result of their detailed analysis.
So if you are really, really, really super duper interested in the "how exactly" ...
... WTF haven't you asked NIST?
A simple question for you Derek.
Please don't evade it.
Not after I've gone to such lengths to answer all of your questions, simply, directly & in detail.
Wrong.
Wrong again.
Wow. You're darn near illiterate, aintcha?
I said right there above, and re-iterate now, that I have all the evidence that I need to exercise my engineering judgment to assert with supreme confidence that there was no "lost energy" during WTC7's collapse.
See? I didn't weasel out of anything.
Your ignorance does not constitute my error. Or my "throwing anyone under any bus."
If you were literate, you might realize that "everyone give Tom a hand" is not the general consensus of the posters here.
Just an observation about "hearing what you want to hear"...
That seems to be something of a pattern in you.
tom
That's a lot of bravado Tom, bravo! But you still fail to answer the simple questions. Please do so, if you're able. There are plenty of calculators on line that use the Structural Stability Research Council’s numerical methods, just plug in the geometry, materials and click the mouse button! Don't let your budding twoof-slaying fans down, they are cheering you on as I type.
2a. How did no energy dissipate from the WTC 7 columns? Explain this in terms of the Lagrangian energy theory. Tell me all about the dissipation term; please don't forget that ol' serpent in the garden.
There is a starting point for all Hades breaking loose, and NIST makes this much clear. The unstable condition started at column 79, you and NIST both stated it buckled. You and NIST both stated the others buckled as well. If you want your cop out (bolt/weld) fantasy to work out, you must demonstrate that either Cantor or Frankel was in error with their AISC connection designs, something you might have a hard time doing, I suspect. But I’m willing to watch you make this case, can you? Ultimately you have to come to terms with your own statement: "they buckled Derek" or NIST's similar statements. With this column buckling as you and NIST have stated, you will not get PE to KE transfer without overloading, strain hardening, energy dissipation and ultimately distortion failure across the 3 stages of collapse short of additional forces to the system. So either there were additional forces that we are unaware of or there was energy dissipation. Which is it twoof-slayer?
Tell me exactly how you can bypass the dissipation Tom? Your NIST graph you're so proud of makes my point, not yours. Unless there is an external force, deal with the Lagrangian dissipation energy term (also implicit in Hamilton's theory).
2b. What were the critical buckling loads of the 24 interior WTC 7 columns? Assume w14x730 without built up, and then with the built up sections.
There were 23 other interior columns that were quickly vexed according to NIST models and commentary (not according to tested physical evidence, once again…just a friendly reminder)...and some columns were built up, quite heavily towards the bottom I might add. Tell me about the critical buckling load capacity of these interior ASTM A572 columns Tom, especially at the 8th floor where NIST offers gravity load data. You can do it; your fans are all rooting for you Tom. Go Tom go!
2c. Will these values handle (with the critical buckling load solved) the 8th floor gravity loads at each column location? Answer with and without respect to the built up sections, please.
No false premise, unless you're looking for the weasel way out. And I know you would never think to do such a thing. This will help establishe stability and redundancy. And no Tom, no horizontal progression is evident in the NIST
woo model, sorry, see for yourself. Look closely. Closer...
2d. What were the critical buckling loads of the 57 exterior WTC 7 columns?
This is where we examine your “north wall only” focus and the curious fate of how those wimpy-puny-pathetic Frankel steel W14x730
just couldn't help but buckle, I mean break at the welds and bolted splice connections, excuse me. What were their carrying capacities Tom? Both critical and allowable will establish something very important.
2e. Will these critical and allowable column loads handle the 8th floor gravity loads at each column location?
Will they? This needs to be established as well.
3. ...How did those WTC 7 floor 13 framing beams both buckle and push the intersecting 79 to 44 girder (with or without shear studs, depending on which NIST report you read) off its seat @ column 79? How exactly?
Which is it?
Loss of vertical support, buckle, push?
Push, loss of vertical support, buckled?
Buckle, push, loss of vertical support?
Loss of vertical support, push, buckle?
Push, buckle, loss of vertical support?
Oh, I got it, they pushed, then buckled (we’ll suspend man’s accumulated knowledge of solid mechanics for the moment, for Tom’s sake), then lost vertical support, right? Do I have that right? Because we all know that the suspect area evidence was tested to confirm this ridiculous NIST hypothesis that you endorse with an eager heart.
