Advantages of seismic isolation bearing and damper in reducing seismic damage in buildings

The Advantages of seismic isolation bearings and vibration damper in reducing seismic damage in buildings are mainly reflected through comparison with traditional seismic design.

There are two methods to reduce earthquake damage in buildings:

Method 1: Traditional seismic design - 'hard resistance'

Increase section size and reinforcement ratio → high stiffness and seismic force (cyclic); Difficult to repair after an earthquake

Method 2: Seismic reduction and isolation design - "using flexibility to overcome rigidity"

Principle:

Isolation of seismic effects on upper and lower structures, prolonging the basic period of the structure, increasing damping, hysteresis energy dissipation, and horizontal force dispersion

Effect:

Reducing seismic force dissipation and coordinating seismic energy for seismic resistance

Preconditions:

Reliable connection with good mechanical properties to meet large horizontal displacement

a. Traditional seismic design - strengthening structural stiffness and strength, and strength resistance design.

Bridges, building structures, and traditional seismic techniques all rely on strengthening the stiffness and strength of the structure; Thus improving the ability of the structure to resist earthquake damage.

For example, in the framework structure of a building, steel bars - strong columns and weak beams; Increase the cross-section of beams and columns; Measures such as improving the reinforcement ratio of beams and columns are particularly prominent in some reinforcement projects.

b. Shock absorption control technology - increases the plastic deformation capacity of the structure, absorbs and consumes seismic energy, and achieves the purpose of shock absorption.

Shock absorption, also known as energy dissipation and shock absorption, is the process of consuming the energy input into the structure through the relative displacement and velocity of the energy dissipator, providing additional damping to achieve the expected seismic resistance and shock absorption requirements.

The most common energy dissipators are viscous dampers, buckling constrained energy dissipation braces, metal yield type dampers, and friction dampers.

c. Isolation control technology - increases the flexibility of the structure and blocks the transmission of seismic energy.

In bridge engineering, seismic isolation devices are installed at the supporting parts of the bridge to separate them from the top surface of the bridge piers consolidated in the foundation; In construction engineering, it is generally necessary to add isolation devices between the upper structure and the foundation.

In isolation structures, isolation devices have varying horizontal stiffness and sufficient stiffness under wind and small earthquakes. During medium to large earthquakes, the horizontal stiffness of the isolation device decreases, prolonging the natural vibration period of the isolation structure and moving away from the natural vibration period of the upper structure. This isolates some seismic energy and reduces the seismic energy input to the upper structure. And the isolation device enters the plastic deformation stage before the upper structure, and seismic energy is mainly consumed by the plastic deformation and damping of the isolation layer. Therefore, the upper structure can basically maintain elasticity without serious damage.