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[Pandarsenic]

PS: Oh... and what about the building that is not crashed by a plane but falls exactly the same way as in a demoliton (the central beams go down first collapsing the entire building into itself)... I couldnt contain myself... 

Maybe the NSA accidentally flew one of their black helicopters into the tower?

[mainiac]

This was not caused by an airplane I dont know how many floors above... someone, dont know who, planted demolition explosives here.

Many of the other supports had collapsed, leaving this set carrying a much heavier load then they were ever intended to carry.  This load was a stress in the vertical direction, perpendicular to the perpendicular cross section of the beam.  However, any stress along the cross section of a column creates a sheer stress along the non perpendicular cross sections of the column.  Look at the column right behind the firefighter dead in the center.  You see the angle it split at?  That's the angle of maximum sheer for this particular material.  This is a textbook case.

Once that column went, the entire column system above it unbalanced.  The column in the foreground was subjected to thousands of tons of sheer stress in the vertical direction.  Judging for the cross section of the other column, these beams weren't intended to withstand even small amounts of vertical sheer stress.  No surprisingly, it snapped like a twig.  You can see the break wasn't as clean as the first column.  That's because it wasn't breaking along the plane of maximum sheer in this case, just tearing under an extreme sheer.


The angle at which the first column broke is completely what I'd expect.  I'd experienced that phenomena myself.  But don't take my word for it, you can test it yourself!

You yourself could produce an angle like that, just hold a long piece up chalk by the ends and pull it <---- apart ----> until it splits.  So long as you are careful to the direction of your forces along the axis of the chalk, you will see a sheer split at an angle, like in the picture.  Although you are using tension rather then compression, it's the same principle.  Might take a few tries.

Once you do that, try taking a piece of chalk and snapping it in two with a typical motion.  Unless your chalk fractures (something that's not an issue with these columns), it will split off at a nice 90 degree angle, like the second column did.

If those columns were taken down by explosives, both of them would have had a 90 degree, as they both would have gone under a horizontal sheer force, not a sheer force along the plane of maximum sheer.  Therefore, what this picture proves is that NO explosives were planted at this set of columns.

[mainiac]

Ok I admit I am not yet a Structural Engineer, im missing 3 years to graduate... (if everything goes well) But talking wih a proffesor(about this subject) I might have in the future he told it was very strange the way the beams were broken and how they were supposed to kind of bend and break in more randomized ways (Im not sure how to express it).

Okay, first of all, I'm really scared by the prospect of you wanting to be a structural engineer but not being able to spot a textbook example of the most likely way a column can fail.

But more importantly, I am pants crapping terrified by the thought that your professor is that incompetent.  Please, tell me what college you attend so I can know to stay far away from the work of your schools alumni.  Oh, and you should probably think about transferring.

[Alexhans]

Thanks for the explanation... Ill look into it...
I still havent studied steel structures...    Im used to Reinforced concrete buildings....
And i dont believe my professor was incompetent... probably i misunderstood him...
And youll probably stay away from the alumni anyway because it is not in your country..
and i should probably stop posting now...

[Torak]

I'm a bully for telling someone the truth, damn.

[Cheeetar]

I'm a bully for telling someone the truth, damn.

SHAME ON YOU, TORAK, SHAME ON YOU!

[Cthulhu]

I thought you were better than that, Torak.  Telling the truth when fiction is much more exciting...

Shame.

[Nilocy]

Acctually, it was the moon landing set they flew into the towers. 2 birds with one stone.

Seriously though, why do people insist on thinking the government is always out to get them? Its fairly darn rediculous. The governments are they to serve the people, not the other way around. The 9/11 attacks were caused by an extremist group who really hated American policies. Get over it, they did a bad thing, they're going to pay eventually.

[Dae]

You know, the only thing I meant is that everyone here has made up his mind on things people told him, and those people knew it because someone else told them etc. For every agent of the NSA testifying it isn't conspiracy there must be one who could testify it is.
Just don't be so fast rejecting a theory : in most cases, you know no better than the one defending it. Had you heard the conspiracist theories first, perhaps you'd defend them now instead of undermining them.

That's why I think looking for info by ourselves would be pretty interesting.

Also, I'm pretty sure there wasn't any explosive in the buildings (and mainiac's explaination reinforces this). No matter the reason why, I guess a plane stuck in a building would have great chances of destroying it. Even though it hadn't destroyed the WTC, I doubt it would've made a difference on the international scale.

EDIT : Ideally, Governements are here to serve. IRL, they're made of people, who just can't live without power and money and are so afraid of losing what they have that everything else gets less important. For example, the President here decided a few months ago that national TV channels wouldn't broadcast advertisement anymore (well, around prime-time to be more precise). Even though it meant erasing half of the incomes of those channels belonging to the country.
So he deliberately made the country lose quite comfortable incomes.
In the next two months, a private TV channel, belonging to the President best man at his marriage, had million euros more from advertisement : the companies, that couldn't sell their products on 3 out of 6 'basic' channels, turned towards the private companies...

Selfless politics are quite rare.

[Aqizzar]

You know, the only thing I meant is that everyone here has made up his mind on things people told him, and those people knew it because someone else told them etc. For every agent of the NSA testifying it isn't conspiracy there must be one who could testify it is.
Just don't be so fast rejecting a theory : in most cases, you know no better than the one defending it. Had you heard the conspiracist theories first, perhaps you'd defend them now instead of undermining them.

"Must"?  Absolutely not.  If any of this had a shred of reality behind it, don't you think there would have been by now even one leaker, compared to the literally thousands of people who have leaked (and a job like that would've involved hundreds of people in some way) who never mentioned anything of the kind?

All positions are not relatively worthwhile or sane.  There is a need to consider practical reality in an argument.

That's why I think looking for info by ourselves would be pretty interesting.

And so we come to the Lone Hero Complex at the heart of it all.  I can see it as clearly as you - you can picture yourself, running through the bowels of the Pentagon, gripping a big wad of files marked 'Super Top Secret Conspiracy Proof: Don't Show Anyone!', dodging bullets from the Men In Black hunting you down.

[mainiac]

For every 10,000 agents of the NSA testifying it isn't conspiracy there must be one who could lie with a straight face that there is.

Fixed

[chaoticag]

I had to stop watching the video at the 17:52 mark because they kept saying that a plane didn't crash into the pentagon, whereas a friend's relative (a journalist) who showed up at the highschool I was at to tell us about journalism was commuting to work when the plane crashed into the pentagon. He saw the plane crash into the pentagon. He got out his car, just like other people at the place and looked at the damage. He then rushed to work.

And to the people claiming that there was no evidence of a plane, I have to say that once it is loaded with explosives, it can become hard to find evidence of a plane. I doubt there was any evidence of a plane at the World Trade Center, such as a wing or tail etc.

[Jude]

I know the Bush administration was evil and horrible and despicable, but the stuff they actually did was bad enough without people making up more tinfoil-hattish reasons to hate them. Come on.

[Cajoes]

"Oh our housing market is in a slump, let's blow up two of our most important economic structures as well as our country's military HQ! That will get things rolling, ah-yuck!"

Yeah, I'll go with unfortunate but preventable terrorist attack rather than gross incompetence of that calibre.
Since neither side is willing to back down from this faux argument, I suggest the thread is locked.

How's that for conspiracy, oh Nimrod of Assyria?

[Aqizzar]

Sweet, I've been quote'd.

Makes me feel a little sorry that I might have stolen that particular turn of phrase from Yahtzee Croshaw.  Not that it is any less applicable.