WTC7 and the girder walk-off between column 79 and 44

[Justin39640]

Take a look at the photo of how columns are fireproofed with gypsum on page 340 of this U.S. Gypsum document http://www.usg.com/documents/construction-handbook/chapter10.pdf.

They are supported by a frame around the column. The aircraft impact acceleration was high at the exterior wall but it was attenuated by the failing columns and floors as well as the aircraft breaking up. It could not generate enough acceleration at the core to cause the gypsum framing to come off the core columns.

No

 

[pgimeno]

NCSTAR 1-6 just tries to say the core was thermally weakened. It does not provide a substantiated analysis for that statement. Additionally, it does not provide any substantiation for overload and failure of the east and west perimeter wall columns, which had a factor of safety against gravity loads of 5.00 to 1. The NIST load redistribution on the perimeter is at worst about 30% more than what was normally on the columns which was about 20% of their capacity. So here we have 1.3 x 20% = 26% of their capacity. In that case the columns would have still had a factor of safety of just under 4.00 to 1. So NCSTAR 1-6 Chapter 8 does not explain the collapse propagation across the entire building emanating from the south wall, and interestingly Dr. Bazant picks up after the upper section is already falling.

So we have this big hole in the official story where nobody explains how a south wall failure could cause a propagation across the building. That is why I asked you to try and explain it. If you really think it was a natural occurrence you should be able to do that.

I don't see a problem with it. Core column failure and subsequent failure of perimeter when the load redistributes easily explains it. And I don't see how the FoS of columns bowed inwards can be the same as for straight columns.

So much for your statement that "I believe you would need to take out about 50% of the columns along with fires to actually effect a collapse". For you, it seems that all it takes for the NIST analysis to produce a collapse is to "substantiate" the thermal weakening of the core and to "explain the collapse propagation across the entire building emanating from the south wall", therefore I guess that if these are proved possible, your 50% figure becomes ludicrous.

 

[Animal]

Take a look at the photo of how columns are fireproofed with gypsum on page 340 of this U.S. Gypsum document http://www.usg.com/documents/construction-handbook/chapter10.pdf.

They are supported by a frame around the column. The aircraft impact acceleration was high at the exterior wall but it was attenuated by the failing columns and floors as well as the aircraft breaking up. It could not generate enough acceleration at the core to cause the gypsum framing to come off the core columns.

 

[Animal]

You are trying to say all of the fireproofing within 10 floors of the impact would have possibly been shaken loose due to the acceleration generated by the aircraft impact.

Once again TS tries to limit the factors to only what works to maintain his religious beliefs.

That means you understand that there was no chance for the debris field moving downward from the impact at the 95th and 96th floors to have any chance of reaching the 98th floor on the other side of the building (and we do know the collapse initiated at the 98th floor in the North Tower).

The problem for your theory is that NIST didn't go that way as they did no test to show what you are saying. They only did debris blast testing on steel coated SFRM. They might have mentioned acceleration and vibration, but they did no testing to show it was possible. When you want to prove something in engineering you do a test.

SFRM has very low mass and the force on its bond would have only been F = ma where "m" was its mass and "a" the acceleration of the building due to the impact. It is quite unlikely that the SFRM would have dislodged all the way on the other side of the building and that is why NIST did not test a specimen on a shaker to prove it.

You really have no clue what you are talking about. It truly is amazing to watch you spin like a top while tap dancing to reaffirm your cult religion.

 

[Newtons Bit]

Take a look at the photo of how columns are fireproofed with gypsum on page 340 of this U.S. Gypsum document http://www.usg.com/documents/construction-handbook/chapter10.pdf.

They are supported by a frame around the column. The aircraft impact acceleration was high at the exterior wall but it was attenuated by the failing columns and floors as well as the aircraft breaking up. It could not generate enough acceleration at the core to cause the gypsum framing to come off the core columns.

And that was standard construction practice in the 60's?

 

[Gamolon]

NCSTAR 1-6 just tries to say the core was thermally weakened. It does not provide a substantiated analysis for that statement. Additionally, it does not provide any substantiation for overload and failure of the east and west perimeter wall columns, which had a factor of safety against gravity loads of 5.00 to 1. The NIST load redistribution on the perimeter is at worst about 30% more than what was normally on the columns which was about 20% of their capacity. So here we have 1.3 x 20% = 26% of their capacity. In that case the columns would have still had a factor of safety of just under 4.00 to 1. So NCSTAR 1-6 Chapter 8 does not explain the collapse propagation across the entire building emanating from the south wall, and interestingly Dr. Bazant picks up after the upper section is already falling.

