抛物线拱桥在移动荷载作用下的动力响应分析

建立抛物线双铰拱桥的强迫振动的运动微分方程,分析了拱桥在移动荷载作用下的横向振动问题,将运动微分方程解耦,得到拱桥在移动荷载作用下振动时的动力响应并加以分析,通过实例计算,得到了拱桥在移动荷载不同行驶速度时的动力挠度曲线,并进行了比较分析。     

悬索桥加劲梁的风振特性及损伤识别研究

悬索桥服役一段时间以后,在风荷载的作用下将造成主要构件加劲梁抗弯刚度的削弱进而导致结构损伤。对悬索桥的主要构件加劲梁进行分析,得出加劲梁在侧向风荷载作用下的振动特性,并利用损伤结构柔度差值曲率的变化对其进行损伤识别。     

Response of a train moving on multi-span railway bridges undergoing ground settlement

This paper presents an incremental-iterative procedure to investigate the influence of ground settlement on dynamic interactions of train–bridge system. The train is simulated as a sequence of identical sprung mass units with equal intervals and the bridge system as a series of simple beams with identical properties. To resolve the train-induced vibrations of a beam structure undergoing support settlement, this study decomposes the total beam response into two parts: the static response due to vertical support settlement and the dynamic component caused by inertia effect of beam vibration. An exact solution for static displacement is presented by exerting the support displacements on the beam statically. Thus the remaining dynamic response of the vehicle/bridge coupling system is solved by Galerkin’s method and computed using an iterative approach with Newmark’s finite difference formulas. Numerical studies indicate that for the dynamic interactions of train–bridge system, the inclusion of ground settlement is generally small on the bridge response, but it can amplify drastically the vertical response of the moving train, especially for the concave-up settlement profile. This conclusion is of significance in aligning a rail route that has to cross a region with local land subsidence.     

纵横梁桥面系统主梁绝对最大挠度的0.618算法

纵横梁桥面系统中主梁的跨度较长，纵梁上直接承受的车队荷载数量多且数值大，主梁设计中刚度校核是关键内容。作者研究了1组平行车队荷载直接沿着纵梁移动时，主梁绝对最大挠度数学模型的建立；并给出了相应的计算方法，以计算机为工具，适用于任意有限多个平行移动荷载，对于主梁的设计计算与安全评估，有一定的实用价值。     

移动荷载作用下大跨度铁路斜拉桥纵向共振机理

列车荷载作用下铁路斜拉桥将在不同方向上发生振动,列车竖向荷载作用下导致的主梁纵向振动将影响道床稳定性和伸缩装置的使用,甚至影响行车安全性和舒适性。采用等效纵向荷载研究移动荷载作用下斜拉桥纵向振动机理,推导纵向共振速度估算公式。以一大跨度铁路斜拉桥为实例,分析了不同速度的移动荷载作用下结构动力响应。结果表明,当移动荷载速度与估算纵向共振速度接近时,移动荷载通过桥梁时的纵向加载频率与桥梁一阶纵向振动频率接近,斜拉桥发生纵向共振现象,主梁和桥塔动力响应显著增大。     

山区悬索桥轨索滑移法施工的关键技术及其装置研发

针对山区的特殊建设条件,提出了悬索桥主梁架设的轨索滑移法施工技术。该方法是利用悬索桥主缆和吊索作承重结构,吊索下端连接吊鞍,吊鞍上支承轨索,利用在轨索上运动的运梁小车输送节段梁,待到达安装位置后,借助缆载吊机进行垂直吊装和安装。以矮寨特大悬索桥施工为背景,介绍了轨索滑移法架梁系统的组成和关键技术,以及核心组件吊鞍、运梁小车和轨索系统等的结构设计和计算分析。对整个架梁系统,介绍了整体缩比模型试验和足尺模型试验的试验方法和试验结果,并总结了实际工程应用情况。通过模型试验和工程应用的研究结果表明:轨索滑移架梁法能快速实现悬索桥的主梁架设,并具有很好的安全性和经济性,具有广阔的应用前景。     

风-汽车-桥梁系统空间耦合振动研究

为了考虑侧风引起的车轮相对于桥面的侧向相对滑动,在车轮与桥面之间引入了一个特殊阻尼器,这个阻尼器的阻尼系数依赖于车辆与桥梁的竖向耦合运动。在综合考虑路面粗糙度、车辆悬挂系统以及车轮相对于桥面侧向相对滑动的基础上,提出能够考虑桥梁的静风响应、抖振响应、汽车-桥梁耦合振动、系统的时变特性以及结构几何非线性和气动荷载非线性影响的风-汽车-桥梁系统空间耦合振动分析模型,编制了相应的分析程序。该程序既可以预测不同路面粗糙度,车速以及干、湿、雪、冰路面状况下行驶于桥梁上车辆的行车安全性,也可以评价低风速下车辆驾驶舒适度以及侧风和车辆移动荷载对桥梁振动的影响。     

