Vehicle-Bridge Interaction Simulation and Damage Identification of a Bridge Using Responses Measured in a Passing Vehicle by Empirical Mode Decomposition Method

To prevent early bridge failures, effective Structural Health Monitoring (SHM) is vital. Vibration-based damage assessment is a powerful tool in this regard, as it relies on changes in a structure’s dynamic characteristics as it degrades. By measuring the vibration response of a bridge due to passing vehicles, this approach can identify potential structural damage. This dissertation introduces a novel technique grounded in Vehicle-Bridge Interaction (VBI) to evaluate bridge health. It aims to detect damage by analyzing the response of passing vehicles, taking into account VBI. The theoretical foundation of this method begins with representing the bridge’s superstructure using a Finite Element Model and employing a half-car dynamic model to simulate the vehicle with suspension. Two sets of motion equations, one for the bridge and one for the vehicle are generated using the Finite Element Method, mode superposition, and D’Alembert’s principle. The combined dynamics are solved using the Newmark-beta method, accounting for road surface roughness. A new approach for damage identification based on the response of passing vehicles is proposed. The response is theoretically composed of vehicle frequency, bridge natural frequency, and a pseudo-frequency component related to vehicle speed. The Empirical Mode Decomposition (EMD) method is applied to decompose the signal into its constituent parts, and damage detection relies on the Intrinsic Mode Functions (IMFs) corresponding to the vehicle speed component. This technique effectively identifies various damage scenarios considered in the study.

Self-excited vibration problems of maglev vehicle-bridge interaction system

The self-excited vibration problems of maglev vehicle-bridge interaction system were addressed, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the coupled model containing the quintessential parts was built, and the mechanism of self-excited vibration was explained in terms of energy transmission from levitation system to bridge. Then, the influences of the parameters of the widely used integral-type proportion and derivation(PD) controller and the delay of signals on the stability of the interaction system were analyzed. The result shows that the integral-type PD control is a nonoptimal approach to solve the self-excited vibration completely. Furthermore, the differential-type PD controller can guarantee the passivity of levitation system at full band. However, the differentiation of levitation gap should be filtered by a low-pass filter due to noise of gap differentiation. The analysis indicates that a well tuned low-pass filter can still keep the coupled system stable.

Dynamic Impact Factor Induced by Idling Vehicle-Bridge Coupling Vibration

To analyze the impact effect induced by vehicle-bridge coupling vibration during traffic congesting, hundreds and thousands of congestion scenarios consisting of various vehicle platoons were collected and used to develop vehicle models as well as traffic congestion load models. Furthermore, the idling vehicle-bridge coupling model was established by the finite element method and the congestion models were applied to calculate dynamic impact factors. Compared with the value specified in Chinese codes, the calculated values were 1.15-2.67 times as large as the latter, which indicates the impact factors caused by idling vehicle-bridge coupling under congestion situations were much larger than those in normal traffic conditions. As a result, a calibration factor of 1.7 was recommended for bridge design or evaluation when considering vehicle-bridge coupling vibration under heavy traffic congestion. The proposed analytical model, analysis method, and results could also be beneficial references to further investigation in this field.

Safety evaluation of a vehicle–bridge interaction system using the pseudo-excitation method

A method for analysing the vehicle-bridge interaction system with enhanced objectivity is proposed in the paper, which considers the time-variant and random characteristics and allows finding the power spectral densities(PSDs) of the system responses directly from the PSD of track irregularity. The pseudo-excitation method is adopted in the proposed framework, where the vehicle is modelled as a rigid body and the bridge is modelled using the finite element method. The vertical and lateral wheel-rail pseudo-excitations are established assuming the wheel and rail have the same displacement and using the simplified Kalker creep theory, respectively. The power spectrum function of vehicle and bridge responses is calculated by history integral. Based on the dynamic responses from the deterministic and random analyses of the interaction system, and the probability density functions for three safety factors(derailment coefficient, wheel unloading rate, and lateral wheel axle force) are obtained, and the probabilities of the safety factors exceeding the given limits are calculated. The proposed method is validated by Monte Carlo simulations using a case study of a high-speed train running over a bridge with five simply supported spans and four piers.

