新型U型梁车桥耦合环境振动实测与分析

为探讨城市轨道交通U型梁车桥系统车桥耦合振动对周边环境的影响,采用线性化轮轨模型建立了31个自由度的车辆动力学模型。以重庆市轨道交通一号线工程中梁山以西高架区间所采用标准跨径为30m的单线小U结构为对象,采用自编程序和通用对机车车辆过桥时的车桥耦合振动进行了分析,实测了周边地面受到车桥耦合振动的响应,并通过计算与实测结果的对比分析对所建立的理论模型和编制的程序进行了验证,对U梁引起的环境振动进行了评价。结果表明,U型梁具有良好的环境振动控制效果。     

高速铁路车-桥耦合体系地震响应分析

为了研究车桥耦合体系在地震作用下的响应,采用有限元方法,在现有有限元模型基础上,建立了更为精细的高速铁路车-桥耦合模型,计算了车桥体系的动力特性及典型地震动输入下的反应。同时还建立了单桥有限元模型,比较了单桥模型和车桥耦合模型的自振特性和地震响应的差异,得到了桥面加速度反应放大系数。结果表明:在给定的典型地震动作用下,车桥耦合模型地震响应放大系数与单桥模型有较大差异,同时输入地震动频谱特性对桥面地震加速度响应有显著影响。     

地震环境下铁路轮轨动态安全性能及脱轨研究进展

针对地震环境下铁路轮轨动态安全性及列车脱轨问题,本文详细地评述了近些年来国内外的研究进展情况。首先分析了地震作用下轮轨相互作用模型,包括密贴轮轨接触模型、简化轮轨弹性接触模型、轮轨弹性接触模型;然后分别评述了地震激励模型及输入方法的研究进展;接着分析了地震作用下列车脱轨判断准则、铁路地震预警系统及防脱轨措施的研究进展;接下来分析了车辆-轨道耦合动力学理论在地震作用下列车脱轨研究中的应用前景,并结合笔者目前现有工作,对车辆高速跳轨脱轨时的轮轨动态接触几何状态及其边界条件进行了初步的探讨;最后,建议了地震环境下列车运行安全性及脱轨机理等方面的今后研究重点。     

电梯轮轨系统平面外静力本构模型及其验证

针对电梯地震破坏中的对重脱轨现象,对电梯轮轨系统的平面外接触作用力学机理进行了研究,通过对轮轨系统导靴、导轨及其支架的各个构件的深入分析,判断了它们间的作用关系。并在一定简化基础上提出了电梯轮轨系统平面外静力本构模型,给出了轮轨系统的平面外刚度公式,并通过静力试验对该模型进行了验证,通过参数化分析探究了影响电梯轮轨系统平面外作用的关键参数。     

地震作用对轻轨铁路车桥系统耦合振动的影响

本文分析地震作用对考虑土-结构相互作用的轻轨铁路车桥系统耦合振动的影响。文中建立了车桥系统考虑土-结构相互作用的三维空间模型，推导了考虑地震作用车桥系统的耦合振动方程，并编制了相应的计算程序。以时速100km的列车通过天津轻轨的一座四跨预应力混凝土连续刚构桥为例，对受天津波和El Centro波地震作用的车桥系统的耦合振动响应进行了仿真分析。结果表明：地震作用下车桥系统的耦合振动响应近似为桥梁地震响应与车桥系统耦合振动响应之和；地震作用对车桥系统横桥向耦合振动响应的影响最大，对竖向耦合振动响应的影响较小，而对顺桥向耦合振动响应的影响甚微；且不同地震波激励的影响程度有所不同。由此得出结论，地震作用与车桥系统的耦合振动存在很大程度的耦合，因此，在对高架桥梁上的轻轨铁路进行车桥耦合振动分析时必须考虑地震作用的影响，以保证列车运行的安全性和稳定性。     

