WTC Discussion: Core Column Temperature & Failure.

[28th Kingdom]

Sir,

What a splendid point you have brought up. The oven in household stoves reach these types of temperatures. Here is the link to the NIST Media Public Briefing. Page 31 shows the temps of each column:

http://wtc.nist.gov/pubs/Media_Public_Briefing_040505_final.pdf

No they do not. The graph shows several column temperatures of 500+ Celcius. Unless you've got some high-powered oven, I don't think so.

The air and the fire, meanwhile, was much hotter. See page 30.

Comparisons to ovens are illegitimate. Your oven has opportunity to draw off the heat, and the air temperature (which never gets to 400-500C) is not the oven body temperature.

Also, please try to recall that the reason not all the column have temperatures is because they are GONE due to the impact.

then why are the pictures labeled "all floors"

let me give you some background on how they dtermined these temperatures

they analyzed the paint on the columns to find out the temperature they had been exposed to, NIST states that these number are not representative for all the columns since many of them didnt have enough paint left to analyze

knowing that, does it stand to reason that paint exposed to higher temperatures was burned off and could not be analyzed by NIST?

You do make a fair point, because it's the air in the oven of a stove that reaches around 300C, and not the metal/steel inside of it. The max air temp on the impact floors was a bit higher than this at around 1000C...however, look at how many core columns are left on each tower. WTC 1: 41 WTC 2: 37 - and there are no core columns on WTC 2 with a temp above 250C.

"However, when bare steel reaches temperatures of 1,000 degrees Celsius, it softens and its strength reduces to roughly 10 percent of its room temperature value. Steel that is unprotected (e.g., if the fireproofing is dislodged) can reach the air temperature within the time period that the fires burned within the towers. Thus, yielding and buckling of the steel members (floor trusses, beams, and both core and exterior columns) with missing fireproofing were expected under the fire intensity and duration determined by NIST for the WTC towers. " NIST FAQ 7

http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

NIST claims that unprotected steel can reach the air temperature within the time period that the fires burned. Okay, that's fine...but NIST clearly shows us that this did not happen. In fact, on WTC 2, the core columns only reached a max temp of around 250C - that's 1/6th of steel's melting point i.e 1500C - I know NIST didn't claim the steel melted, I'm just giving a comparison.

"Left", however, does not mean intact. Note the damage to remaining columns on page 18.



However your are missing many core columns from impact and the outer columns are at higher temps. WTC2 is missing a LOT more than WTC1.



Again, this ignores the fact that many more core columns were missing in WTC2 and that the side columns were heated to higher temps.

What sides are you referring to? The sides of the buildings? Those are virtually unheated except for one corner on WTC 2. And out of the 37 (non-severed) core columns, NIST shows only twelve of them have any signs of heat. (with a max temp of about 250C) And according to page 21 - only one of these remaining (non-severed) core columns has heavy damage. The rest only show light to moderate damage.

So how did all of these core columns fail? The core columns on the floors above the impact obviously had no heat and damage, so how did they fall down on the impact floor(s) core columns when 37 of the core columns on WTC 2 were completely non-severed with only one of the remaining 37 columns showing heavy damage, and only 12 of the 37 showing low temps around 250C.

I am talking about the side of the building columns. They are important to the structure and they got hot!

Combine that heat wekaness with the severed and damaged columns and I am amazed you guys can't figure out the cause of failure.

Now keep in mind this building failure is going to be examined for, oh, about the next century or so in failure analysis class in Architecture and Engineering schools around the world. They are going to be analyzing to hell and back and , with no signifigant quibbles, are going to come to much the same conclusion!

Yet somehow you know better, are you that arrogant?

"Based on this comprehensive investigation, NIST concluded that the WTC towers collapsed because: (1) the impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; and (2) the subsequent unusually large jet-fuel ignited multi-floor fires (which reached temperatures as high as 1,000 degrees Celsius) significantly weakened the floors and columns with dislodged fireproofing to the point where floors sagged and pulled inward on the perimeter columns. This led to the inward bowing of the perimeter columns and failure of the south face of WTC 1 and the east face of WTC 2, initiating the collapse of each of the towers." NIST FAQ 2

http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm

Is it so surprising that we can't understand how the core columns came down, considering the fact, that NIST doesn't even explain what happened to them? Just because the floors and perimeter columns collapse, doesn't mean the core columns will do the same thing. So how did the 37 non-severed core columns on WTC 2 fail, when only 12 of them suffered minimal heat? That leaves 25 non-severed non-heated core columns with only 5 of the 25 suffering any damage (1 light damage, 1 heavy damage & 3 moderate damage) So that leaves 20 completely undamaged and unheated core columns. Now, how did those fail?

in WTC 2 the perimiter columns failed due to the bowing, upon this failure all load normally supported by the perimiter columns was placed on the core, including about 50% of the gravity load and 100% of wind shear and tranverse loads (which the core was never designed to take)

why is the cores failure so surprising again?

Do you have a source for the perimeter columns normally taking 50% of the gravity load?

