Miragememories
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Are you applying that prejudice to all scientists who are religious, or just the ones who disagree with you?
MM
WTC7 and the girder walk-off between column 79 and 44
- Thread starter Gamolon
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Are you applying that prejudice to all scientists who are religious, or just the ones who disagree with you?
MM
Pithy. Punchy. Pointless.
000063
Tell you what; I'll get up against the wall now to save The Revolution some time. Wouldn't want to get caught in the rush.Worry not for me. When your 9/11 bubble bursts and the neocon organizations become persona non grata the Team Holocaust lies will explode like the WTC towers.
My derail aside, let's talk about the bulk of post 1737. You claimed the collapses according to the official story were unprecedented, implying that that makes them impossible. I presented about a dozen things about a CD theory that would be unprecedented. You didn't even pretend to address that part, and I suspect that if I hadn't mentioned your being a denier, you've either ignored it or responded with a one-liner, like you're trying now.
Pithy one liner that doesn't actually answer anything. Quelle suprise. Do you how hard it is to prevent even one person from getting a message out? And wouldn't the guards be able to figure it out themselves? Who's watching the watchmen here? And who's watching those watchmen? Is it watchmen all the way down?
He's using it to compare Tony's belief system to that of the religious. It has nothing to do with whatever religious beliefs he may or may not have.
And once again, you hovered around, and then swoop in and swipe at someone's post when you think you can understand enough for a "rebuttal".
NoahFence
Banned
Ever since he got bitch-slapped on the Millette study he's been awful skittish about typing anything other than character assasination....
Let me guess; Oystein was heavily involved in proving him wrong.
NoahFence
Banned
Naturally...
Tony Szamboti
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I need no hints as I'm am not making the assertion. Do the math or retract. list all assumptions and show working. That is the MINIMUM required to even start a discussion on whether or not you are correct.
Hint: You are grossly over simplifying the problem.
These calculations were done by a structural engineer named Ron Brookman and he has sent a letter to the NIST about it. I don't have a copy of his calculations so I did them here myself to prove to those of you here that what Gerrycan said in his video was correct on this issue. That is that the stiffener would take the vertical load, once the web was beyond the seat, and prevent the flange from folding.
The load I used was based on the 53 x 45 foot area to the east of the girder and 10% of the area west of it. I looked at the west side area in the NIST report and the girder in question only carries one short beam from that area with the six longer beams of that area going to the girder between columns 76 and 79. Bear in mind that each girder support carries 25% of the loads of an area as there are three other supports. So the area is approximately equivalent to 27.5% of the area to the east x 125 psf which is 75 psf dead load and 50 psf live load. The load is thus 53 x 45 x 125 x 0.275 = 81,984 lbs.
The stress is a combination of bending stress and shear stress on the weld between the stiffener and parent material of the girder.
Bending stress = MY/I where the bending moment (M) equals the distance from the web to the center of pressure on the flange multiplied by the load. Y is the distance to the neutral axis and would be the midpoint of the weld length and flange thickness = (0.855" + 18")/2 = 9.428". I is the moment of inertia and is equal to the height of the weld cubed divided by 6 for a double sided weld. So (18^3)/6 = 972 in^4.
The moment is 81,984 lbs. x 4.5 inches = 368,928 inch lbs., and the bending stress is (368,928 x 9.428)/972 = 3,578 psi, when the web is 3.5 inches past the seat and the center of pressure on the flange is 4.5 inches from the web.
The shear stress is just force/throat area. The 5/16" fillet weld is on both sides of the stiffener so throat area is 2 x 0.707 x 0.3125" x 18" = 7.954 sq. inches. The shear stress is 81,984 lbs./7.954 sq. inches = 10,308 psi.
The resultant stress = sqrt[shear stress^2 + bending stress^2] = 10,911 psi.
The weld was made using E70 weld metal, which has a tensile yield strength of 58 ksi and a shear yield strength of 0.577 x 58 ksi = 33.4 ksi.
The factor of safety would be 33,400/10,911 = 3.0, so this weld would certainly stay put and keep the flange from folding while the girder web was moved beyond the seat.