厦门海沧大桥钢箱梁的装配焊接

厦门海沧大桥是３跨连续全悬浮钢箱加劲梁悬索桥。叙述了该桥钢箱梁节段的制作、工地焊接和装配焊接质量控制。     

Vibration of railway bridges under a moving train by using bridge-track-vehicle element

During the last two decades, much attention has been paid to various vibration problems associated with railways. They include the dynamic response of railway bridges and railway tracks at grade under the action of moving trains. However, studies on the role of track structures on the vibration of railway bridges are rather limited. In this paper, a new element called bridge-track-vehicle element is proposed for investigating the interactions among a moving train, and its supporting railway track structure and bridge structure. The moving train is modelled as a series of two-degree-of-freedom mass-spring-damper systems at the axle locations. A bridge-track-vehicle element consists of vehicles modelled as mass-spring-damper systems, an upper beam element to model the rails and a lower beam element to model the bridge deck. The two beam elements are interconnected by a series of springs and dampers to model the rail bed. The investigation shows that the effect of track structure on the dynamic response of bridge structure is insignificant. However, the effect of the bridge structure on the dynamic response of the track structure is considerable.     

实际车辆荷载作用下的预应力混凝土连续梁桥动力响应分析及验证

以一座三跨单箱单室预应力混凝土连续箱梁桥为对象,利用车辆-桥梁耦合振动关系建立单梁车辆、桥梁运动微分方程,通过二者变形协调、相互作用力协调关系实现车辆-桥梁的耦合关系;修正了自编的桥梁动力响应计算程序,通过建立在桥梁上的高速弯板称重系统实现对实际过桥交通荷载的识别,并将识别出的实际车辆荷载信息输入已建立的桥梁动力响应计算程序,快速计算出在实际车辆荷载作用下的桥梁动力响应,并利用ANSYS软件进行静力验证,用实际过桥车流产生的动应变进行动力验证。     

长跨柔性悬索桥风致抖振响应分析

以某主跨500 m的大跨度悬索桥为工程背景,对长跨柔性悬索桥在脉动风荷载作用下的抖振响应进行了分析和计算,得到了一些有借鉴性的结论。模态分析表明,大跨度悬索桥的自振频率较低,为典型的风敏感柔性结构。当同时考虑抖振力和自激力时,根据极值理论可以得到悬索桥主梁的抖振位移响应极值,结果表明,竖向、水平和扭转方向的最大抖振位移响应极值均发生在主跨跨中处,且数值较大,在结构设计中不容忽略。     

Vibration reduction of elastically supported beams under moving loads by tuned mass devices

This study is aimed at the physical interpretation of the function of a tuned mass (TM) in suppressing the vibration response of an elastically supported beam to a moving train. The train is simulated as a sequence of moving loads, and the vibration shape of the elastically supported beam is approximated as the combination of a flexural sine mode and a rigid body mode. By distinguishing free vibration from forced vibration, resonance of the beam is identified as the superposition of the free vibrations induced by the moving loads that are in phase. The reverse is also true for the phenomenon of cancellation. Moreover, the mechanism of the TM in reducing the resonant response of the beam to the moving loads can be interpreted using similar concepts. From the parametric study, it is concluded that the use of a mass ratio of 0.01 is most efficient for the TM. To achieve the greatest effect of mitigation, the frequency of the TM should be tuned to that of the elastically supported beam.     

Vibration reduction of elastically supported beams under moving loads by tuned mass devices

This study is aimed at the physical interpretation of the function of a tuned mass (TM) in suppressing the vibration response of an elastically supported beam to a moving train. The train is simulated as a sequence of moving loads, and the vibration shape of the elastically supported beam is approximated as the combination of a flexural sine mode and a rigid body mode. By distinguishing free vibration from forced vibration, resonance of the beam is identified as the superposition of the free vibrations induced by the moving loads that are in phase. The reverse is also true for the phenomenon of cancellation. Moreover, the mechanism of the TM in reducing the resonant response of the beam to the moving loads can be interpreted using similar concepts. From the parametric study, it is concluded that the use of a mass ratio of 0.01 is most efficient for the TM. To achieve the greatest effect of mitigation, the frequency of the TM should be tuned to that of the elastically supported beam.     

