Abstract

Elastomeric bearings are critical structural bridge components that transfer loads between the bridge superstructure and substructure. Their influence on the bridge's seismic behavior depends on their anchorage method, which can alter how forces are distributed throughout the structure. This study examines the seismic performance of simply supported highway bridges with prestressed concrete girders, focusing on the influence of different elastomeric bearing anchorage methods. A benchmark bridge designed under the current Chilean bridge code is analyzed. For this bridge, the following three elastomeric bearing configurations are evaluated: unbonded bearings at piers and abutments, bonded bearings at both locations, and a proposed hybrid configuration employing bonded bearings at abutments and unbonded bearings at piers. In addition, the effect of bridge column flexibility is also analyzed, considering three column heights for each bearing configuration. Detailed three-dimensional nonlinear numerical models were developed in OpenSees. The seismic performance assessment of the case studies included nonlinear static analyses, nonlinear response history analyses, and fragility assessments. Results show that unbonded bearings limit substructure demands but lead to excessive superstructure displacements and high unseating probabilities. Bonded bearings effectively control displacements but amplify substructure demands. The proposed hybrid configuration balances these trade-offs, reducing substructure damage while maintaining effective superstructure control. The fragility analysis highlights the effectiveness of the proposed hybrid configuration in achieving a balanced seismic response, especially for bridges with more flexible columns, where it outperforms other configurations in reducing bridge system fragility. These findings underscore the potential of hybrid bearing configurations to optimize overall bridge seismic performance.