This means the girder would not fall off the seat until it was pushed at least 9.5" to the west, due to the girder having these 18" tall flange stiffeners. It has already been shown that the maximum westward expansion of the beams to the east, at any temperature, was 4.75".
This shows the alleged walk-off failure was impossible and the NIST needs to put these stiffeners in the report and correct their analysis.
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NoahFence
Banned
Lots of words! Well done. Numbers, too.
Can you put some together that form some description of evidence?
Christopher7
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For those who thought that Tony answered my questions about his assumptions in his analysis, he did not.
The following are assumptions built into the equation that he used.
1. Linear stress profile through beam thickness
2. Neutral axis of bending stays at midplane of beams.
3. Young's modulus is a function of temp only, not stress level.
4. He ignored composite action of concrete in conjunction with beam.
These are four assumptions built into the equation that he used. All 4 are violated in the case of thermally induced deformation of the beam/concrete composite floor.
In addition, in the setup of his analysis:
5. He ignored construction loading of beams. This has a huge effect when it is combined with 3. above.
[Note that Tony's excuse for this error is "I said that I wasn't figuring construction loads." Saying that one is going to include an assumption that leads to a significant error does not excuse producing results that contain a significant error. If Tony wishes to make this gross assumption, it is his job to show that this assumption will produce a relatively small error. He didn't do this.]
6. He ignored possibility shedding of load from beam/concrete composite to concrete alone. (Not certain that this is going to happen. It depends on whether the concrete can support its own weight in these large areas, or if it fractures at all - or most - of the fracture points where the shear studs have pulled. But it deserves a look by the person doing the analysis.)
The suggestion that "Tony used the same assumptions as NIST did" is nonsense, and would be uttered only by someone who had zero understanding of the difference between an algebraic solution and a FEA solution.
This analysis has multiple sources of non-linear behavior. It can only be solved accurately & reliably by using non-linear FEA methods.
Tom
PS. Sorry it took awhile to get back to this. Real life takes precedence.
The following are assumptions built into the equation that he used.
1. Linear stress profile through beam thickness
2. Neutral axis of bending stays at midplane of beams.
3. Young's modulus is a function of temp only, not stress level.
4. He ignored composite action of concrete in conjunction with beam.
These are four assumptions built into the equation that he used. All 4 are violated in the case of thermally induced deformation of the beam/concrete composite floor.
In addition, in the setup of his analysis:
5. He ignored construction loading of beams. This has a huge effect when it is combined with 3. above.
[Note that Tony's excuse for this error is "I said that I wasn't figuring construction loads." Saying that one is going to include an assumption that leads to a significant error does not excuse producing results that contain a significant error. If Tony wishes to make this gross assumption, it is his job to show that this assumption will produce a relatively small error. He didn't do this.]
6. He ignored possibility shedding of load from beam/concrete composite to concrete alone. (Not certain that this is going to happen. It depends on whether the concrete can support its own weight in these large areas, or if it fractures at all - or most - of the fracture points where the shear studs have pulled. But it deserves a look by the person doing the analysis.)
The suggestion that "Tony used the same assumptions as NIST did" is nonsense, and would be uttered only by someone who had zero understanding of the difference between an algebraic solution and a FEA solution.
This analysis has multiple sources of non-linear behavior. It can only be solved accurately & reliably by using non-linear FEA methods.
Tom
PS. Sorry it took awhile to get back to this. Real life takes precedence.
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Christopher7
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ozeco41
Philosopher
FTFY - You have fallen for his trick.
And, no, I'm not going to spell it out for you yet again.
Remember this:
His details may well be sort of near the right ball park - see tfk's comments. But he has the context and assumptions wrong. BTW that is just as he did with "Missing Jolt" and is the same type of error as Chandler makes for his claims BTW. Multiple degrees notwithstanding.Me posting as econ41-13 Nov 2007 said:
You may mislead the ordinary members. But not the competent engineers.
Christopher7
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Baseless vacant claims of knowledge with no actual facts to back them up.FTFY - You have fallen for his trick.
