Key Techniques of Design of Extradosed Cable-Stayed Bridge on Chengdu-Kunming Railway

The Jinsha River Bridge in Panzhihua City of Chengdu-Kunming Railway is a prestressed concrete extradosed cable-stayed bridge with spans of (120+208+120) m. Double-celled single-box prestressed concrete girder with variable heights is adopted for the main girder, and the H-shaped reinforced concrete structure is used for the bridge pylon, of which the height above the bridge deck is 28 m and the ratio of pylon height to girder span is 1/7.5, respectively. The stayed cables, which are made of 1 860 MPa epoxy-coated steel wires, are anchored to the main girder after passing through the split tube cable saddle area on the pylon. A system of pylon-girder consolidation and pier-girder separation with three-friction double-spherical friction pendulum aseismatic bearing + shear tenon combined support is adopted in the bridge, which not only solves the seismic problems of the bridge but also is favourable for the smooth running of trains and the setting of the beam-end expansion device. In accordance with the characteristics of extradosed cable-stayed bridges, the cable force and configuration of prestressed steel tendons of the girder are determined according to the live load ratio of the cable-girder. The vehicle-bridge coupling dynamic analysis of the bridge indicates that not only the dynamic performance of the bridge but also the safety and comfort of the train passing the bridge meet the requirements of the railway code. © 2019, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.