This section provides an easy-to-understand explanation of the features and differences of the three typical technologies used to protect buildings against earthquakes: seismic resistance, vibration control, and base isolation. The structural performance of buildings is classified into three categories: protection of human life, prevention of damage, and maintenance of functions. Protection of human life is the minimum performance required to prevent a building from collapsing or collapsing and to prevent harm to the surrounding area. Damage prevention is the ability to prevent the loss of property value of a building due to an earthquake or to restore value by facilitating repair. It also includes the protection of the cultural value of the valuable building itself, which cannot be restored. Functional maintenance is the ability of a building to continue to function as expected after an earthquake, and includes the protection of the objects contained within the building. Seismic design has long been used to protect these functions. In recent years, however, vibration control f design has been actively used to satisfy these functions to a higher degree. Vibration control methods can be broadly classified into vibration control and seismic isolation, both of which are based on seismic design with the addition of vibration control functions.
Seismic Resistance Resistance to shaking
This is a design method that strengthens the building itself to withstand the shaking of earthquakes. By making the pillars and walls strong, the building is restrained from deformation, preventing it from collapsing or falling apart. Although earthquake-resistant structures can provide sufficient performance in terms of protecting human life, they may be damaged and become difficult to maintain functionality in the event of severe vibrations. The buildings themselves, however, were severely damaged and had to be replaced. However, many buildings themselves were severely damaged and were demolished. In 2000, the new earthquake-proofing standards, which were further strengthened in light of the 1995 earthquake, went into effect.
Figure 1: Image of building earthquake resistance
Vibration control (vibration) Absorb shaking
Seismic damping (vibration control) is a method of absorbing earthquake shaking that enters a building by means of a special device, which helps the building to stop shaking. The shaking of the building is suppressed by applying a resisting force to the vibration and damping it. Typical examples are vibration control dampers and mass dampers (TMD and AMD). They prevent amplification of building shaking and subdue it quickly, thus reducing damage to the building. Thus, in addition to protecting human life, they also prevent damage and maintain functionality.
Seismic dampers are generally used to counteract seismic vibration, while TMDs and AMDs are used to counteract wind sway and other vibrations in areas targeted for habitability.
Figure 2: Image of building vibration control (vibration)
Seismic isolation Shaking is blocked
This is a design that intercepts seismic shaking (prevents shaking from being transmitted to the building). Typical examples are devices such as laminated rubber installed in the foundation of a building to prevent ground shaking from being transmitted to the building. As a result, the shaking applied to the upper building is greatly reduced.
Figure 3: Image of seismic isolation of a building
*References
The Architectural Institute of Japan (ed.) Easily Understandable Building Vibration Control