钢桥面板顶板与U肋接头疲劳效应分析

A Numerical Study on the Fatigue Effect of Trough-Deck Plate Weld Joint to Steel Bridge Deck System

针对钢桥面板顶板与U肋焊接接头,开展疲劳应力有限元分析,研究该构造细部的疲劳效应,为钢桥面板抗疲劳设计与维护提供参考。建立了钢桥面板板壳单元模型,以焊趾处热点应力为指标,分析过焊孔对接头受力影响以及轮载作用下顶板应力历程及应力幅值。结果表明,板壳单元有限元模型局部细化网格尺寸不超过1.0倍顶板厚度,可得出稳定的热点应力计算值。过焊孔的设置削弱了横隔板对顶板的支撑作用,使过焊孔区域顶板应力有所增大。不设置过焊孔时,接头处由于存在较大几何与刚度突变,应力集中更加明显。热点应力对轮载的横向位置比较敏感。轮载在纵桥向与横桥向的应力影响范围都比较小,可忽略车轴、轮重及车辆间的应力叠加效应。

In this paper, a finite element analysis is conducted to study the fatigue effect of trough-deck weld ioint in steel bridge deck system. Shell elements are applied to model the deck system,and the stress at the hot spot is used as an indicator in the analysis. The stress variation of deck plate under the wheel load is monitored,and the influence of access hole on the stress of trough-deck joint is evaluated. Results show that hot spot stress is stable when the mesh size of the model is smaller than the thickness of deck plate. Access hole weakens the reinforcing effect of cross-beam to deck plate, which results in the increase of stress and deformation of deck plate around access hole. For the model without access hole,there is a relatively large change on geometry and stiffness,the stress concentration on trough-deck weld joint is more obvious. Also,the stress at the hot spot is sensitive to the lateral position of wheel load. The stress variations along longitudinal and transverse direction are both relatively small, and thus the interactive influence among axles, wheels and vehicles can be ignored.