超高车辆与箱梁立交桥碰撞简化计算模型评估分析

为了考察受超高车辆撞击装配式钢筋混凝土箱梁跨线桥的冲击动力和破坏行为，以一起近来发生的实际工程事故为案例进行精化有限元数值分析，并提出了双质量-并联弹簧（double mass-parallel spring, DM-PS）简化车辆模型，以有效地模拟超高车辆与桥梁的非对心碰撞行为。所建议DM-PS简化模型的有效性通过与两种广泛使用的车辆模型包括全尺（full scale, FS）模型和简单刚体（simple rigid, SR）模型的比较而得到充分地评估。计算结果表明：采用FS模型可得到与事故现场照片基本一致的跨线桥撞击区域破坏特征；SR模型高估结构的局部破坏，弱化结构的整体变形；DM-PS模型对于预测结构破坏具有较高的准确性。因此，所提出的DM-PS模型为超高车辆撞击桥梁结构防护设计提供了一个简单有效的分析手段。在此基础上，利用DM-PS模型进行了详细的结构行为参数分析，深入考察了车辆撞击速度、撞击质量、撞击位置以及结构形式等效应。所得到的结论为：相比撞击质量，结构的冲击动力行为对于撞击速度有更高的敏感性；跨中受撞和边跨受撞的变形和破坏模式有较大差异，边跨受撞对于单侧支座损伤更严重；...

Analysis on assessment of simplified compuational models for collision of over-height vehicles with box-girder flyovers

To investigate the dynamical responses and failure behaviors of prefabricated reinforced-concrete (RC) box-girder flyovers caused by collision of over-height vehicles, a recent actual engineering accident is taken as an example to carry out refined numerical analysis by the finite element method, and a double mass-parallel spring (DM-PS) simplified vehicle model is proposed to effectively simulate the eccentric collision between the over-height vehicle and bridge superstructures. The effectiveness of the proposed DM-PS model is fully assessed through comparison with two widely-employed vehicle models, i.e., a full-scale (FS) model and a simple rigid (SR) model. The comparisons display that the failure characteristics of the collision area can be obtained by using the FS model, which is basically consistent with the photos of the accident scene; the SR model overestimates the local damage of the structure and underestimates the overall structural deformation; while the DM-PS model has high accuracy for predicting the structural failure. Therefore, the proposed DM-PS model can provide a simple and effective analysis tool for the protection design of bridge structures subjected to over-height vehicle collision. On this basis, a detailed parameter analysis of the structural behaviors is carried out by the DM-PS model, and the effects of vehicle collision velocity, mass, position, and structural form are investigated in depth. It is shown that the structural sensitivity of the impact dynamic behavior to the collision velocity of the vehicle is significantly greater than that of the collision mass of the vehicle; the deformation and failure modes of mid-span collision and side-span collision are quite different, and the damage of side-span collision to one side base is more serious; the box plate and reinforced plate in the box girder can effectively improve the structural impact resistance. Numerical results and conclusions can provide a reference for the crashworthiness design of bridges. The critical information of the finite element analysis process is presented in detail.