Ok, I need a lesson (or lessons) in structural engineering if someone would be so kind to answer some questions.

How is the factor of safety being applied in this scenario? Meaning, does it apply to the structure as a whole when functioning at 100% or can it apply to sections or individual components of the total structure? For example, take the structural components that made up floor 95. Were those components designed to carry the gravity loads of everything above that particular floor PLUS 5 times said load?

What happens to the safety factor when certain components of the structure are weakened or removed? Does the safety factor change accordingly? For example. The 95th floor was able to support 5 times it's design load. If I remove 28 of the the 240 columns, weaken a dozen more, remove 1 or 2 core columns and weaken a few more, do the remaining structural components still function at that factor of safety of 5 as a whole?

I guess my question is, does the factor of safety apply to increased loads applied to a 100% functioning structure or can it also apply to a structure with failed/removed/weakened components.

I'm not sure if I'm expressing my question correctly.

Thanks.

 

[LSSBB]

Wake me when the thread is back on topic. Tony finally revealing what the reply of the peer reviewers was to his paper would be a good start.

 

[ozeco41]

Ok, I need a lesson (or lessons) in structural engineering if someone would be so kind to answer some questions.

How is the factor of safety being applied in this scenario? Meaning, does it apply to the structure as a whole when functioning at 100% or can it apply to sections or individual components of the total structure?...

FOS applies to individual components but the sum of those components adds up to an overall FOS. BUT that is not the trick that Tony is playing. Nor is it the key issue. So I won't try to explain FOS further at this stage - It may lead to confusion rather than clarification.

The key issue is that taking out columns does not mean that their load is uniformly re-distributed. Taking out 1/4 of columns does not add 33% load to all other columns - even if the columns were originally equally loaded. Tony made this statement:

...I believe you would need to take out about 50% of the columns along with fires to actually effect a collapse.

...which is not the statement that a structural engineer would make unless his intention was to mislead.
What happens when columns are removed depends on which columns are removed and the spatial relationship of the columns that are left.

Here is a rough sketch which I did to illustrate the issue - a very theoretical building with three columns. Lets say three rows of columns:

Case 1A has a 'top block' of mass 400 and that 400 is carried across the columns left to right 100 on the left, 200 on centre and 100 on right. Cut out the right column and the loads on left and centre become 0 and 400. I think it should be apparent to a lay person why that is so but if not I can explain further.

So 33% of columns removed leads to double the load on one remaining column and zero load on the other.

The Case 1B answers are in parenthesis - original uniform loads of 133 -133-133 - cut out one and the central column load becomes 400 so a tripling of load on one column when 33% of columns removed. Again more explanation if needed.

My Case 2A sketch shows the effect of removing the right side column (or row of columns) for either Case 1A or Case 1B.

The third sketch - Case 2B - goes a bit further but let's not go there yet.

The point I have illustrated is that how the load redistributes when a proportion of columns is removed is not a uniform re-allocation. It depends very much on which columns are removed and more so on which ones are left and their spatial relationships.

Not as simple as Tony would have you think.

Two other tricks out of the three currently in play are:
A) Tony's standard tactic of focussing on a single factor when the issue involves multiple factors. That one already noted and called by Animal:

Once again TS tries to limit the factors to only what works to maintain his religious beliefs....

AND
B) Attempted 'reverse burden of proof' as per this one:

...So we have this big hole in the official story where nobody explains how a south wall failure could cause a propagation across the building. That is why I asked you to try and explain it. If you really think it was a natural occurrence you should be able to do that.

Not so - it is Tony's claim and his burden of proof to make out that claim - it is no-one else's responsibility to prove the opposite. If you go back through this thread you will find that the same errors have been identified several times previously.

So getting back to your original queries:

... For example, take the structural components that made up floor 95. Were those components designed to carry the gravity loads of everything above that particular floor PLUS 5 times said load?

