WTC 1 & 2. What happened after collapse initiation?

[rwguinn]

You don't understand the material. The design strength doesn't change. This is based upon the minimum rupture strength of the material (which is basically the same for each of the grades).

I know you truthers like thinking you already know everything about engineering, but this is a good example where just doing a quick google search misleads the uninformed.

You mean archetects and SE's don't design to Maximum allowable?

 

[Newtons Bit]

yeah would like you to see do it in another language and standards you are not used to

when 60 and 100 KSI is the same for you its fine for me

So what you're saying is that you don't understand "ranges from 60 to 100ksi" is not "100 ksi" and that your ignorance of the standards, engineering practice and the english language should excuse you and other truthers from being held accountable for arguments from ignorance?

I really don't think so.

 

[DC]

So what you're saying is that you don't understand "ranges from 60 to 100ksi" is not "100 ksi" and that your ignorance of the standards, engineering practice and the english language should excuse you and other truthers from being held accountable for arguments from ignorance?

I really don't think so.

it is you that said that there is no significant diffrence, well 60 compared to 100 KSI seems significant to me.... maybe in the US there is not so much love for such details?
and why i am ignorant to standards? ASTM standars are not the standards we use in my country.....

 

[rwguinn]

it is you that said that there is no significant diffrence, well 60 compared to 100 KSI seems significant to me.... maybe in the US there is not so much love for such details?
and why i am ignorant to standards? ASTM standars are not the standards we use in my country.....

60ksi compares with 60 ksi very well, thank you
"Ranges from 60 to 100ksi" simply means that it is 60ksi minimum.
You damn well don't design to maximum.
You are liar, and ignorant enough of basic principles that you can't even learn from those who know what they are doing...

 

[Heiwa]

Sorry, that's wrong. Can you actually do a real analysis instead of just pulling stuff out of your rear end?

So I will clarify. Tensile (pulling, axial) strength is one thing - the load is easy to apply to pull the bolt apart; if you apply the test load sideways to produce pure shear in the bolt across the cross area, it shears off at less than the (axial) tensile strength. If the bolt surface is rough it shears off earlier than if its polished, etc. Why do you ask? Problems of any kind?

 

[GlennB]

it is you that said that there is no significant diffrence, well 60 compared to 100 KSI seems significant to me.... maybe in the US there is not so much love for such details?
and why i am ignorant to standards? ASTM standars are not the standards we use in my country.....

If we were discussing building collapse in Cambodia, Guatemala, New Zealand, Finland - or wherever it happened - it might be reasonable to use the standards that apply in that country.
We aren't. It happened in the USA.

I'm a UK citizen and am used to stones, ounces, miles and so on. But I live in mainland Europe so I use kilos, metres and so on in discussion.

Don't make feeble excuses for yourself, DC.

 

[Newtons Bit]

So I will clarify. Tensile (pulling, axial) strength is one thing - the load is easy to apply to pull the bolt apart; if you apply the test load sideways to produce pure shear in the bolt across the cross area, it shears off at less than the (axial) tensile strength. If the bolt surface is rough it shears off earlier than if its polished, etc. Why do you ask? Problems of any kind?

Umm. No. I asked you what the shear strength of two bolts in shear was. You just pulled a number out of your rear end for the capacity of one. I was asking if you could actually do some math to justify what you think the shear strength of bolt was.

And you just come up with more bs. Are you trying to change the subject? Just provide the two line calc for bolt shear strength.

 

[Newtons Bit]

it is you that said that there is no significant diffrence, well 60 compared to 100 KSI seems significant to me.... maybe in the US there is not so much love for such details?
and why i am ignorant to standards? ASTM standars are not the standards we use in my country.....

Suppose you're an engineer. You're analyzing the capacity of a bolt in an existing structure. You don't have access to the mill reports. You know it's an A307 Bolt.