And, no, I'm not going to spell it out for you yet again.
Remember this:
His details may well be sort of near the right ball park - see tfk's comments. But he has the context and assumptions wrong. BTW that is just as he did with "Missing Jolt" and is the same type of error as Chandler makes for his claims BTW. Multiple degrees notwithstanding.
You may mislead the ordinary members. But not the competent engineers.
BTW, Tony, you do realize that the beams are not pushing the end of the girder parallel to the seat, don't you. The end of the girder is being pushed perpendicular to the girder's axis (line to col 44 or most proximal surviving girder-to-beam anchor.)
Did you allow for this in your calculations?
What point did you use for the center of rotation of the end of the girder?
How much initial overlap did your analysis give the girder on the seat?
How much lateral motion before the central web of the girder at the flange stiffener plate drop off of the support plate because of the angle between the girder & the support plate?)
What allowances did you make for any deformation of the column in this calculation?
Do you think that the column is going to remain immobile (i.e., no flexing) when it loses its horizontal supports?
When those lateral supports for the column collapse, do you assert that there will be no lateral motion at all from the column?
I agree that the flange stiffener plate will prevent the lower flange from buckling under the load. However, did you check the point on the central web co-linear with the top of the stiffener plate to make sure that it also wouldn't buckle?
___
Now you appear to be saying that Mr. Brookman did some or all of the calculations.
Please clarify: Who did what calculations?
Please post his letter & his calculations, so that we can compare your results with his.
Finally, tho, you guys did something right. You sent off an analysis to NIST.
What took so long?
Is this the very first time that you guys have done this? If not, could you list some previous analyses that you sent to NIST & their reply?
tk
Did you allow for this in your calculations?
What point did you use for the center of rotation of the end of the girder?
How much initial overlap did your analysis give the girder on the seat?
How much lateral motion before the central web of the girder at the flange stiffener plate drop off of the support plate because of the angle between the girder & the support plate?)
What allowances did you make for any deformation of the column in this calculation?
Do you think that the column is going to remain immobile (i.e., no flexing) when it loses its horizontal supports?
When those lateral supports for the column collapse, do you assert that there will be no lateral motion at all from the column?
I agree that the flange stiffener plate will prevent the lower flange from buckling under the load. However, did you check the point on the central web co-linear with the top of the stiffener plate to make sure that it also wouldn't buckle?
___
Now you appear to be saying that Mr. Brookman did some or all of the calculations.
Please clarify: Who did what calculations?
Please post his letter & his calculations, so that we can compare your results with his.
Finally, tho, you guys did something right. You sent off an analysis to NIST.
What took so long?
Is this the very first time that you guys have done this? If not, could you list some previous analyses that you sent to NIST & their reply?
tk
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Your reply demonstrates that you haven't the slightest clue what I was referring to. (It had nothing to do with the stiffener.)
What a non-surprise.
tk
Tony Szamboti
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Tom, you shouldn't forget that drawings which revealed certain details of the girder connection, like the 12" wide seat, the 2" thick x 14" deep x 18.875" wide plate pg under the seat, and the 3/4" thick x 5.5" wide x 18" tall flange stiffeners on the girder, were only recently released.
With these details known and factored into the analysis, it is now clear that a walk-off failure of the girder between columns 44 and 79, under the 13th floor in the northeast corner of WTC 7, was impossible, and the NIST needs to correct their analysis and the report.
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Christopher7
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I asked 13 questions & made 1 request (#11 above).
You answered 1.
Kinda sorta.
Care to answer any of those others? It should be easy.
The late release of these details didn't stop you from asking NIST any questions about any of your other issues over the last several years.
Or is this now your one-and-only issue with the NIST report?
You keep saying this.
Yet you still haven't addressed any of the issues that I posted at 12:06 am above.
Care to give it a shot?
Yet you haven't addressed any of the issues regarding your linear analysis of portions of just two components versus NIST's nonlinear FEA analysis of all the components of the entire floor.
Yet you haven't heard anything back from NIST regarding the questions that you (or is it Mr. Brookman) are submitting to NIST.
