Seismic Performance of a Curved Continuous Rigid-Frame Composite Girder Bridge Under Ground Motions

Abstract

To investigate the seismic performance and damage evolution of a curved continuous rigid-frame composite girder bridge under near-fault velocity pulse-like ground motions, a refined three-dimensional full-bridge finite element model was established, incorporating pile–soil interaction, expansion joint pounding, shear key damage, and nonlinear hysteretic behavior of high damping rubber bearings (HDRBs). Nonlinear time-history analyses were conducted under E1 and E2 seismic levels using near-field pulse records (short, moderate, and long periods), a near-field non-pulse record, and a far-field record. The fiber section capacity-to-demand ratio method was adopted to assess pier damage. Results show that near-field pulse-like motions govern the structural response, with long-pulse records producing the most unfavorable displacements and internal forces. Under E2, HDRBs exhibit significant yielding and hysteretic energy dissipation, effectively protecting the piers but imposing greater deformation demands on expansion joints and unseating preventers. Continuous girder piers display a transverse frame effect and a longitudinal S-shaped moment distribution with a secondary peak at the upper-middle portion due to higher modes. Rigid-frame hollow thin-walled piers exhibit S-shaped internal force distributions associated with abrupt section changes, and the tallest pier reaches a capacity-to-demand ratio of 0.82, indicating moderate yielding. The vertical seismic component amplifies transverse bending–torsion responses of curved girders through spatial coupling. The findings provide a scientific basis for ductility design and damping detailing of similar complex curved bridges.