Tokyo's innovative solution to keep old skyscrapers from toppling during earthquakes

Six 300-ton pendulums could help stabilize old skyscrapers during powerful earthquakes.
Written by Tyler Falk, Contributor
名倉 百合子
The videos of swaying skyscrapers in Tokyo during the powerful earthquake in 2011 that hit off the coast of Japan are absolutely terrifying. Thanks to strict building codes and the location of the earthquake's epicenter, the skyscrapers were spared. 

But if Tokyo were to take a direct hit from a high-magnitude earthquake, the scene could be much worse.

There are many older skyscrapers that don't have earthquake-resistant technology that's required to be built into new skyscrapers.

That's where the innovation comes in. Real estate developer Mitsui Fudosan and Kajima Corp., a construction and engineering company, are teaming up to install six 300-ton steel pendulums, known as "tuned mass dampers," on the roof of the Shinjuku Mitsui building, a 55-story skyscraper built in 1974, instead of tearing it down and building a new tower. The idea is that the massive pendulums will counteract the massive seismic waves during an earthquake and keep the building upright. As Next City reports, the technology is being used in new buildings but isn't common as a retrofit to older buildings. But it could be extremely effective at dampening the blow of a powerful earthquake with an epicenter near Tokyo, according to Next City:

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.
The mechanism won't be cheap, around $51 million. But it's certainly cheaper than rebuilding and definitely cheaper than the alternative when a devastating earthquake inevitably hits Tokyo. The pendulums will be added to the Shinjuku Mitsui in 2015, and possibly other older skyscrapers if everything goes well.

Photo: Flickr/shinnygogo and Kajima Corp.

This post was originally published on Smartplanet.com

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