Effect of bonding or unbonding on seismic behavior of bridge elastomeric bearings: lessons learned from past earthquakes in China and Japan and inspirations for future design

Abstract

Economical laminated elastomeric bearings are well-adopted options for load transmission components of bridges from superstructure to substructure. In most cases, the design of such elastomeric bearings primarily depends on the requirements from service-level conditions such as superstructure thermal movements, with little consideration of extreme loads like earthquakes. However, bridge elastomeric bearings are very likely to be subjected to earthquake hazards, particularly for bridges located in high seismic regions. This study presents an overview of the observed typical damages of bridge elastomeric bearings in the past major earthquakes mainly in China and Japan. Comparisons of different damage patterns are conducted based on the different installations of bridge elastomeric bearings (bonding or un-bonding). The effect of bearing installation methods on the overall seismic behavior of bridges is also discussed. A desirable installation method for bridge elastomeric bearings against strong earthquake loads is recommended, which is expected to overcome the critical limitations of current design practice.