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15th March 2009, 08:52 AM | #81 |
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Greg, as you know, I have been working on a computer program to calculate stresses in a purely elastic, axial collision of a WTC top (floors 93 to 111) with the WTC base (floors 92 and down). In the process, I calculate a spring constant for each floor, using the mass of columns, only (no spandrels, e.g.). I also calculate the total mass for each floor, using the assumption that the mass remaining when you subtract the absolute total mass from the column masses, is to be evenly divided between 111 floors. (So, I ignore differences in spandrel weights, service floors, etc., and I completely ignore the basement floors).
Also, to repeat, I haven't carefully double checked everything, yet. Caveat emptor. Even so, I read this thread and got curious as to how theoretical maximum load that is within the elastic limit compares to the static weight. I just added a few lines of code,
Quote:
Whoa, after I posted the above, I noticed that my spring constant calcs were using total mass, instead of column mass. Here are the corrected figures:
Quote:
=================================== Spring constant calcs: // compute spring constants; from F = (YA / L) * Delta_L = (YV / L^2) * Delta_L , // k = (Y(m/rho) / L^2 ) where Y is Young's modulus = 200 GPa |
15th March 2009, 10:03 AM | #82 |
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Well, I use mass 16 500 tons, total core cross area 2.1 m˛ and average yield stress 248 MPa (<critical buckling), so my (average) FoS is abt 3 of upper part C (and yours is 2.29).
The FoS of the core due to plane damages is of course of no importance. A structure with FoS 3 or 2.29 cannot be rigid as suggested by NIST and Bazant & Co. You have to agree with that. However, as I always say; the main observation/conclusion in my paper is that a small upper part C of a structure of many elements cannot crush the lower part A of the structure due to gravity alone and some local failures and nobody seems to be able to debunk that! FoS of local steel elements do not really matter. You did not find anything wrong with that. It seems plenty of people are trying to make models of various kind to prove the opposite, i.e. that upper part C of a structure can crush down lower part A of similar structure (a little stronger as it carried part C before) by dropping part C from a certain height and then allowing gravity alone to crush part A. It is a futile exercise as part C will be damaged by part A and then be stopped. Quite easy to show with, e.g. full scale simulations of any structures. |
15th March 2009, 10:16 AM | #83 |
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Heiwa
Simply stating that "I use mass of..." is not appropriate; this thread has been started specifically for you to support your assertion that FoS>3 - something which you have wholly failed to do, and something which several posters here have shown to be wrong. I'm afraid that I must press you to clarify your position, and your calculations, on this issue. Moreover you try to claim once again that FoS is not relevant to the collapse mechanism, albeit that this is now caveated in respect of core damage. Yet you quite specifically and clearly used FoS in support of your arguments regarding gravity-driven collapse. Now you can't have it both ways - either it is important, in which case you need to clarify your figures properly, or it isn't and you deliberately introduced spurious material. Which is it? |
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15th March 2009, 10:34 AM | #84 |
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FoS is just a description of the capacity over demand of an element in an intact structure and gives you a feeling of the redundancy of the structure.
Re 'gravity-driven collapses' you should by now know my position, i.e. a small upper part C of a structure of many elements cannot crush the lower part A of the structure due to gravity alone and some local failures. Try to debunk that! KISS. |
15th March 2009, 10:48 AM | #85 |
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And FoS>3 is a lie to exaggerate that "feeling". Architect nailed it, spurious -3 a: of falsified or erroneously attributed origin : forged b: of a deceitful nature or quality ps- It takes about 30 seconds to show that most building code is going to have FoS around 2 for any element. Greg's calculation reflects this, and if memory serves NIST places it around 1.5. |
15th March 2009, 11:17 AM | #86 |
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NIST confirmed WTC 1 was not built according to code?
However, as I always say; the main observation/conclusion in my paper is that a small upper part C of a structure of many elements cannot crush the lower part A of the structure due to gravity alone and some local failures and nobody seems to be able to debunk that! FoS of local steel elements do not really matter. Try to debunk that! Try to build a model with two parts C and A of similar structure that collapses when C drops on A! |
15th March 2009, 11:21 AM | #87 |
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Based on mass 16500 tons, cross area 2.1 m˛ and yield stress 248 MPa FoS is abt. 3. Where is the lie?
