简化的混合试验在桥梁抗震中的应用

由于地震荷载的不确定性,桥梁结构在地震作用下的响应也各不相同。要全面的对桥梁进行性能评价以及后续的加固措施比较困难。本文以一座三跨变截面连续梁桥为例,评价在罕遇地震下桥梁的破坏形态,为其加固提供理论指导。本文采用Midas civil建立桥梁的三维结构模型,采用弹塑性时程分析得到墩柱顶部水平力较大。为了较详细的分析墩柱的受力情况,采用了有限元与实验结合的方法,将水平力的时程函数作为实验输入的节点动力荷载,研究桥梁破坏特性。最后通过土木工程非线性有限元软件FEA建立墩柱的实体模型与实验做对比。结果表明,这种方法能够充分反应桥梁在地震作用下的破坏形态,并且能够提高工作效率。     

既有单跨拱桥结构评估中的动荷载试验

以某既有单跨拱桥为例,在其结构安全性检测与评估中,简述了动荷载试验准备及试验过程。利用有限元软件MIDAS建立桥梁模型,模拟得到桥梁自振频率理论值。再通过脉动试验、动力试验检测得到相应实测数据。根据数据分析该既有单跨拱桥动荷载检测结果,与有限元模拟结果对比,最后对桥梁结构的安全性进行了评估,为养护维修提供了科学的依据。     

三跨曲线刚构桥地震谱响应分析

以一座三跨连续刚构桥为研究对象,利用大型通用有限元程序,建立了其三维有限元动力计算模型。通过模态分析,得到桥梁的自振特性。借鉴建筑结构抗震设计标准地震反应谱,进行桥梁的地震谱响应分析。通过模态的扩展和组合,得到了节点的应力和节点位移响应的时间历程曲线。为曲线连续刚构桥的抗震理论研究和工程设计提供参考依据。     

桥梁抗震性能计算分析

以某市中环快速化改造工程桥为研究对象,结合大型通用有限元程序,建立实桥空间有限元计算模型,计算分析桥梁结构的动力特征。利用反应谱法得到地震荷载下所须的振型阶数,对全桥进行动力特性分析。根据桥梁抗震设计原则,分析计算桥梁下部结构的受力情况。计算结果为同类桥梁抗震设计提供参考数据和分析基础。     

现有铁路钢桥的评估

对现有铁路钢桥进行一系列的动力试验、加速度测量、评估、有限元模拟和安全指数计算。采用专门列车进行动力试验,并获取动力参数。这些参数还可用于建立桥梁的有限元模型。如果模型能够反映实际工况,就能用于计算每种工况下桥梁结构的安全指数。这些安全指数可用于计算杆件的破坏可能性,因此可采用本模型评估桥梁的可靠性。通过了解现有桥梁结构的实际工况,本研究可为新的货运列车重级荷载研究提供可靠依据。     

公路装配式简支梁桥空间受力特性分析

基于三维实体单元建立朗江大桥其中1孔的三维有限元模型,计算该孔的动力特性,并采用DASP动力测试系统对其中6跨进行了动载实验,比较分析其动力特性,同时对其中1跨进行了静力荷载实验,深入探讨了各片梁的空间受力行为,以达到提高整体承载力的目的。     

铁路简支梁桥动力响应数值分析与实测验证

以某铁路简支梁桥为工程背景,基于有限元软件ANSYS实现了列车荷载作用下简支梁桥自振特性分析与动力响应计算,并利用现场实测加速度响应对有限元计算结果进行了验证。基于验证后的有限元模型,研究了跨径、车速及车重等关键因素对铁路简支梁桥动力响应的影响,采用移动荷载模型分析该简支梁桥在列车荷载作用下的动力响应。结果表明:简支梁桥自振频率及加速度特征值与有限元计算值总体上吻合较好,但由于现场实测存在多种环境因素干扰,局部对比结果存在差异;有限元计算的加速度平均值大于现场实测值,但幅值相差不大且都呈周期性变化;桥梁1阶及3阶自振频率的实测值与有限元计算值较为接近;跨径、车速及车重等关键因素均对桥梁动力响应产生一定影响,随着列车车速的提高,简支梁桥动力响应明显增加,列车驶离桥梁后,桥梁自由振动的振幅随车速的提高显著增大;简支梁桥跨径与车重均对跨中截面挠度影响显著,在设计过程中应予以重视;所得结论可为铁路桥梁的动力性能评价提供参考。     

江津观音岩长江大桥减震分析

为了研究黏滞阻尼器和软钢阻尼器对大跨度斜拉桥的减震效果,对桥梁结构在采取减震措施前后的动力响应进行了分析.以主跨436m的江津观音岩长江大桥为背景,利用ANSYS软件建立三维有限元模型,计算了大跨度斜拉桥半漂浮体系的动力特性和地震响应,并与塔梁固结体系的计算结果进行了对比分析;研究了黏滞阻尼器和软钢阻尼器控制半漂浮大跨...     

