拱形钢桁梁桥结构分析与构造细节设计

Structural Analysis and Detail Design of Arched Steel Truss Beam Bridge

钢桁架结构通常节点密集,设计复杂多样。现结合绍兴市某拱形下承式钢桁梁桥,介绍其总体布置、结构设计,并基于有限元分析理论,采用通用有限元软件ANSYS对该桥的活荷载计算模式、上下弦杆节点、梁端节点、横肋与下弦杆及小纵梁相交节点的构造细节设计进行计算对比分析。研究表明,整体式节点设计中节点板处竖杆腹板采用渐变断开式设计,可满足应力、屈曲稳定的要求;拱梁结合点处的应力集中范围与大小受圆弧半径、支点相对位置的影响,支点靠近拱梁结合点对结构受力有利;支撑桥面板的横肋下翼缘可与小纵梁、下弦杆采用半刚性节点,虽一定程度上会增大翼缘断开范围腹板应力,但整体应力水平较低。

Steel truss structures usually have dense joints and complex designs.Combined with an arched through steel truss beam bridge in Shaoxing City,its overall layout and structural design are introduced.And based on the finite element analysis theory,the general finite element software ANSYS is used to calculate,compare and analyze the live load calculation model,upper and lower chord joints,beam end joints,transverse rib and lower chord joints,small longitudinal girder intersection joints and the structural detail design.The research shows that the gradual break design used for the vertical bar web at the joint plate in the integral joint design can satisfy the requirements of stress and buckling stabilization.The range and magnitude of stress concentration at the joint point of the arch beam are affected by the radius of the arc and the relative position of the fulcrum.The fulcrum close to the joint point of the arch beam is beneficial to the structural stress.The lower flange of the transverse rib supporting the bridge deck can adopt the semi-rigid joints with the small longitudinal beam and the lower chord.Although the web stress in the flange breaking range will be increased to some extent,the overall stress level is low.