What happens to the safety factor when certain components of the structure are weakened or removed? Does the safety factor change accordingly? For example. The 95th floor was able to support 5 times it's design load. If I remove 28 of the the 240 columns, weaken a dozen more, remove 1 or 2 core columns and weaken a few more, do the remaining structural components still function at that factor of safety of 5 as a whole?

I guess my question is, does the factor of safety apply to increased loads applied to a 100% functioning structure or can it also apply to a structure with failed/removed/weakened components.

I'm not sure if I'm expressing my question correctly.

Thanks.

Given my simplified explanation you can probably now see that your other questions are more complicated to answer than you may have thought.

Do you want to take it further? If so let's try one or two questions at a time so we can head in the right direction.

 

[Animal]

Tony's standard tactic of focussing on a single factor when the issue involves multiple factors. That one already noted and called by Animal:

I have had the unfortunate opportunity to work with engineers like TS. They are the reason you will find a roof conductor running straight through the middle of a large window because it is the most direct route, or a big ugly breaker box in the office lobby etc.

 

[Gamolon]

I have another question for Tony. Here is a quote from him on another forum.

Using Gregory Urich's mass analysis for the 98th floor perimeter columns, their wall thickness would have been .289". The yield strength at this location was at least 65,000 psi, so a 14 inch box column with about a 16 square inch cross section could handle about 200,000 lbs. with a 5 to 1 safety factor. Given this for 59 columns, each perimeter wall could support about 12 million lbs. with a 5 to 1 safety factor or 48 million lbs. counting all four perimeter walls. The total weight of the upper section of WTC 1, from the 98th floor up, was about 69 million lbs. and the core took about 42% of that load leaving about 40 million lbs. for the perimeter to support.

So let's see if I get this right using Tony's numbers and his way of thinking.

69,000,000 total lbs. from the 98th floor up. 40,000,000 lbs. for the perimeter columns to handle and 29,000,000 lbs. for the core.

47 columns in the core. If I sever 4 core columns, that leaves 43 columns (about 8% less). That means the core lost it's ability to support 2,320,000 lbs. Where did that load go? According to your thinking, the core just went from supporting 42% of the load from the 98th floor and above down to 36%.

That moves 2,320,000 lbs. of load to the perimeter columns. That moves us up to 42,320,000 lbs. for the perimeter columns to support because that load didn't just disappear.

I count about 33 perimeter columns that were severed on one side for the north tower. That gives us 6,600,000 lbs. that the severed perimeter columns could not support anymore. That moves us up to 48,920,000 lbs. for the remaining perimeter columns to support.

You said above that 48,000,000 lbs. was what the perimeter columns could support with a safety factor of 5 to 1. Now we're 920,000 lbs. OVER that figure. I didn't even add in the weakened (in addition to the severed) perimeter columns due to the impact or the weakened core columns due to fire that would have transferred even more to the columns.

Now what?

 

[Gamolon]

FOS applies to individual components but the sum of those components adds up to an overall FOS. BUT that is not the trick that Tony is playing. Nor is it the key issue. So I won't try to explain FOS further at this stage - It may lead to confusion rather than clarification.

The key issue is that taking out columns does not mean that their load is uniformly re-distributed. Taking out 1/4 of columns does not add 33% load to all other columns - even if the columns were originally equally loaded. Tony made this statement:
...which is not the statement that a structural engineer would make unless his intention was to mislead.
What happens when columns are removed depends on which columns are removed and the spatial relationship of the columns that are left.

Here is a rough sketch which I did to illustrate the issue - a very theoretical building with three columns. Lets say three rows of columns:
[qimg]http://conleys.com.au/webjref/cutcols.jpg[/qimg]
Case 1A has a 'top block' of mass 400 and that 400 is carried across the columns left to right 100 on the left, 200 on centre and 100 on right. Cut out the right column and the loads on left and centre become 0 and 400. I think it should be apparent to a lay person why that is so but if not I can explain further.

So 33% of columns removed leads to double the load on one remaining column and zero load on the other.

The Case 1B answers are in parenthesis - original uniform loads of 133 -133-133 - cut out one and the central column load becomes 400 so a tripling of load on one column when 33% of columns removed. Again more explanation if needed.

My Case 2A sketch shows the effect of removing the right side column (or row of columns) for either Case 1A or Case 1B.

