车撞混凝土桥墩精细化建模方法  

Refined modeling method for impact resistance research of bridge piers

作　　者：刘莉萍 刘万锋 郭建博 杜婷 邓锷[3] LIU Liping;LIU Wanfeng;GUO Jianbo;DU Ting;DENG E(School of Civil Engineering,Longdong University,Qingyang 745000,China;Provincial Key Laboratory of Loess Engineering Properties and Application in Universities,Qingyang 745000,China;School of Civil Engineering,Central South University,Changsha 410075,China)

机构地区：[1]陇东学院土木工程学院,甘肃庆阳745000 [2]甘肃省高校黄土工程性质及工程应用省级重点实验室,甘肃庆阳745000 [3]中南大学土木工程学院,湖南长沙410075

出　　处：《铁道科学与工程学报》2022年第6期1666-1674,共9页Journal of Railway Science and Engineering

基　　金：庆阳市科技成果转化资金资助项目(FT2019-05);2021年甘肃省高等学校创新基金项目(2021A-126);甘肃省教育科学“十三五”规划2020年度一般课题(GS[2020]GHB4803)。

摘　　要：车桥碰撞属于典型的非线性动力过程,采用理论方法通常难以求解。有限元方法(Finite element method,FEM)是研究车桥碰撞问题的重要工具,但其前处理过程涉及参数及算法众多,实际操作极其繁杂。为提升研究者建模效率,同时提高模型计算精度,提出一种精细化建模方法,该方法操作步骤为:1)以实际工程为背景,建立完整车辆-桥梁碰撞模型,并进行验证;2)进行网格敏感性分析,选择合适网格尺寸,取得计算效率与精度的平衡;3)对重力荷载进行初始加载,避免桥墩产生P-delta效应。研究结果表明:该精细化建模方法能较好地还原真实事故情况,并且碰撞过程满足能量守恒定律,沙漏能仅为总能量的2.3%;网格尺寸为35 mm和50 mm时桥墩的损伤情况、碰撞力和最大位移均比较接近,100 mm网格桥墩产生的碰撞力和最大位移偏大;ANSYS/LS-DYNA软件默认加载方式下的桥墩轴力呈现幅度较大的波动,最大轴力比预期轴力高75%,采取的重力初始化方法能够在一定程度上消除ANSYS/LS-DYNA软件的固有弊端,避免P-delta效应。该精细化建模方法能有效实现车桥碰撞模拟,并且能够取得良好的精度,可为未来的研究者提供建模思路,提升建模效率。Vehicle-bridge collision is a typical nonlinear dynamic process that is difficult to be solved by theoretical methods.Finite Element Method(FEM) is an important tool to study vehicle-bridge collision,but the preprocessing involves too many parameters and algorithms,and the actual operation is extremely complicated.To improve the modeling efficiency of researchers and the calculation accuracy of models,a refined modeling method was proposed.The operation steps of this method are as follows:1) a complete vehicle-bridge collision model is established and verified against an actual highway bridge;2) conducting grid sensitivity analysis and selecting an appropriate grid size to achieve a balance between computational efficiency and accuracy;3) carrying out initial loading of gravity load to avoid the P-delta effect of the bridge pier.The results showed that:1) the refined modeling method can well reconstruct the actual accident situation,and the energy conservation law is satisfied in the collision process.The hourglass energy is only 2.3% of the total energy;2) when the grid size is 35 mm and 50 mm,the damage,collision force and maximum displacement of the bridge pier are close,while the collision force and maximum displacement of bridge pier with a 100 mm grid are larger;and 3) the axial force of the pier under the default loading mode of ANSYS/LS-DYNA software fluctuates greatly,and the maximum axial force is 75% higher than the expected axial force.The gravity initialization method adopted can eliminate the inherent disadvantages of ANSYS/LS-DYNA software to a certain extent and avoid the P-delta effect.This refined modeling method can effectively realize vehicle-bridge collision simulation and achieve good accuracy,which can provide modeling ideas for future researchers and improve modeling efficiency.

关 键 词：有限元方法 车桥碰撞 接触算法 网格尺寸 重力荷载初始化 

分 类 号：U447[建筑科学—桥梁与隧道工程]