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15th March 2009, 11:40 AM | #88 |
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15th March 2009, 12:00 PM | #89 |
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15th March 2009, 01:01 PM | #90 |
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Dear Heiwa, Why have you changed this text TODAY in your site Remember that the outer core columns are extremely solid, e.g. no. 501. It is an H-beam with two flanges 17x3.5 inch connected by a 2.2x12.6 inch web. In metric terms the flanges are 430x90 mm and the web is 56x320 mm. Such thick plates, 56 and 90 mm cannot buckle under any circumstance when the compressive stress is only 30% of yield stress, even if the temperature is 500°C. The (smallest) moment of inertia I of this section is about 120 000 cm4 and its radius of gyration r is thus of the order 35 cms. With a free length l of 350 cms the slenderness ratio (l/r) is 10! Removing three floors as support and the free length is 1 400 cms and the slenderness ratio is still only 40! Such a column will not buckle! by this one §7.2 of page ...nist1.htm Remember that the outer core columns are extremely solid, e.g. no. 501. It is an H-beam with two flanges 17x3.5 inch connected by a 2.2x12.6 inch web. In metric terms the flanges are 430x90 mm and the web is 56x320 mm. Such thick plates, 56 and 90 mm cannot buckle under any circumstance when the compressive stress is only 30% of yield stress, even if the temperature is 500°C. The (smallest) moment of inertia I of this section is about 120 000 cm4 and its radius of gyration r is thus of the order 11 cms. With a free length l of 350 cms the slenderness ratio (l/r) is 32! Such a column will not buckle! Same for the wall columns that have a radius of gyration r of abt 15 cms and a slenderness ratio of 24, when supported by spandrels and floors. We know how the core columns were joined and that it seems most failed at their weld planes, with little to no buckling involved. ??? Because I have written TODAY in my site that you don't know how is calculated the radius of gyration ?? |
15th March 2009, 01:51 PM | #91 |
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What site do you have? I have never visited it and I haven't got a clue who you are! But you are right - I corrected a typo in my article today. Doesn't change the conclusions, though: the main observation/conclusion in my paper is that a small upper part C of a structure of many elements cannot crush the lower part A of the structure due to gravity alone and some local failures and nobody seems to be able to debunk that! FoS of local steel elements do not really matter.
Try to debunk that! Try to build a structure with two parts C and A of similar structure that collapses when C drops on A! |
15th March 2009, 01:58 PM | #92 |
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15th March 2009, 02:13 PM | #93 |
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I think that Heiwa's tactic is for us to identify the many shortcomings in his paper, he'll fix 'em to the point where we can't respond, and then he'll flog it around the doors as the paper that beat the debunkers.
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15th March 2009, 02:15 PM | #94 |
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Designed safety factors give you a "feeling" for the redundancy of the structure which, in turn, presumably means that one analysing the structure doesn't have to produce meaningful - or indeed accurate - structural calculations? Is that your position?
However, back to reality.
Originally Posted by Architect
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15th March 2009, 02:20 PM | #95 |
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15th March 2009, 02:26 PM | #96 |
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Enough of your hissy fit. This thread is for you to support your claim that FoS>3. That you have made a significant change to your website following criticism here is noted, even if you didn't have the balls to flag it up yourself. Now, answer the technical issues put to you.
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15th March 2009, 03:07 PM | #97 |
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will
Yes, this thread is A question to Heiwa &c and you have got the answer. And there is no significant change to my web site.
Of course I spent some space in my article to debunk the suggestion that upper part C would perfectly impact lower part A column/column to produce crush down, but that is a non-starter for obvious reasons. No broken column can ever impact itself after failure. So I changed the assumption! I disconnected part C, lifted it with a crane and dropped it so column/column impact takes place. Result? Well lower part A compresses like a spring (assuming the elements do not fail) and that's it. Same thing with upper part C + that it bounces. No crush down! Details are given in the article. Happens every time similar, flexible structures collide as assumed. Compare pizza boxes, sponges, lemons. But it could never take place at WTC 1! Part C is suggested to drop and then it must contact part A columns/floor and part A will also contact part C columns/floor, local failures will be produced in both parts ... and arrest will soon follow. You see the contact is not between similar structures! A column hitting a thin floor is not a lemon hitting a lemon. It is a knife hitting a lemon. But it doesn't happen either! A column hitting a floor! So what happens? If you read my article carefully, you will see that part C is destroyed prior to even touching part A!! Why is that? Well, it is not due to FoS 3 or 2.29 of the columns. So I will not spend more time on FoS. Unless you can debunk; the main observation/conclusion in my paper is that a small upper part C of a structure of many elements cannot crush the lower part A of the same structure due to gravity alone and some local failures to start it! FoS of local steel elements do not really matter. Try to debunk that! Propose a structure with two parts C and A of similar structure (C has previously been carried by A) that is crushed down, when C drops on A! To me it is a paranormal event but maybe you can explain? Then we can discuss! In a friendly and lively way! |
15th March 2009, 03:21 PM | #98 |
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Heiwa