Maglev self-excited vibration suppression with a virtual sky-hooked damper

This work addresses the problem of self-excited vibration,which degrades the stability of the levitation control,decreases the ride comfort,and restricts the construction cost of maglev system.Firstly,a minimum model containing a flexible bridge and a single levitation unit is presented.Based on the simplified model,the principle underlying the self-excited vibration is explored.After investigations about the energy transmission between the levitation system and bridge,it is concluded that the increment of modal damping can dissipate the accumulated energy by the bridge and the self-excited vibration may be avoided.To enlarge the equivalent modal damping of bridge,the sky-hooked damper is adopted.Furthermore,to avoid the hardware addition of real sky-hooked damper,considering the fact that the electromagnet itself is an excellent actuator that is capable of providing sufficiently fast and large force acting on the bridge to emulate the influence of the real sky-hooked damper,the technique of the virtual sky-hooked damper is proposed.The principle underlying the virtual sky-hooked damper by electromagnet is explored and the vertical velocity of bridge is estimated.Finally,numerical and experimental results illustrating the stability improvement of the vehicle-bridge interaction system are provided.

高速磁浮车-轨耦合系统动态机理与振动响应

对高速磁浮车-轨耦合系统进行动态机理和振动响应研究。首先,对高速磁浮中的各类耦合关系进行建模;其次,分别分析了动态和静态条件下的车-轨耦合作用机理;然后,建立了高速磁浮车-轨耦合动力学有限元模型;最后,对磁浮列车高速通过桥梁时轨道梁、功能件的动力响应和车-轨共振速度进行分析。结果表明:高速运行时车-轨作用频率不同,长时间共振速度下运行时车-轨振动明显增大;若桥梁动力放大系数小于1.2,则基频比最小值为1.16;若桥梁动力放大系数小于1.3,则基频比最小值为1.04。

磁轨关系建模对高速磁浮动力学仿真的影响

为研究磁轨关系建模方式对高速磁浮列车动力学仿真的影响,本文首先建立将磁轨关系简化为2、4、12三种等效集中力数量的单电磁铁模型,计算单电磁铁模型在正弦轨道不平顺下受到的悬浮力,得到不同相位、不同角频率的轨道不平顺激扰对悬浮力的影响。其次通过修正后的德国高速低干扰谱设置轨道不平顺,对比分析不同单电磁铁模型的悬浮力变化;并建立高速磁浮列车动力学模型,通过动力学仿真计算得到列车车体与摆杆间接口的垂向载荷数据,最后通过雨流计数法得到接口载荷幅值数据并进行分析。研究结果表明:等效集中力数量对仿真计算中第1位摆杆接口载荷的影响较大,随着等效集中力数量的增加,所得载荷数据中大幅值循环占比逐渐减小,小幅值循环占比逐渐增大。在低速时等效集中力数量对于仿真结果的影响较为显著,而在时速600 km时影响较小。

An Analysis of the Dynamic Behavior of Damaged Reinforced Concrete Bridges under Moving Vehicle Loads by Using the Moving Mesh Technique

This work proposes a numerical investigation on the effects of damage on the structural response of Reinforced Concrete(RC)bridge structures commonly adopted in highway and railway networks.An effective three-dimensional FE-based numerical model is developed to analyze the bridge’s structural response under several damage scenarios,including the effects of moving vehicle loads.In particular,the longitudinal and transversal beams are modeled through solid finite elements,while horizontal slabs are made of shell elements.Damage phenomena are also incorporated in the numerical model according to a smeared approach consistent with Continuum Damage Mechanics(CDM).In such a context,the proposed method utilizes an advanced and efficient computational strategy for reproducing Vehicle-Bridge Interaction(VBI)effects based on a moving mesh technique consistent with the Arbitrary Lagrangian-Eulerian(ALE)formulation.The proposed model adopts a moving mesh interface for tracing the positions of the contact points between the vehicle’s wheels and the bridge slabs.Such modeling strategy avoids using extremely refined discretization for structural members,thus drastically reducing computational efforts.Vibrational analyses in terms of damage scenarios are presented to verify how the presence of damage affects the natural frequencies of the structural system.In addition,a comprehensive investigation regarding the response of the bridge under moving vehicles is developed,also providing results in terms of Dynamic Amplification Factor(DAFs)for typical design bridge variables.

考虑内部空腔的单箱多室轨道梁温度场数值模拟方法

磁浮交通系统的相关规范对轨道梁的温度变形有着极其严格的要求。目前已有的轨道梁温度场研究中,对混凝土箱梁内部空腔的边界条件大多进行简化处理,计算结果难以满足磁浮规范的精度要求。为解决这一问题,基于大跨度公路-磁浮合建桥的可能性,提出了考虑内部空腔作用的单箱多室轨道梁温度场的数值模拟方法。以湖南郴州赤石大桥为背景,建立了大气环境下由腔内空气与混凝土流固耦合传热的单箱四室轨道梁模型,并用COMSOL有限元软件进行数值分析。将数值模拟结果与实测温度数据进行对比,结果显示全域全时程最大相对误差仅为4.03%,表明提出的数值模拟方法可以用于轨道梁温度场分析;与简化模拟方法相比,该方法能够满足公路-磁浮合建桥的轨道梁的精度要求;研究明确了内部空腔对于轨道梁温度场的影响。

