Seismic performance assessment of base-isolated tall pier bridges using friction pendulum bearings achieving resilient design

Abstract

Traditional seismic isolation bearings, which are widely adopted in conventional bridges between superstructures (girders) and piers, are not effective for tall pier ones, due to the considerable distributed mass and corresponding seismic inertial force of columns. To address this issue, applying isolators at the base of pier columns appears to be a promising approach mitigating seismic demands of tall pier bridges. This paper investigated the feasibility and efficiency of base isolation by implementing friction pendulum bearings (FPBs) at the bottom of tall piers. The seismic performance of the FPB-isolated bridge system was evaluated through nonlinear time history analysis and compared with its counterparts using fixed base. The results showed that with the employment of FPBs, the tall pier columns would remain elastic during strong earthquake excitations, and the displacement demands of FPBs were less than 40% of the pre-determined capacity. Through parametric analysis, a greater value of radius (R) of concave surface was recommended for designing FPBs; while the friction coefficient (μ) should be careful determined to achieve balance between seismic displacement and force demands.