Why the Towers Fell - Tuesday night on Nova

[ABErickson]

"A team of forensic engineers investigates the World Trade Center's collapse. "

Thought some may be interested.

 

[spanky]

i think i saw this a few months ago. it was interesting.

 

[BooneRebel]

Wasn't it because of those big plane thingies? There, I've freed up an hour for you Tuesday night.

 

[BDawg]

No, IIRC it was the fires that weakened the structure.

 

[spanky]

Originally posted by: BDawg
No, IIRC it was the fires that weakened the structure.

yeah, thats what it was. they were saying if there weren't so much jet fuel that kept the fires burning... the flames would've burned themselves out and the towers would still be up. the huge amount of jet fuel kept the fires going, which melted the steel structures... then just pancaked down.

 

[thedan]

Hey, I haven't seen anything on that, but what temp does jet fuel burn at? And what temp does huge skyscraper steel supports melt at?

Also, why did it collapse *straight* down.

 

[BDawg]

Originally posted by: thedan
Hey, I haven't seen anything on that, but what temp does jet fuel burn at? And what temp does huge skyscraper steel supports melt at?

Also, why did it collapse *straight* down.

Because the structural supports ran straight down the middle of the building.

 

[vetteguy]

I saw this a while back, it was pretty interesting. I can't believe at one time (maybe still are) there was a group that wanted to sue the architects/engineers who designed the WTC for not making them resilient enough to an airplane hit. What was interesting about this show was that they DID design them to withstand a hit from the biggest commercial jetliner of the time. The problem was, this was 25+ years ago, and planes are larger today, so there's no way they could have known.

 

[thedan]

Ok, what about the burning temps?

 

[Linflas]

If I recall correctly from when this originally aired it was not so much the burning temperatures as it was the amount of area burning combined with secondary ignition sources (desks, papers, PC's etc) that eventually caused the collapse. When the planes hit the fire retardant was blown off of the supporting structures which also contributed to the ultimate collapse. They likened the jet fuel to the starter fluid you spray to light some charcoal. It rather quickly burns off but causes the other burnable material to ignite. The program was quite interesting and a good view for anyone interested in knowing more.

 

[Draco]

I believe the fires burned at around 1800 degrees. I believe steel starts to lose it's strength at 1500? In any case it was hot enough to bring it all down.

 

[ElFenix]

burning temp for jet fuel is pretty high... you can put out a match with it... but that high? other things must have started burning too.

 

[Mrburns2007]

1. No sprinklers
2. Double layers of sheetrock used but were blownoff from the exploding planes leaving the steel exposed.
3. the way the building was designed with the skeleton on the outside.

 

[dexvx]

Originally posted by: vetteguy
I saw this a while back, it was pretty interesting. I can't believe at one time (maybe still are) there was a group that wanted to sue the architects/engineers who designed the WTC for not making them resilient enough to an airplane hit. What was interesting about this show was that they DID design them to withstand a hit from the biggest commercial jetliner of the time. The problem was, this was 25+ years ago, and planes are larger today, so there's no way they could have known.

Umm.. the Boein 747 was intro'ed in the 70s. It is still the biggest passenger liner to date. The planes that crashed into them were smaller, 757/767 class jets. In any event, they survived the initial crash as expected.

 

[yakko]

Originally posted by: thedan
Also, why did it collapse *straight* down.

That is because it was designed to fall straight down in the event it ever came to that. Could you imagine how much more damage would have been done if the fell on their side?

 

[notfred]

Originally posted by: dexvx

Originally posted by: vetteguy
I saw this a while back, it was pretty interesting. I can't believe at one time (maybe still are) there was a group that wanted to sue the architects/engineers who designed the WTC for not making them resilient enough to an airplane hit. What was interesting about this show was that they DID design them to withstand a hit from the biggest commercial jetliner of the time. The problem was, this was 25+ years ago, and planes are larger today, so there's no way they could have known.

Umm.. the Boein 747 was intro'ed in the 70s. It is still the biggest passenger liner to date. The planes that crashed into them were smaller, 757/767 class jets. In any event, they survived the initial crash as expected.

It first flew in '69, and the first orders for it were placed in '66.