July 19th, 2011
07:51 AM ET

Scientist: Tae Bo workout sent skyscraper shaking

Seventeen people performing a vigorous Tae Bo workout caused tremors that forced the evacuation of a South Korean skyscraper earlier this month, the building's owners say.

Prime Group, owner of the 39-story TechnoMart commercial-residential high-rise in Seoul, said 17 middle-aged people were working out to the pop song "The Power" by Snap on July 5 when their movements set the upper floors of the tower shaking for 10 minutes, according to a report from the Korea JoongAng Daily.

Scientists recreated the event in the 12th floor gym, according to a report in the Korea Times.

“We observed the vibrometer while performing the same kind of aerobic exercise that was performed at the time of the shaking which occurred on July 5. We noticed that the shaking was felt in the upper floors while the exercise was being performed while no other place showed signs of tremor,” Chung Lan, a professor of architectural engineering at Dankook University, told the Korea Times.

“It just happens to be that the vibration cycle caused by Tae Bo collided with the vertical vibration cycle unique to the building,” Chung told the Korea Times. The action amplified the building's vibration and caused the shaking, he said.

Chung was one of six professors from the Architectural Institute of Korea who inspected the building and recreated the Tae Bo exercise.

Tae Bo is a mixture of boxing and tae kwon do.

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Filed under: South Korea • World
soundoff (322 Responses)
  1. Battleborn

    “It just happens to be that the vibration cycle caused by Tae Bo collided with the vertical vibration cycle unique to the building,”

    Lost in translation? Surely the cycles 'coincided' rather than 'collided'.

    July 19, 2011 at 3:15 pm | Report abuse |
    • kauppily

      Collided is correct. Colliding waves creates havoc.

      July 19, 2011 at 3:34 pm | Report abuse |
    • Logic

      Nope, just lost in your interpretation... "Collided" makes a great deal more sense when you consider a vertical wave or force vector encountering a horizontal wave or force vector roughly perpendicular to it would result in a net wave or force vector somewhere in between the two planes. The resultant vectors likely created the "shaking" of the building.

      July 19, 2011 at 3:45 pm | Report abuse |
    • rsc

      Well, actually, sound (or vibration) waves, when at certain frequencies amplify when they are in phase with each other. This is called constructive interference. COLLIDING, would be the two that are not in phase with each other, and in turn will cause DESTRUCTIVE INTERFERENCE. Which doesn't cause chaos...it actually reduces the amplitude of the two waves. Now, yes there would be some residual vibration from this combination, but not as much as the combining of the two. Also, these towers are build in areas closer to earthquakes and this type of construction is taken very seriously, so I doubt anything is poor construction.

      Research propagation and constructive/destructive interference.

      July 19, 2011 at 3:51 pm | Report abuse |
    • Keith

      Nope to Logic and kauppily. it should in fact be coincided, as-in the frequency of the vibration from the exercise coincided with the natural frequency of the building. It does appear to be something lost in translation.

      July 19, 2011 at 3:52 pm | Report abuse |
    • Laura

      Waves collide but frequencies coincide.

      Of course, I would be happy if everyone would just learn the difference between "your" and "you're".

      July 19, 2011 at 4:12 pm | Report abuse |
    • ck


      July 19, 2011 at 4:16 pm | Report abuse |

    OK here is a very easy analogy, we"ve pretty much all heard of a wine glass shattering when in close proximity of a certain auidible frequency, right? This is the same exact phenomenon, only this time the resultant outcome is not of a magnitude sufficient to cause structural degradation. HAVE A GREAT DAY!

    July 19, 2011 at 3:22 pm | Report abuse |
  3. Matt

    You know what I just thought of? The time where uncle Phil was dancing with baby Nicky and Will came running down the stairs screaming: EARTHQUAKE!!!!

    July 19, 2011 at 3:27 pm | Report abuse |
  4. ToughBreak

    I call BS..!!.... THERE IS no way 17 middle-aged people, of any nationality, could do ANYTHING in unison. Unless of course, the TechnoMart commercial-residential high-rise in Seoul.. is built of straw...... 1...2...3...4...SHOUT OUT..!!..5..6..... kung-foo-you-too... 7...8... SHOUT

    July 19, 2011 at 3:30 pm | Report abuse |
    • iamthefredman

      I posted earlier about this. It is impossible (except in a Bruce Willis or Will Smith movie) that 17 people can jump around on the 12th floor of a 39 story tower and shake the entire building to such an extent that the people were so afraid they evacuated the building. Poor construction &/or flawed design similar to the infamous mistake at the Citigroup Center building in NYC (where I used to work as property manager). Check out "citigroup center repairs" on Google. How would this building hold up in an earthquake? Not at all.

