Seismic energy dissipation and local concentration of damage in bridge bents

Abstract

Seismic damage on bridge systems is basically concentrated on the piers. Hence, it is necessary to develop comprehensive studies oriented to improve our understanding of the bridge bents seismic response. Accordingly, the seismic behaviour and local concentration of damage within a typical bridge bent were analysed, considering different rotational restrictions of the foundation-soil system and different steel ratio arrangements. The contributions to structural damage of both, maximum deformation and cumulative damage, were assessed for records with different characteristics. The results showed that the amount of damage dissipated by the bent and the distribution of damage were strongly affected by the flexural strength variation along the columns. In models with non-uniform strength distribution, the inelastic demands were concentrated on few plastic hinges and bent degradation and failure were reached before the energy dissipation capacity of all potential hinges occurred. The analyses results also showed that the rotational restriction imposed by the foundation had a notable influence on the energy dissipation capacity and location of damage. Finally, the determination of damage indices in plastic hinge regions showed that most of the damage is produced by the cumulative effect of plastic energy dissipation, independently of the ground motion characteristics.