Abstract:Taking a newly-built urban elevated project in Shanghai as an example, the construction technology of segmental prefabrication and assembly as well as vertical prestressed post-tensioning for ultra-high columns is studied and discussed, and its key processes and technical points are analyzed, which can provide a reference for the similar projects. As the project crosses over the existing rail transits and urban expressways, a multi-level interchange ramp is adopted. The ramp column is mostly ultra-high single column with relatively small cross-sectional dimension. After prefabricated segmentally in a precast yard and transported to the construction site, the ultra-high columns are installed in place by large hoisting equipment. After assembled into an integral column, its length-to-width ratio is relatively large. Moreover, due to the influence of the surrounding environment, a full-shadow sound barrier needs to be installed later, resulting in a significant increase in the additional load and root bending moment borne by the ramp columns. Therefore, the vertical prestress must be applied and post-tensioned to the ultra-high ramp columns to enhance their load-bearing capacity and ensure the safety of the bridge structure under force. A self-locking anchorage system is adopted for the vertical prestress construction of the ultra-high columns.
