3 ms·

A building is intrinsically stable. [...] if the building displaces itself one centimeter to the left, the forces in the building pull it back. No part of it is

A building is intrinsically stable. [...] if the building displaces itself one centimeter to the left, the forces in the building pull it back. No part of it is intrinsically unstable. http://query.nytimes.com/gst/abstract.html?res=9A03EFDA1F3BE633A25757C0A9679C946596D6CF http://query.nytimes.com/gst/abstract.html?res=9A03EFDA1F3BE... January 4, 1914, Sunday [...] Several of New York City's skyscrapers are away out of plumb and have a tendency to emulate the famous leaning tower of Pisa according to the engineering department of the Building Bureau.

jerf 18y ago
The "out-of-plumb" is their set-point then. No law of nature says buildings have to be straight up. If what I described didn't happen, they'd fall over, so therefore it must happen.
- jerf 18y ago
  To whomever thought they needed to downmod that, I recommend a study (or review) of elementary static Newtonian physics. I'm hardly making stuff up, this is Physics 101. My comment was deliberately drawn in parallel to the discussion of normal force that everyone should get when they first forget to include normal force in their force diagram, but remember gravity; if that was true, the object would fall through the table (or whatever surface), therefore clearly there is a normal force. If the forces on a building didn't stabilize it, it would therefore fall over. It sounds simple when you say it, but it's not so simple the first ten times you hand in your force diagram and get a big red mark on it, until you learn. (Looking at the downmod pattern, though, there's someone who isn't liking the idea that regulation may not be perfect, and expressing that with downmods. Interestingly, my real point is that it can't be perfect for mathematical reasons, which is actually a completely different argument from whether or not it can improve things. But you do need to set out from a policy perspective with the goal of improving, not perfecting, because plans based on perfecting things always cause more trouble when they go wrong. The plan has no slack left over.)
likpok 18y ago
But they are in fact stable. Just the equilibrium point isn't quite where the engineers intended.

jerf 18y ago

The "out-of-plumb" is their set-point then. No law of nature says buildings have to be straight up. If what I described didn't happen, they'd fall over, so therefore it must happen.

jerf 18y ago
To whomever thought they needed to downmod that, I recommend a study (or review) of elementary static Newtonian physics. I'm hardly making stuff up, this is Physics 101. My comment was deliberately drawn in parallel to the discussion of normal force that everyone should get when they first forget to include normal force in their force diagram, but remember gravity; if that was true, the object would fall through the table (or whatever surface), therefore clearly there is a normal force. If the forces on a building didn't stabilize it, it would therefore fall over. It sounds simple when you say it, but it's not so simple the first ten times you hand in your force diagram and get a big red mark on it, until you learn. (Looking at the downmod pattern, though, there's someone who isn't liking the idea that regulation may not be perfect, and expressing that with downmods. Interestingly, my real point is that it can't be perfect for mathematical reasons, which is actually a completely different argument from whether or not it can improve things. But you do need to set out from a policy perspective with the goal of improving, not perfecting, because plans based on perfecting things always cause more trouble when they go wrong. The plan has no slack left over.)

likpok 18y ago

But they are in fact stable. Just the equilibrium point isn't quite where the engineers intended.