车辆-轨道系统振动响应分析--Timoshenko梁与Euler梁轨道模型的比较

近年来，铁路的高速化、高运量化以及轻微的地震灾害等因素加速了轨道结构的沉降或变形，导致车辆轨道系统振动的加剧。本文运用车辆-轨道耦合动力学理论，编制了基于Timoehenko梁钢轨模型的车辆-轨道耦合振动仿真分析软件，分析了车辆-轨道系统的垂向振动特性，并与基于Euler梁模型的VICT软件的仿真结果进行了比较分析。结果表明：仿真结果与VICT的仿真结果基本一致，但在较高频域，前者能更好地反映轮轨系统的高频特性。因而，在研究轮轨高频振动及轮轨噪声时。采用Timoshenko梁钢轨模型更具合理性。     

连续弯箱梁自行车桥地震响应分析

为研究厦门市弯箱梁自行车桥的地震响应规律,采用SAP2000有限元软件建立自行车高架桥三维壳体模型,在考虑多遇地震和罕遇地震水准作用及不同加载方向的基础上,分别采用反应谱分析法和时程分析法进行该桥的动力响应分析。结果表明：自行车桥z方向位移分量最大,且z方向分量极值均发生在曲线分叉段;相对剪力而言,桥墩竖向支反力相对较小;E1和E2地震水准响应情况随时间的变化趋势基本一致,桥梁结构未进入塑形状态,抗震性能良好,安全性指标较高;反应谱法计算得到的响应包络值相对3条不同的地震时程结果的峰值大,在实际桥梁抗震分析过程中需要综合考虑两者的分析结果。文章研究结果对今后自行车桥设计和抗震性能分析具有指导意义,并可为研究者对该类桥的进一步研究提供借鉴。     

基于车桥耦合振动的常用简支空心板梁桥冲击系数分析

通过Universal Mechanism和ANSYS软件相结合建立了车桥耦合振动模型,考虑车型、行车速度、车重和桥梁频率等因素,对工程常用的4种标准跨径装配式混凝土空心板梁桥进行了车桥耦合振动模拟。研究表明:冲击系数随车速增加而上升;随车重增加而增大;随桥梁频率的增加而降低。在多种因素中,车速对冲击系数影响最为明显。     

核环吊缩尺模型抗震性能动力时程分析

为研究核环吊在地震作用下的瞬态响应机理,完成了核环吊缩尺模型的抗震实验,并采用ABAQUS时程分析法研究了缩尺模型的动力响应。首先介绍了核环吊缩尺模型实验的设计方法和准则;其次通过与谱分析的对比分析说明了进行动力时程分析的必要性;最后介绍了ABAQUS中时程分析法的具体方法和步骤。仿真与实验结果的对比分析表明:ABAQUS的Slide-Plane连接单元可准确地模拟大车与小车不跳轨情况下的轮轨约束,验证了关键参数设置方法的准确性,为今后的核环吊产品的抗震设计提供了借鉴和参考。     

考虑行波效应的车桥系统地震响应分析

借助虚拟激励法,本文研究了非一致水平地震作用下三维车桥耦合时变系统的非平稳随机振动问题。通过轮轨间位移协调关系将列车和桥梁运动方程进行耦合,建立了考虑行波效应的多点地震激励下列车-桥梁时变系统运动方程。水平地震激励假设为均匀调制多点异相位完全相干随机激励;轨道不平顺激励假设为多点异相位完全相干平稳随机激励。采用时变系统的虚拟激励法将这些随机激励分别转化为一系列虚拟的确定性激励,然后通过数值积分求解相应的虚拟响应,进而方便地得到系统随机响应的时变功率谱密度函数和标准差等。数值算例中,通过Monte Carlo法验证了本文随机振动分析方法的正确性和有效性,并讨论了地震波视波速、场地土条件等对系统随机响应的影响。     

地震作用下磁悬浮车-桥垂向耦合动力学研究

以德国Transrap id高速磁悬浮列车为例,建立了高速磁悬浮列车与线桥动态相互作用模型,并对磁悬浮列车以不同速度通过不同桥跨情况下的车桥系统地震反应进行了数值模拟;研究了地震作用下,不同车速和不同桥跨对磁悬浮车-桥梁垂向耦合动力学系统的影响,得到了几点有意义的结果和结论。     