Let's be quite clear. On the gravity collapse thread you posted a claim in support of your argument. This stated, unequivocally, that the safety factor at the towers was greater than 300%. Your actual quote is "FoS>3". You have been challenged to prove this figure. And you have not. In fact, as we scan through the pages, we find that all you've done is produce a half-baked discussion on yield in individual elements. There is no substantive back-up. Posters have pointed to significant errors in your calculations. Gregory has shown you how one might actually progress an argument. And another poster caught you changing your own website on the sly to reflect the criticisms put to you here. Whenever you're pressed, you return to gravity collapse. These derails have been singularly unsuccessful. Every single time, you are brought back to the issue of how you calculated factor of safety and how you address the demand to capacity information. Now, after 3 pages, the best you can muster is:
Originally Posted by Heiwa
You see, Heiwa, what's clear from this thread is that your approach - your paper - is founded on sand. You just don't get structures, or buildings, or the WTC. You're not a player, and you never will be. And I'm going to remind you of this every time I see a new, incorrect claim. You gave it your best shot, and were found wanting. |
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15th March 2009, 03:26 PM | #99 |
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15th March 2009, 03:27 PM | #100 |
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DGM et al; I suggest we set this thread to one side for now and leave it as it is, a perfect example of Heiwa's inability to support information which he presented in support of his own argument. A perfect metephor for the Truth Movement as a whole.
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15th March 2009, 03:35 PM | #101 |
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But you seem to get upset about FoS! Now, try to debunk the real message in my paper - that C crushing A by gravity is not possible.
Make an effort! How can C crush A? It is a paranormal event. NIST could not explain it, Bazant assumed that C was rigid and then C crushed A but as everyone knows, C was not rigid. Bazant was cheating. Pls do not start new threads about irrelevant things. |
15th March 2009, 03:39 PM | #102 |
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And what a great quote to end the thread on. There we have it, readers. Heiwa, in considering the structural modelling of the collapse, does not think it important to consider safety factors. He did until we asked him to back it up, but now it's "irrelevant". All talk and no show.
Game, set, and match. |
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15th March 2009, 03:55 PM | #103 |
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15th March 2009, 11:38 PM | #104 |
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OK Heiwa,
It was a coincidence... But the mistake was great : a buckling resistance overevaluated near 10 times (slenderness)˛ !!!!! Best regards |
16th March 2009, 12:46 AM | #105 |
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Or only 3 times? I was fascinated by: quote
Remember that the outer core columns are extremely solid, e.g. no. 501. It is an H-beam with two flanges 17x3.5 inch connected by a 2.2x12.6 inch web. In metric terms the flanges are 430x90 mm and the web is 56x320 mm. Such thick plates, 56 and 90 mm cannot buckle under any circumstance when the compressive stress is only 30% of yield stress, even if the temperature is 500°C. Urich treat this monster column with length 3.5 m as 'slender' and apply the famous formula to it. But this core corner column, there are four!, is nothing but slender. It will not follow the idealistic formula. It would have been pretty simple to pick out this column from the rubble - 90 mm thick flanges!! - and see how they fractured ... due to bending? How apply an impact load on them? I am pretty certain that these columns were cut using some exotic controlled demolition device. That the upper part C was destroyed prior to part A is affected is pretty obvious from all videos. I cannot understand that the liers do not accept that, but try to explain or develop some strange crush down model with gravity. Luckily it is not possible. When two structures of similar types, parts C and A, collide, both are affected and the stronger elements will damage the weaker elements. As these core corner columns are the strongest elements in the structure, they should have remained undamaged! On the other hand, the structures being destroyed by controlled demolition, these columns are the first to be cut. Heiwa PS - your web site is pretty awful! |
16th March 2009, 01:33 AM | #106 |
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Heiwa, the relation between slenderness ratio and resistance to buckling is squared - so when you changed the values you were using by more than 3x, you admitted that the resistance to buckling was 10x lower than the original values you supposed. That's an order of magnitude.
I could refer you to page 149 of B.S. Benjamin's Statics, Strengths and Structures for Architects, which states:
Quote:
But, the subject of this thread is your own ridiculous assertion that the Safety Factor for the loads in all of the steel in the WTC structure was greater than 300%. You can't back that up and won't ever be able to. The only reason that I bring up the above is that it so aptly demonstrates how you've failed to consider various failure modes, have done simply awful math whenever you provided any whatsoever, and simply can't be depended upon to know what you're talking about when it comes to building structures. |
16th March 2009, 02:09 AM | #107 |
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16th March 2009, 02:09 AM | #108 |
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16th March 2009, 02:10 AM | #109 |
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Originally Posted by Minadin
Let me stress that, Heiwa; you've been caught out, and for all to see. |
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16th March 2009, 02:17 AM | #110 |
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It's still amazing to me that he can (pretend to) look at just the compressive load and assume that he's done some sort of comprehensive structural analysis.