      July 19, 2011 at 3:42 pm | Report abuse |
    • RandomOne

      Wow. Snap wasn't kidding when they say in their song "It's getting kinda hectic."

      July 19, 2011 at 3:55 pm | Report abuse |
    • Greg0311

      No. Just no. The same process that caused the upper portions of that building to tremble is the same thing that caused the original Tacoma Narrows Bridge to collapse in like 20mph winds. You wouldn't think 20mph winds would do what they did, but they did. Google it, you'll see.

      July 19, 2011 at 3:57 pm | Report abuse |
    • J

      first of all, the citigroup building was not a mass-damping issue, it was a torsional resistance due to extreme (hurricaine) wind loads.

      Second, most, if not all, high-rise buildings have tuned-mass dampers in them to account for periodic earthquake motion. The tae bo likely hit a different frequency that resonated either within the floor joists and secondary structural members, which then translated to the primary, and was felt as vibration, or, it hit a harmonic frequency which could also cause this. It is not at all far-fetched, nor is it shoddy construction. Its a fact of resonance.

      Search for tacoma narrows bridge, tesla resonance, tuned mass damper, or building resonance. Any of these, and all of them combined should give you a crash course in structural engineering principles realated to this topic.

      July 19, 2011 at 3:57 pm | Report abuse |
    • MythBusterFan

      The Myth Busters shook an entire highway bridge with about 10 pounds of weights vibrating to match the harmonic frequency of the bridge. They had the entire span shaking within a matter of minutes. Over the years, there have been balcony and floor collapses associated with harmonic response when groups of people were dancing, or moving as a group.

      You might be surprised to see how little weight would be required to collapse a building or stadium with the right frequency of movement.

      July 19, 2011 at 3:58 pm | Report abuse |
    • J

      Exactly – we call this toungue-in-cheekily "soccer hooligan loading".

      July 19, 2011 at 4:01 pm | Report abuse |
    • jasi

      you obviously haven't seen koreans dance..
      you're missing out.

      July 19, 2011 at 4:14 pm | Report abuse |
  5. Wow

    Tae Bo shooked the building. What would an earthquake do? Are these buildings made out of plastic.?

    July 19, 2011 at 3:31 pm | Report abuse |
    • Dave

      Plastic would have had more of a dampening effect and would have been less likely to shake. Every struture has a certain frequency at which is resonates. If it is constatly shaken at that same frequency then the movement of the structure will continue to amplify.

      July 19, 2011 at 3:45 pm | Report abuse |
  6. prads

    Well thats what you get if you buy anything thats "MADE IN CHINA""

    July 19, 2011 at 3:42 pm | Report abuse |
  7. OldDotte

    A human Tesla Earthquake Machine?

    July 19, 2011 at 3:45 pm | Report abuse |
  8. Boommer210

    Chuck Norris could do it by just closing a door

    July 19, 2011 at 3:51 pm | Report abuse |
    • phoenix05

      Yea, well David Caridine could do it with a thought from his grave.

      July 19, 2011 at 4:10 pm | Report abuse |
  9. intheruins

    No more. Tae-bo. For you.

    July 19, 2011 at 3:55 pm | Report abuse |
  10. 858faith

    SUMO Tae Bo.

    July 19, 2011 at 3:57 pm | Report abuse |
  11. Aldo1968

    Marching bands on parade stop marching when going over a bridge for fear that the vibration of marching in unison will cause the bridge to sway/collapse. The same thing is going on here.....
    I've seen a 4 x 4 post snap from the repeated hammering while building a deck.
    Never underestimate the power of a single repeated vibration. This is very possible

    July 19, 2011 at 3:59 pm | Report abuse |
    • J

      I can vouch for this from personal experience. While the bridge didn't collapse, we definitely caused a standing wave in the deck. It could easily be felt when our marching band in high school marched accross the bridge.

      July 19, 2011 at 4:03 pm | Report abuse |
  12. www.twitter.com/hlmelsaid

    Shacking researches.

    July 19, 2011 at 4:00 pm | Report abuse |
  13. andy

    I still say that was too many people having breakfast burritos early morning... which by mid-morning made their way down the digestive systems and BANG!!!..... invisible mushroom clouds traveling within the building looking for exit path....resulting in the shaking of the building....

    July 19, 2011 at 4:01 pm | Report abuse |
  14. IronCelt

    Remember the Kansas City hotel balcony collapse in the early eighties? It happened during a dance. Lots of people died.

    July 19, 2011 at 4:07 pm | Report abuse |
  15. phoenix05

    Rice paper walls just don't cut it.

    July 19, 2011 at 4:11 pm | Report abuse |
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