Research on Damage and Failure Mechanisms and Seismic Vulnerability Analysis of Ribbed Arch Aqueduct Structures via Endurance Time Analysis

In this paper, the Changgangpo aqueduct is taken as the research object to establish a three-dimensional nonlinear finite element model of the ribbed arch aqueduct structure. This study focuses on the dynamic response analysis, damage evolution rule, and failure mode of the ribbed arch aqueduct structure at different seismic intensities. The results indicate that the displacement response of the aqueduct structure increases steadily with the duration of seismic activity. In addition, when material damage characteristics are considered, the displacement failure response of the structure also increases gradually. During a 20 s seismic event, the peak curvature response of the arch foot, accounting for damage conditions, reaches 0.0167, which is 31.1% lower than the 0.0219 observed under linear elastic conditions. This reduction is primarily caused by damage to and failure of the concrete, which increases structural damping and absorbs significant energy, thereby reducing the effect of earthquakes on the structure and decreasing internal forces. The study also analyzes the damage evolution process and typical damage states of the aqueduct structure, including the trough body, ribbed column, and arch rib. Severe damage occurs mainly in the trough body, abdominal arch, midspan ribbed column, and arch foot of the upper pier. The failure mechanism of the bearing members, such as the lower abdomen arch, ribbed column, and arch rib, is revealed to be primarily shear failure and bending failure. In addition, a vulnerability curve of the aqueduct structure is constructed to estimate the failure probability under seismic loads. The research results reveal the seismically vulnerable parts and seismic performance of ribbed arch aqueduct structures, which can provide a theoretical basis for the seismic design and reinforcement of similar aqueduct structures.