应用高强预应力体系的简支箱梁结构设计及影响分析

Analysis on Influence of Structural Optimization Design of Simply Supported Box Girder with High Strength Prestressed System

为研究应用高强预应力体系对高速铁路简支箱梁结构设计及受力性能的影响,分析国内已发布的标准通图中适应1860 MPa预应力强度等级梁体的构造尺寸参数特征,在满足构造要求的基础上拟定适应2200、2300、2400 MPa级高强预应力体系的梁体跨中截面腹板厚度及底板厚度;建立线单元及实体单元有限元模型,分析采用高强预应力体系的简支箱梁运营阶段及运梁阶段的受力性能。结果表明:随着预应力强度等级提高,腹板和底板构造尺寸减小,采用所拟截面的梁体运营阶段各受力性能指标均满足规范要求,同时梁体的预应力度、残余徐变上拱度有所增加,梁体抗弯刚度、抗扭刚度有所减小,抗弯强度无明显变化;运梁车荷载作用下梁体最大主拉应力随着优化后腹板和底板尺寸减小而增大,在所拟截面下,梁体的腹板、底板厚度的减小值须有所限制,以保证施工荷载作用下结构的横向受力性能。

In order to study the influence of high strength prestressed system on the structural design and mechanical performance of the simple supported box girder of high speed railway,the structural dimension parameters of the beam adapted to the prestressed strength level of 1860 MPa in the standard general diagram published in China were analyzed.On the basis of meeting the structural requirements,the thickness of the web plate and the bottom plate of the mid-span of the beam suitable for the high strength prestressed system of 2200 MPa,2300 MPa and 2400 MPa were proposed.The finite element model of line element and solid element was established to analyze the mechanical behavior of simple supported box girder in operation and transport stage.The results show that with the increase of prestressed strength,the structural size of web and bottom plate decreases,and the mechanical performance indexes of the beam in the operation stage with the proposed section meet the requirements of the code.At the same time,the prestress degree and residual creep camber of the beam increase,the flexural rigidity and torsional rigidity of the beam decrease,and the flexural strength of the beam has no obvious change.The maximum principal tensile stress of the beam body increases with the decrease of the size of the web and bottom plate after optimization.Under the proposed section,the reduction value of the web and bottom thickness of the beam body should be limited to ensure the transverse mechanical performance of the structure under construction load.