Performance-based seismic assessment of a base-isolated bridge-pier

Abstract

In structural assessments, plastic strains beyond the elastic limits play an important role in the inelastic responses under seismic effects. In this article, an isolated concrete-pier is analysed by using performance principles and the related code recommendations. Seismic performance analyses are realised by employing recorded earthquakes using the nonlinear pushover and the time history methods. The nonlinear analyses are implemented with user-defined plastic hinges. The hinge properties are derived on the basis of moment-curvature analysis and experimental results. Results of the solutions are presented comparatively for various parameters of the problem, such as pier reinforcement ratios, peak ground accelerations (PGAs) and different quakes. The results showed that residual plastic rotations of the pier section, configured with the minimum reinforcement ratio which satisfying the code-requirements, remain within the acceptable limits and they fulfil the FEMA-356 performance requirements even for strong earthquakes provided that a high ductility and proper design secured. Vulnerable functions with PGAs are displayed for the plastic rotations and isolator/deck displacements. However, the shear deformations of the isolator and the deck displacements exceed the allowable limits and they are in vulnerable risk if the pier section is configured by the minimum code-requirements.