临界荷载作用下通过有限元分析的桥寿命动力放大系数

建立桥梁设计和既有结构评估的精确标准要求需要充分评估重载交通荷载以及重载作用导致的动态交互作用。目前的方法一般是首先计算典型的静态荷载作用,然后加上一个放大系数作为动态作用的限值。这种方法明显减少了高静态荷载和高动态扩大作用同时发生的可能性。提出了一个评估程序,只考虑临界荷载,可以有效和精确地确定典型静力（最大寿命）和动力（包括动态交互作用）荷载的特征值。采用蒙特卡罗模拟确定所选桥的临界静力荷载,建立三维有限元桥梁数据库和模型,对各种车辆荷载组合进行分析。建立识别临界荷载过程的模型,分析得到临界总荷载作用。然后可以得到临界静力荷载作用与相应的总荷载作用的相关性,进而外推确定一个特定的动力扩大系数。     

整体桥台桥梁应用及有限元分析

介绍了整体桥台桥梁的特点、存在的问题和有限元分析方法,并对一座单跨整体桥梁进行了三维有限元分析,给出了在桥梁整体升温和桥面板局部升温两种荷载模式下整体桥台桥梁的荷载效应。     

Evaluation of a steel railway bridge for dynamic and seismic loads

In this study, dynamic and seismic assessment of a railway bridge system with four discrete spans giving service on a double track railway line and located in an earthquake-prone region in Turkey is presented. A three-dimensional computer model of the bridge was generated using a commercial general finite element analysis software. Field measurements such as static and dynamic tests as well as material tests were conducted on the bridge system. Validation of the finite element model was performed based on the results of these tests. The calibrated 3D model of the bridge structure was then used for necessary calculations regarding structural assessment and evaluation according to train loads as well as seismic loads. Additional members were proposed to transmit seismic loads to supports. The fourth span, which had a permanent imperfection due to truck collision was studied in detail. Results have shown that due to excessive amount of capacity loss, the only choice was to write off the fourth span.     

既有铁路桥的动载试验及有限元分析

对青藏铁路某简支板梁桥进行现场动载试验,得到该桥梁结构在列车通过时的动力响应;同时建立有限元模型对该桥进行动力学的有限元分析得到数值解,将实测值和计算值进行对比分析,判断了其承载力和工作性能,为桥梁的加固与否提供依据。     

列车荷载作用下铁路斜拉桥索-梁相关振动研究

为了研究大跨度铁路斜拉桥的索-梁相关振动,基于拉索非线性振动理论,开发了有限元索动力单元,该单元在静力计算中为普通直杆单元,动力特性计算中可以计算拉索局部自振频率,动力时程计算中可以计算拉索非线性振动与整体结构振动的相互作用;编制了计算程序,建立了大跨度铁路斜拉桥有限元模型,同时使用索动力单元模拟斜拉索,最后研究了列车通过斜拉桥时梁、塔的带动下拉索发生索-梁相关振动的特性。结果表明:对于大跨度铁路斜拉桥,列车在设计速度范围内通过桥梁时索-梁相关振动不会导致拉索产生大幅振动。     

Assessment of existing steel railway bridges

A series of dynamic tests, acceleration measurements, evaluation, finite element model simulations and safety index calculations were performed on existing steel railway bridges giving service on railway network. Dynamic tests were fulfilled by using a special test train on these bridges to obtain the dynamic parameters and these parameters were then used to refine the finite element models of the bridges. Once the models have been updated to represent the actual condition, safety indices were calculated for structural components of the bridges for each proposed loading condition. These safety indices were used to calculate failure probabilities of structural members. As the final step, system reliability of the bridges was evaluated based on proposed system models of the bridges. It is believed that this study will provide a reliable background for proposed heavier axle loads resulting from new freight trains by realizing the current condition of bridge structures.     

车速对铁路桥梁动力响应的影响分析

针对桥梁结构对移动列车动力响应的复杂性,通过有限元分析软件ANSYS分析石太铁路一简支梁桥在不同车速下的动力响应,得出了铁路筒支梁桥在高速列车作用下的一些动力响应特性,从而为铁路简支梁桥的合理设计提供科学依据。     

高速列车与铁路简支梁桥动力相互作用研究

通过有限元分析软件建立桥梁有限元模型,以移动车轮加簧上质量模拟车辆,对不同工况下高速行驶的列车与简支桥梁的动力响应进行了研究和比较,得出了高速列车与桥梁系统的一些动力响应特性。     

Fatigue assessment and strengthening measures to upgrade a steel railway bridge

The present paper deals with the experimental and analytical study of a 19th century riveted steel truss railway bridge to assess its current condition and remaining time of life. The analysis includes static and dynamic field measurements and laboratory tests. The evaluation of the capacity of the bridge for the trainloads, as well as for the seismic and wind loads, as specified by current design codes, was performed using a finite element model. Besides, after the owner's recent decision to upgrade the bridge to meet modern standards and new types of trains, the necessary strengthening was proposed, and the new estimation of the remaining fatigue life of the bridge after the suggested strengthening was also provided.     

Dynamic behavior of hybrid framed arch railway bridge under moving trains

In this study, the dynamic behavior of a concrete-filled steel tube (CFST) hybrid framed arch railway bridge under moving trains are investigated through an in-site dynamic test. The bridge was tested under train loadings in different scenarios and at different speeds of the trains. The free vibration characteristics, strain, displacement, and acceleration of the bridge structure were measured to evaluate the dynamic responses of the train-bridge coupling system. A three-dimensional finite element model, which took into account the train-bridge coupling and track irregularities, was established to analyze the behaviors of the train-bridge system. The model was validated against the in situ test results. The impact effect on the girder was greater than that of the arch frame. The acceleration responses of the trains on the bridge increased with the train’s speed. The riding comfort of the trains was evaluated based on the measured dynamic responses of trains.     

双线高速列车过桥在不同速度下的影响分析

基于弹性系统动力学总势能不变值原理及形成矩阵的"对号入座法则",提出了一种可以考虑公路桥面板变形影响的桁段单元,并用该单元建立桥梁有限元模型,对某公铁两用钢桁斜拉桥方案进行了车桥时变系统振动分析,得出的相关结论为相关问题的研究提供了理论基础。