Tuned mass dampers have a proven efficacy for reducing vibrations on bridges and even spacecraft, but buildings weren’t outfitted with them until relatively recently. According to a 2013 study by Masashi Yamamoto and Takayuki Sone in the journal Structural Control and Health Monitoring, dampers on a 24-story building in Tokyo were shown to reduce the energy of an earthquake by 35 to 65 percent.
Tokyo's innovative solution to keep old skyscrapers from toppling during earthquakes
— By Tyler Falk on December 20, 2013, 1:35 PM PST
Done that: http://en.wikipedia.org/wiki/Taipei_101
The pendulum only counters lateral movement. There is still the violent vertical - up and down movement in most quakes - not unlike lifting the building and dropping it - which crushes support columns and foundations - depending on the wave frequency. The added weight of the pendulum only compounds the vertical forces. Unfortunately devices like this creates a false sense of security, but probably better than nothing.
@dduggerbiocepts This is not that "new" it has been there for a while. I haven't gotten to see others but I've seen two in Japan.
I got to see the pendulum in the Landmark Tower (tallest building in Japan) as well as the dampers in the base of the building. The whole building sits on vertical as well as lateral dampers in the base of the building. They fold the pendulum. Massive pillars suspend other pillars and those suspend a set of pillars, etc. until finally the counter weight. I don't remember the layers, but it was quite a few. This was completed in the 1990's.
The Otemachi Urbannet Building was completed in 1990, and that whole building sits on dampers, but it is a short building and is rather squat and it has a huge atrium, thus making the whole building a tube. So movement won't bring the building down. The dampers take both veritcal and lateral movement. The facia are about 1 inch off of the ground and the whole building is allowed to move about 4 inches laterally and a bit less vertically. Also for rolling earthquakes, the building dampers are independent so if one side goes higher than the other, it will sustain it. I've been through a number of earthquakes in this building, and the odd part is that even after the earthquake has ended, the building is still moving. I takes about a minute to settle down depending upon the magnitude of the earthquake.
In other words, the pendulum is to handle lateral movement, and tall towers are always (yes, all of the time, 24/7) swaying. But for a while now, at least two decades, buildings are supported on vertical dampers, but they can only be seen while the building is being built. The pendulums take up above ground floors so they are quite visible (walls hide them, but you can tell where they are) but for the base dampers, since they are underground, cannot be seen. Rolling movement is also taken care of by the independent dampers. The main thing is that the veritcal movement has already been thought of and taken care of. Of course there are limitations on how much movement and duration, like if a 5 minute 9.0 struck directly underneath your building, and have violent movement, it would be dust.
When we were desgining our house in Tokyo, we went to many contractors and one had a large platform, to test houses resistance to earthquakes, and somehow they've recorded the movements of several earthquakes and on the small platform, you can exerience many earthquakes that have occurred around the world. Some are extremely violent, and some earthquakes were tilting on one side, those are the rolling earthquakes. On the three that I tried, I could not remain standing. I think they got the P and S wave sensors around the world to get the 3D movments. In otherwords, three directions of movement is known and accounted for.
The author either doesn't know about the dampers or didn't mention them. Pendulums are mainly to help minimize the normal everyday swaying and secondarily for earthquake movement minimization.
No false sense of security, and these buildings are real. So retrofitting old buildings would be hard, but you can still handle vertical movement by allowing 3 axis pendulum mounts.
Yes, but depending on the nature of local seismic plates, this type of mechanism might be better than you think. Generally speaking, the types of earthquakes in a region are fairly similar for the locally generated quakes. Now quakes generated further away can of course different types, but since they are located further away the degree of the forces are dampened.
I imagine theoretically you could have some kind of huge gyroscope sitting up top to force a stabilization, but that is not exactly realistic cost wise especially when energy usage is taken into account.
@richard233 @dduggerbiocepts The gyroscope idea is novel. However, it would need to be in the middle of a builing or on the bottom floors. Thus, you would be losing valuable floor. A giant gyroscope would dampen movement, so if you put one on top, the base of the building would move but the top would remain in one place. The building will fall apart. Try it with Jenga, hold the top steady but move the bottom. The best thing is to strengthen the structure so that the whole building will move.
Prior to the Great Hanshin earthquake a shopping arcade had strengthened their building, the complained about having to pay for it, even though most things fell of their shelves, the building was fine. They were really glad then.
Japan does have earthquakes it with vertical motion because it sits on the edge of the Asian plate and the Pacific plate is a subduction zone. But that is how Japan formed, so if that were elsewhere, Japan would not exist. One day Hawai`i will go under Japan. I used to joke about that, when I first moved to Japan until the time I left 21 years later, Hawai`i (my birthplace) has moved over 10 meters closer to Japan, but the airfares did not go down.