轨道交通复合截面连续 U 梁桥 设计与施工

上海市轨道交通 17 号线在国内首次采用预应力混凝土 U 型+箱型复合截面连续梁桥，设计中针对常规 U 型截面梁适用跨径有限，难以用于大跨连续梁桥的难题，提出箱型截面与 U 型截面上下组合形成的复合截面， 通过有限元方法分析研究截面的力学特性，明确其设计方法及控制指标，并应用于主跨跨径 70 m 的连续 U 梁桥。 采用预制节段悬臂拼装，施工周期短，对周边环境影响小，施工质量优良，经济效益显著。施工期间的应力跟踪 监测以及成桥后的静载试验结果表明：连续 U 梁桥的设计合理、施工可靠、结构安全。

Design and Construction of a Continuous Through Girder Bridge with a Composite U-Shape Section for the Rail Transit

A prestressed concrete continuous beam bridge with a composite section that combines a U-shape section with a box section is first constructed for the No.17 rail transit line in Shanghai. To increase the applicable span of a through girder with a U-shape section to satisfy the requirements of large-span bridges, a continuous through girder with a new section composed of upper U-shape and lower box sections is introduced. The mechanical properties of the girder are analyzed using the finite element method, and its design procedure and standards are subsequently determined. The main span of the continuous through girder bridge with the composite section is 70 m. This new segmental concrete bridge was constructed using the free cantilever technique and incremental launching of precast segments, shortening the construction period, reducing its environmental impact, guarantees the segment quality, and distinguishes the financial gains. The stress changes in the construction period and results of a dead load test on a completed segmental bridge were analyzed, demonstrating an excellence in the design and construction of the bridge and verifying its safety.