夜郎湖大桥主拱圈悬臂浇筑施工挂篮优化分析

夜郞湖大桥为净跨径210m的上承式钢筋混凝土箱形拱桥,主拱圈采用斜拉扣挂悬臂浇筑法施工时,提出了一种新型三角桁架式挂篮。挂篮自重(含模板)82.5t,最大承重188t,初步设计采用4根锚吊杆,锚固在拱圈底板。为验证挂篮初步设计方案的可行性,采用MIDASCivil和MIDASFEA有限元软件分别建立挂篮整体模型和拱圈1号节段模型,分析挂篮及拱圈局部受力性能;并根据分析结果进行挂篮优化设计及分析。结果表明:初步设计方案下挂篮应力较大,拱圈节段在锚吊杆锚固附近的主拉应力过大,不能满足施工要求;将锚吊杆数量优化为2根,并将锚固位置移至拱圈顶板后,与初步设计方案相比,优化方案的经济性更好,拱圈节段受力更合理,新型挂篮的优化设计方案可行。

Optimization Analysis of Form Traveler Cantilever Casting Construction of Main Arch Ring of Yelang Lake Bridge

The Yelang Lake Bridge is a deck-type reinforced concrete box arch bridge with a net span of 210 m. A new type of form travelers with triangular trusses was proposed for the construction of the main arch ring by cantilever casting method with cable-stayed buckle method. The dead weight of form traveler (including the weight of formwork) is 82.5 t, and its maximum load is 188 t. In the preliminary design of the form traveler, four anchor suspenders were used to anchor the bottom of the arch ring. In order to verify feasibility of the preliminary design scheme of the form traveler, we established overall models of the form traveler and the section 1 models of the arch ring by using MIDAS Civil and MIDAS FEA finite element software, respectively, analyzed the overall mechanical properties of form traveler and the local mechanical properties of the arch ring, and optimized the design and analysis of the hanging basket according to the analysis results. The results show that, under the preliminary design scheme, the stress of form traveler is large, and the main tension stress of arch ring segment near anchorage of anchor suspender is too large to meet the requirements of construction. After the number of anchor suspender is optimized to 2 and the anchorage position is moved to the arch ring roof, the optimized scheme is more economical and the stress of the arch ring segment is more reasonable compared to the preliminary design scheme. The optimized design scheme of the new form traveler is feasible.