1)Lead Rubber Bearings for Bridges (Seismic Isolator)

Seismic Isolator is installed as a Damping Equipment under building structures so as to control the tremor of structure against the loads of earthquake.

Base Isolation System, which is a branch of manual technique to reduce the tremor of structure, is widely applied to the large sized structures such as road bridges, rail bridges and nuclear power station to minimize damages from dynamic loads like earthquake. Also because it has the economic and functional efficiency with comparative perfection, the Base Isolation System is studied and used in the world, especially in USA and Japan.

So many bridges and buildings to which the Base Isolation System is applied are constructed in many countries including USA and Japan all over the world, and the constructed structures showed so high thefunction of isolation from earthquake that they proved the safety when arising the earthquake in practice.

Also the installation of Earthquake Absorbing Bearing is likely to be required in the world in order to get the efficiency of seismic force damping function and of constructive cost down for the lower parts of structures.

2) Special Features of Lead Rubber Bearings for Bridges

* Strong Points

As it is made of vulcanized rubber layers, reinforced thin steel plates laid alternatively in the elastomeric pad, and one or several lead cores inserted through the elastomeric pad and top & bottom steel plate, Earthquake Absorbing Lead Rubber Bearing not only controls the volume of displacement with resisting the first horizontal loads, but also prevents the bridge from falling down with absorbing the second horizontal loads at the time of earthquake.

* Property of Lead as a Suitable Material for Earthquake Absorbing Work

Lead is a suitable material used for earthquake absorbing work owing to the followings; first, as lead has a high malleability, it is able to be transformed from small to large range at a low temperature, second, the melting point of lead, it is 20°C, which is lower than other metal, makes it easily possible for lead to return to original molecular structure.

* The Economic Design

* The More Excellent Safety

* Easy Installation

3) General Characters of Lead Rubber Bearings for Bridges

A) Function & Applicable Bridge

* Function

The MP Earthquake Absorbing Lead Rubber Bearing is made so as to fulfill the earthquake absorbing function as well as general bridge bearings

* Applicable Bridge

A)This bearing is mainly applicable to small & medium bridge and not suitable for large bridge because of installation with a limit of dimensional height and volume according to the displacement moved from earthquake or impact load So it's restricted on the scale of bridge.

B)Types of Lead Rubber Bearing

Because of the earthquake absorbing function, this Lead Rubber Bearing is manufactured for free movement to all directions.

C) Mechanical Properties of Lead Rubber Bearing

Earthquake Absorbing Lead Rubber Bearing shows following mechanical properties toward the loads of both in a short and long term.

If Lead Rubber Bearing takes loads in a short term such as live loads from wind or earthquake on a little scale, it will control the tremor of structure by the action of reinforced steel plate, laminated rubber and the first stage ofstiffness of lead, on the other side, if Lead Rubber Bearing takes loads in a long term such as live loads from the change of temperature or earthquake on a large scale, it not only shall control the tremor of structure but also ensure the safety of movement by the action of lead core which absorb the horizontally large energy after yield of lead core.

The horizontal hysteresis properties are shown as a following hysteresis curve combined the elasticity of steel laminated rubber with the plastic transformation of lead core.