Challenge: Demonstrate Sagging floor Trusses Pulling in Perimeter Columns

JSanderO said:
Thanks Bit... I am well aware of the technology used in the WTC buildings.

Archi(tect) Bunker
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It appears you are more aware of how to spread BS, and projecting.

As you drift off making up stuff, remember...
enik said:
I see Gamolon has issued a challenge in another thread. I will offer an even simpler one. Show with your own FEA or calculations how the perimeter columns of WTC 1 were pulled in by up to 54” by sagging floor trusses.

Bonus, demonstrate how this instability caused the initiation sequence for collapse of WTC 1.
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Is enik tilting at windmills?

Will this thread help him reach his goal?
http://s1.zetaboards.com/LooseChangeForums/topic/4724858/1/
Inside Job Evidence is in the Physics of WTC #1
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Can you help him?
 
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Newtons Bit said:
Do you consider the challenge satisfied? You verified my results in RISA.
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I did another analysis using the NIST value of modulus of elasticity at 600 C per the following:

Modulus of elasticity is reduced by 25 percent at 600 C for steel and by 50 percent to 75 percent for concrete. Section 4.1.2 page 60 NIST NCSTAR 1-6.
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If we go to the chart on page 63, it shows a modulus of 30,000,000 psi at 0 C. 25% reduction places it at 22,500,000 psi.

Now if we apply this value to the RISA model, we get a maximum deflection of 0.011” for both cases.

Do you disagree with this?

To answer your question, are you 100% satisfied that sagging floor trusses developed 6 kips per column?
 
enik said:
I did another analysis using the NIST value of modulus of elasticity at 600 C per the following:



If we go to the chart on page 63, it shows a modulus of 30,000,000 psi at 0 C. 25% reduction places it at 22,500,000 psi.

Now if we apply this value to the RISA model, we get a maximum deflection of 0.011” for both cases.

Do you disagree with this?
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:confused: That's way less than deflection than a hand-calc shows. You're doing something wrong.

To answer your question, are you 100% satisfied that sagging floor trusses developed 6 kips per column?
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Why wouldn't I be?
 
Newtons Bit said:
That's way less than deflection than a hand-calc shows. You're doing something wrong.
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I figured as much. That is why I included the attachments. I get about 1.3” using ABAQUS and hand calculations for the first part. What do you get in RISA?

Newtons Bit said:
enik said:
To answer your question, are you 100% satisfied that sagging floor trusses developed 6 kips per column?
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Why wouldn't I be?
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I just wanted to be sure you had no doubts.
 
enik said:
I figured as much. That is why I included the attachments. I get about 1.3” using ABAQUS and hand calculations for the first part. What do you get in RISA?
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I'm not at work today, though I can check tomorrow. The deflection for a lateral only case will vary linearly with modulus of elasticity. The only thing that makes any sense at all is that you put in a modulus of elasticity that is 1000 times to large.

I just wanted to be sure you had no doubts.
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Why would I?
 
Newtons Bit said:
I'm not at work today, though I can check tomorrow. The deflection for a lateral only case will vary linearly with modulus of elasticity. The only thing that makes any sense at all is that you put in a modulus of elasticity that is 1000 times to large.
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Yes, I forgot the units were KSI. I now get 1.795" for the first case and 3.135" for the second case.
 
Newtons Bit said:
So, what was the point of this exercise?
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In reference to my challenge, we have common ground on software for analyzing; therefore I wanted to see what results were generated by using NIST inputs. Did you get the same results?
 
enik said:
In reference to my challenge, we have common ground on software for analyzing; therefore I wanted to see what results were generated by using NIST inputs. Did you get the same results?
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Well, there's an important part of the "NIST inputs" that you're missing.

The AISC Fire Facts document gives reduced Modulus of Elasticity and Yield Strength changes are based on equilibrium behavior. That is, behavior without regards to strain rates. It's a useful tool for looking at linear non-dynamic problems.

That's not what the "NIST inputs", as you're calling it, is doing. They break out the Modulus of Elasticity from creep behavior. Take a look at Fig. 4-5 (b) on pg. 65 of NCSTAR 1-6:



It plots stress-strain behavior and breaks out the effect of elastic behavior (which uses the Modulus of Elasticity) and creep. It then shows the effect of creep of this as well. Keep in mind that creep here is based on 400C and 30 minutes of load. If you want to use the "NIST inputs", you're going to build a model that uses creep at 600C and about 60 minutes load. I can't do that in RISA, which is why I'm using the AISC Facts for Fire reductions in Modulus of Elasticity.
 
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Newtons Bit said:
Well, there's an important part of the "NIST inputs" that you're missing.

The AISC Fire Facts document gives reduced Modulus of Elasticity and Yield Strength changes are based on equilibrium behavior. That is, behavior without regards to strain rates. It's a useful tool for looking at linear non-dynamic problems.

That's not what the "NIST inputs", as you're calling it, is doing. They break out the Modulus of Elasticity from creep behavior. Take a look at Fig. 4-5 (b) on pg. 65 of NCSTAR 1-6:

It plots stress-strain behavior and breaks out the effect of elastic behavior (which uses the Modulus of Elasticity) and creep. It then shows the effect of creep of this as well. Keep in mind that creep here is based on 400C and 30 minutes of load. If you want to use the "NIST inputs", you're going to build a model that uses creep at 600C and about 60 minutes load. I can't do that in RISA, which is why I'm using the AISC Facts for Fire reductions in Modulus of Elasticity.
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I understand why you used a low modulus of elasticity. But I have to go with what is published in the NIST report. Maybe if I have the time, I might try a creep analysis.
 
enik said:
I understand why you used a low modulus of elasticity. But I have to go with what is published in the NIST report. Maybe if I have the time, I might try a creep analysis.
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What I'm getting at, is you can either use the numbers in the AISC "Facts for Fire" values, or you can use the values in NIST with the creep analysis. You can't do the latter without a creep analysis and expect an accurate result.
 
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