Tony,
This conversation is starting to get surreal...
You published a paper with Mr. Legge. I just became aware of your interpretation of a particular graph.
I asked if you stood behind that paper. You replied:
Are you saying that you don't think the graph shows that it takes more energy to further deform the column once it is in the plastic range?
I was frankly puzzled, because there is absolutely nothing in that paper that makes this claim. I answered you directly, [
http://www.internationalskeptics.com/forums/showthread.php?postid=4983748#post4983748 ] that "No, that not what I am saying & that's not what you said."
Then I addressed - directly - several of the comments that you made that I believe (OK, you got me... "that I know") to be incorrect. In order to be precise with your statements, I addressed them by cutting & pasting your words verbatim. And then asserted that several of your comments were wrong, and explain exactly why they are (IMO) wrong.
My comments were:
1. Why did you use curves for 43A instead of A36 steel? (Since the towers were made with A36.)
2. The correct interpretation of those curves shows the decrease in yield strength, ultimate strength & elastic modulus with rising temp.
3. Bulk modulus cross sectional expansion is irrelevant once the columns go into bending. (Others have shown it to be inconsequential, even if the column stresses stay purely compressive.)
4. Your comment that "As the steel sags ... the inherent strength of the steel will increase" is totally, utterly wrong.
5. Your comment that "the yield strength of steel increases as the degree of distortion increases" is totally wrong.
6. Since the effect that you claim in 5. above is false, it cannot, as you further claim, become more pronounced at elevated temperatures.
7. Your claim that "initial sag in steel cannot be catastrophic..." is wrong.
8. Your claim that "A rising temperature will be needed to offset both the significant increase in yield strength and the slight increase in cross-section area, if collapse is to progress" is completely wrong.
9. You comment that "the upper section should only have moved down slowly and only continued to do so if additional heat was supplied" is both unproven by anything that this paper offers and completely wrong to boot.
___
And now, you AGAIN come back with this reply...
I don't see how you can interpret those graphs any other way but to say that once the steel yields and is into the plastic zone, additional load or heat energy is required to generate additional strain.
Tony, I don't get it. You're clearly not dumb. You don't strike me as being intentionally, insultingly rude like Heiwa.
Why do you keep suggesting that I've said ANYTHING about energy added after buckling??
Tom
PS. BTW, just to be complete with you, I do believe that you have to add mechanical energy to continue to collapse a beam after it buckles. A small, trivial amount of energy compared to the amount to bring the beam up to the point of buckling.
As described by the correct graph (on the left below).
The energy required is, as indicated on this graph, the area under the Force vs. deflection curve.
And, as shown, FAR from getting stronger, the beam gets much weaker after buckling.
Tom
