特大跨中承式钢箱桁架拱桥极限承载力研究

发布时间：2018-01-11 19:45

本文关键词：特大跨中承式钢箱桁架拱桥极限承载力研究　出处：《重庆交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：以某主跨519m的特大跨有推力中承式钢箱桁架拱桥为工程背景,对特大跨中承式钢箱桁架拱桥的弹性稳定、极限承载力及破坏机理进行研究。主要研究内容和结论如下:1对依托工程桥梁进行弹性稳定分析,研究不同荷载工况下结构的稳定安全系数和失稳模态,结果表明:特大跨中承式钢箱桁架拱桥最易出现面外同向侧倾和面外反对称弯扭失稳;拱圈与桥面系交界处平联布置较少部位是稳定薄弱区。2探讨了各结构参数对特大跨中承式钢箱桁架拱桥弹性稳定的影响,结果表明:“K”字形和菱形体系是拱圈最佳平联布置形式;相较于竖直吊杆,交叉斜吊杆和网状斜吊杆能显著提高结构的面内稳定性,而对面外稳定性影响较小;拱肋轴向刚度、拱肋面外抗弯刚度分别对结构的面内、面外稳定性有显著影响。3建立了以截面力与变形之间的弹塑性关系考虑材料非线性效应的特大跨中承式钢箱桁架拱桥极限承载力数值分析模型,对依托工程桥梁进行弹塑性大位移全过程分析,依据目标节点的荷载-位移曲线和构件塑性渐变发展状况,得出特大跨中承式钢箱桁架拱桥破坏的三个阶段:弹性阶段、塑性区扩展阶段、破坏阶段。4分析结构构件塑性扩展过程和最终塑性区分布位置,结果表明:至受载极限状态时,拱肋共出现四大塑性区,且塑性区在上、下弦杆交替出现;结构破坏源于拱肋渐次形成的四大塑性区充分发展时,结构变成了几何可变体系。5探讨了各影响因素对结构极限承载力的影响,结果表明:钢材强度和材料非线性效应对极限承载力有较大影响;相对面外初始几何缺陷,面内初始几何缺陷对极限承载力的影响更为显著;施工路径仅影响初始屈服荷载系数,对极限承载影响微小;整体温变作用和横风荷载对结构极限承载力的影响均较小。
[Abstract]:Based on a 519m large-span thrust steel box truss arch bridge, the elastic stability of the large-span through steel box truss arch bridge is studied. Research on ultimate bearing capacity and failure mechanism. The main research contents and conclusions are as follows: 1. Based on the analysis of the elastic stability of the supported bridge, the stability safety factor and instability mode of the structure under different load conditions are studied. The results show that the out-of-plane and out-of-plane anti-symmetric bending and torsional instability are most likely to occur in large-span through steel box truss arch bridges. The influence of structural parameters on elastic stability of large-span steel box truss arch bridge is discussed in this paper. The results show that "K" zigzag and rhombus are the best flat arrangement form of arch ring. Compared with vertical suspenders, cross inclined suspenders and reticulated slant suspenders can significantly improve the in-plane stability of the structure, but the influence of the opposite and outer stability is relatively small. The axial stiffness of the arch rib and the bending stiffness of the arch rib face are respectively on the in-plane of the structure. Based on the elastic-plastic relationship between cross-section force and deformation, a numerical analysis model of ultimate bearing capacity of large-span steel box truss arch bridge is established, in which the material nonlinear effect is taken into account in the elastoplastic relationship between cross-section force and deformation. The whole process of elastic-plastic large displacement is analyzed based on the load-displacement curve of the target node and the progressive plastic evolution of the member. It is concluded that there are three stages of failure of large-span steel box truss arch bridge: elastic stage, plastic zone extension stage, failure stage .4 analysis of structural members plastic expansion process and final plastic zone distribution. The results show that there are four plastic zones in the arch rib at the limit state of load, and the plastic zone is in the upper part and the lower chord appears alternately. When the structural failure originates from the full development of the four plastic zones gradually formed by the arch ribs, the structure becomes a geometric variable system. 5. The influence of various factors on the ultimate bearing capacity of the structure is discussed. The results show that the strength of steel and the nonlinear effect of material have great influence on the ultimate bearing capacity. Compared with out-of-plane initial geometric defects, the effect of in-plane initial geometric defects on ultimate bearing capacity is more significant. The construction path only affects the initial yield load coefficient, and has little effect on the ultimate bearing capacity. The effect of global temperature variation and crosswind load on the ultimate bearing capacity of the structure is small.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U441;U448.22

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