The third sketch - Case 2B - goes a bit further but let's not go there yet.

The point I have illustrated is that how the load redistributes when a proportion of columns is removed is not a uniform re-allocation. It depends very much on which columns are removed and more so on which ones are left and their spatial relationships.

Not as simple as Tony would have you think.

Two other tricks out of the three currently in play are:
A) Tony's standard tactic of focussing on a single factor when the issue involves multiple factors. That one already noted and called by Animal:
AND
B) Attempted 'reverse burden of proof' as per this one: Not so - it is Tony's claim and his burden of proof to make out that claim - it is no-one else's responsibility to prove the opposite. If you go back through this thread you will find that the same errors have been identified several times previously.

So getting back to your original queries:
Given my simplified explanation you can probably now see that your other questions are more complicated to answer than you may have thought.

Do you want to take it further? If so let's try one or two questions at a time so we can head in the right direction.

Thank you! That helps!

 

[Gamolon]

It can get even more simplistic.

Tony states (in the above quote) that each perimeter wall could support 12,000,000 lbs. each including a safety factor of 5 to 1.

The calculated load supported by each perimeter wall (according to Tony) from the 98th floor up was 10,000,000 lbs. (40,000,000 lbs divided by 4 walls).

Removing 33 perimeter columns in one wall (due to the plane impact severing these columns) reduces the 12,000,000 lbs. by 6,600,000 lbs.

10,000,000 lbs. > 5,400,000 lbs. isn't it?

 

[NoahFence]

You said above that 48,000,000 lbs. was what the perimeter columns could support with a safety factor of 5 to 1. Now we're 920,000 lbs. OVER that figure. I didn't even add in the weakened (in addition to the severed) perimeter columns due to the impact or the weakened core columns due to fire that would have transferred even more to the columns.

Now what?

Run from the thread?

 

[Spanx]

Just makes you wonder how the thermite managed to ignite on the 98th floor when no fireproofing was dislodged.

 

[Gamolon]

I never saw these before. They explain the towers construction. My apologies if they've been posted elsewhere.

http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi1.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi2.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi3.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi4.pdf
http://www.engr.psu.edu/ae/WTC/AISI/wtcaisi5.pdf

 

[Gamolon]

I have an issue with one of Tony's pieces of information in his quote from another forum below.

Using Gregory Urich's mass analysis for the 98th floor perimeter columns, their wall thickness would have been .289". The yield strength at this location was at least 65,000 psi, so a 14 inch box column with about a 16 square inch cross section could handle about 200,000 lbs. with a 5 to 1 safety factor. Given this for 59 columns, each perimeter wall could support about 12 million lbs. with a 5 to 1 safety factor or 48 million lbs. counting all four perimeter walls. The total weight of the upper section of WTC 1, from the 98th floor up, was about 69 million lbs. and the core took about 42% of that load leaving about 40 million lbs. for the perimeter to support.

According to PDF #5 that I linked above, figure 7 (right diagram), the grade of steel used in the 98th floor area was "High Strength Steel". The left diagram of figure 7 shows the yield strengths for "High Grade Steel". That range is from 45,000 to 65,000.

First question. Why does Tony say the "yield strength at this location was a LEAST 65,000" psi when it should say the "yield strength was at LEAST 45,000 psi and at most 65,000 psi?

Second question. What was the grade of steel used in the perimeter columns that high up? Is there a link/source for this? I would think higher grades of steel would be used LOWER in the tower and decrease as you went up.

If I am misunderstanding anything, please let me know.

Figure 7 of the #5 PDF above.

 

[Tony Szamboti]

I have another question for Tony. Here is a quote from him on another forum.



So let's see if I get this right using Tony's numbers and his way of thinking.

69,000,000 total lbs. from the 98th floor up. 40,000,000 lbs. for the perimeter columns to handle and 29,000,000 lbs. for the core.

47 columns in the core. If I sever 4 core columns, that leaves 43 columns (about 8% less). That means the core lost it's ability to support 2,320,000 lbs. Where did that load go? According to your thinking, the core just went from supporting 42% of the load from the 98th floor and above down to 36%.

That moves 2,320,000 lbs. of load to the perimeter columns. That moves us up to 42,320,000 lbs. for the perimeter columns to support because that load didn't just disappear.