The standard says that the bolt has a tensile strength between 60 and 100 ksi. Knowing that is costs more money for a mill to get that bolt to a higher strength, what value of the tensile strength should you use?

 

[Heiwa]

AA. It's as if the columns were built in 36 ft (~12 meter) sections that separated from the structure at the connections! Sorry, but that has a very mundane explanation other than your presupposed LCD sequence. Many of the connections in the perimeter columns failed at least in part because of lateral shear stresses exceeding the capacity of the connections to hold.

BB. The structure is not going to simply telescope into itself and be contained inside the lower structure as your model hypothesizes. That would almost inevitably require that the perimeter columns have such redundancy that they can resist concentrated lateral shearing forces enacted by 150,000 tons of structure getting compacted in the space of a few floors. And that stretches reality to assume any portion of that model would be correct.

AA. Any evidence for that? E.g. analysis of the fracture surfaces of a column?

BB. I only use telescoping to describe the implosion of the 33 000 tons upper block prior any initiation of local failures below and resulting destruction of the lower structure. The outer wall assemblies - columns held together by spandrels - have enormous redundancy. They had no problem to carry the upper block.
After initiation (alleged columns failures) any loose load from above is only applied on the floors below and will only cause local damage to the floors and evidently produce a lot of friction. No big loads will be transmitted to the columns below. So that they can slice the upper block apart in peace and quiet as explained before.

Do a proper damage structure analysis FDS.

Development of progressive Collapse Analysis Procedure and Condition Assessment for Structures by Professor Ted Krauthammer, Protective Technology Center, The Pennsylvania State University, Robert L. Hall, PhD, Stanley C. Woodson, PhD, James T. Baylot, PhD, John R. Hayes, PhD, US Army Engineer Research and Development Center, Young Sohn, PhD, Defense Threat Reduction Agency, at http://www.nibs.org/MMC/ProgCollapse presentations/HallSohn Paper.pdf

 

[X]

You mean my model test? It is a model, so it is smaller. And the columns are just 1 mm thick and not 12 or 40/60 mm as the wall and core columns in question. And I just use four columns, not 260+.
So when you heat the four model columns, 1 mm thick, it goes faster to heat them to 500°C than the real thing. In reality it would of course take much longer to heat a 12 mm or 40/60 mm column. Actually it is very strange that it takes as long to heat a 12 mm wall column and a 40/60 mm core column so that they fail simultaneously, but that apparently happened on 9/11. One of these strange things prior initiation.
But what happens when you have heated the 1 mm thick model column (actually a dia 20 mm pipe with wall thickness 1 mm under compression at 0.3 yield stree to get similar slenderness ratio as reality - no scaling there) to 500°C?
Actually nothing! And that was the whole purpose of the experiment.

Thanks for you interest!

Heiwa:

I would like to see the calculations showing that your "exepriment" represents a valid scale model for the scenario being addressed.

Surely as a ship designer you have vast experience with the intricacies of scaling, and are well aware of the care needed to be taken when designing scale models for testing.

Please provide calculations validating the scaling used in your "experiment" design.

 

[Heiwa]

Umm. No. I asked you what the shear strength of two bolts in shear was. You just pulled a number out of your rear end for the capacity of one. I was asking if you could actually do some math to justify what you think the shear strength of bolt was.

And you just come up with more bs. Are you trying to change the subject? Just provide the two line calc for bolt shear strength.

So I gave the answer for one bolt. Evidently an identical second bolt will shear off at the same load.

Anyway, bolted connections are inherently unsafe so designers use much bigger FoS for them than for a completely welded one. It seems bolts were only used in WTC1 to fix the floor to the column. Then they added a little steel bar below to support the connection (and to assist transmitting the vertical load on the floor to the column).

BTW & OT - why do you use such foul language. Did your mother teach you that or did you pick it up at university? Or are you only 10 years old?

Everyone needs to remember to attack the argument and not the arguer. This applies to all members and all those posting in this thread.

