An Active Seismic Device with a Dynamic Center of Gravity

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An Active Seismic Device with a Dynamic Center of Gravity

  1. 1. Summary

Most seismic device technologies are passive. This technique is an active seismic device technology with a dynamic center of gravity. It is affected by gravity that installed fixed structures on the surface of the earth. Thus, the structure is fixed at the bottom of the center of gravity. When an earthquake occurs, the seismic waves show motion in up, down, left, and right directions. The types of surface waves are shown in the figure as below.



S(Secondary Wave)



L(Long Wave)



R((Rayleigh wave)

In the seismic wave, the S wave (secondary wave) propagates in transverse waves and moves up and down. Long waves propagate in transverse waves and move horizontally. The R wave (Rayleigh wave) has a large amplitude such as L wave. The action is most damaging because it emits energy in the reverse oval shape at the end.

A damage of Earthquake is caused by surface waves, and damages are generated from left to right motion in a unit structure. From the viewpoint of the structure, Newton’s motion law is applied.

When we look at the point of action of the structure, kinetic energy is concentrated on the opposite side in the direction of the earthquake movement. Thus, it is exceeded into the vertical load limit of the support the structure which will fall or break.

This apparatus is a device for solving such a problem. This device constitutes the center of gravity of the object as a floating structure.

Therefore, the vertical structure has an equilibrium balance when an earthquake occurs, so it has a function as an excellent earthquake protection facility.


  1. 2. Configuration of the device

This apparatus is composed it of which is a vibration damping device, a vibration damping device, and a vibration isolation device.

This device is determined by selecting each device according to the earthquake intensity of the user. Therefore, seismic protection devices can be installed at reasonable cost.

1) Seismic Devices – This device reduces a power of seismic waves with high-strength PC structures and laminated rubber plates. (figurel , figure )

2) Vibration damping device – This device is a device that distributes attenuated seismic waves and shows the dynamic center of gravity using the force of the seismic waves itself, and is a device for maintaining the balance of the support. (figure )

3) Vibration isolator: This is a device that separates the attenuated seismic waves from the ground and construct seismic equipments by using the drag force. (figure )

  1. 3. Uses of the device

1) Electrical equipment: Substation equipment using high voltage, gas circuit breaker,  transformer

2) Gas facilities: LNG static pressure chamber, LNG storage tank

3) Bridge equipment: Bridge support structure

4) Railway facilities: railway lines, curved railway tracks, soft ground railway tracks

5) Structural support consisting of pilotti

This device is a seismic device with dynamic center of gravity. If installed in a soft ground, it is effective as an earthquake proofing device.

  1. 4. Effect

1) It is economical because it will not be discontinued when the equipment is used for repair or replacement in existing facilities

2) It is easy to expand the protection facility of earthquake when it build up for new facilities of earthquake protection.

3) The construction time is short and construction is simple.

4) This device has a great effect of earthquake protection in soft ground.

5) This equipment is easy to recover earthquake damage after preservation of infrastructure equipment after earthquake disaster .

6) In terms of cost, it is economically feasible to compare the cost of earthquake protection equipment with the cost of secondary social damage caused by damage equipment in case of earthquake disaster.


Credit to : CR Corporation Ltd.



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