New quake damping pendulums for skyscraper buildings

Japanese engineers are using innovative technology consisting of quake damping pendulums on tall buildings to counter shaking due to temblors in skyscrapers.
The anti-quake technology is based on the idea that heavy pendulums counter the ground moving action caused by an earthquake.
When an earthquake - with long-period seismic motion - begins, it pushes the base of a tall building in the direction of the seismic activity - the top of the building is left motionless for a moment, which soon catches up, but by then, the bottom has moved back in the opposite direction.
Such motions can cause tall buildings to sway violently resulting in damage or even destruction of the building, Phys.Org reported.

In order to counter such motion in newly built skyscrapers, pendulums are installed on the upper floors.
They work by automatically swaying counter to the motion created by the earthquake. The result is a reduction in swaying and hopefully, damage to the building and harm to its occupants.

Two Japanese companies, Mitsui Fudosan and Kajima Corporation, plan to install quake damping pendulums atop the Shinjuku Mitsui Building in downtown Tokyo by 2015.
The building was built before new quake dampening technology was developed for skyscrapers.
Many of Tokyo's skyscrapers were built long before the new pendulum technology was developed, leaving them at risk when the next quake strikes, the report said.

Engineers, in this new effort, have devised a means for adding pendulums to the tops of existing skyscrapers.
The 55 story Shinjuku Mitsui Building - which was observed to sway approximately two meters during the 2009 Great East Japan Earthquake - will be outfitted with six such pendulums, each hung inside its own frame and weighing 300 tonnes.