Numeric Study on the Critical Angle of Seismic Incidence for High-Speed Railway Bridges with Round-Ended Piers Based on the Fragility Method

Considering the difference of seismic capacity in different cross-sectional directions of round-ended piers, the effects of the critical angle of seismic incidence on high-speed railway bridges is analyzed by the fragility method. The detailed three-dimensional finite element (FE) model of a typical three-span high-speed continuous girder railway bridge is developed in OpenSees. The fragility curves with respect to cross-sectional direction under different angles of seismic incidence are obtained. The critical angle of seismic incidence is determined by comparing the median value of the fragility function in the critical cross-sectional directions at different angles of seismic incidence. Results show that the difference between the critical angle of seismic incidence determined by the longitudinal direction and that determined by the critical cross-sectional direction is small, but the fragility curves are significantly different. The seismic capacity difference of round-ended piers in all cross-sectional directions is significant, which must be considered in seismic analysis, otherwise the probability of damage to the bridge will be seriously underestimated.