自锚式悬索桥主缆架设施工技术

江阴市新沟河大桥主桥为双索面钢筋混凝土自锚式悬索桥,主梁采用5跨连续预应力钢筋混凝土加劲梁形式。作为自锚式悬索桥,其施工工艺为先梁后缆,将主缆锚固于成型的主梁上,利用主梁来抵抗水平轴力;而主缆则通过吊索传递、承担着桥梁上部结构的全部恒载和使用期的全部活载。由于主缆架设线形对悬索桥结构的几何形状有着强烈的敏感性,其架设线...     

Health monitoring data in assessing critical behaviour of bridges

A baseline finite element model has been developed and used for system identification of the Confederation Bridge in Canada. The model was calibrated using the test data collected by the health monitoring system during two field tests. The frequencies and mode shapes obtained from the modal analyses were in good agreement with the values obtained from the tests. The model was used to simulate the bridge responses to the field tests. Continuity of the bridge model beyond the baseline model is essential in analysing its behaviour under moving truck loads. Coupling of the longitudinal movements of the pier tops with vertical movement of the deck and rocking vibration of the drop-in girders were observed in modal analyses of the extended model, which was then used for seismic analyses. The possibility of slippage of the drop-in girder as well as its separation from the bearings during strong ground motions should be considered in designing and future extension of the instrumentation program and the analyses of the recorded data for similar structures.     

车辆-桥梁耦合系统垂向振动的随机分析

研究车桥耦合系统在轨道高低不平顺激励下的垂向平稳随机振动。车辆采用二系悬挂6个自由度的4轴客车空间模型,桥梁采用空间梁单元模型,轨道不平顺假设为多点异相位平稳随机激励。采用虚拟激励法将轨道不平顺转化为一系列的简谐荷载形式。运用分离迭代法求解车桥耦合系统振动方程。分别采用虚拟激励法和Monte Carlo法对单跨33.3m简支梁进行随机振动分析,验证了方法的正确性。最后,以1列火车通过单跨33.3m简支梁为例,研究了车桥时变耦合系统的垂向随机动力特性。     

列车运行引起高架桥群桩基础地面振动分析

采用半解析数值方法分析列车运行引起高架桥群桩基础地面振动,研究合理设计桩基减小地面振动。半解析数值模型包括列车–轨道模型、高架桥模型、群桩模型。列车轨道模型中采用多质点弹簧–阻尼模型模拟列车,采用美国功率谱描述轨道随机不平顺,使用Euler梁模拟钢轨,采用Hertzian非线性公式描述轮轨接触,采用振型分解法求解轮轨作用力。铁路高架桥采用弹性支座简支梁模拟,采用传递系数矩阵和群桩影响因子分析桥墩下群桩的动力阻抗,根据桥墩的动力平衡方程求得桥墩–地基相互作用力,采用Green函数求得弹性半空间地面振动。研究铁路高架桥下群桩参数对地面振动的影响,分析不同桩长、桩直径、桩间距和轨道不平顺条件下地面振动速度1/3倍频程的大小。结果表明:轨道不平顺对桥墩作用力有较大影响,对小于6 Hz的地面振动影响较小,对大于6 Hz的地面振动影响较大。合适调整桥梁跨度与车速组合可减小地面振动。车速小于260 km/h时,桩径对地面振动影响较小;车速大于260 km/h时,增加桩径可减小地面振动。适当增加桩间距可避开振动增大区、减小地面振动随车速的增加。合理设计桩长可减小地面振动的增大区域。     

移动车辆载荷作用下桥梁的动态响应（II）

在桥梁车辆振动分析的古典理论基础上,利用ANSYS软件建立了桥梁的有限元模型,通过数值模拟计算分析了不同激振频率的简谐力通过桥梁时,桥体发生的动态响应特征,为移动荷载作用下桥梁振动的控制提供依据。     

预应力简支梁桥在移动荷载作用下的非线性动力特性分析

考虑预应力梁的剪切变形和几何非线性,建立梁的动力学基本方程式,应用增量谐波平衡法,分析计算梁在预应力作用下的横向振动问题。通过实例计算,得到梁在移动车辆荷载作用下的幅频响应曲线和力与位移的非线性响应关系,并给出了外激励频率不同且初始预加力变化时动挠度的变化规律。计算结果表明,梁非线性位移明显大于线性位移,且荷载与位移呈明显非线性关系,非线性因素的影响不可忽略;施加预应力可以提高梁的动抗弯刚度,减少梁的动挠度值。为预应力混凝土桥梁的设计和动力特性分析提供一定的理论依据。     

移动车辆载荷作用下桥梁动态响应(Ⅰ)

在车辆不同速度作用下桥梁的变形有其复杂性,对其研究为工程界所广泛关注。本文利用AN-SYS软件建立了桥梁的有限元模型,通过数值模拟计算分析了车辆以不同速度通过桥梁时,桥体发生的动态响应特征,从而为移动荷载作用下桥梁振动控制措施的改进提供依据。