I count about 33 perimeter columns that were severed on one side for the north tower. That gives us 6,600,000 lbs. that the severed perimeter columns could not support anymore. That moves us up to 48,920,000 lbs. for the remaining perimeter columns to support.

You said above that 48,000,000 lbs. was what the perimeter columns could support with a safety factor of 5 to 1. Now we're 920,000 lbs. OVER that figure. I didn't even add in the weakened (in addition to the severed) perimeter columns due to the impact or the weakened core columns due to fire that would have transferred even more to the columns.

Now what?

You have succeeeded in completely confusing yourself here. Reread what I said and try again.

 

[Tony Szamboti]

I have an issue with one of Tony's pieces of information in his quote from another forum below.



According to PDF #5 that I linked above, figure 7 (right diagram), the grade of steel used in the 98th floor area was "High Strength Steel". The left diagram of figure 7 shows the yield strengths for "High Grade Steel". That range is from 45,000 to 65,000.

First question. Why does Tony say the "yield strength at this location was a LEAST 65,000" psi when it should say the "yield strength was at LEAST 45,000 psi and at most 65,000 psi?

Second question. What was the grade of steel used in the perimeter columns that high up? Is there a link/source for this? I would think higher grades of steel would be used LOWER in the tower and decrease as you went up.

If I am misunderstanding anything, please let me know.

Figure 7 of the #5 PDF above.
[qimg]http://i238.photobucket.com/albums/ff290/gamolon/figure7.png[/qimg]

Read the NIST report and you will see that the exterior columns at the 98th floor were at least 65,000 psi yield strength.

 

[Tony Szamboti]

FOS applies to individual components but the sum of those components adds up to an overall FOS. BUT that is not the trick that Tony is playing. Nor is it the key issue. So I won't try to explain FOS further at this stage - It may lead to confusion rather than clarification.

The key issue is that taking out columns does not mean that their load is uniformly re-distributed. Taking out 1/4 of columns does not add 33% load to all other columns - even if the columns were originally equally loaded. Tony made this statement:
...which is not the statement that a structural engineer would make unless his intention was to mislead.
What happens when columns are removed depends on which columns are removed and the spatial relationship of the columns that are left.

Here is a rough sketch which I did to illustrate the issue - a very theoretical building with three columns. Lets say three rows of columns:
[qimg]http://conleys.com.au/webjref/cutcols.jpg[/qimg]
Case 1A has a 'top block' of mass 400 and that 400 is carried across the columns left to right 100 on the left, 200 on centre and 100 on right. Cut out the right column and the loads on left and centre become 0 and 400. I think it should be apparent to a lay person why that is so but if not I can explain further.

So 33% of columns removed leads to double the load on one remaining column and zero load on the other.

The Case 1B answers are in parenthesis - original uniform loads of 133 -133-133 - cut out one and the central column load becomes 400 so a tripling of load on one column when 33% of columns removed. Again more explanation if needed.

My Case 2A sketch shows the effect of removing the right side column (or row of columns) for either Case 1A or Case 1B.

The third sketch - Case 2B - goes a bit further but let's not go there yet.

The point I have illustrated is that how the load redistributes when a proportion of columns is removed is not a uniform re-allocation. It depends very much on which columns are removed and more so on which ones are left and their spatial relationships.

Not as simple as Tony would have you think.

Two other tricks out of the three currently in play are:
A) Tony's standard tactic of focussing on a single factor when the issue involves multiple factors. That one already noted and called by Animal:
AND
B) Attempted 'reverse burden of proof' as per this one: Not so - it is Tony's claim and his burden of proof to make out that claim - it is no-one else's responsibility to prove the opposite. If you go back through this thread you will find that the same errors have been identified several times previously.

So getting back to your original queries:
Given my simplified explanation you can probably now see that your other questions are more complicated to answer than you may have thought.

Do you want to take it further? If so let's try one or two questions at a time so we can head in the right direction.

Your sketches are not analogous to the complete wall of 59 columns with 40 inch center to center spacing on both the east and west perimeter walls and NIST does not provide a mechanism for their collapse.

 

[carlitos]

I love how the NIST report can be cited as both being full of lies and a valuable source of information. It's almost biblical; inerrant regarding yield strength, yet full of lies about fire propagation.