Key Design Techniques for Egongyan Railway Transit Bridge

The Egongyan Rail Transit Bridge in Chongqing is located 70 m upstream of the existing Egongyan Bridge, the main bridge of which is a self-anchored suspension structure of a semi-floating system, with five spans of 50, 210, 600, 210 and 50 m. The stiffening girder incorporates the steel boxes in the central and side spans and the concrete boxes in the anchor spans and the anchor sections. The towers are portal-frame structures, designed as full-cross-section compressive components. The main cables, composed of steel wire strands installed by PPWS method, are arranged in parallel with center-to-center distance of 19.5 m. The side and central spans all have hanger cables comprising parallel steel strands. The hanger cables are connected with the main cable clamps via pin connection, and anchored to the stiffening girder by anchor boxes. The two legs of the tower have separated pile caps, beneath each pile cap are 9, φ3.0 m bored piles. Vertical and horizontal diaphragms are added on the anchor cross beams to divide the anchor chamber into 4 cells, with the intention of optimizing the load bearing capacity of the anchor cross beams of the main cable. The results of analysis show that the global and local stability of the bridge meets the related code requirements. Restricted by the built conditions, the bridge was constructed first as a cable-stayed structure, and then transformed to be the final suspended structure, which is an innovation in bridge construction. © 2020, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.