Lead Rubber Bearing-Square type, LRB-S

Excellent seismic isolation characteristics and economical design

Features

An economical design with the preserved performance of the conventional LRB, providing an economical design of framework and seismic isolation device.
Shows the stable characteristics in all the horizontal directions, and the reliability to the severe deformation is verified.
The square shape provides the reduced cost from the ease of fire resistant coating etc.
A compact design of smaller footprint of one rank down size as compared to the circular type of same specification.

Structure

LRB-S is an all in one seismic isolation device assembly of the laminated rubber to function as a load supporting and vibration isolation, and the lead plug to function as an energy absorbing function (damper). The compact size provides a good working performance requiring no big space for installation.

LRB (Round Type)

Function of Laminated Rubber (Isolator)

(1) Load supporting function
Steel reinforced rubber will firmly support the building.
High rigidity in the vertical direction as compared to the single rubber provides with the stable support of the building.
(2) Horizontal Elasticity Function (Elongated period)
Transforms the vibration of earthquake to a slow movement.
Softness in the horizontal direction will calm down the severe vibration of earthquake, and elongates the period of vibration of the building.
(3) Restoring Function
Restores the building to the original position
The restoration force of the rubber will return the building to the original position after the earthquake terminated.

Function of Lead Plug (Damper)

(4) Vibration Damping Function
Damps the severe vibration of building
The Lead Plug will be plastically deformed along with the deformation of laminated rubber to absorb the seismic energy, quickly damps the vibration.
(5) Trigger Function
Depresses the vibration other than the earthquake
High rigidity of the lead plug will hold the building until the external force becomes as high as a certain level to prevent the vibration due to the storm wind etc.

Basic Characteristics

This graph shows the relation of force and displacement when the certain deformation is applied to the LRB-S, under the estimation of a severe earthquake. The design model and the actual measurement show a good match, proving the stable performance of the LRB and high design precision. The restoration characteristics of the LRB-S is indicated in the two lines (bi-linear model), which provides a simple modeling for structural analysis.