Seismic Fragility of Large-Span Elevated U-Shaped Aqueduct Based on Incremental Dynamic Analysis

This study uses a U-shaped aqueduct structure in a specific irrigation area as the research object to examine the damage patterns of large-span elevated U-shaped aqueduct structures under seismic action. A single-span aqueduct model that integrates fluid–structure interaction is created with the finite element program ANSYS. The incremental dynamic analysis approach is utilized to perform nonlinear dynamic time–history assessments for three types of bearings—plate rubber bearings, pot rubber bearings and lead-core rubber bearings—under conditions of an empty condition, a half-full condition and a design water level. Seismic fragility curves for the bearings and piers subjected to transverse seismic stress are developed using capacity–demand ratio models and specified damage limit states. The findings demonstrate that the likelihood of aqueduct components being damaged increases substantially as seismic intensity increases, with bearings failing before piers. Under the conditions of empty, half-full and design water levels, the structural mass increases as a result of higher water levels. This alters the dynamic response characteristics and increases the likelihood of failure in a variety of damage states. The probability of plate rubber bearings experiencing minor damage exceedance increases from 11.75% to 61.6% as the water level rises from vacant to design conditions. Lead-core rubber bearings provide better seismic isolation than plate rubber bearings and pot rubber bearings. This greatly lowers the aqueduct structure’s displacement response and damage likelihood. Under design water level circumstances, the chance of mild damage to lead rubber bearings is 8.64%, at a peak ground acceleration of 0.4 g. The damage probabilities for the pot rubber bearings and the plate rubber bearings are 80.68% and 97.45%, respectively. The research findings establish a theoretical foundation for the seismic design and damage evaluation of aqueduct structures in places with high seismic activity, ensuring the stable operation of water transfer projects and sustainable water resource utilization, presenting considerable technical applicability.