An Experimental Investigation of Unbonded Laminated Elastomeric Bearings and the Seismic Evaluations of Highway Bridges with Tested Bearing Components

Abstract

This paper presents an experimental program performed to investigate the behavioral characteristics of unbonded steel-reinforced laminated elastomeric bearings (U-SLEBs), which have been widely used for highway bridges in China. The influences on the friction behaviors, stiffness, and energy dissipations of the different parameters, such as compressive stresses, loading rates, and rubber material, were discussed. The responses of the U-SLEBs were compared with those of the bonded steel-reinforced laminated elastomeric bearings (B-SLEBs). Then, effective analytical models were developed, which considered the mechanical degradation of the U-SLEBs and simulated the realistic behaviors of the B-SLEBs. The seismic responses of a multispan continuous bridge with tested bearing components were also evaluated. The results showed that the mechanical properties of the U-SLEBs tended to degrade due to friction sliding. However, the degrees of the decrease were found to be dependent on the influencing parameters. Meanwhile, the B-SLEBs exhibited stiffening behaviors that led to tearing under large displacement demands. The bridges using U-SLEBs were found to suffer less damage due to the reliable sliding behavior of U-SLEBs. It is recommended that shear keys, which are reasonably designed in the transverse direction, be constructed in order to achieve better seismic performance.