128m双线铁路简支钢桁梁桥设计

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

赵寨颖河双线特大桥主桥为128m下承式简支钢桁梁桥。主桁采用带竖杆的三角形腹杆体系;主桁弦杆均采用箱形截面,内力较大的腹杆采用箱形截面,内力较小的腹杆采用H形截面;在上弦杆平面内设置交叉式上平纵联;采用密横梁整体正交异性板有砟桥面系。该桥采用在岸边临时支架上拼装钢桁梁及导梁,在河中设置2个临时支墩的半悬臂拖拉法施工。采用MIDASCivil 2006建立主梁三维有限元模型,计算主梁杆件内力及位移、预拱度、自振特性,计算结果表明该桥设计合理,满足规范要求。

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.