轨道约束系统对高速铁路多跨简支梁桥地震反应的影响

文中结合高速铁路多跨简支梁桥及轨道系统的特点,建立了考虑钢轨、轨道板以及桥梁结构的线桥一体化模型,采用反应谱法研究了轨道约束系统以及相邻后继结构对所选桥跨地震反应的影响。研究结果表明:轨道约束系统对相邻墩高相差较大的多跨简支梁桥的地震反应影响较大,因此对其地震反应分析时应采用线桥一体化模型;由于受端刺等路桥过渡段结构纵向刚度的影响,后继结构的桥梁跨数越少,对边墩地震反应的卸载作用越显著。     

T形刚构桥桥墩参数对车-桥动力响应影响研究

为研究T形刚构桥桥墩参数对车-桥动力响应的影响，以某高速铁路（77m+144m+77m）T形双薄壁连续刚构桥为研究对象，基于刚柔耦合理论，采用多体动力学和有限元联合仿真技术，建立考虑桩土效应的列车-桥梁动力相互作用模型，计算分析T形刚构桥墩宽度、厚度及混凝土强度等级变化对车-桥耦合系统的动力响应影响。结果表明:T形刚构桥墩宽度、厚度及混凝土强度等级的改变，对桥上车辆系统的安全性指标、舒适性指标影响较小；T形刚构桥墩参数改变，对桥梁系统横向位移、垂向加速度、横向加速度影响较小，而对垂向位移影响较大，但变化幅值均在高速铁路设计规范要求的范围内；在其他条件参数不变的情况下，可通过将桥墩宽度降低到设计宽度的75%—80%，或厚度降低到设计厚度的80%—85%，或桥墩混凝土强度等级降低为C35—C40对该高速铁路T形双薄壁连续刚构桥进行优化设计。     

Effect of unsupported sleepers on wheel/rail normal load

The paper reviews some important published papers on the effects of railway track imperfections on track dynamic behavior, and investigates the effect of unsupported sleepers on the normal load of wheel/rail in detail through a numerical simulation. The numerical simulation is based on a coupling dynamic model of vehicle–track. In the model, the vehicle is modeled as a multi-body system, and the track is considered as a 3-layer model with rails, sleepers, and ballast masses. Each rail of the track is modeled with a Timoshenko beam resting on discrete sleepers. The lateral, vertical, and torsional deformations of the beam are taken into account. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed, and therefore such a track model can consider the effect of the discrete support by sleepers on the coupling dynamic behavior of the vehicle and track in the simulation. In calculating the coupled vehicle and track dynamics, Hertzian contact theory and the theory by Shen et al. are, respectively, used to calculate the normal forces and the creep forces between the wheels and the rails. The motion equations of the vehicle–track are solved by means of an explicit integration method. A nonlinear spring and a nonlinear damper are used to simulate a gap between the unsupported sleeper and the ballast mass. The numerical results obtained indicate that the gaps between the unsupported sleepers and ballast masses have a great influence on the normal load of the wheel and the rail.     

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 external 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.     

高速列车-桥梁竖向随机振动的时域分析方法

提出时间相关多维有色噪声形式的轨道不平顺激励下列车-桥梁耦合系统协方差响应的时域递推方法。用白噪声滤波法生成轨道不平顺有色噪声过程,在宽频带内识别滤波器参数以同时实现滤波成型和波长截断功能。提出基于高阶Pade近似的累次时滞系统,以实现列车多轮对下轨道不平顺激励的大时滞再现;再结合成型滤波器构造列车下轨道不平顺激励的一致白噪声模型。建立列车-桥梁垂向振动的状态方程,将其与激励模型联立得到一致白噪声激励下的列车-桥梁扩阶状态方程。将方差递推法推广到时变系统,求解列车-桥梁系统的随机振动。分析结果与Monte Carlo模拟法符合良好,表明了方法的正确性。     

