1 000m级中承式拱桥试设计研究

Trial Designing Study of Half-through Arch Bridge with Main Span of 1 000m

摘要:

针对拱桥随着跨径增大稳定性下降、且在移动荷载作用下容易发生剪切、弯曲变形等问题，提出了解决方案。在主梁和拱肋之间加入刚性杆件形成三角网，使三角网与拱肋、主梁形成连续的系列三角形。利用三角形稳定性，提高了主梁和拱肋的线刚度，从而提高结构的整体刚度。桥梁在移动荷载下，三角形必然受非节点荷载作用，降低了稳定性，设置吊杆、立柱以增加弹性约束，减少节点间的弯剪变形。此外，采用整体式节点，简化其构造，并采用预制拼装方法，施工方便快捷。给出了该方案的具体结构形式，阐述了力学原理，并对跨径1 008m中承式拱桥进行试设计。有限元结果表明：该方案拱桥强度、刚度、稳定性及动力特性均满足要求，较传统拱桥具有更好的力学性能及经济性。

Abstract:

The arch bridge stability declines when the span increases. The phenomena such as shearing and bending deformation tend to happen with moving load. Put the rigid bar between the main girder and arch rib to form a triangulation network， and then the triangulation network， arch rib and main beam compose a continuous series triangles. The stability of the triangle is used to improve the linear stiffness of the main beam and arch rib， so as to improve the overall stiffness of the structure. When the bridge is under moving load， the triangle must be subjected to the non-node load， which reduces the stability of the triangle. Therefore， suspender and columns are set to increase the elastic constraint and reduce bending and shear deformation between nodes. In addition， integral nodes can be used to simplify the structure with the proposed method of precast-assemble for construction which is convenient and fast . The concrete structure of the scheme is given， the mechanics principle is expounded， and the trial designing of half-through arch bridge with the main span of 1 008m is carried out. The finite element results show that the strength， stiffness， stability and dynamic characteristics of the presented arch bridge meet the requirements with a better mechanical properties than traditional arch bridges and proposed design is more economical.