体外预应力加固铁路盖板涵应力增量分析

Analysis of stress increment in railway slab-culvert due to reinforcing by external prestressing

构建了顶板底部直线布置体外预应力筋加固盖板涵的计算模型,利用盖板涵加载变形前后的几何关系,探讨体外预应力筋应力增量与梁体挠度及混凝土压应变的关系,推导出了铁路运营阶段体外预应力加固盖板涵体外筋应力增量的表达式。可用该式计算在三分点荷载、均布荷载和集中荷载作用下用跨中挠度及混凝土压应变表达的体外筋应力增量。通过室内试验和相关文献验证了本文表达式的正确性,可为体外预应力加固盖板涵结构设计提供指导。

A model of a slab-culvert strengthened with external prestress in the bottom was established. The culvert deformations before and after the loading were investigated. The relationship among the stress increment in prestressing strands, the deflection and the compression stress in concrete was studied. An expression for this stress increment in railway operadon stage was deduced. The expression can be used to calculate the mid-span deflection and the stress increment in prestressing strands in the case of three-point loading,uniform loading or concentrated loading. This expression proved correct through lab test and previous references, and it can provide guidance for culvert structure strengthened with external prestress.