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。     

既有铁路简支T梁桥的动载试验研究及有限元分析

对青藏铁路某简支T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;同时采用midas/civil软件建模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。     

单线铁路双跨简支π梁桥在列车动载作用下力学性能的研究

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;同时采用midas/civil软件建模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。     

某单索面双塔部分斜拉特大桥地震反应研究

通过分析桥梁的自振特性,检验桥梁截面的抗弯扭性能,采用地震反应谱法和时程分析法分别研究了在最大悬臂施工及成桥运营状态下桥梁结构的抗震性能,结果表明,在当地地质条件下,该桥具有良好的抗震稳定能力。     

Advanced dynamic finite element analysis of a skew steel railway bridge

The aim of this paper is to present advanced modelling techniques for dynamic analysis of steel railway bridges. Finite element analyses of a case study skew bridge are carried out and the results are compared with available field measurements. Initially, eigenvalue analyses of different models are carried out in order to obtain the fundamental mode shapes and bridge frequencies and to assess the capability of each model to capture the dynamic behaviour of the bridge. Single-span, three-span and full bridge models are investigated with different elements such as shell, beam and combinations of these. A very good agreement between the fundamental dynamic properties of the bridge and empirical results is found. Following the eigenvalue analyses, time history dynamic analyses are carried out using the full bridge model. The analyses are carried out for different train speeds and the strain histories are compared with available field measurements. In terms of fatigue assessment, the mean stress range values obtained from the strain histories at selected locations on the bridge members are also compared to each other. The results show that a full bridge model using a combination of beam and shell elements is a reasonably accurate and computationally efficient way of capturing the dynamic behaviour of a bridge and estimating the mean stress range for fatigue damage calculations.     

Aerodynamic investigations for the tender design concepts of the Øresund cable-stayed bridge

For the Øresund link project two alternative tender designs were proposed, one single-level box girder solution and a double-level truss girder solution. Aerodynamic investigations, comprising wind tunnel section model tests as well as full-scale predictions, were carried out for the cable-stayed part of the two design alternatives. The section model tests covered static and dynamic tests for various configurations of bridge deck equipment, aiming at the detection of possible instabilities or vortex shedding effects and recording of the buffeting response. Cross-sectional admittance functions and aerodynamic derivatives have been estimated, and employed for full-scale predictions of dynamic displacements at a chosen value of the characteristic mean wind speed.     

拉索板式钢拱桥的动力分析

对Barqueta桥进行了理论和试验工作。Barqueta大桥横跨Guadalquivir河,连接Seville城市和Cartuja93科技园,高峰时期,车流占据一条半的车道达一个多小时。通过原型试验对桥的动力响应进行观测。试验程序包括两种活荷载条件下的动力研究:一种是一条半车道布满车辆,另一种是桥上没有车辆。基于获取的数据,进行了模型的参数估计。通过不同的技术手段确定了频率范围从0～6Hz的10个模型,其中两个模型非常相似。对交通与结构之间的交互作用也进行了研究。从三维有限元模型中得到的结果与试验结果进行了比较,结果具有很高的一致性。最后,损伤评价技术被用于鉴定结构的完整性。从2005年7月的试验中获得的结果与2006年10月用损伤指标方法获得的结果具有相关性。     

The effects of the repair operations and replacement of the elastomeric bearings on the modal characteristics of a highway bridge

In this paper, the extraction of the dynamic properties of a two span simply supported pre-stressed concrete skew highway bridge has been reported. The experimental work has been carried out according to a predetermined repair program involving the replacement of the elastomeric bearings. The operational modal analysis (OMA) technique has been used for the extraction of the modal properties of the bridge. The dynamic parameters of the bridge have been derived with the use of the frequency domain decomposition (FDD) as well as the stochastic subspace identification (SSI). Five modal tests have been carried out during different stages of the repair operations. One of these tests has been performed under normal traffic and the rest of the experiments have been carried out in the condition of traffic closure. Supporting numerical analyses have demonstrated close agreement between experimental and numerical results. In addition, the effects of the variation of the values of the shear modulus of the elastomeric bridge bearings on the dynamic properties of the bridge have been investigated. As a result of the experimental and numerical studies, it has been demonstrated that some additional retrofit measures also needed to be taken.     

