Hardfire: Szamboti / Chandler / Mackey

[Hokulele]

I have a rather shocking fluorescent green shirt and jittering paisley necktie combination. Wear it to weddings, mostly. It's quite nice, in its own way, though it tends to damage recording equipment.

If any CTist ever doubts your engineering credentials, I can just refer them to this post.

 

[ElMondoHummus]

[Derail]
We now have a button to push to rile Hokulele. I'm thinking about going to the local Goodwill store to look for day-glo shirts with abyssmally complex patterns, just so I can photograph them and PM her the pictures.
[/Derail]

 

[Tony Szamboti]

And now a word from "Capt. Obvious"...
Try to make sure that they apportion speaking time "by side" (in which case you'd get 50%) and not "by person" (in which case you'd get 33%).

tom

Like Ryan I will refrain from debating him on this forum until after the debate is over and will only make this one post here on his thread.

However, I just want it to be known that I would have preferred if there were two individuals on both sides of the argument. I mentioned this to Ron Wieck also, and he did say he had a couple of people in mind to appear with Ryan, but I am not sure how successful he was in getting someone.

As for time sharing it should not be by person and the opposing viewpoints should get 50% each.

Please don't expect me to respond to this any further or any post in this thread. I only wanted to say the debating rules should be fair to each side.

 

[bill smith]

And now a word from "Capt. Obvious"...
Try to make sure that they apportion speaking time "by side" (in which case you'd get 50%) and not "by person" (in which case you'd get 33%).

tom

Can't do that Captain. The Truth Movment do not have a unified view of say the collapse dynamics on 9/11 for instance. Given that all three participants are scientists with theeir own distinct analyses they will therefore need equal time to make their seperate cases. I thought that would be bleedin' obvious Captain ?

 

[Dave Rogers]

Ryan, in case you haven't seen it, take a look at post #1510 in the "Why a one-way crush down is not possible" thread. I've done some maths to put behind the rather obvious point that a jolt wouldn't be seen if the upper block is tilted. Tony's replied to it once, but now I think he's carefully pretending it doesn't exist. Let me know if you want a copy of the spreadsheet that I calculated it from (although it's one of mine so it may not be entirely clear, or even intelligible!)

Dave

 

[NutCracker]

Can't do that Captain. The Truth Movment do not have a unified view of say the collapse dynamics on 9/11 for instance. Given that all three participants are scientists with theeir own distinct analyses they will therefore need equal time to make their seperate cases. I thought that would be bleedin' obvious Captain ?

So there are multiple versions of the truth. Enlightening..

Unfortunately, there is only one version of reallity.

Thank you for pointing out that at least two of the 'scientists with their own distinct analyses' are wrong.


Oh, please do reread 'The Truth Movment do not have a unified view of say the collapse dynamics on 9/11 for instance.' It might be a hint to you that each member of the TM is talking from his R*** E**.

Thank you.

 

[bill smith]

So there are multiple versions of the truth. Enlightening..

Unfortunately, there is only one version of reallity.

Thank you for pointing out that at least two of the 'scientists with their own distinct analyses' are wrong.


Oh, please do reread 'The Truth Movment do not have a unified view of say the collapse dynamics on 9/11 for instance.' It might be a hint to you that each member of the TM is talking from his R*** E**.

Thank you.

No problem.

 

[tfk]

And now a word from "Capt. Obvious"...
Try to make sure that they apportion speaking time "by side" (in which case you'd get 50%) and not "by person" (in which case you'd get 33%).

tom

As for time sharing it should not be by person and the opposing viewpoints should get 50% each.

Can't do that Captain. The Truth Movment do not have a unified view of say the collapse dynamics on 9/11 for instance.
... blah, blah, nonsense, blah...
I thought that would be bleedin' obvious Captain ?

.
So, let's see.

• You claim the ability to decide something in which you have zero input, much less decision-making authority.
• Your rationalization is, in essence, "... because the Twoof Movement is too incompetent to string together a single cogent thesis".
• It appears certain that at least two of the three people involved (RM & TS, who will have a say in the matter) disagree with you. Including one that might consider you to be on his side of the argument. (Note: I emphasize the word "MIGHT" in the previous sentence. I don't know Tony's tolerance for embarrassing quacks, so I won't attempt to speak for him.)

The above three points are incontestable, were posted prior to your comment, and render your position laughable.

And yet you STILL assert your position to be "obvious"...??

There has to be some word for your particular pathology, bill.

Does anyone know of a psychological condition where someone attempts to make others feel awkward by publicly embarrassing themselves?

I am seriously curious about this. TAM? Anyone?

Tom

 

[newton3376]

Deleted

 

[bill smith]

.
So, let's see.

• You claim the ability to decide something in which you have zero input, much less decision-making authority.
• Your rationalization is, in essence, "... because the Twoof Movement is too incompetent to string together a single cogent thesis".
• It appears certain that at least two of the three people involved (RM & TS, who will have a say in the matter) disagree with you. Including one that might consider you to be on his side of the argument. (Note: I emphasize the word "MIGHT" in the previous sentence. I don't know Tony's tolerance for embarrassing quacks, so I won't attempt to speak for him.)

