【摘要】 北盘江大桥主桥为(82.5+220+290+220+82.5)m的预应力混凝土空腹式连续刚构桥,其三角区下弦采用挂篮辅以扣索施工,上弦采用支撑于下弦顶面的支架现浇施工,后续梁段采用挂篮悬臂浇筑施工。为研究该桥在施工过程中的受力特性,建立全桥有限元模型,对临时扣索张拉及拆除、预应力张拉、后续梁段施工等工况进行计算分析。结果表明,由于梁段浇筑、扣索张拉、预应力张拉的影响,上弦支架部分应力集中;三角区扣索索力变化不大,基本上随施工进度递减;中跨合龙后,支架拆除对主梁及斜腿受力影响不大,扣索拆除使主梁及斜腿应力峰值有效降低。更多还原

【Abstract】 The main bridge of Beipan River Bridge is a prestressed concrete open-web continuous rigid-frame bridge with span arrangement(82.5+220+290+220+82.5) m.The lower chord of the triangle area of the bridge was concreted by the form traveler by the aid of fastening stays,the upper chord was concreted in situ on scaffolding supported on the top of the lower chord and the successive segments of the main girder were cantileveredly concreted also by the form traveler.To study the mechanical behavior of the bridge in the construction process,the finite element model of whole bridge was established and the load cases of tensioning and removing of the temporary fastening stays,tensioning of prestressing and construction of the successive segments were calculated and analyzed.The results of the calculation and analysis show that owing to the influence of concreting of the segments and tensioning of the fastening stays and prestressing,the stress in the part of the scaffolding supporting the upper chord is concentrated,the variations of cable forces in the fastening stays in the triangle area are not great and basically become less and less with the proceeding of the construction.After the closure of the central span is completed,the influence of removing of the scaffolding on the force conditions of the main girder and slant legs is not much and the removing of the fastening stays effectively reduces the peak values of the stress in the girder and legs.更多还原