Seismic Fragility Analysis of Curved Bridges with Precast Segmental Pier Columns Considering Directionality of Multisupport Earthquake Motions

Precast segmental pier columns (PSPCs) have been recently developed in the context of accelerated bridge construction. Although extensive studies have examined the seismic performance of bridges with PSPCs, research specifically focusing on curved bridges supported by PSPCs remains relatively limited. In addition, the spatial effects of seismic motions and the randomness of their incident direction are critical factors influencing the seismic performance of bridge systems. This paper presents a seismic fragility analysis of curved bridges with PSPCs (CBs-PSPCs) considering the directionality of input multisupport earthquake motions (MSEMs). First, a representative four-span curved bridge located on heterogeneous geological conditions is selected, and a refined three-dimensional (3D) finite element (FE) model of the corresponding CB-PSPCs is developed in OpenSees. Next, an artificial simulation method for MSEMs, accounting for wave passage effect, bidirectional coherence, and local site conditions, is introduced, and the 3D MSEMs under different incident directions are stochastically synthesized. Finally, the effects of MSEMs incident directions on the seismic response and fragility analyses of the CB-PSPCs are investigated, and the influences of incident directions on the structural seismic performance under various seismic excitation and pier column types are systematically analyzed. Numerical results indicate that the incident direction significantly affects the seismic performance of the CB-PSPCs, and its impact varies for different piers. The differences between the largest and smallest fragility median PGAs of each pier are distributed within the range of 23.4%–30.5% under various incident directions. Furthermore, uniform seismic excitation tends to underestimate the effect of incident directions on the seismic response and fragility of the CB-PSPCs. Compared to the curved bridge with monolithic pier columns (MPCs), the influence of incident directions on the seismic behavior of the CB-PSPCs is more pronounced. These findings underscore the necessity of considering the incidence direction of MSEMs to achieve reliable seismic performance assessment and design of CBs-PSPCs.