Replying to this modbox in thread will be off topic  Posted By: LibraryLady

 

[pomeroo]

A. Nothing really happened. My helmet got a scratch and the brick slipped off.

B. Sorry to hear that. Nothing should really happen. A very safe experiment.

You claimed that dropping the top third of a building onto the bottom two-thirds from a height of two miles would cause no damage to the bottom part. Your ridiculous error got you laughed off the forum. Oddly, you haven't yet acknowledged that you were hopelessly wrong. Are you planning to explain how you could make such a blunder?

Why not?

 

[DC]

Suppose you're an engineer. You're analyzing the capacity of a bolt in an existing structure. You don't have access to the mill reports. You know it's an A307 Bolt.

The standard says that the bolt has a tensile strength between 60 and 100 ksi. Knowing that is costs more money for a mill to get that bolt to a higher strength, what value of the tensile strength should you use?

when i dont know the grade i would use the standard of the lowest grade.

 

[pomeroo]

???? Two miles drop? How do you accomplish that? Already at a two metres drop the upper block columns miss the lower columns.

Sorry, try again.

 

[Newtons Bit]

when i dont know the grade i would use the standard of the lowest grade.

Suppose it was Grade B. What Tensile Strength do you use?

 

[Heiwa]

Heiwa:

I would like to see the calculations showing that your "exepriment" represents a valid scale model for the scenario being addressed.

Surely as a ship designer you have vast experience with the intricacies of scaling, and are well aware of the care needed to be taken when designing scale models for testing.

Please provide calculations validating the scaling used in your "experiment" design.

The slenderness ratio does not need to be scaled. And the objective of the test is just to confirm what happens to one (or four) column(s) with small slenderness ratio under certain compression (i.e. 0.3 yield that need not be scaled either), when heated to 500°C = nothing.

See http://www.mace.manchester.ac.uk/pr...HotRolledCarbonSteel/mechanicalProperties.htm for that.

Full scale 'tests' are done frequently, i.e. accidental fires take place in buildings with steel structures incl. columns. Steel columns with slenderness ratio <35 and normally compressed (<0.3 yield) simply do not collapse when heated to 500°C.

The perpetrators of 9/11 knew that, so they had to provide extra energy to destroy the WTCs.

 

[DC]

suppose It Was Grade B. What Tensile Strength Do You Use?

60 Ksi

 

[Heiwa]

You claimed that dropping the top third of a building onto the bottom two-thirds from a height of two miles would cause no damage to the bottom part. Your ridiculous error got you laughed off the forum. Oddly, you haven't yet acknowledged that you were hopelessly wrong. Are you planning to explain how you could make such a blunder?

Why not?

???? Two miles? Where have you got that from? Read my articles and what I claim there. Pls, do no invent ridiculous claims. Two miles!

 

[Newtons Bit]

60 Ksi

Now then: do you get why I said it doesn't matter what grade the bolt is?

 

[pomeroo]

???? Two miles? Where have you got that from? Read my articles and what I claim there. Pls, do no invent ridiculous claims. Two miles!

You silly liar. I started this thought experiment by asking you to consider what happens if I magically remove the 109th floor of a 110-story building. The 110th floor drops onto the 108th. A certain amount of damage is done to both parts, but the building remains standing. Next, I asked if pulling out the 80th floor and allowing floors 81 through 110 to drop onto the 79th floor is the same thing. You insisted, insanely, that it was, that "Newton's laws" require that a "new equilibrium" be established. You completely ignored the enormous differences in the masses of the upper parts. Yes, the force pushing up must equal the force pushing down, BUT the total force is much greater than the structure can withstand. To drive home the point, I asked what happens if I lift the top third of the building two miles and drop it onto the bottom two-thirds. You stuck by your lunatic garble of basic physics and maintained that a new equilbrium is established. Amid gales of laughter, you ran away, realizing that you had made a horse's ass of yourself.

You can't hope to lie your way out of your blunder.