车-桥耦合振动2019年度研究进展

车辆运行于桥梁上,车辆与桥梁之间相互作用、相互影响,称为车-桥耦合振动。车-桥耦合振动理论为桥梁设计、线路运营、维护及管理提供了理论基础、分析方法和评估手段,具有重要的工程应用价值。自20世纪起,众多学者已经开展了大量卓有成效的研究工作。近年来,中国交通运输行业飞速发展,稠密的交通网、紧张的运能、复杂的线路条件等因素对传统的车-桥耦合振动理论提出了新的挑战,也催生了相关先进理论技术的发展。为了促进该领域后续更加全面深入的基础研究,对轨道不平顺作用下的车-桥耦合振动、轨道不平顺作用下的车-桥耦合随机振动、风车-桥耦合振动、地震车-桥耦合振动、磁浮交通车辆轨道梁耦合振动等5个方面在2019年的研究进展进行了总结,并对研究热点和展望进行了梳理。

常导磁浮列车动态磁轨关系研究

研究常导磁浮列车动态磁轨关系,从车辆-轨道耦合动力学思想出发,结合特定悬浮控制规律,建立考虑微小波动时的单磁铁动态悬浮控制数学模型;通过悬浮控制的磁浮车辆-轨道的相互作用研究具有特定悬浮控制系统的车辆在运行过程中的动态磁轨关系。研究结果表明:间隙反馈系数对悬浮系统的初始状态影响很小;当系统受到外界激扰时,间隙反馈系数对悬浮状态影响变大,随着间隙反馈系数的增大,悬浮间隙的动态变化趋于稳定;车辆在桥梁上运行时,悬浮间隙一直处于波动状态,且车辆在进、出桥梁时波动最大,动态悬浮间隙与车速成正比,车辆载重与桥梁振动幅度成正比。当车速超过250km/h后,动态悬浮间隙受车速的影响迅速增大,磁轨关系的线圈电流、电磁悬浮力的变化与悬浮间隙变化基本一致。

磁浮车轨耦合系统稳定性分析

车轨耦合振动现象从磁浮列车诞生起,时至今日都没有解释清楚和彻底解决.如何合理的设计车辆和轨道,抑制车轨耦合振动成为磁浮列车系统研究的热点问题.本文建立了简化的车轨耦合系统数学模型,在单铁悬浮系统稳定性条件的基础上,基于奈奎斯特稳定性理论假设了系统相频曲线的变化规则,得到了车轨耦合系统稳定的充分性条件.文末最后证明假设是成立的,计算简化了系统稳定条件式,并以数值计算的方法验证了该稳定性条件的正确性.

磁浮列车与轮轨高速列车对线桥动力作用的比较研究

以德国 Transrapid高速磁浮列车和日本新干线高速列车为基础 ,通过建立高速磁浮、轮轨列车与线桥动态相互作用模型 ,计算了不同行车速度 (1 0 0～ 50 0 km/h)和不同桥跨 (1 2～ 32 m)情形下高速列车与桥梁结构的动力响应 ,并进行了细致的对比分析。结果表明 :磁浮列车在高速特别是超高速运行条件下的乘坐舒适性明显优于轮轨高速列车 ;磁浮与轮轨高速列车作用于轨道的每延米荷载大体相当 ;高速磁浮列车对小跨度 (2 2 m以下 )桥梁的动力作用小于轮轨高速列车 ,而对中等跨度尤其是大跨度桥梁 。

基于概率密度演化理论的磁浮列车−轨道梁耦合系统随机动力分析

为研究磁浮列车引起的轨道梁随机振动问题,建立磁浮车辆-控制器-轨道梁耦合系统时变随机动力分析模型,运用数论选点法(NTM)选取N-维代表性点集和随机谐和函数法(SHF)生成随机轨道不平顺时域样本,进而将概率密度演化理论(PDEM)引入磁浮动力分析系统,采用Newmark-β时程积分法和带TVD(total variation diminishing)格式的双边差分法求解概率密度函数、均值和标准差。以常导(EMS)磁浮列车通过三跨连续型轨道梁为例,基于MATLAB平台自主开发程序,计算车辆子系统和轨道梁子系统的随机动力响应及概率密度函数,采用Monte Carlo法(MCM)和文献计算结果验证本文模型的计算效率和精度,并对行车速度和支座刚度对系统随机动力响应的影响规律进行分析。研究结果表明:基于概率密度演化理论的磁浮系统随机动力分析模型具有很高的计算效率和精度,与Monte Carlo法相比,求解效率提高了1~2个数量级;在相同随机轨道不平顺激励下,轨道梁中跨跨中加速度、首车车体加速度、轨道梁中跨跨中挠度的概率密度曲线规则程度依次减小;系统随机响应随车速增大而增大,但并非呈线性增大;车辆和轨道梁动力响应均值随支座刚度增加而减小并逐渐趋于稳定;当采用较柔的支座时,响应将被放大。

A novel refined dynamic model of high-speed maglev train-bridge coupled system for random vibration and running safety assessment

Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.

高速磁浮列车对轨道的动力作用及其与轮轨高速铁路的比较

研究了现有文献关于高速列车动力学方面的论述 ,就高速磁浮列车对轨道的动力作用及其与轮轨高速铁路的比较展开讨论。得到的主要结论是 :地面高速轨道交通应以 30 0 km/h左右的轮轨高速铁路为主体 ;在需要 40 0～ 60 0 km/h超高速的特定条件下 ,也可以采用磁浮高速列车 ,作为一种补充。因此 ,一方面要积极修建上海浦东机场高速磁浮试验线 ,一方面要尽早启动京沪轮轨高速铁路的建设。

基于滑动单元的高速磁浮列车-轨道梁耦合系统的动力相互作用分析

基于一种滑动单元,使用弹簧阻尼磁浮力模型,推导了适用于高速磁浮列车-轨道梁系统的滑动单元的刚度矩阵.在有限元OpenSees软件平台上建立了二维平面内高速磁浮列车-轨道梁耦合系统的有限元模型.以TR08磁浮列车和上海Emsland磁浮轨道梁为例,进行建模计算,得到了磁浮列车与桥梁的动力响应及其振动规律.通过与文献中的结果进行对比,验证了模型结果的可靠性,改进后的滑动单元可用来研究高速磁浮列车-轨道梁耦合系统的车桥耦合动力问题.

高速磁浮轨道检测系统地面处理软件的设计

为了解决高速磁浮轨道检测数据量大、处理难度大、处理程序不方便一线工人操作的问题,对数据处理类软件的设计方法进行了研究,分析了高速磁浮轨道检测各数据对象在处理工具与处理流程方面的差异性,设计了基于LabVIEW、Matlab及Python混合编程的高速磁浮轨道检测系统地面处理软件;该软件利用LabVIEW简单快捷的软件交互界面开发,结合Matlab强大的计算能力和Python在图像处理领域的成熟算法,快速完成工程软件的开发工作,实现大量数据的“一键式处理”,解决实际工程需求;同时将不平顺处理模块、磁场处理模块及图像处理模块单独封装为可执行文件进行调用,极大地提高了代码运行的稳定性和可维护性,便于进行功能扩展。

磁浮交通系统动力学分布式协同仿真接口的设计与实现

针对磁浮列车与桥梁及外部空气流场动力相互作用的数值仿真分析,首先采用多体动力学SIMPACK、有限元分析ANSYS、流体动力学CFD/FLUENT等大型通用仿真软件,建立流固耦合、机电耦合、结构刚弹性耦合的高速磁浮列车耦合大系统动力学模型,然后使用分布式耦合仿真平台进行联合仿真,实现高速磁浮列车的数值仿真和参数优化分析。对于SIMAPCK与分布式耦合仿真平台数据交互的问题,提出了借助Matlab/SIMULINK等工具开发出SIMPACK与耦合式分布式平台的接口。仿真算例表明,开发的接口模块实现了不同数值分析模型之间实时数据的可靠交互,分布式协同仿真计算结果准确可信。

中低速磁浮列车-桥梁系统竖向耦合振动理论分析与试验验证

为探讨中低速磁浮列车-桥梁系统竖向动力相互作用特性,文章将中低速磁浮列车进行两种方式的简化,考虑PID主动悬浮控制系统,基于模态叠加法,建立2种类型的中低速磁浮列车-桥梁系统竖向耦合振动分析模型。随后基于长沙中低速磁浮运营线桥梁动载试验,对建立的2种仿真模型进行对比与验证。基于仿真模型2,以不同梁高的桥A、桥B、桥C为研究对象,对中低速磁浮列车-桥梁系统耦合振动特性进行分析。研究表明:将磁浮列车简化为均布荷载的方式能较为准确的模拟实际状况;桥梁刚度的减小会导致作用于车辆和桥梁上的电磁悬浮力增大,使得车体和桥梁的动力响应变大;磁浮列车低速运行时悬浮力频谱分布较离散,而正常速度运行时较集中;中低速磁浮列车-桥梁系统竖向存在着由电磁悬浮力自身频率引起的共振现象,该共振频率较低。