Once the floors had collapse, what load was the core supporting? It only had to support itself

page 6 of NISTs final report



when the perimeter columns failed the floors hadnt collapsed yet, so there load was tranferred to the core columns, which were almost instantly overwhelmed by the weight

after the collapse was more or less complete some part of the core was left standing, but this quickly collapsed for 2 reasons

1: i was not designed to withstand any transverse load at all
2: it sustained an unknown amount of damage during the collapse

If the perimeter columns failed first and they were holding 50% of the gravity load...than why didn't the floors fall down from where they were connected to the perimeter columns? What do you mean by the perimeter columns failed...do you mean the floors weren't connected to them anymore?

Actually, that's exactly how they constructed the WTC Towers. They built the core columns first...and then added the outer perimeter and floors. So we know the core columns can stand on their own, because they were up before the floors and outer perimeter were even added.

This is a topic that got started in another thread...and instead of derailing that other person's topic, I thought I would consolidate the posts into a new thread. I hope this is okay. Note to moderators: If this is considered spam, I apologize.

 

[GlennB]

Could you kindly explain what point/ question you are trying to put here ?

 

[defaultdotxbe]

Actually, that's exactly how they constructed the WTC Towers. They built the core columns first...and then added the outer perimeter and floors. So we know the core columns can stand on their own, because they were up before the floors and outer perimeter were even added.

the WTC was not constructed with the entire core standing on its own, theres no reason to beleive it could have stood on its own without the rest of the building (remember the perimeter columns sustained 100% of the transverse load) plus the core sustained an unknown amount of damage during the collapse itself

If the perimeter columns failed first and they were holding 50% of the gravity load...than why didn't the floors fall down from where they were connected to the perimeter columns? What do you mean by the perimeter columns failed...do you mean the floors weren't connected to them anymore?

im not sure what your asking here, by "perimeter columns failed" i mean the columns broke and were no longer supporting any load

 

[28th Kingdom]

im not sure what your asking here, by "perimeter columns failed" i mean the columns broke and were no longer supporting any load

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

 

[defaultdotxbe]

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

your not making any sense here

when the p[erimeter columsn failed they were no longer transfering the load to the ground, so the load was transfered to the core columns which failed because twice as much weight was on them than they were designed for, is that really that hard to understand without you trying to throw out strawmen?

 

[28th Kingdom]

What part of the perimeter column transfered the load to the ground? This is what failed, yes? So what part of the perimeter columns, failed?

 

[beachnut]

Actually, that's exactly how they constructed the WTC Towers. They built the core columns first...and then added the outer perimeter and floors. So we know the core columns can stand on their own, because they were up before the floors and outer perimeter were even added.

No, they built the building all at once, the outside is the lateral support the inside primary gravity load. The inside core does not support lateral loads. The core would be toppled by the wind!

The core can not stand without the exterior support. you are wrong

 

[JFM]

What part of the perimeter column transfered the load to the ground? This is what failed, yes? So what part of the perimeter columns, failed?

No, I've tried. I don't understand why you ask this. Everyone knows the top of a column transfers the load to the ground.

 

[GlennB]

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

You're becoming incoherent , 28th.

 

[beachnut]

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

No most the gravity load is on the core. Show your work otherwise.

 

[defaultdotxbe]

No most the gravity load is on the core. Show your work otherwise.

the NIST report says it was shared about equally between the core and perimeter columns, 28th quoted my citation in his initial post

 

[babazaroni]

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

When a perimeter column fails, as in broken by plane impact, it will still support all the floors attached to it, because it's load is now transferred to the other columns.

In other words, the broken column still supports the floors connected to it, and the other columns support the broken column. It's a connected system.

Why don't you just get to your point?

 

[Horatius]

So if the perimeter columns weren't supporting any load...than the floors were no longer attached to them, right? If the floors are still attached to the perimeter columns...than the perimeter columns would still be supporting it's half of the gravity load, right?

Since you need pretty pictures to let you understand anything, here's an ugly picture that might help.

When the sagging of the floor trusses pulled the perimeter columns out of plumb, they were no longer able to support their design load. All the perimeter columns above this point still supported their floors, but the overall load was transferred to the ground through the core columns, past the point of failure. Thus almost the entire mass of the structure above the failed point rested on the core. The perimeter columns below the failed point only supported their part of the mass of the floors below that point.

Get it now?

 

[28th Kingdom]

What is a truss made out of?

 

[Bell]

What is a truss made out of?

Truss components.

 

[Arus808]

Aluminum, steel, iron, wood, concrete, or combination of alloys.

 

[defaultdotxbe]

What is a truss made out of?

do you have a point?

it seems like your contantly trying to bait us so you can make you point, but you never get to a point, you just change the subject and start baiting again

 

[28th Kingdom]

How does a steel truss sag? Especially when 95% of the steel columns on the impact floors were only heated to 250C...why were these trusses so hot?

 

[defaultdotxbe]

How does a steel truss sag? Especially when 95% of the steel columns on the impact floors were only heated to 250C...why were these trusses so hot?

you like to ignore my explanation of that, even though you quoted it in this thread

let me give you some background on how they dtermined these temperatures

they analyzed the paint on the columns to find out the temperature they had been exposed to, NIST states that these number are not representative for all the columns since many of them didnt have enough paint left to analyze

knowing that, does it stand to reason that paint exposed to higher temperatures was burned off and could not be analyzed by NIST?

 

[Bell]

How does a steel truss sag? Especially when 95% of the steel columns on the impact floors were only heated to 250C...why were these trusses so hot?

Maybe because all of the burning office stuff that was inside of the towers?