甘溪特大桥空腹三角区施工阶段受力分析  

Force Analysis of Open Web Triangular Area of Ganxi Super Bridge during Construction

作　　者：孙克强[1] 李百富 薛其林 SUN Keqiang;LI Baifu;XUE Qilin(CCCC Second Highway Engineering Co.,Ltd.,Xi’an,Shaanxi 710065,China;China Railway Bridge Research Institute Co.,Ltd.,Wuhan,Hubei 430034,China)

机构地区：[1]中交第二公路工程局有限公司,陕西西安710065 [2]中铁大桥科学研究院有限公司,湖北武汉430034

出　　处：《中外公路》2024年第4期180-189,共10页Journal of China & Foreign Highway

摘　　要：甘溪特大桥是主跨300 m的空腹式连续刚构桥,空腹三角区上弦箱梁采用可伸缩部分立柱后支配合挂篮悬浇,下弦箱梁采用全斜拉扣挂法配合挂篮悬浇。为分析采用该施工方法在三角区临时结构体系中的受力特性,总结三角区临时结构体系施工过程中受力变化规律,验证施工方法的有效性,并提出临时扣索和支撑立柱的最佳解除时机,采用有限元结构分析软件模拟全桥施工过程。结果表明:采用该工法施工,结构受力满足规范要求。三角区施工过程中,已施工的上、下弦箱梁以受压为主,受下一节段混凝土浇筑、立柱支顶、扣索张拉等工序影响,其间会出现短暂轻微受拉状态。三角区合龙完成时,箱梁截面以受压为主,局部存在轻微受拉。全桥合龙后三角区箱梁为全受压状态,较三角区合龙状态压应力增加明显。临时扣索、立柱拆除后,上、下弦箱梁出现了明显的应力重分布,但仍为全受压状态。临时扣索索力峰值均出现在三角区合龙完成前,三角区合龙后总体呈下降趋势,临近拆除前有所回升。后方临时立柱在施工过程中支撑力总体呈下降趋势,前方立柱呈上升趋势,临近拆除前立柱支撑力增幅均较大。经比选,推荐全桥合龙后先拆立柱、再拆扣索。Ganxi Super Bridge is an open web continuous rigid frame bridge with a main span of 300 m,and the upper chord box girder in the open web triangular area adopts the post support of a few telescopic columns with the hanging basket for suspension casting.The lower chord box girder adopts the full cable-stayed buckle method with a hanging basket for suspension casting.To analyze the force characteristics of the temporary structural system in the triangular area during the construction process using this method,the force variation law during the construction process of the temporary structural system in the triangular area was summarized to verify the effectiveness of the construction method,and the optimal time to remove temporary buckle cables and support columns was proposed.The finite element structural analysis software was used to simulate the entire bridge construction process.The results show that the force of the structure meets the specification requirements by using this construction method.During the construction of the triangular area,the upper and lower chord box girders constructed are mainly compressed,and there will be a temporary and slight tension state during this period affected by the concrete pouring of the next section,column roof support,buckle cable tensioning,and other processes.When the closure of the triangular area is completed,the section of the box girders is mainly compressed,and there is slight tension in some parts.After the closure of the whole bridge,the box girders in the triangular area are in the full compression state,and the compressive stress increases significantly compared with the closure state in the triangular area.After the removal of temporary cables and columns,the upper and lower chord box girders have obvious stress redistribution,but they are still in a full compression state.The peak value of temporary cable force appears before the closure of the triangular area.After the closure of the triangular area,it generally shows a downward trend and rises near the demoli

关 键 词：甘溪特大桥 空腹式连续刚构桥 三角区 临时扣索 支撑立柱 受力分析 

分 类 号：U448.23[建筑科学—桥梁与隧道工程]