Lead Rubber Bearings

Based on the concept of reducing earthquake loads, ‘‘seismic isolation design’’ is considered as the most effective design technology to damp earthquake loads of a structure. With seismic isolation design it is possible to provide seismic isolation not only for the new structures but also for the old structures by installing special isolators between the foundation and superstructure system. Using seismic isolators; Instead of increasing the resistance of the structure against the earthquake loads, the period of the structures is extended and the earthquake force acting on the structure is reduced. In addition, with the using of isolators, displacements occur in the isolator, so the bearing system exhibits rigid motion and the earthquake resistance of the structure is increasing. Seismic isolation should be used in all structures that need to function immediately after the earthquake, such as hospitals, fire stations, transportation stations, airports, bridges, power generation facilities, first aid centers, historical buildings.

Seismic Isolators are designed in 3 types within Arfen Bridge;

1. Lead Core Seismic Isolators

2. High Damping Seismic Isolators

3. Frictional Pendulum Type Seismic Isolators

Lead Rubber Bearing (LRB)

Lead rubber bearings (LRB) are long-term isolators that do not require maintenance and are used to reduce damages caused by earthquake energy. The high energy damping capacity and the reduction of horizontal movements are the biggest advantages with respect to simple elastomeric bearings. The lead core isolators are designed to have a horizontal movement capacity from 70% to 200% of the isolator height. In this type of isolators; the lead core consumes energy and reduces the seismic forces and displacements that affect to the structure. In addition, the structures provide resistance to the wind. If the seismic forces exceed the design loads, the rubber isolators meet their high shear forces while maintaining their stability due to their great elasticity. Thanks to the elasticity of the rubber, the structure returns to its original position after the earthquake.

High Damping Rubber Isolator (HDRB)

The damping capacity is increased by adding extra materials to the natural rubber. High damping rubber bearings consist of reinforced multilayers with steel plates between HDRB specially compounded damping rubber and rubber layers. Steel plates provide vertical rigidity and rubber horizontal flexibility. They can be made rectangular or circular accordance to client request.

Friction Pendulum Seismic Isolator (FPS)

This type isolator works with the energy damping principle by friction. If the seismic forces acting on such isolators exceed the static frictional force limit, the steel sphere in the isolator begins to slip on the concave bottom plate. Then the isolator allows the structure to oscillate like a pendulum. The pendulum isolators are designed with a single curved surface or multi curved surface for the need of the system. Compared to other models, the dimensions are smaller. One of the most important advantages is that the torsional effects that are possible in the structure effect prevent.

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