Construction Materials

Seismic Isolation structure protect lives and property from earthquakes

Nowadays, "seismic isolation structure" is regarded as a technology to prevent damage or collapse of buildings from earthquake. Seismic isolation bearing can prevent damage to buildings, it is also effective to ensure the safety inside the building.

Seismic Isolation structure (bearing) is a technology to protect lives and assets. In Japan, it's used for many buildings, such as apartment, hospital, city hall, office, factory and warehouse etc. Its effectiveness had been proven in Kobe earthquake, Niigata Chuetsu earthquake, Fukuoka West Offshore earthquake and recent Tohoku Pacific earthquake. What is about "seismic isolation structure", the structure of seismic-isolated building, mechanism, effect and mechanism of seismic isolation bearing will be explained in this contents.

Movement of seismic isolation bearing during performance test
assuming at large earthquake.


Dec.20, 2013
newUpdated Movies (Video Brochures) page.

Point - The difference of seismic isolation, seismic vibration control and seismic resistant structures.

When the large earthquake energy is transmitted to buildings, the buildings may suffer from damage or collapse. How to deal with earthquakes, methods of construction or structure has been devised and measured by earthquake prone country, Japan. The buildings have 3 types of structure, seismic isolation, seismic vibration control and seismic resistant structures.
Illustration below describes the differences of each other.

Seismic isolation structure - The Structure which is mounted on seismic isolation bearing  installed between the building and foundation, softly responding to seismic force and reducing the earthquake input to the building. Seismic vibration control structure - The structure which is installed with vibration control devices(damper etc.) in the building to absorb earthquake energy for reducing the damage on building. Seismic resistant structure - The structure that resists earthquake by strength and tenacity of main structural members such as columns ,beams, bracing and shear wall.

Performance of Seismic Isolation Bearing

Seismic isolated building is mounted on seismic isolation bearings. While supporting the weight of building ,seismic isolation bearings can perform large horizontal movement to protect the building from earthquake.

In this video,
- Structure of seismic isolation building
- Structure of seismic isolation bearing which is supporting the weight of building
- You can see the deformation of seismic isolation bearing during an earthquake by animation.

Click to Play

(1 minutes 15 seconds)

Difference of shaking in seismic isolation, seismic vibration control and seismic resistant.

This video introduce an example of assumed seismic response results after earthquakes for indoor or structural members(column/ beam / wall etc.) by using actual structural design and ground motion [which is a very rare earthquake (occurs at once in hundred of years) notification waves; Kobe phase] to perform the earthquake simulation of seismic isolation, seismic vibration control and seismic resistant structures.

Simulation results vary depending on building/ ground motion. Let's perform the earthquake simulation for reinforced concrete structure 14F apartment* with following outline of design.

  1. Seismic resistant building
    Grade1 (Resistant grade commonly for apartment)
  2. Seismic vibration control building
    Dampers (low yield steel) is given in Y direction, compare to seismic resistant structure, vibration control effect reduces about 20% or more by amount of dampers with sufficient balance arrangement when the maximum of inter-story deformation.
  3. Seismic isolation building
    Effective period for maximum response displacement is about 4s

* X direction: Shear wall Y direction: rigid frame

Click to Play

(2 minutes 10 seconds)

The difference of indoor conditions

During massive earthquake, indoor furniture is likely to fall apart from damages to the building.

In case of seismic isolation structure, due to the effectiveness of seismic isolators the building will be shaken gently that prevent furniture fall down and ensure the safety.

This video is taken based on the shaking table test with full scale house model on actual seismic waves. The effectiveness of seismic isolation structure can be observed when comparing the indoor condition between seismic isolation structure and non-seismic isolation structure.

Video source: Ichijo Komuten

Click to Play

(1 minutes 44 seconds)

Fall scene of the furniture is included in this video.

Maintenance of seismic isolation structure

In order to ensure that seismic isolation structure exhibits the required seismic isolation function and maintain the safety of building in future, inspection and verification by the owner and building administrator are needed. (Refer to Article 8 and 12 of Building Standard Law)

Inspection and verification shall be carried out including the surrounding of building, seismic isolation pit, plumbing as well as the seismic isolation bearings.

In this video, as an example of actual seismic isolation structure, you can see the inspection works and description of inspection items conducted by professional inspector(seismic isolation structure inspection engineer)

* For more information about the inspection, please refer to "Maintenance standard of seismic isolated building ,2010" The Japan Society of Seismic Isolation.

"Maintenance of seismic isolation structure" Part I (6 minutes 44 seconds)
- Introduction
- Inspection at seismic isolation pit

"Maintenance of seismic isolation structure" Part II (3 minutes 31 seconds)
- Inspection for surrounding of building
- Notes of caution

Click to Play

Part I (6 minutes 44 seconds)

Click to Play

Part II (3 minutes 31 seconds)