主跨390m中承式钢桁提篮拱桥结构选型研究

Research on Structure Selection of Half-through Steel Truss Basket-handle Arch Bridge with 390m Main Span

为研究中承式钢桁提篮拱桥的结构选型和力学性能,文章以犀牛大桥为例,通过数理统计、归纳演绎和有限元数值模拟等方法,得到了犀牛大桥结构总体布置参数和力学特性。研究结果表明:犀牛大桥最佳矢跨比为1/4.5,合理拱轴线为悬链线,对应的拱轴系数为1.2;犀牛大桥为大跨度窄拱桥,拱桥宽跨比远小于规范限值,通过拱肋内倾3.5°、设置密布的纵向(K形)和横向(X形)联结系来保证结构施工和运营横向稳定性;拱脚桁肋弦杆应用了PBL加劲型矩形钢管混凝土新型结构和拱肋外包混凝土的方案,既改善了拱脚受力,又起到了防撞的作用;拱桥施工采用“化整为零”的加工制造和“集零为整”的拱肋节段整体缆索吊装的施工方案,成功解决了在施工现场场地狭小、运输条件差等山区大跨度拱桥难以施工的问题。研究可为类似工程提供参考。

In order to study the structural selection and mechanical properties of the half-through steel truss basket-handle arch bridge, this paper takes the Rhino Bridge as the research object, and obtains the overall layout parameters and mechanical properties of the rhino bridge structure through mathematical statistics, inductive deduction and finite element numerical simulation.The results show that the optimal rise-span ratio of Rhino Bridge is 1/4.5, the reasonable arch axis is catenary, and the corresponding arch axis coefficient is 1.2. This bridge is a long-span narrow arch bridge, and the width-span ratio of the arch bridge is far less than the specification limit. The lateral stability of the structure construction and operation is ensured by the 3.5° inclination of the arch rib and the densely distributed longitudinal(K-shaped) and transverse(X-shaped) connections. The new PBL stiffened rectangular concrete filled steel tube structure and the scheme of outsourcing concrete of arch rib are applied to the chord of arch foot truss rib, which not only improves the force of arch foot, but also plays a role in collision prevention. The arch bridge construction adopts the construction scheme of“break the whole into parts”manufacturing and“set zero as integer”integral cable hoisting of arch rib segments, which successfully solves the problem of difficult construction of long-span arch bridges in mountainous areas under the limited conditions of narrow construction site and poor transportation conditions. The indexes of the bridge meet the specification requirements, and the structure is safe and reliable, which provides design reference for similar projects.