Historical Building Collapses

[JAE]

Just wondering, in light of the NY collapse of the twin towers, if the WTC destruction was the largest physical "demolition" in history. I suppose there was a lot of big stuff bombed away in WWI and WWII, etc. But I can't think of anything as big as WTC.

Anybody?

 

[brad]

JAE,
Depending on your definition of 'largest', it either was definitively the largest, or quite likely the largest.
Since there is only a handful of taller structures than the WTC, by virtue of it being the only one that big to be demolished, it must be the largest. Therefore, a definitive 'yes' by that measurement.

If 'largest' is defined in terms of weight, I would guess that it is still the largest. After all, there aren't many structures in the world that can accomodate that many people; and the last opportunity for truly large-scale destruction was WWII, and there were even fewer structures of that size then. Of course, as soon as I make strong statement to this effect, I expect somebody will come along and prove me wrong.

One thing that I have thought about since the attacks--I wonder whether somebody is evaluating an approach similar to this as an efficient improvement to implosion of very tall structures. By no means am I intending to lighten the gravity of the situation; but as a naturally curious individual, it seems like structural engineers may be able to learn from the relative efficiency of this 'demolition'.

When I saw that coming down the first time, I initially presumed that the terrorists had somehow managed to wire it for an implosion, since it looked like a picture-perfect implosion of a building. How practical would local collapse, followed by dynamic crushing be? Or is this essentially what is already done?

As implosion is by no means my field, I'm curious if somebody else who knows more could comment on my line of thought.

Brad

 

[JAE]

Brad: I'm certainly not an implosion expert either. But what happened, I agree, was very "vertical". The fire made it a mess, though.

I think what happened was fairly simple and probably very similar to what demo experts use, understand, and expect.

 

[ludvik]

I am reading an excellent book right now called "Why Buildings Fall Down" by Mario Salvadori. It is written in a pop science format, and has an excellent explaination of how dozens of prominent building and bridge collapses came to be.

Just a side note to give you an idea of the mood in new york city... I book this book in of all places the Museum of Modern Art Design Store in downtown Manhattan a few days ago. Normally that place is filled exclusively with trendy and overpriced nick nacks for the home. Now, post-WTC, they have books on structural engineering.

Michael

 

[JAE]

Could it possibly be that we structural engineers will become famous like Hollywood stars?

Hope not.

 

[Qshake]

Watch out JAE, we could be the next Bruce Willis, Sly Stallone or even Arnold Schwartzenegger!

 

[JAE]

"I'll be back"

"Yippee Yi-ay Ki-ay, Cowboy"

"Yo, Adrian!"

 

[ludvik]

you're a rock star baby!

 

[Imagineer]

There were several dams bombed in WWII. They probably massed more than the WTC. MoF, the current "Bunker Buster" is a direct decendent of the "Dam Buster.

Imagineer

 

Implosion is a common term that doesn't necessarily describe the physics of the actual demo being done. Usually load bearing structure is weakened (honeycombed), followed by local collapse, as bradh states, and the weight of the superstructure finishes the job by means of its own weight. WTC is a textbook example.

 

[JOM]

Wasn't there a collapse of TV tower in the States this year (Nebraska?). It was staggeringly tall - would that rate as the tallest structural "demolition"? Cheers,
John.

 

[Hush]

For a single intentional demolition I would think Hiroshima or Nagasaki would have to take the cake.

 

[PSE]

You could take a look at:

The Johnstown PA flood of 1889 when the S. Fork Dam broke and the town and several upstream villages disappeared. 2200 casualties.

The Chicago Fire of 1871 burned some 2000 acres of the city, destroying some 18000 buildings, 100,000 homeless and some 200 million in property damage (1871 dollars!)

The Hamburg Firestorms in WWII ended with some 50,000 casualties and 22 square Kilometers of the city destroyed.

Personally, I think the largest is still in the works. The Yangtze 3 Gorges Dam is expected to displace some 1.9 million people from their homes/villages by creating a reservoir some 600 kilometers in length. Hope that sucker never breaks!

Regards

 

[HamishMcTavish]

As I understood it I thought that the WTC would have withstood the impact if it wasn't for the poor fire coverage of fire retardant on the beams. The beams softened in the fire and progressively collapsed under their own weight...

As with any design problem you can only design for what you can anticipate. Structural engineers may like to think that this is just something else to include in the design basis, however this will add to cost and may even be redundant if better security were implemented by the airlines.

Does anyone know if the design standards will change? No more things should be presumed to exist than are absolutely necessary - William of Occam

 

[Rjeffery]

Mr. McTavish,

You are correct, except for one detail I think. The bar joists supporting the light weight concrete floor were covered with the required amount of spray applied fire-resistant material (SRFM) The unfortunate thing was that the SRFM did not have the strength to resist the blast of the plane and subsequent explosion of the atomized jet fuel.

If another method of fire proofing the joists was used, perhaps the buildings would be still standing. Or maybe not.

I can't fly so I am glad I wasn't on the top floors of the WTC. I can swim but I am still glad I don't live down stream from the Yangtze 3 Gorges Dam.

 

[unclesyd]

There are couple of good post concerning the WTC disaster on Eng-tips.

A very good site for information is:

http://www.engr.psu.edu/ae/wtc/wtctragedy.html

I understand that the Three Gorges Dam already has some unexplained cracking.

There is a big difference in the "dam buster" and the penetrating bomb. Though the idea of a penetrating bomb came from the same designer (Wallace). "The bunker buster" was developed at Eglin Air Force base in Florida. It was different design from the WWII penetrating bombs.
If I remember right it only took weeks from conception to testing for the "bunker buster".