What is the function of elastomeric bearings in bridges and what are the typical signs of distress?

The function of elastomeric bearings in bridges is to provide a flexible interface between the bridge superstructure and substructure, allowing for controlled movements and rotations while still supporting vertical loads. These bearings accommodate thermal expansion and contraction of the bridge deck, as well as movements caused by traffic and other loads. They also help to distribute loads evenly and reduce stress concentrations. Typical signs of distress in elastomeric bearings include cracking, bulging, delamination (separation of layers), excessive deformation, and sliding or shifting out of position. Hardening or stiffening of the elastomer can also indicate degradation. These signs suggest that the bearing is no longer performing as designed and may need to be repaired or replaced to ensure the continued structural integrity of the bridge.