腹板受损U型梁承载力及破坏机理分析

Analysis of Bearing Capacity and Failure Mechanism of U-type Girder with Damaged Web

研究目的:为研究腹板损伤情况下U型梁的竖向承载力,采用显式动力分析软件LS-DYNA建立简支U型梁精细有限元模型,并根据足尺模型试验结果对有限元模型进行校核验证。通过在U型梁翼缘一定范围内施加侧向位移荷载,模拟U型梁腹板在极端状况下不同程度的损伤,并对不同腹板损伤程度的U型梁承载力进行分析。研究结论:(1)随着腹板损伤程度的提高和损伤范围的扩大,U型梁竖向变形刚度和承载力呈显著下降趋势,最大下降幅度达到53%和44%;(2)随着底板挠度增加,U型梁受损一侧腹板首先出现较大的面外变形,在腹板受损薄弱截面继而出现竖向贯通裂缝,最终结构发生非对称弯曲失稳破坏;(3)U型梁腹板对于结构整体竖向承载力贡献明显,在桥梁结构设计和运营阶段对腹板的防护设计要尤为重视;(4)本文研究可为U型梁桥的防撞设计提供一定参考。

Research purposes:In order to investigate the vertical bearing capacity of U-type girder under the condition of web damage,LS-DYNA was employed to establish the refined finite element model of a simply supported U-type girder,and the model was verified by full-scale model test results.Through applying lateral displacement within a certain range of the flange of U-type girder,web damage at different levels was simulated.Moreover,the vertical bearing capacities of U-type girder with different levels of web damage were investigated.Research conclusions:(1)The deformation stiffness and vertical bearing capacity of U-type girder decreased up to53%and 44%with the increase of the web damage level and range.(2)As the deflection of bottom slab increasing rapidly,significant out-plane deformation appeared at the damaged side firstly,vertical penetrating cracks appeared in weak section of damaged web subsequently,and the structure lost its capacity in the way of asymmetric bending buckling finally.(3)The web of U-type girder contributes significantly to the vertical bearing capacity of the structure.Special attention should be paid for protecting U-type girder’s web at the design and operation stage.(4)The research results will provide reference for the anti-collision design of U-type girder.