Seismic response analysis of an as-built RC bridge with base-isolated deck

The seismic vulnerability assessment of existing and new lifeline systems, especially transportation systems, is becoming of paramount importance in resilient social communities. A number of transportation systems world-wide were built in the late 60s and early 70s; such systems were designed primarily for gravity loads. Consequently, most of the bridges do not employ seismic details and hence their structural performance are generally inadequate under earthquake ground motions. The present analytical work assesses the earthquake performance of a typical existing reinforced concrete (RC) bridge designed for gravity loads only and retrofitted with base isolators. Friction pendulum bearings were utilized as isolation devices for the RC bridge continuous deck. The earthquake response of the isolated bridge has been investigated through dynamic nonlinear analyses. The comprehensive numerical investigations carried out herein prove the effectiveness of the isolation systems in preventing the onset of damage in the RC piers, especially limiting the maximum shear at the base of the piers and the inter-storey drift, preventing the onset of plastification in the frame sections and inhibiting the occurrence of the shear failure in the transverse beams of the RC portal frames of the piers.