斜铁路钢桥的高等动力有限元分析

介绍斜铁路钢桥动态分析的模型。给出一个有限元分析的案例及其与实际测量结果的对比。首先,通过不同模型的特征值分析,得到基础模型选型和桥梁频率,以及评估每个模型分析桥梁动态性能的能力。通过壳单元、梁单元以及组合单元对单跨、三跨和全比例桥梁建模。结果显示,桥梁基本动态特征数值分析结果与试验结果吻合。全比例桥梁模型用于分析特征值和动力时程分析。对不同列车时速和应变记录的分析与实际测量进行比较。疲劳评估通过选取桥梁某一位置的平均应力值也进行了比较研究。结果表明,采用梁单元和壳单元的组合单元的全比例尺模型,可以高效准确地预测桥梁的动力性能和疲劳破坏的平均应力值的范围。     

Fatigue assessment of a composite railway bridge for high speed trains. Part I: Modeling and fatigue critical details

Steel bridges for high speed trains may sustain excessive fatigue damage due to stronger dynamic effects induced by the increased train speed. Dynamic tests were carried out on a composite railway bridge for high speed trains. A detailed finite element (FE) model of the bridge was established and validated by the dynamic test results. Six types of structural details in the bridge were considered for fatigue evaluation. The stress history of each concerned detail during a single train passage was generated by the validated FE model. The stress spectrum, obtained through Rainflow cycle counting of stress history, was used to calculate the fatigue damage of each detail, based on the detail category specified S–N design curve and the Palmgren–Miner damage rule. Among various structural details, the load carrying fillet weld around the gusset plate of the diagonal bracing at the bridge bearing is predicted to be the most fatigue critical detail. In this paper, a general methodology for determination of fatigue critical details is presented, which can serve as a basis of enhanced fatigue evaluation by using local stress approaches. In “Part II: conditions for which a dynamic analysis is needed” as the continuation of this paper, fatigue assessment will be investigated based on the dynamic stresses predicted by different approaches, i.e. static analysis considering dynamic amplification factor, direct dynamic analysis with a moving load model or a train–bridge interaction model.     

土-钢组合铁路桥的动力响应

对长跨钢涵洞铁路桥进行实际动力响应研究。桥为土-钢组合结构,长11m。通过测量不同车速下桥的应变和位移,对桥进行试验,同时,对垂直道床振动以及制动力的影响也进行了测量。研究显示:车速对位移、推力和力矩的影响较大;所测的动态位移与推力比超出相应静态响应的20%,远大于桥设计规范所规定的值;力矩到1/4点时,动荷系数高达1·45,高于关键点的值。鉴于从强迫振动试验中测得了高的阻尼值,与普通桥相比这种桥的类型对共振并不敏感。     

基于微分等价递归算法的桥梁体系耐久性可靠度动态评估

结构耐久性可靠度评估应以体系为对象,并且要体现结构性能的自身特征及动态时变特性。基于贝叶斯动态更新技术,以混凝土碳化深度为随机变量,利用体现结构个性特征的实桥检测信息对传统静态碳化模型进行修正。以可靠度指标为评价标准,引入能计入构件间相关性的微分等价递归算法,并将其嵌入到贝叶斯动态更新框架中,构造出体系碳化耐久性动态评估模型和计算流程,形成了复杂体系碳化耐久性动态可靠度计算方法,采用MATLAB平台开发了计算程序。利用碳化试验模拟实桥检测数据,对钢筋混凝土拱桥进行了体系动态耐久性评估,发现模型更新后拱圈和立柱的碳化耐久性可靠度比更新前有所增大,而桥面板则有所降低,体系耐久性可靠度低于构件可靠度。     

基于动载试验的某双曲拱桥动力性能评价

为了延长桥梁的使用寿命,需要对桥梁做相应的评估,并采取对应的措施。本文就是在某双曲拱桥加固后,根据需要进行了动载试验,并将动载试验的结果与建立的有限元模型的计算结果相对比发现。该双曲拱桥加固后的自振频率、冲击系数和阻尼比等动力性能参数均符合要求,可为同类双曲拱桥的动力性能测试提供借鉴。     

