Design of 128-m Span Simply-Supported Steel Truss Girder of a Double-Track Railway Bridge

The main bridge of Zhaozhaiying River Double-Track Railway Bridge is a 128 m-span simply-supported through steel truss girder bridge.The main truss of the bridge is the triangle web member system with vertical members,of which the chords and the web members to sustain great internal forces are of box sections while the web members to sustain little internal forces are of H-shape sections.In the plane of the upper chords,the crisscross top lateral bracings are arranged and the floor system of the truss is the ballast floor system of integral orthotropic plates supported on the densely arranged cross beams.The bridge was erected by the semi-cantilever pulling construction method,i.e.,the steel truss girder and steel launching nose were first assembled on the temporary scaffolding on bank and were then pulled in place on the two temporary piers set in the river.The MIDAS Civil 2006 was used to establish the three-dimensional finite element model for the main truss of the bridge,the internal forces and displacement of the members,the precambering and natural vibration characteristics of the truss were calculated and the results of the calculation prove that the design of the truss girder is rational and can satisfy the relevant requirements in the codes.