Dynamic analysis of train–bridge system subjected to non‐uniform seismic excitations

Based on the theory of dynamic wheel–rail interactions, a dynamic model of coupled train–bridge system subjected to earthquakes is established, in which the non‐uniform characteristics of the seismic wave input from different foundations are considered. The bridge model is based on the modal comprehension analysis technique. Each vehicle is modelled with 31 degrees of freedom. The seismic loads are imposed on the bridge by using the influence matrix and exerted on the vehicles through the dynamic wheel–rail interaction relationships. The normal wheel–rail interaction is tackled by using the Hertzian contact theory, and the tangent wheel–rail interaction by the Kalker linear theory and the Shen–Hedrick–Elkins theory. A computer code is developed. A case study is performed to a continuous bridge on the planned Beijing–Shanghai high‐speed railway in China. Through input of typical seismic waves with different propagation velocities to the train–bridge system, the histories of the train running through the bridge are simulated and the dynamic responses of the bridge and the vehicles are calculated. The influences of train speed and seismic wave propagation velocity on the dynamic responses of the bridge–vehicle system are studied. The critical train speeds are proposed for running safety on high‐speed railway bridges under earthquakes of various intensities. Copyright © 2006 John Wiley & Sons, Ltd.     

Dynamic interaction of bridge–train system under non‐uniform seismic ground motion

The probability that an earthquake occurs when a train is running over a bridge in earthquake‐prone regions is much higher than before, for high‐speed railway lines are rapidly developed to connect major cities worldwide. This paper presents a finite element method‐based framework for dynamic analysis of coupled bridge–train systems under non‐uniform seismic ground motion, in which rail–wheel interactions and possible separations between wheels and rails are taken into consideration. The governing equations of motion of the coupled bridge–train system are established in an absolute coordinate system. Without considering the decomposition of seismic responses into pseudo‐static and inertia‐dynamic components, the equations of motion of the coupled system are formed in terms of displacement seismic ground motions. The mode superposition method is applied to the bridge structure to make the problem manageable while the Newmark‐β method with an iterative computation scheme is used to find the best solution for the problem concerned. Eight high‐speed trains running over a multi‐span steel truss‐arch bridge subject to earthquakes are taken as a case study. The results from the case study demonstrate that the spatial variation of seismic ground motion affects dynamic responses of the bridge–train system. The ignorance of pseudo‐static component when using acceleration seismic ground motions as input may underestimate seismic responses of the bridge–train system. The probability of separation between wheels and rails becomes higher with increasing train speed. Copyright © 2011 John Wiley & Sons, Ltd.     

地铁列车曲线运行引起学校建筑物振动响应分析

地铁以其快捷、准时、运量大等优点,已成为重要的轨道交通形式,但由此引起的环境振动问题日益突出。针对杭州市地铁3号线曲线地段的某中学建设工程,利用有限元软件ABAQUS,对车辆-普通整体道床轨道系统的竖向耦合模型进行振动响应分析,得到考虑轨道高低不平顺影响的轨道振动源强。应用有限元软件MIDAS GTS/NX,建立双孔平行曲线盾构隧道-土-桩-建筑物系统的三维有限元模型。以轨道支点力作为激励对地铁列车运行时的隧道-土-桩-建筑物系统的振动响应进行计算,研究地铁振动波在地层中的传播规律和建筑物的动力响应特性。根据相关环境振动控制标准对建筑物的振动舒适性进行评价。结果表明：轨道加速度和扣件动支点力的最大值分别约为40 m/s²和30 kN;地层和建筑物的振动以竖向为主,水平Y向振动略大于水平X向振动;地面加速度随着距隧道中心线距离的增加而逐渐衰减;各建筑物楼层的振动主频位于16~40 Hz;部分建筑物楼层的振动响应水平已超出了规范的限值要求,建议对地铁轨道或建筑物采取适当的减振措施。