Dynamic analysis of a cable-stayed deck steel arch bridge

A theoretical and experimental research work in relation to the cable-stayed Barqueta bridge is described in this paper. Barqueta bridge, across Guadalquivir river, links the city of Seville with Scientific Park Cartuja 93. During rush hour cars may cover one half of the bridge lanes for more than one hour. Full-scale tests were carried out to measure the bridge dynamic response. The experimental program included the dynamic study for two different live load conditions: the bridge with one half of its lanes full of cars, and the bridge empty of cars. Modal parameter estimations were made based on the acquired data. Ten vibration modes were identified in the frequency range of 0-6 Hz by different techniques, two of these modes being very close to each other. The traffic-structure interaction is also studied. Experimental results were compared with those obtained from a three-dimensional finite element model developed in this work. Both sets of results show very good agreement. Finally, a damage identification technique has been applied to determine the integrity of the structure. Results obtained from a test developed in July 2005 have been correlated with experimental results obtained in October 2006 using the damage index method.     

组合钢箱梁桥荷载试验检测技术研究

为研究某跨度为54m的钢-混组合箱梁桥的整体受力性能,对该桥进行了静、动载试验,并根据试验和理论计算结果对其承载能力及工作性能进行了评价。试验和理论计算结果表明:该桥在静载作用下的控制截面的应力和变形满足设计要求,在动载作用下测试所得的自振频率和冲击系数与理论分析计算结果基本一致。     

Dynamic testing of a soil–steel composite railway bridge

Actual dynamic response of a long-span corrugated steel culvert railway bridge is studied. The bridge, which is a type of soil–steel composite structures, has a span of 11 m. Tests were carried out by measuring strains and displacements during passages of a locomotive at different speeds. Vertical ballast accelerations as well as the effects of braking forces were also measured. The tests showed that the speed has a large influence on the displacements, thrusts and moments. The measured dynamic displacements and thrusts are as much as 20% larger than the corresponding static response. This is greater than the values specified in bridge design codes. Dynamic amplification factors as high as 1.45 were obtained for the moments at the quarter point which is found to be much larger than the values for the crown point. This type of bridge structure is believed to be less sensitive to resonance from passing trains than other common bridge types, due to the high damping values obtained from the forced vibration tests.     

城市高架桥动力特性研究

桥梁结构的动力特性就是结构振动的基本特性,是对桥梁结构进行地震反应分析的基础.因此,对高烈度地区城市高架桥动力特性进行试验和理论研究很有必要.本文以高架桥常见的结构形式桥面连续简支梁结构为例,建立三维有限元模型,进行了模态分析并与试验结果进行对比分析.其结论可为同类型桥梁结构进行设计和分析作为参考.     

钢筋混凝土简支T梁桥空间建模及动力分析

根据钢筋混凝土简支T梁桥的结构特点,基于大型通用结构分析软件ANSYS平台,建立了全桥结构的空间有限元模型,进行了全桥结构动力分析,得到了该桥基本的动力特性参数。     

Dynamic analysis of a bridge repaired by CFRP: Experimental and numerical modelling

A significant number of existing reinforced-concrete bridges all over the world require maintenance and repair. Hence, the need for a rapid evaluation procedure for the diagnosis of existing bridges. This paper presents the application of a dynamic analysis methodology for structural evaluation of reinforced-concrete bridges. The methodology is based on the application of ambient vibrations non-destructive testing method and the identification of the structure total response using finite element method. A case study of a three span reinforced concrete bridge in a strong seismic activity area in the north of Algeria is analysed. The ambient vibration testing was carried out on the bridge, before and after its repair by the application of carbon fibre composites. The tests were conducted using an acquisition system made up of four accelerometers with three components placed at specific locations on the bridge. The finite element model gave comparable results to the experimental ambient vibrations tests. The modal parameters of the bridge before and after repair were identified by this in situ testing. The application of composite material to strengthen the structure increases the transverse rigidity of the structure and thus its modal frequency.     

土-桩-结构相互作用对大跨悬索桥动力特性的影响研究

本文以国内第一大跨桥梁———润扬长江公路大桥南汊悬索桥为研究对象,基于大型有限元分析软件ANSYS建立了该桥的三维有限元模型,其中采用质量-弹簧体系模拟了土-桩-结构的相互作用。以此为基础对润扬悬索桥的自振特性进行了分析,重点研究了土-桩-结构相互作用因素对大跨悬索桥动力特性的影响,与现场动力测试结果的良好吻合表明了有限元分析结果的可靠性。研究结果为大桥的损伤预警和状态评估奠定了研究基础。