Research on structural safety of extra-long-span cableway bridge in reservoir area of Shuangjiangkou Hydropower Station

Addressing the challenge of assessing the structural safety of ultra-long-span vehicle-carrying cableway bridge, Yelong cableway Bridge, a domestic ultra-long-span suspension bridge with a span of 390 m located in a reservoir area, was taken as the research object.The main cable parameters were derived through theoretical calculations, and a finite element model was established by using Midas Civil software to verify its reliability.Field tests were conducted to investigate the bridge′s safety performance.The results showed that the errors in anteroposterior ratio calculated by the finite element model during the empty-cable and unloaded stages were 0.43% and 0.11%, respectively, and the tension errors were 1.05% and 2.96%, indicating high accuracy and reliability of the finite element analysis.Under eccentric loading of a 60-ton heavy vehicle, the maximum increment in cable force was 24.2 kN, and the safety factor of the main cable was 2.93, demonstrated sufficient safety reserve of the main cable.The actual main cable alignment was smooth and showed good agreement with theoretical values.The static load deflection verification coefficients ranged from 0.47 to 0.88, indicating adequate structural stiffness reserve.The first-order natural frequency was 0.254 Hz, and the impact coefficient was no larger than 1.279, suggesting normal dynamic response.The measured longitudinal slope ranged from 4.25% to 7.16%, allowing smooth vehicle climbing and meeting the requirements of heavy-duty traffic.The research results can provide a reference for the mechanical safety research and operational maintenance of similar suspension bridges during service life.