基于裂纹扩展分析的正交异性钢桥面板疲劳响应研究

Fatigue Response of Orthotropic Bridge Deck Based on Crack Propagation Analysis

轮载下正交异性钢桥面板的局部效应显著,相邻各疲劳易损细节的疲劳行为相互影响,特别是随着某个细节裂纹扩展,相邻细节疲劳应力可能增大,桥面板疲劳性能呈加速劣化趋势。疲劳应力响应及桥面板性能劣化评估已成为钢桥面板运营期面临的挑战和亟待进行的工作。为合理评估开裂正交异性钢桥面板的疲劳性能演化情况,基于既有足尺模型疲劳试验,综合采用有限元程序ANSYS和Franc3D的多尺度交互技术模拟钢桥面板典型疲劳易损细节裂纹扩展行为,探究裂纹扩展过程中各关键细节(顶板与U肋连接焊缝、U肋与横隔板连接焊缝、横隔板开孔处)的疲劳应力响应和演化情况。结果表明:裂纹扩展对正交异性钢桥面板局部变形(挠度)影响很小;不同开裂模式下,各细节处应力变化规律存在较大差异,裂纹扩展的响应呈现出局部特征,仅对最近的细节主拉应力有一定的增大效应;顶板与纵肋焊缝连接处和横隔板开孔处的裂纹扩展对相邻疲劳细节的主拉应力提升效果较显著,可能导致该处萌生裂纹。研究结果可为开裂后正交异性钢桥面板的疲劳性能评估提供参考。

The local effects of orthotropic steel decks(OSDs)under wheel loading can be significant and fatigue behavior of adjacent details interacts with neighbouring ones.The fatigue stress in adjacent details may increase as a crack in one detail propagates,leading to an accelerated deterioration trend in the fatigue performance of the OSDs.Fatigue stress response and the assessment of performance degradation have become challenges and pressing tasks in the service of steel bridge decks.A multi-scale interactive approach was employed to assess the fatigue evolution of cracked OSDs based on existing full-scale model fatigue tests.This approach comprehensively utilized the finite element software ANSYS and Franc3D to simulate the crack propagation behavior of typical fatigue prone details in steel bridge decks,to investigate the fatigue stress response and evolution of various critical details(such as the top plate-to-U-rib weld,U-rib-to-crossbeam weld,and crossbeam hole)during the process of crack propagation.The results indicate that crack propagation has minimal impact on the local deformation(deflection)of OSDs.Different details exhibit significant variations in stress changes due to being in distinct cracking modes,and the response of crack propagation displays local characteristics,only having a moderate increasing effect on the principal tensile stress of the nearest detail.Crack propagation at the top plate-to-longitudinal rib weld junction and at the crossbeam hole significantly increases the principal tensile stress in adjacent details,potentially leading to crack initiation at those locations.These findings can serve as a reference for the assessment of fatigue performance in cracked OSDs.