宽幅矮塔斜拉桥最大悬臂阶段主梁受力分析

Stress Analysis of Wider Girder of an Extradosed Cable-stayed Bridge Based on the Largest Cantilever Construction Stage

矮塔斜拉桥主梁不仅受轴向压力,还要承担相当部分的弯矩和剪力,所以其受力复杂,空间应力的不均匀现象十分严重。并且随着箱梁的宽度的增大剪力滞效应更加严重,施工过程中主梁截面剪力滞对结构的影响较成桥以后更大。本文以在建的江肇高速公路西江特大桥为研究背景,采用有限元理论,建立了拉索锚固区梁段空间有限元模型,分析最大悬臂施工阶段的主梁空间受力状态。分析结果表明该桥设置后浇段的施工方法在最大悬臂施工阶段主梁的受力状态合理,对同类桥型的设计和施工具有一定的参考意义。

The girder of the extradosed cable-stayed bridge not only resists the axial pressures,but also bears a considerable part of the moment and shear force.So its distribution of stress is complicated,the inhomoge-neous phenomenon of spatial stress is very severe.Moreover,the phenomenon of shear lag is worse as the width of the box girder is increasing.It is indicated that the structure is more affected by the shear lag of girder during the construction stages than the completed bridge stage.This paper is based on xijiang super large bridge in Jiang-Zhao Highway which is being built,finite element theory is adopted.The segmental finite element model of girder of anchorage zones with cable forces applied is established and the spatial finite element analysis is carried out.The spatial stresses of girder on the longest cantilever construction stage are analyzed.The results reflect that the construction method for setting a late poured band of this bridge and the stressed state of girder on the longest cantilever construction stage are reasonable.The research has significance for design and construction reference of the similar bridge in a certain degree.