侧向撞击作用下U形梁抗倾覆稳定性与失效模式

在对国内外相关规范关于桥梁抗倾覆稳定性计算方法与脱轨荷载调查分析的基础上,计算了U形梁在保持抗倾覆稳定性下的最大侧向碰撞荷载,对比了欧洲规范EN 1991-1-7:2006和TB 10002-2017《铁路桥涵设计规范》中U形梁的抗倾覆稳定性计算式。基于有限元分析方法对腹板侧向承载力进行仿真分析,明确了U形梁在侧向撞击作用下的失效模式。研究结果表明:2种规范计算得到的最大侧向碰撞荷载有所差异,但均大于3.5 MN;列车脱轨情况下的脱轨荷载模式和作用位置对U形梁抗倾覆稳定性的影响显著;U形梁跨中区域加载侧的底板和腹板在侧向位移加载模式下发生了大面积塑性损伤,腹板还发生了明显的侧向变形;U形梁在侧向撞击作用下的失效模式表现为腹板侧向承载力达到极限而发生破坏,通过拟静力分析确定U形梁腹板侧向极限承载力为1.5 MN,结构整体不会倾覆失稳。在设计和使用阶段应对U形梁腹板的损伤和承载力评估予以重点关注。

Stability Against Overturning of U-shaped Girder and Failure Mode Under Lateral Collision

Based on the investigation and analysis of the calculation method of stability against overturning and derailment load in relevant codes at home and abroad,the maximum lateral collision load of U-shaped girder under the condition of maintaining stability against overturning was calculated.The calculation formulas of stability against overturning of U-shaped girder in European code EN 1991-1-7:2006 and TB 10002-2017 Code for Design on Railway Bridge and Culvert were compared.Based on the finite element analysis method,the lateral bearing capacity of web was simulated,and the failure mode of U-girder under lateral collision was defined.The research results show that the maximum lateral collision loads calculated by the two codes are different,but they are greater than 3.5 MN.The derailment load mode and action position under the condition of train derailment have significant influence on the stability against overturning of U-shaped girder.The bottom and web at the mid-span loading side of U-shaped girder have large area plastic damage under the lateral displacement load mode,and the web also has obvious lateral deformation.The failure mode of U-girder under the lateral collision is that the lateral bearing capacity of web reaches the limit and the failure occurs.Through the quasi-static analysis,the ultimate bearing capacity of U-girder web is determined to be 1.5 MN,and the whole structure will not overturn and lose stability.In the design and service stage,the damage and bearing capacity evaluation of U-shaped girder web should be paid more attention.