Key Techniques for the Installation of Stiffening Girders in the Jixin Yellow River Three Gorges Bridge

To address the challenges of installing stiffening girders for long-span suspension bridges in mountainous deep canyons with complex terrain， this study conducted innovative research on construction techniques based on the Jixin Yellow River Three Gorges Bridge project. Confronting special conditions including restricted road transportation in U-shaped valleys， 30-meter annual water level variations of the Yellow River， and non-navigable waterways， this paper proposed an integrated construction scheme of "modular decomposition + on-site assembly， component transportation + intelligent cable lifting". Key technical solutions include： 1） factory prefabrication of each steel truss segment into 58 components （upper/lower chords， webs， deck panels， upper/lower crossbeams）， followed by road transportation to on-site assembly yards for "3+1" preassembly into standard lifting units； 2） the development and deployment of specialized multi-axle modular transporters for segment transportation within the canyon significantly improved transport efficiency； 3） an intelligent cable lifting system was implemented， achieving millimeter-level positioning accuracy at a rate of 2 segments per day； 4） an innovative "scaffolding + swing method" combination for cable lifting blind zones， enabling precise placement through hydraulic synchronization control for a maximum inclination of 63° and horizontal displacement of 15 m. Practical results demonstrated that the vertical installation accuracy was within ±2 mm for all 34 segments， the construction period was reduced by 20%， and the structure achieved a 100% acceptance rate in the initial inspection. The research validated the applicability of modular transportation and intelligent lifting techniques in deep-canyon suspension bridges， while the swing method effectively extended cable lifting coverage. The developed integrated technical system provides a valuable reference for similar canyon bridge projects， demonstrating significant economic benefits and promotion potential.