A Kinder, more Professional Thread on the WTC

[trunks2k]

First - Both buildings had damage to the "outer skin" on impact.

Secondly, the outer skin is not the main support structure. The core is. It's the CORE.

You are correct in that the main core is the primary support structure. But the outer skin was also a key part of the support structure. Damage the outer skin, and you have SEVERELY weakend the over all stability of the building.

 

[applepowerpc]

Damage the outer skin, and the building does not implode on itself into its own footprint. Demolition experts specifically target the inner core only for this very reason.

 

[Yusuf Evans]

Conspiracy theorists I bet you guys also believe that aliens landed in Roswell as well, yeah?

 

[applepowerpc]

Um, no. Do you believe in the conspiracy theory that 18 Arabs simultaneously hijacked 4 airliners on the same morning and rammed them into buildings?

 

[Glaz]

You guys are wasting your time arguing this stuff.

 

[Arkanin]

Prophetable,

I won't lie to you; I don't have a degree in structural engineering. But it looks like the people who do have that training mostly agree that the building's collapse after those stresses is not a big surprise.

 

[applepowerpc]

re: soupy I disagree. Whether or not the government was complicit in 9/11 changes EVERYTHING.

 

[arnegrim]

Let's go over some points again:

Both buildings were designed for plane impacts.

Not these planes... loaded to the gills with fuel.

The Fires could not have significantly weakened the Steel Supports.

The fires could not have reached 800 degrees?!?

The Core Steel Supports would not collapse unless they were weakened, even if the rest of the building collapsed around them.

The fires could not have reached 800 degrees?!?

Any damage done to the supports by the initial crash would have been minor, when one considers the amount of supports in both the Core and the outer supports.

No. Again... you need to research the construction and design method of the towers.

The load from any of these damaged supports would have been transferred to the remaining supports, of which there were plenty (If any supports were damaged by the impact in anyway!)

The outer skin was highly damaged! More so in the second tower hit which is why it collapsed first.

The structural integrity of the World Trade Center depends on the closely spaced columns around the perimeter. Lightweight steel trusses span between the central elevator core and the perimeter columns on each floor. These trusses support the concrete slab of each floor and tie the perimeter columns to the core, preventing the columns from buckling outwards.

http://www.civil.usyd.edu.au/wtc.shtml

 

[applepowerpc]

The fires could not have reached 800 degrees?!?

Not 800 degrees, 2000 degrees. And I might point out that there were people jumping out of the WTC. If the 2000 degree fires were weakening the outer structure, how were the people able to make it to the windows? They'd be already dead.

 

[arnegrim]

No... my point is that at 800 degrees, the steel would lose roughly half its load bearing capacity and rigidity.

As to people jumping... most were from the floors above the impact.

 

[Yusuf Evans]

Um, no. Do you believe in the conspiracy theory that 18 Arabs simultaneously hijacked 4 airliners on the same morning and rammed them into buildings?

Actually, that's a fact. Why? Well, let's see here. I have a few Marine buddies who were stationed at the Pentagon the day of the attacks, and I also watched the airplanes fly into the WTC towers that morning on TV. Those are facts. What you guys are believing is a theory that cannot be proven, period.

 

[Glaz]

re: soupy I disagree. Whether or not the government was complicit in 9/11 changes EVERYTHING.

except we've argued this 5900946380 gazillion times on CF and no one is changing their minds.

 

[applepowerpc]

Most? If it's truly even an 800 degree fire they would have to be ALL somewhere else.

 

[Arkanin]

With respect, can everyone stop playing junior structural engineer here? I mean, it seems that most of the professionals in SE agree that the buildings' collapse is very mathematically reasonable, and from what I have seen, the force is a more significant factor than fire. It is the synergy of the two that took her down, though, but still. The floor / ceiling plates failure was also as much or more of a significant factor than the steel structural supports.

In conclusion, I don't have a degree in this, but it might be smart to read the math behind the building from someone who actually does.

 

[applepowerpc]

I took 3000-level classes in it. If that makes me junior-level, so be it.

 

[Arkanin]

I took 3000-level classes in it. If that makes me junior-level, so be it.

Well then by all means go ahead and tell us what you think because you have more qualifications than I do. Have you seen the link I posted a couple pages ago? Structural engineer of 17 years explaining the mathematics behind why he thinks it collapsed. I would look forward to hearing your thoughts.

 

[arnegrim]

Most? If it's truly even an 800 degree fire they would have to be ALL somewhere else.

Is there any indication they weren't?

 

[Marek]

Well then by all means go ahead and tell us what you think because you have more qualifications than I do. Have you seen the link I posted a couple pages ago? Structural engineer of 17 years explaining the mathematics behind why he thinks it collapsed. I would look forward to hearing your thoughts.

He also might want to look at these:

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html

http://www.tam.uiuc.edu/news/200109wtc/

http://www.civil.usyd.edu.au/wtc.shtml

http://web.mit.edu/civenv/wtc/

All of these were written by experts and all the articles are from scholarly sources. It's too bad that the conspiracy theorist cannot provide anything of the sort beyond the questionable Professor Jones from BYU.

 

[Alarum]

Despite the fact that any person with a microwave and some cheese can quickly verify the statement that solids loose structural integrity at certain temperatures, people seem to be insisting that steel is 100% fine, up until it melts.

Hey, don't trust me! Stick some cheese in the microwave, get it warm. Then try to break it. Pretty easy? Not as easy if its cold, not at all as easy. And yet it is still, clearly, solid.

Now steel isn't cheese. But the principle is similar. It gets weaker at higher temperatures. For those claiming they've researched it, and it needs to hit 2000 degrees before any effect happens... lousy research.

 

[applepowerpc]

You just demonstrated precisely why it is impossible for the building to implode at near free-fall velocity due to weakening steel rods.