The above three points are incontestable, were posted prior to your comment, and render your position laughable.

And yet you STILL assert your position to be "obvious"...??

There has to be some word for your particular pathology, bill.

Does anyone know of a psychological condition where someone attempts to make others feel awkward by publicly embarrassing themselves?

I am seriously curious about this. TAM? Anyone?

Tom

Three opinions = three equal shares of the time allowed. It is a show run on democatic principles is it not ? Although if I remember correctly there was some dispute about that the last time

 

[GlennB]

.
Does anyone know of a psychological condition where someone attempts to make others feel awkward by publicly embarrassing themselves?

You have a pm.

 

[tfk]

Ryan, in case you haven't seen it, take a look at post #1510 in the "Why a one-way crush down is not possible" thread. I've done some maths to put behind the rather obvious point that a jolt wouldn't be seen if the upper block is tilted. Tony's replied to it once, but now I think he's carefully pretending it doesn't exist. Let me know if you want a copy of the spreadsheet that I calculated it from (although it's one of mine so it may not be entirely clear, or even intelligible!)
Dave

Hey Dave,

I'd like to see your numbers.

I scanned thru your post #1510. One thing that I don't get regarding your stress-strain model for A36. Perhaps I'm not reading it right.

You say

Next, I consider the case where an upper block of mass M of this structure falls on a lower block. I'm assuming that the angle of tilt is small enough that each column of the upper block impacts on the corresponding column of the lower block. For the behaviour on impact, I'm taking a greatly simplified model of column failure, in which the resistive force increases linearly up to the ultimate strength at 0.2% compression, then decreases linearly to zero at a further 3% compression. This has the useful property that the energy absorbed by the column is approximately correct, therefore the impulse applied to the upper block is reasonable."

.
It seems to me that this will give you only about 50% of the energy absorption capability of the steel.

Usually the 0.2% stain level is the yield strength, instead of the ultimate strength, of course.

NIST gives a good models for stress strain in NCSTAR 1-3D, Appendix D - for both room & elevated temperatures. Plus they give models for high strain rate properties in Appendix E.

Those ought to do you. But if you need something simpler...

A quick & dirty, but still accurate (in terms of energy absorption), would be a linear stress-strain up to the average stress between the yield & ultimate strengths ((sy + su)/2), and a constant stress from there up to failure strain levels.

I've taken the column length as 4m, representing the height of a single floor. I'm also assuming that the moment of inertia of the upper block is very large, and that its rotational velocity is zero throughout the collision; in other words, the tilt angle is taken to be invariant."

.
The use of 1 story columns will, I believe, result in significant errors. I believe that an unavoidable aspect of the 3 story, staggered columns produced an unexpected weakness to progressive collapse, and an effect that will have a significant impact on the specific effect that you are trying to model: the jolts.

The reason for this is, of course, the fact that, by the time the upper block has reached any particular floor, 2/3rds of the supports have already been destroyed prior to the impact, taking with them far more than 2/3rds of the stuctural integrity of that floor.

I don't have a bunch of time right now, but I'll offer comments once I see your spreadsheet.

BTW, I applaud this effort of yours.

Tom

 

[Dave Rogers]

It seems to me that this will give you only about 50% of the energy absorption capability of the steel.

Usually the 0.2% stain level is the yield strength, instead of the ultimate strength, of course.

NIST gives a good models for stress strain in NCSTAR 1-3D, Appendix D - for both room & elevated temperatures. Plus they give models for high strain rate properties in Appendix E.

Those ought to do you. But if you need something simpler...

A quick & dirty, but still accurate (in terms of energy absorption), would be a linear stress-strain up to the average stress between the yield & ultimate strengths ((sy + su)/2), and a constant stress from there up to failure strain levels.

I'll put that in and see how it changes things. I'm not a structural engineer so I don't know the details of this sort of thing; I started by using a guessed function and hoped that somebody who knows better would suggest something more appropriate.

The use of 1 story columns will, I believe, result in significant errors. I believe that an unavoidable aspect of the 3 story, staggered columns produced an unexpected weakness to progressive collapse, and an effect that will have a significant impact on the specific effect that you are trying to model: the jolts.

The reason for this is, of course, the fact that, by the time the upper block has reached any particular floor, 2/3rds of the supports have already been destroyed prior to the impact, taking with them far more than 2/3rds of the stuctural integrity of that floor.

That would be trickier, as I'd have to exclude specific columns. However, from what you're saying, it looks like I've underestimated the steel strength x2 but overestimated the structural strength by x3, giving an overall overestimate of about 50%. That means that I should have overestimated the jolt intensity rather than underestimated it, which makes the conclusion a conservative one.

Not sure when I'll get round to doing more on this. Life is busy.

Dave

 

[TruthersLie]

I just hope it is Mark Roberts.

Then we can see them both wipe the floor with you both.

 

[bill smith]

.
So, let's see.

