车辆撞击作用下RC桥墩动力响应

采用LS-DYNA建立了钢筋混凝土(RC)桥墩水平撞击有限元模型,简要介绍了有限元建模技术及相关参数的取值,并通过与水平撞击试验结果进行对比,验证了目前较为常用的2种混凝土本构模型和钢筋本构模型的有效性,进而验证了有限元结果的有效性,并进一步研究了桥墩在等代车辆撞击作用下的破坏机理,分析了与桥墩动力响应和损伤程度有关的影响参数。结果表明:对于水平撞击试验而言,采用MAT_SCHWER_MURRAY_CAP_MODEL(145^#)混凝土和MAT_PLASTIC_KINEMATIC(3^#)钢筋材料模型构建的有限元模型能够更加准确地反映RC桥墩在等效车辆撞击作用下的动力特性、剪切破坏模式和损伤分布; 在等代车辆撞击作用下,混凝土的损伤累积主要集中于墩底剪切带处,而桥墩其他部位的混凝土未出现明显损伤累积; 参数分析结果表明,增大撞击质量能够显著增大撞击荷载峰值、桥墩变形和损伤程度; 提高撞击位置会使桥墩破坏模式由局部剪切破坏转变为整体弯曲(或弯剪)破坏; 在相同撞击冲量下,撞击荷载峰值、桥墩变形和耗能会随撞击速度增加而增大。

Dynamic Response of RC Bridge Pier Under Vehicle Impact Load

Through LS-DYNA, the finite element model of reinforced concrete(RC)pier under horizontal impact was established, and the finite element modeling technology and the value of relevant parameters were briefly introduced. By comparing with the results of horizontal impact test, two kinds of commonly used constitutive models of concrete and reinforcement were verified, so the validity of the finite element results was verified. The failure mechanism of the bridge pier under the impact of equivalent vehicles was further studied, and the influence parameters related to the dynamic response and damage degree of the bridge pier were analyzed. The results show that for the horizontal impact test, the finite element model established by MAT_SCHWER_MURRAY_CAP_ MODEL(145^#)concrete and MAT_PLASTIC_KINEMATIC(3^#)reinforced material model can more accurately reflect the dynamic characteristics, shear failure mode and damage distribution of RC piers under the impact of equivalent vehicles. Under the impact of equivalent vehicles, the damage accumulation of concrete is mainly concentrated in the shear zone at the pier bottom, while no obvious damage accumulation occurs in other parts of the pier. Parameter analysis shows that increasing the impact mass can significantly increase the peak value of impact load, pier deformation and damage degree. Increasing the impact position will change the failure mode of pier from local shear failure to global bending(or bending shear)failure. Under the same impact impulse, the peak value of impact load, pier deformation and energy consumption will increase with the increase of impact velocity.