Friction-Based Energy Dissipation Efficiency of Thermal Elastomeric Bearings Effect on Seismic Vulnerability of Ordinary Bridge Substructure

Thermal elastomeric bearings, which generally accommodate thermal elongation and shrinkage rotations in bridge superstructure, can account as seismic isolators too. During moderate to strong earthquakes, the bearing possibly starts to slid on its concrete seat due to have no positive connection to the seat. As a result, a huge amount of seismic energy will be dissipated in wide force-deformation hysteretic cycles between elastomeric end layer of bearing and the concrete seat. This behavior initiates the idea of concurrent usability of thermal elastomeric bearings as seismic isolators as an economical response to AASHTO increment in design earthquake return period in 2008. The challenging problem with the approach is the large superstructure displacements and the risk of deck failure due to bearing unsetting. It this study, friction coefficient and elastomeric hardness have been considered as two affecting factors on deck and bearing displacements. The main effects of those parameters on substructure and superstructure are discussed and the probability of deck failure is presented.