双线铁路箱梁施工阶段跨中截面应力的有限元分析

在双线高速铁路建设中，广泛采用整体箱型梁结构形式。本文采用弹性力学有限元方法。建立了8节点六面体等参数单元的三维应力分析有限元模型。结合双线铁路预应力混凝土简支箱梁的施工，利用SAP90通用结构有限元分析程序，建立了整体箱梁三维实体单元模型，通过梁单元施加预应力荷载效应。箱梁采用后张法施工工艺，分别以预应力初张拉阶段、预应力终张拉完成、二期恒载作用为分析荷载工况，计算了箱梁跨中截面应力，给出在施工过程中箱梁跨中截面的应力随预应力张拉的变化及分布情况。通过有限元分析结果与铁路桥涵设计规范的比较得出，该箱梁结构设计合理，施工方案可行。本文所采用的分析方法和结论对于双线铁路箱粱的设计与施工有一定的借鉴意义。

Finite Element Analysis of the Mid-span Cross-section Stresses of Double-track Railway Box Beams in the Construction Phase

During the construction of doube-track high-speed railways, box beam structures are used widely. In this paper, the elasticity finite element method is used to built the three-dimension model with eight-nodes hexahedron isoparametric elements. According to construction of prestressed concrete simply supported box beams of the double-track railway, the solid three-dimension finite-element model is established using the SAP90 program. Under the initial tensioning stage, end tensioning stage and secondary dead load, the stresses of the whole beam are analyzed. The stress fluctualions and distributions of the mid-span section are presented against varations in prestressed tensioning. Compared with the railway bridge and culvert design specifications, the box beam structure design and construction method are seen rational and feasible. The analytic method and results in this paper has reference value to design and construction of box beams of double-track railways.