Anti - Seismic devices
- LRB LEAD RUBBER BEARING
Lead rubber bearings (LRB) consist of alternate layers of elastomeric material and vulcanized reinforcement steel plates with a central lead core. The energy dissipation of bearings is from the lead core, the bearings provide a high level of damping of up to 30% due to high absorption capacity of the lead core. Thanks to its energy dissipation capacity, the LRB bearings can reduce the horizontal displacement. Normally, LRB bearings have round shape but sometimes they can be manufactured in square shape and can be equipped with more than one lead core.
Upon the occurrence of earthquake, LRB bearing can lengthen the natural vibration period of bridge and reduce the horizontal force caused by structure weight.
Structure of LRB bearing:
2. HDRB HIGH DAMPING RUBBER BEARING
High damping rubber bearings (HDRB) consist of alternate layers of elastomeric material and vulcanized reinforcement steel plates. As the reinforcement steel plates are fully embedded in the elastomeric material they are sealed and thus protected against corrosion. The bearings can also be supplied with additional anchor plates, allowing easier replacement of the device in case of maintenance needs. The HDRB devices are made from natural rubber (NR) providing a high resistance against mechanical wear.
The HDRB devices help limit the energy transferred from the ground to the structure in the event of an earthquake. They provide a high level of damping of up to 16% since they are made up of a chemically improved rubber compound providing better damping and displacement capacity
Structure of HDRB bearing: