Dynamic Response Impact of Vehicle Braking on Simply Supported Beam Bridges with Corrugated Steel Webs Based on Vehicle-Bridge Coupled Vibration Analysis

A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this method.The method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are analyzed.The results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the bridge.Notably,the influence of wheelto-bridge friction forces is of particular significance and cannot be overlooked.When the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking acceleration.Under favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by codes.It is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking.

Experimental investigation on vibration characteristics of the medium-low-speed maglev vehicle-turnout coupled system

The steel turnout is one of the key components in the medium–low-speed maglev line system.However,the vehicle under active control is prone to vehicle–turnout coupled vibration,and thus,it is necessary to identify the vibration characteristics of this coupled system through field tests.To this end,dynamic performance tests were conducted on a vehicle–turnout coupled system in a medium–low-speed maglev test line.Firstly,the dynamic response data of the coupled system under various operating conditions were obtained.Then,the natural vibration characteristics of the turnout were analysed using the free attenuation method and the finite element method,indicating a good agreement between the simulation results and the measured results;the acceleration response characteristics of the coupled system were analysed in detail,and the ride quality of the vehicle was assessed by Sperling index.Finally,the frequency distribution characteristics of the coupled system were discussed.All these test results could provide references for model validation and optimized design of medium–low-speed maglev transport systems.

Internal Vibration and Synchronization of Four Coupled Self-Excited Elastic Beams

The vibration behavior and the synchronization between some internal points of four coupled self-excited beams are numerically studied. Coupling through the root of the beams is considered. The transverse displacements of the internal points and the beam tips are monitored, and the power spectra of the resulting time series are employed to determine the oscillation frequencies. The synchronization between beams is analyzed using phase portraits and correlation coefficients. Numerical results show multiple frequencies in the vibration pattern, and complex patterns of synchronization between pairs of beams.

Influence of vehicle-road coupled vibration on tire adhesion based on nonlinear foundation

The influence of pavement vibration on tire adhesion is of great significance to the structure design of vehicle and pavement.The adhesion between tire and road is the key to studying vehicle dynamics,and the precise description of tire adhesion affects the accuracy of dynamic vehicle responses.However,in most models,only road roughness is considered,and the pavement vibration caused by vehicle-road interaction is ignored.In this paper,a vehicle is simplified as a spring-mass-damper oscillator,and the vehicle-pavement system is modeled as a vehicle moving along an Euler-Bernoulli beam with finite length on a nonlinear foundation.The road roughness is considered as a sine wave,and the shear stress is ignored on the pavement.According to the contact form between tire and road,the LuGre tire model is established to calculate the tire adhesion force.The Galerkin method is used to simplify the partial differential equations of beam vibration into finite ordinary differential equations.A product-to-sum formula and a Dirac delt function are used to deal with the nonlinear term caused by the nonlinear foundation,which realizes the fast and accurate calculation of super-high dimensional nonlinear ordinary differential equations.In addition,the dynamic responses between the coupled system and the traditional uncoupled system are compared with each other.The obtained results provide an important theoretical basis for research on the influence of vehicle-road coupled vibration on tire adhesion.

Impact coefficient and reliability of mid-span continuous beam bridge under action of extra heavy vehicle with low speed

To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.

Numerical analysis of dynamic response of vehicle–bridge coupled system on long-span continuous girder bridge

To systematically study the vehicle-bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle-bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the ＂set-in-right-position＂ rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long- span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the ＂general code for design of highway bridges and culverts （China）＂. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle-bridge system.

COUPLING VIBRATION OF VEHICLE-BRIDGE SYSTEM

By applying the sinusoidal wave mode to simulate the rugged surface of bridge deck,accounting for vehicle-bridge interaction and using Euler-Bernoulli beam theory, a coupling vibration model of vehicle-bridge system was developed. The model was solved by mode analyzing method and Runge-Kutta method, and the dynamic response and the resonance curve of the bridge were obtained. It is found that there are two resonance regions, one represents the main resonance while the other the minor resonance, in the resonance curve. The influence due to the rugged surface, the vibration mode of bridge, and the interaction between vehicle and bridge on vibration of the system were discussed. Numerical results show that the influence due to these parameters is so significant that the effect of roughness of the bridge deck and the mode shape of the bridge can't be ignored and the vehicle velocity should be kept away from the critical speed of the vehicle.

A vertical coupling dynamic analysis method and engineering application of vehicle–track–substructure based on forced vibration

Purpose–This study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approach–The track and substructure are decomposed into the rail subsystem and substructure subsystem,in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener.The rail is treated as a continuous beam with elastic discrete point supports,and spring-damping elements are used to simulate the constraints between rail and fastener.Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system,while the external load is used to deal with the reverse effect.The fastener failure is simulated with the methods that cancel the forced vibration transmission,namely take no account of the substructure–rail interaction at that position.Findings–The dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method.Local fastener failure will slightly affect the vibration of substructure and carbody,but it will significantly intensify the vibration response between wheel and rail.The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value,respectively,under the train speed of 350 km$h
1.At the same time,the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%,respectively,from the normal value.Originality/value–This method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.

Seismic response analysis of road vehicle-bridge system for continuous rigid frame bridges with high piers

The objective of this study is to investigate the effects of earthquakes on road vehicle-bridge coupling vibration systems. A two-axle highway freight vehicle is treated as a 13 degree-of-freedom system composed of several rigid bodies, which are connected by a series of springs and dampers. The framework of the earthquake-vehicle-bridge dynamic analysis system is then established using an earthquake as the extemal excitation. The equivalent lateral contact force serves as the judgment criteria for sideslip accidents according to reliability theory. The entire process of the vehicle crossing the bridge is considered for a very high pier continuous rigid frame bridge. The response characteristics of the vehicle and the bridge are discussed in terms of various parameters such as earthquake ground motion, PGA value of the earthquake, incident angle, pier height, vehicle speed and mass. It is found that seismic excitation is the most influential factor in the responses of the vehicle-bridge system and that the safety of vehicles crossing the bridge is seriously impacted by the dual excitations of earthquake and bridge vibration.

Analytic solution for size-dependent behaviors of micro-beam under forced vibration

This paper focuses on the size-dependently mechanical behaviors of a micro-beam under forced vibration.Governing equations of a micro-beam under forced vibration are established by using the modified couple stress theory,Bernoulli-Euler beam theory and D’Alembert’s principle together.A simply supported micro-beam under forced vibration is solved according to the established governing equations and the method of separation of variables.The dimensionless deflection,amplitude mode and period mode are defined to investigate the size-dependently mechanical behaviors of a micro-beam under forced vibration.Results show that the performance of a micro-beams under forced vibration is distinctly size-dependent when the ratio of micro-beam height to material length-scale parameter is small enough.Both frequency ratio and loading location are the important factors that determine the sizedependent performance of a micro-beams under forced vibration.

Flight Dynamic Analysis of Hypersonic Vehicle Considering Liquid-Solid Coupling

With the liquid propellant making up 60%—70% of the takeoff weight of the hypersonic vehicle,the dynamic load caused by great propellant sloshing interacts with the flexible structure of the aircraft.Therefore,the dynamic model displays characteristics of strong coupling with structure/control and nonlinearity.Based on the sloshing mass dynamic simplified as a spring-mass-damping model,a rigid-flexible-sloshing model is constructed.Moreover,the effect on the dynamic performance of the coupled model is analyzed with changing frequency and damping.The results show that propellant sloshing dynamics significantly affects the rigid body motion modes,especially flexible mode and short mode.The right half plane pole(RHP)moves far from the imaginary axis with the consumption of the propellant.The flexible mode attenuates with the increase of the sloshing damping,and the coupling becomes stronger when sloshing frequency is close to the short mode frequency or the flexible frequency of the beam.

The effect of subgrade inhomogeneity induced by freeze-thaw on the dynamic response of track-subgrade system

The developed vertical coupling model of Vehicle-Track-Subgrade which considered subgrade layer vibration is present- ed. The equations of motion for the ballast, top and bottom subgrade layers are presented in detail. Through inputting different coefficients, the dynamic response of track-subgrade system in a seasonal frozen region in different seasons is obtained by the developed model and the uneven freeze-thaw action of subgrade soil is presented in this model. The ef- fect of subgrade inhomogeneity induced by uneven freeze-thaw on the dynamic response of track-subgrade system was studied and the conclusions are as follows. The force at the interface of ballast and top subgrade layer and the defor- mation of ballast induced by a passing train changed sharply at the stiffness mutation zone. The force and deformation decreased with increasing stiffness ratio with the same amplitude of irregularities as the excitation source. The force and deformation were larger with larger amplitudes of irregularities. There was an obvious effect of uneven deformation and stiffness of subgrade on the dynamic response of track-subgrade system.

Dynamic Characteristics of Metro Vehicle under Thermal Deformation of Long-Span Cable-Stayed Bridge

In order to study the influence of thermal deformation of long-span cable- stayed bridge (LSCSB) on the dynamic characteristics of metro vehicle on the bridge, based on the theory of vehicle-track coupled dynamics, the rigid-flexible coupled dynamic model of metro vehicle-track-LSCSB system is established by using finite element method and multi-rigid-body dynamics. Adopting this model, the deformation of LSCSB subject to temperature is analyzed, then the comprehensive effect of track random irregularity and rail deformation caused by temperature load is considered to study the dynamic characteristics of metro vehicle running through the bridge, and finally the influences of temperature increment and running speed on concerned dynamic indices of vehicle are studied. The results show that the LSCSB deforms obviously subject to temperature load, and the overall performance is that the cooling is arched, and the heating is bent, and the shape variable changes almost linearly with the temperature load. According to the parameters studied in this paper, the rail deformation caused by temperature load increases the wheel-rail vertical force, derailment coefficient and wheel load reduction rate by 1.5%, 3.1% and 5% respectively. The vertical acceleration of the vehicle body decreases by 2.4% under the cooling condition, while increases by 3.7% under the heating condition. The dynamic response of the bridge changes under temperature load. The maximum vertical and horizontal displacement in the middle of the main beam span are 6.24 mm and 2.19 mm respectively, and the maximum vertical and horizontal acceleration are 1.29 cm/s2 and 2.54cm/s2 respectively. The derailment coefficient and vertical acceleration of vehicle body are more affected by temperature load, and the wheel load reduction rate and wheel-rail vertical force are more affected by speed. The conclusion of this paper provides a reference for subsequent scholars to study the influence of thermal deformation on the dynamic response of vehicles on LSCSB.

9号道岔区铺设减振垫浮置板的行车安全性及舒适性研究

地铁道岔区在基本轨、尖轨处以及道岔钢轨接头处存在大量钢轨不连续地段,轮轨相互作用强烈,轨道系统振动明显,减振垫浮置板轨道作为一种高等减振措施已应用于地铁线路道岔区。为探究减振垫浮置板应用于9号道岔的适用性,并作为减振地段与普通无砟轨道的过渡段的可行性,以某地铁高架9号道岔为研究对象,建立桥上道岔三维有限元模型,仿真分析地铁B型车在120 km/h直向过岔和30 km/h侧向过岔的情况下,列车的行车安全性、舒适性以及轨下结构形变。对比在9号单开道岔区域设置的2种刚度过渡方式的优劣及其减振效果,较为系统地论证了在9号道岔区域铺设减振垫浮置板的可行性。研究结果表明:1)列车通过铺设减振垫浮置板的9号道岔区域时,浮置板位移极值出现在转辙区域和心轨区域,最大位移出现在尖轨位置,可增大尖轨处单板橡胶垫支承刚度,以保证轨道结构变形均匀;2)列车逆向侧向通过设置过渡段的减振垫浮置板道岔区时,2级过渡方式的车体最大垂向加速度、最大横向加速度、最大脱轨系数、最大轮重减载率、轨道刚度变化率以及减振效果等指标均优于1级过渡方式;3)在道岔区铺设减振垫浮置板,列车直向和侧向通过时的行车安全性和舒适性均能满足相关评价指标,且2级过渡方式更优。研究结果可为后续道岔区减振设计研究提供一定的理论参考。

基于结构振动响应的长型浮置板轨道隔振器失效检测方法

目前钢弹簧浮置板轨道的隔振器失效判别主要依赖于人工巡检或视觉成像系统,但此类方法效率低、检测滞后且成本高昂。本文提出了一种自动化的检测方法,该方法利用残差学习思想和卷积神经网络基本理论构建数据分类器,并通过列车动荷载作用下的结构动力响应对现役某常见的长型浮置板轨道进行隔振器失效的检测识别。首先,基于车-轨垂向耦合动力学建立考虑隔振器不同服役状态的地铁车辆-浮置板轨道垂向耦合动力学仿真分析模型,进而生成多种运营工况下的数据集,用于网络的训练和性能测试;其次,进一步研究了传感器布置方式对网络检测性能的影响,以决定适宜的传感器布置方案;最后,在实际地铁线路中开展试验,对所提出的方法进行了验证。结果表明:通过对传感器布置位置进行优化,深度残差网络模型的检测准确性显著提升;合理设置传感器的数量也可以提高本文方法的检测性能;此外,通过适当选取传感器布置方案,本文提出的基于深度残差网络的隔振器失效检测方法在仿真数据中实现了98.99%的准确度,并在试验数据中实现了96.33%的准确度。该方法具有较高的可行性和应用潜力,可为地铁浮置板隔振器智能运维提供参考,并有望在未来用于隔振器失效的自动化检测。

基于等效刚度阻尼系统的中低速磁浮列车与大跨度桥梁耦合振动响应分析

针对中低速磁浮列车与大跨度连续梁桥的耦合动力响应问题,本文基于等效刚度阻尼系统建立多编组磁浮列车模型;基于国内在建磁浮专线连续梁桥(35m+55m+35m),采用ANSYS中实体单元建立全桥模型.并将两个独立系统在SIMPACK进行车桥耦合,设定车重参数分别为空载、定员和超载,且列车按单线和双线工况运行,计算耦合系统的动力响应.结果表明,本文建立的列车模型受到轨道激励时,磁浮间隙在额定范围内浮动,即等效刚度阻尼系统有良好的控制效果;车辆磁浮间隙的变化量、车体竖向加速度与车重成反比,而磁浮力与车重成正比;在计算工况下,桥梁主跨及边跨的竖向位移均满足设计要求的限值,双线列车超载运行桥梁跨中最大位移仅为4.503mm.说明连续梁桥具有较大的刚度,能满足磁浮车辆安全运行的要求;对比列车单双线运行,主跨跨中的竖向位移最大值后者达到前者两倍,而边跨位移的最大值后者仅比前者增大70%,表明双线列车对开运行对桥梁的动力响应存在增大效应.相关研究成果对磁浮线路建设有一定参考意义.

参数冻结精细指数积分法在非线性车桥耦合振动分析中的应用

描述车桥耦合作用的基本问题是一个时变系统问题,且很多工况下需考虑非线性特性,使得该问题难以得到解析解,甚至数值解也可能很复杂.针对该问题的求解,提出了一种参数冻结精细指数积分法,将其应用于车桥耦合动力学模型的数值分析中.该方法结合了精细积分和指数积分特点,并将时变系数矩阵在每一积分步参数冻结,用于获得系统振动响应的数值解.考虑汽车轮胎与桥面的力和位移耦合关系、桥面沥青铺装层、桥梁材料黏弹性和几何非线性特性,建立了车桥耦合动力学模型,并应用参数冻结精细指数积分法对该模型进行了求解.通过与近似解析解、辛Runge-Kutta算法以及经典的Newmark-β数值积分法计算结果进行对比,验证了所提出方法计算结果的有效性和准确性.在此基础上,制作了缩尺车桥耦合系统模型,测试了跨中挠度响应,进一步验证了理论建模和所提算法的有效性和实用性.通过数值计算分析了所提算法的数值特性,结果表明:提出的参数冻结精细指数积分法不仅可以处理时变、非线性问题,且具有良好的数值计算精度和长时间数值稳定性;由于精细积分的特点,参数冻结精细指数积分法的计算时间步长可以取的较大,可有效提高计算效率.因此,所提出的参数冻结精细指数积分法预期可成为求解车桥耦合动力学问题的一种新的高效算法.

温度作用下大跨度斜拉桥长波不平顺限值研究

研究目的:为研究大跨度斜拉桥在温度作用下的变形及其引起的长波不平顺对列车运行的影响,以泉州湾跨海钢混结合梁斜拉桥为研究对象,在其主梁截面布置温度传感器以监测主梁温度变化,利用ANSYS软件分析实测温度作用下的斜拉桥主梁竖向变形,将温度变形与轨道不平顺叠加且基于弹性系统动力学总势能不变值原理建立考虑该长波不平顺的车桥耦合模型,以研究长波不平顺对列车动力响应的影响、弦测法对其进行评价的适配性,以及温度变形极限条件下的对应限值。研究结论:(1)温度监测系统共收集了1年的温度数据,将其分解为均匀温度和线性温差后,对应的温度变化范围分别为[5.82°C,37.51°C]和[2.36°C,29.94°C],主梁主跨跨中的最大竖向位移为28.6 mm,最小竖向位移为14.1 mm;(2)相比于未考虑温度作用,考虑了温度作用引起的长波不平顺的车桥耦合振动模型得到的列车轮重减载率、竖向加速度和竖向舒适度指标均有一定增大,竖向加速度增幅最为明显;(3)考虑了因列车运行引起的桥梁动态位移的影响后,60 m弦中点弦测法依然能够很好地体现列车振动响应,与车体竖向加速度响应相关性最好;(4)通过分析60 m弦的不平顺计算结果并进行验证,可知桥塔附近是双线行车时会车的危险位置;(5)在温度变形极限条件下列车的竖向加速度达到规范限值,对应的60 m弦矢度限值为7.22 mm;(6)本研究成果可为大跨度斜拉桥长波不平顺的评测方法选取及限值要求提供参考。

风屏障透风率对强风作用下重载铁路刚构-连续梁车桥耦合振动响应的影响

为探究风屏障透风率对强风作用下重载铁路刚构-连续梁车桥耦合振动的影响,先通过节段模型风洞试验获取桥上设置0%,20%,40%,60%和无风屏障5种不同透风率风屏障时车桥系统的三分力系数,再根据弹性系统动力学总势能不变原理建立风-车-桥耦合振动仿真计算分析模型,对不同车速下重载货运列车通过设置不同透风率风屏障刚构-连续梁桥开展风-车-桥系统动力学仿真计算与分析研究。结果表明:在列车上桥初期,桥梁横向位移峰值随透风率的增大而明显减小,而当列车运行趋于满布桥梁时,桥梁的横向位移峰值随透风率的增大变化不明显;列车的动力响应峰值随风屏障透风率的增大而增大,相比于满载编组列车,空载和轻重混编编组列车的动力响应对风屏障透风率的变化更加敏感。综合桥梁动力响应和列车走行安全性评价指标(脱轨系数和轮重减载率),该桥梁应设置40%透风率的风屏障。

CRTSⅢ型板和双块式无砟轨道振动噪声特性研究

【目的】探究高速铁路CRTSⅢ型板和双块式无砟轨道的结构振动与噪声特性。【方法】以有限元、多体动力学与边界元相结合的方法为基础,通过建立高速列车-无砟轨道-箱梁耦合动力学模型和边界元模型,研究列车高速通过时的列车-轨道-箱梁耦合系统的结构动力响应,以及噪声辐射特性。【结果】结果表明,列车通过桥上CRTSⅢ型板与双块式轨道结构段时,列车的最大轮重减载率分别为0.0536与0.1657,下部箱梁挠度分别为1/9673与1/8457。与双块式无砟轨道相比,CRTSⅢ型板的轨道板及底座位移响应更小,并且轨道-箱梁系统的竖向振动衰减更快,减振性能更优。另外,比较两种轨道结构条件下的高架箱梁结构噪声,CRTSⅢ型板段的箱梁噪声总声压级更小。但是,桥下远场点噪声峰值差异较小,峰值频率接近,均为31.5Hz左右;而桥下峰值频率差异较大,Ⅲ型板的峰值频率为63Hz,双块式则为20Hz。【结论】CRTSⅢ型板式无砟轨道更适合在高速铁路桥梁段使用。