Why do the twin towers collapse in similar modes despite different damage?

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Studiot
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I have received the following private message.

Questions should not be asked this way.
However it is a reasonable question so all may benefit from the answer.

A colleague friend ...security edit... makes the claim that regardless of how any of the buildings came down, simple physics should make one question how two completely different collisions, causing completely different damage, caused identical collapses. That the uniformity is "so unnatural, so contrary to everything you learn in physics," one has to question why the buildings didn't topple, instead falling directly into their respective foot prints. That it is untrue that this "lottery ticket chance" of an accident caused an unpredictable collapse, to collapse predictably.

He also claims that the problem of symmetry is never addressed...by anyone. ever.

I do not know much about the structure of the twin towers but observe that since they are likely to be of similar framed construction they will likely be subject to similar collapse modes.

Collapse modes are mostly determined by the structure, rather than the damage.

Any civil engineer should know this.

The following is all about a very famous 'stack of cards' UK collapse that many structures are at risk of.

http://www.google.co.uk/#hl=en&xhr=...i=&aql=&oq=ronan+po&pbx=1&fp=c5f282700dc45ac9
 
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I don't know, Stu, but you might want to steer clear of responding to that PM.
Sounds like a conspiracy theorists' take on the twin tower collapse.

The impacts/collapses have been studied and modeled ad-nauseum by professional engineers. Their findings agree with the majority public perception of aircraft strikes.

But forget all that in conversation with him.
Trust me, it is IMPOSSIBLE to reason with a conspiracy theorist.

I would just leave it alone and move on.
 
Yah I don't even exactly know what he's talking about, but those kinds of people are impossible to deal with.

I do like the idea that uniformity is 100% contrary to physics. Isn't the first thing all students learn in physics for the first couple of semesters is the fact that many many things act in uniform ways? Objects fall at uniform accelerations, simple harmonic oscillators will oscillate uniformly, etc etc.