Don't you think you should hear what they say first?
Care to offer a justification as to why you think that a building that has had most of its lateral supports removed in a contiguous 1/6th of the total floor space, over multiple floors, and is still burning, will maintain its components immobile, unflexing in their original, supported positions?
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Tony,
You'd make your prose a lot easier to follow if you were to supply a quick sketch, showing forces, moments, & identifying where you are trying to calculate stresses. You know, like people supply when they are trying to explain their stuff clearly.
___
And your explanations leave a lot to be desired.
For example, please explain how you got inches4 out of this calculation:
It doesn't help your credibility to leave out dimensions & inexplicably change inches3 into inches4.
Without a diagram, it's tough to tell what you are calculating here.
You'd make your prose a lot easier to follow if you were to supply a quick sketch, showing forces, moments, & identifying where you are trying to calculate stresses. You know, like people supply when they are trying to explain their stuff clearly.
___
And your explanations leave a lot to be desired.
For example, please explain how you got inches4 out of this calculation:
TS said:
It doesn't help your credibility to leave out dimensions & inexplicably change inches3 into inches4.
Without a diagram, it's tough to tell what you are calculating here.
BasqueArch
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What an absurd claim.
Column 79 failed because of its unbraced length. It was also by far the most heavily loaded of all the columns in WTC 7. From the 6th to the 14th floor most of the girders and floors had failed at Columns 79,80,81. (Figure 4-17 p.81 NCSTAR 1-9A). This caused Col 79 to become laterally unstable.
Of the three Column 79 girder connections, one was the seated type (the one in discussion here) the other two fin type. Of the six Columns 80,81 connections, one was the seated type the other five fin, knife or header type connections. Out of the nine girder to Columns 79,80,81 connections, only two were the seated type; the one under discussion here.
NCSTAR 1-9 p. 527 “Shear failure of all the bolts in fin and knife connections, or failure of the weld at the beam and girder web in header connections, resulted in a loss of horizontal and vertical support. …Loss of vertical support (for this seated connection-my note) occurred when the beam or girder walked off the bearing seat or when the bearing seat weld failed.”
Wrong, because of the loss of lateral support to Col. 79 on this and other floors.
Ibid. “The temperature of the girder between Columns 76 and 79 on Floor 13 was sufficient to displace Column 76 to the west and Column 79 to the east.” Add this number of the multifloor unbraced Col 79 push to the push number of the seated girder.
The conclusions that the beams and girders failed were the result of the Fire Dynamics Simulator (FDS), FEA - ANSYS and LS-DYNA models over time, not just one unrelated number.
NCSTAR 1-9 p 536 “ The ANSYS model included nonlinear effects, such as: nonlinear temperature-dependent material properties including thermal expansion, plasticity and creep; nonlinear geometry; and user defined elements that captured the details of temperature dependent connection failures.”
NCSTA 1-9 p487 " When lateral support ot the top (compression) flange was lost, floor beams and girders could laterally displace and buckle in a lateral-torsional mode. ...If a beam or girder twisted half of its flange width laterally, it would not be able to support its gravity loads....Figure 11-19. Cri tical Twist Angle in Beams/Girders."
You have also overlooked other factors:
The girder flange was 1.56” thick and stiffened. The welded seat plate was 1” thick, welded, cantilevered, not stiffened beneath, and 500-600C.
For the displaced girder, the bearing seat, not the girder flange would have failed causing the Col 79 to 44 girder to fall.
1. For the 500-600C bearing seat, the above-average net load (i.e. large floor area from the girder) could have bent the seat or fractured the welds , the girder falls.
2. The beams were attached eccentrically near the top of the girder. The girder rotates by the expanding beams pushing , or the sagging beams pulling, or the girder buckling. The stiffened girder flange bends the bearing seat or fractures the weld or half of its flange width twists laterally. The girder slides off or drops.
NIST disproved that one HE charge could have severed Column 79 because the blast would have created a noticeable 140 dB sound wave.
The demolition of inconsequential WTC 7 by incendiaries is a political delusion.
Fire caused the collapse of the WTC 7.
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