skyscrapers (so I am told) use a quite ingenious device to keep themselves from toppling over in high winds and what have you. In the roof is a large block of metal on computer-controlled casters. depending on the sway of the building, the block is moved in a direction which keeps the center of gravity steady.
Now my question is this. If I were a terrorist who wanted to knock a building down, could I just send the block in the opposite direction? That is, are these just steadying devices (maybe because the mass of the block is not so great), or could they be used to play World Trade Dominos?
I thought that was just the Citicorp center (on 3 legs above a church) that had that.
The other thing I thought was that the idea behind it was to keep the building from swaying so much that the people inside it got sick, not to stop it from falling over.
It wouldn’t make sense to count on that to keep the building from falling over.
None of this is fact however, so I could be wrong.
I don’t think that they use computers to move the counterweights. Most of the buildings I’ve seen these in suspend the weights on springs (big ones. These weights are usually around 20-40 tons), so they naturally swing opposite to the building’s motion, and cancel out much of the sway. The setup is actually quite simple, and works more on basic physics than programming. Any attempt to make an economy-sized domino line will require more than just hacking the buildings’ computer systems.
In addition to storm protection, many skyscrapers in Japan use them as safeguards against earthquake damage.
Well, if you want to just destroy the skyscrayper, your best course of action may be using explosives to destroy the main support of the building. If you want to use this weight to destroy the building, I suggest dislodging the weight (with explosives), causing it to hopefully fall through the middle of the building. I don’t think the actualy counterbalance mechanism is strong enough to topple the building.
Except very few skyscrapers surviving today have a “main support.” They are all extremely redundant, and would require blowing up lots and lots of stuff to knock over. Witness the WTC. Bigass explosion, no dominos.
The secret (looking over my shoulder) is filling the thirteenth floor with pudding of a viscosity of a density of SAE (I can’t tell you the number, of course)paragraph 3a.
Of course, for a really creative way of toppling buildings, we have to go back to the godfather of mad scientists: Tesla. According to Margaret Cheney’s * Tesla: Man out of Time* (which is a little too fawningly uncritical for my taste) Tesla built a palm-sized device that delivered a steady series of light taps at a certain frequency. By tapping at a material’s resonant frequency, his device would cause any structure to fall to pieces within a matter of minutes.
p. 116:
“He put the little vibrator in his pocket and went out to hunt a half-built steel building… He clamped the vibrator to one of the beams.”
“[Tesla’s quote] In a few minutes… the trembling increased in intensity and extended throughout the whole great mass of steel. Finally the structure began to creak and weave… Before anything serious happened, I took of the vibrator, put it in my pocket, and walked away. With the same vibrator, I could drop the Brooklyn Bridge in less than an hour.”
Needless to say, I’m skeptical. Still, if you’re serious about your project mayhem, you may want to look into this. It leaves much less evidence than a truckload of fertilizer.
The Tacoma-Narrows bridge in Washington (state) went down for a similar reason. The wind was gusting at a frequency that reacted with the natural frequency of the bridge so that waves surged through the structure and eventually destroyed it. The wind wasn’t even gusting that hard (around 30 mph, I believe).
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Although Tacoma-Narrows is often given as a textbook example of resonance, what actually happened must have been more complicated than that. The bridge was known to oscillate for days or weeks at a time (its nickname was “galloping gertie”) but the wind simply doesn’t gust at a fixed frequency for long periods.
I don’t think the collapse has ever been properly explained, although there’s a wealth of analysis and opinion on the web. The most likely theory seems to be a kind of positive feedback where the bridge would catch the wind, tilt and then spill it, and this process allowed oscillations to build up with a strong steady wind.
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People who bring skyscrapers down for a living spend a long time drilling LOTS of little holes in walls and filling them with det-cord, identifying major supports and packing charges around them, fiddling about with delay fuses to make some parts go before others, and generally use a whole load of planning and experience to get the job done. If you can find a way to do it with big weights or resonant frequency drivers, you’re going to be rich! You might want to treat mail from ex-demolition guys a bit carefully though.
Of course, we must remember that they are doing this carefully, safely, and legally. It’s likely to be much easier to bring a building down uncarefully, unsafely, and illegally.