Seismic Performance Assessment of Quasi-Isolated Highway Bridges with Seat-Type Abutments

In recent years, Illinois bridge engineers developed an innovative "quasi-isolation" seismic bridge design methodology. The objectives of this study are to assess the seismic performance of prototype quasi-isolated highway bridges, to validate the design strategy, and to provide recommendations for improving bridge seismic performance. A matrix of bridges was computationally studied. Seismic assessment results validate that the current quasi-isolation design strategy is generally effective in preventing global collapse, but the response of a small number of bridges demonstrated a relatively high risk of bearing unseating and severe pier damage. Recommendations for calibrating the current design strategy have therefore been proposed.