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16th March 2009, 03:34 AM | #111 |
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If you check again, you will see that I applied the Euler formula for the columns and suggest that you cannot really apply it to e.g. column 501, &c.
That the perimeter wall columns have FoS>3 for static loads only, everyone seems to agree to. Reason being that the wall columns are also subject to dynamic loads when tower is subject to wind loads. Re the core it should be clear that the outer core columns carry more load than the inner core ones (http://heiwaco.tripod.com/loaddistribution.htm ) and that we disagree on the total core load carried. I suggest 16 500 tonnes, Urich 19 500 tonnes (and Bazant much more). You should also see that the wall columns carry different static loads at each floor as floor spans differ. So my description contains many simplifications just to get a feeling for the structure and its redundancy. Because, regardless of FoS of various elements, upper part C is virtually identical to lower part A. Evidently upper part C can never free fall on lower part A due to the 280+ columns in between that must fail, which is not seen on any video. What is seen on all videos is that part C suddenly telescopes into itself - it gets shorter - while nothing happens to part A. But even if part C would free fall on part A, part C cannot crush down part A. Reason being that part A will destroy part C at collision contact. &c, &c. The liers, suggesting that progressive collapse produces a crush down of structure, cannot produce any evidence for their fantasies. They assume that part C is rigid, which it is not. They assume that the bottom floor of part C cannot get damaged at impact but it is completely unrealistic. They assume that part C remains virtually intact while it ploughs down through part A at 0.7g, &c, but it is impossible. No structure type part C can plough through similar structure in part A due to gravity or any force. It is very easy to prove with sponges or lemons or pizza boxes or similar structures and the same result applies to parts A/C structures. I find it fascinating that so many people at JREF are prepared to support the official, paranormal lies. They cannot even do it in a friendly way. I am prepared to offer $1M to anybody that can produce a structure with two parts C and A of similar/identical structural composition, where, initially part A, fixed to ground, carries part C on top, and later by dropping part C on part A, gravity will then assist part C to crush down part A completely. Maybe JREF will sponsor this program like the other paranormal study? Similar rules will apply. |
16th March 2009, 03:49 AM | #112 |
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16th March 2009, 04:01 AM | #113 |
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1) $1M usually means one million US dollars. Is this what you mean? If so, please produce evidence that you've got the cash. You say you're "prepared." I'll need proof of that.
2) Once that's done, draw up a legal contract stating your offer and conditions. You'll probably want to use a lawyer for that. 3) Then publish your offer, but you may want to limit it to the first person who delivers the evidence to you or something, unless you have many millions of dollars to part with. Okay, Anders? |
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16th March 2009, 04:10 AM | #114 |
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16th March 2009, 04:12 AM | #115 |
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Well, in this model you destroy part A partly (not using gravity) before you drop part C on what is left of it, so it does not qualify.
It should also be understood that part C should volume/mass wise be, say 1/10th of part A, to make it more challenging and similar to WTC 1. Elements of both parts should have indentical connections to other parts. You cannot weaken, e.g. part A before the drop. Good try, though. |
16th March 2009, 04:23 AM | #116 |
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16th March 2009, 04:26 AM | #117 |
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16th March 2009, 04:28 AM | #118 |
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16th March 2009, 04:35 AM | #119 |
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Heiwa is cheating with this definition. In the standard definition of crush-up and crush-down zones, part A and part C are separated by a part B composed of rubble. In this instance, a section between parts A and C is partly removed and partly converted to rubble, becoming part B. At the point where the upper block strikes the lower, the lower block is substantially intact.
Here Heiwa is moving the goalposts. His initial offer was, "I am prepared to offer $1M to anybody that can produce a structure with two parts C and A of similar/identical structural composition, where, initially part A, fixed to ground, carries part C on top, and later by dropping part C on part A, gravity will then assist part C to crush down part A completely." Nothing about relative sizes of parts A and C is specified. The clip satisfies both these conditions, even though neither was specified in the initial offer. It should be perfectly clear that Heiwa's intention all along was to redefine the offer retrospectively to exclude any successful responses. Dave |
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16th March 2009, 04:37 AM | #120 |
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