600 m级四线铁路新型桁架桥力学原理及性能

Mechanical Principle and Properties of a 600 m New Truss Bridge for Four Line Railway

摘要:

对铁路桥梁来说，随着跨度的增大会导致桥梁刚度下降及梁端转角超限等问题，限制了超大跨径高速铁路桥梁的发展，为突破此瓶颈，提出了超大跨径新型桁架桥，该结构体系具有良好的力学性能，而且其刚度远超拱桥，特别适用于铁路桥梁。新体系桁架桥在桁架角点处设置刚度很大的斜杆，有效约束主梁线位移，在中部设置双层桁架，在两侧设置三角桁架，从而增强了结构的抗弯能力、刚度及稳定性。此外，该结构体系以钢结构为主，可采用预制拼装的方法，施工方便快捷。阐述了新型桁架桥的结构形式及其力学原理，并利用有限元软件Midas/Civil对650 m新型桁架桥进行分析研究，结果表明：新型桁架桥强度、竖向刚度、梁端转角、稳定性、整体性及动力特性均满足要求，且较传统拱桥具有更好的力学性能。

关键词:高速铁路桥;新型桁架桥;有限元;刚度;梁端转角

Abstract:

For railway bridges， the increase of span will lead to the decrease of bridge stiffness and the overrun of beam end angle， which limits the development of super long-span high-speed railway bridges. In order to break through this bottleneck， a super long-span new truss bridge is proposed. The structural system has good mechanical properties and its stiffness is much higher than that of the arch bridge， which is especially suitable for railway bridges. In the new system truss bridge， inclined rods with a large stiffness are set at the angle of the truss to effectively restrain the line displacement of the main girder， and double trusses are set in the middle as well as triangular trusses are set on both sides， so that the structure has a better flexural capacity， stiffness， and stability. In addition， the bridge is mainly steel structure， which can be prefabricated and assembled， Therefore the construction is convenient and fast. The structural form and mechanics principle of the new truss bridge are described. By using the finite element software Midas/ Civil， the structure of a 650 m half through span reduction truss bridge is analyzed and studied. The results show that the strength， vertical stiffness， beam end angle， stability， integrity， and dynamic characteristics of the half through span reduction truss bridge satisfy the requirements， and it has better mechanical properties and economy than the traditional arch bridge.

Key words:high speed railway bridge;new truss bridge;finite element;stiffness;beam end angle