• You claim the ability to decide something in which you have zero input, much less decision-making authority.
• Your rationalization is, in essence, "... because the Twoof Movement is too incompetent to string together a single cogent thesis".
• It appears certain that at least two of the three people involved (RM & TS, who will have a say in the matter) disagree with you. Including one that might consider you to be on his side of the argument. (Note: I emphasize the word "MIGHT" in the previous sentence. I don't know Tony's tolerance for embarrassing quacks, so I won't attempt to speak for him.)

The above three points are incontestable, were posted prior to your comment, and render your position laughable.

And yet you STILL assert your position to be "obvious"...??

There has to be some word for your particular pathology, bill.

Does anyone know of a psychological condition where someone attempts to make others feel awkward by publicly embarrassing themselves?

I am seriously curious about this. TAM? Anyone?

Tom

It would also be unfair to add another like RM to the government side. Then it would be two people supporting exactly the same immutable story against two guys who have seperate and individual opinions on the course of events on 9/11. It would look like the government was ganging up on the Truth Movement. So it looks like three equal shares of the time alotted is the only way to go.

 

[newton3376]

It would also be unfair to add another like RM to the government side. Then it would be two people supporting exactly the same immutable story against two guys who have seperate and individual opinions on the course of events on 9/11. It would look likehe government was ganging up on the Truth Movement. So it looks like three equal shares of the time alotted is the only way to go.

The government? ROFL

Last time I checked Mark Roberts didn't work for the government...

The problem here is that you seem to think the "official" story is just another "option" that has "supporters" like so many of the varied and whacko "truther" positions....

No one needs to "gang up" on the truthers because the physical evidence (indeed all the evidence) doesn't support their idiotic ideas.

Maybe you think that by giving the "truthers" 2/3 of the time slot they might not end up looking like moronic, raving lunatics.....




...I have some bad news for you.....

 

[moorea34]

Dave,

The idea that steal columns can reached 3% in compression strain is an urban legend that was initiated by Ross ... But it is a monumental ********... Szamboti has used 1.5% in "the missing jolt", but it remains a semi-monumental ********...

It makes laught anyone who has done a minimum of structural engineering...

That is explained very well here :

http://newtonsbit.blogspot.com/sear...d-max=2008-01-01T00:00:00-08:00&max-results=3

Theoricaly, when you reach yield stress in compression, you don't have any rigidity for the column...
(E=0 for the elasto-plastic model)... And the column is in a buckling phase....
And I don't speak about shear buckling or torsional buckilng.... It's another story


So you will never reach 1, 2 or 3 % in a compression way for the whole column...

 

[Dave Rogers]

The idea that steal columns can reached 3% in compression strain is an urban legend that was initiated by Ross ... But it is a monumental ********... Szamboti has used 1.5% in "the missing jolt", but it remains a semi-monumental ********...

For my purposes, what I want is an expression for force as a function of compression that I'm confident is an overestimate of the column resistance. If it's generally agreed that 3% is not only an overestimate, but a gross overestimate, then I can plug it into the model and see if there is still no jolt; if there isn't, then Szamboti's argument is refuted. At the moment I'm assuming linear increase in force up to the average of yield and ultimate strain at somewhere a bit above 0.2%, then constant force at that value up to 3%, which I think makes my columns twice as strong as Szamboti. I need to check the numbers again, but a first look indicates that the increase in energy absorption doesn't actually affect the jolt significantly; hardly surprising in retrospect, since it's the peaks in the acceleration I'm looking at rather than the collapse time (which is very much affected by the energy absorption). Since I was using ultimate strength rather than yield strength, the jolt is actually less. I'll post some results when I've checked them, but it still looks like - for the structure I've defined - no jolt by the time the angle reaches half a degree.

Ryan, sorry for intruding into your thread with a rather off-topic discussion. Maybe I should start my own thread some time.

Dave

 

[moorea34]

For my purposes, what I want is an expression for force as a function of compression that I'm confident is an overestimate of the column resistance. If it's generally agreed that 3% is not only an

...

Ryan, sorry for intruding into your thread with a rather off-topic discussion. Maybe I should start my own thread some time.

Dave

OK, I understand now

 

[tfk]

moorea34,

Your objection was the same one that I originally had for Bazant's paper. Several of his assumptions were unrealistic. (i.e., the columns falling on the columns, the failure mode of buckled columns instead of fractured bolts & welds, etc.) His assumptions, as several here have noted, was a "limiting case", with every assumption favoring the interruption of the progressive collapse to the street.

But, clearly (well, clearly to me anyway), because of his wildly conservative assumptions, his analysis is not a close, realistic model of what really happened.

My inclination was to try to model it as accurately as possible, choosing conservative alternatives out of "most probable" events. If done right, this model would be much more representative of what really happened.

Each of these approaches has its own place & its own purpose.

If you want a model as close as possible to the real event (for whatever reason that might be), a realistic model is best.

But Bazant, and now DR, are absolutely right if your goal is to close the deal and ("O tempora! O mores!") end the debate.

Using a "realistic model", you simply have some buffoon disagree with one of 100 assumption, and they send you back to number crunching. To preempt such nonsense, the "limiting case model" is the only way to go.

tom