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Abstract In this paper, a refined three-dimensional (3D) vibration model for a train-track-girder-pier coupled system is established and solved using a pseudo-excitation method (PEM). Considering the excitation of random track irregularities, a high-speed railway case study is presented to verify the effectiveness of the model and the method by comparing the results with those given by a Monte Carlo method. A pre-stressed concrete box girder for a high-speed railway bridge with excitation of random track irregularities is used to investigate the influences of train speed and concrete Young's modulus on the random dynamic responses of the coupled system. The results show that the PEM is 1-2 orders of magnitude more computationally efficient for the random dynamic analysis of the train-track-girder-pier systems compared with the Monte Carlo method. The power spectral densities (PSDs) of vertical accelerations of coach body change only slightly with time, but they change significantly with track irregularity frequency. All the first peaks of the PSD curves for the coach body vertical acceleration are shown to appear at around the same fundamental frequency. The concrete Young's modulus of the girder has a large influence on the PSDs of the vertical acceleration of the bridge, but the distribution of vibration energy in the frequency domain varies very little. The results can be applied to railway design and maintenance. Highlights • This study established a refined 3D train-track-girder-pier interacting model. • Monte Carlo simulation results were used to validate the model and PEM. • It provided random dynamic responses of the coupled system in the frequency domain. • The effect of train speed and concrete Young's modulus on the response was observed. • The results can be applied to guide the design and maintenance of the coupled system. [ABSTRACT FROM AUTHOR]

Modelling the vibrational response of railway tracks is a mandatory step to predict rolling noise. This article proposes a model based on the semi-analytical finite element method (SAFE) taking into account the three main characteristics of railway tracks: infinite length in the longitudinal direction, deformable cross-section, and periodic track support. Although this approach is ideally suited to predict rail vibrations, numerical instabilities undermine its reliability at low frequencies. Consequently, a new approach using the second-order Arnoldi reduction (SOAR) is used, which allows to provide the required numerical stability. Lastly, numerical results are compared with classical railway track behaviours described in the literature, as well as experimental data and 3D finite element simulations. [ABSTRACT FROM AUTHOR]

The calculation formulae for change of wind load acting on the car-body are derived when a train moves into or out of the wind barrier structure, the dynamic analysis model of wind-vehicle-bridge system with wind barrier is established, and the influence of sudden change of wind load on the running safety of the train is analyzed. For a 10-span simply-supported U-shaped girder bridge with 100 m long double-side 3.5 m barrier, the response and the running safety indices of the train are calculated. The results are compared with those of the case with wind barrier on the whole bridge. It is shown that the sudden change of wind load caused by wind barrier has significant influence on the lateral acceleration of the car-body, but no distinct on the vertical acceleration. The running safety indices of train vehicle with sectional wind barriers are worse than those with full wind barriers, and the difference increases rapidly with wind velocity. [ABSTRACT FROM AUTHOR]

Railway importance in the transportation industry is increasing continuously, due to the growing demand of both passenger travel and transportation of goods. However, more than 35% of the 300,000 railway bridges across Europe are over 100-years old, and their reliability directly impacts the reliability of the railway network. This increased demand may lead to higher risk associated with their unexpected failures, resulting safety hazards to passengers and increased whole life cycle cost of the asset. Consequently, one of the most important aspects of evaluation of the reliability of the overall railway transport system is bridge structural health monitoring, which can monitor the health state of the bridge by allowing an early detection of failures. Therefore, a fast, safe and cost-effective recovery of the optimal health state of the bridge, where the levels of element degradation or failure are maintained efficiently, can be achieved. In this article, after an introduction to the desired features of structural health monitoring, a review of the most commonly adopted bridge fault detection methods is presented. Mainly, the analysis focuses on model-based finite element updating strategies, non-model-based (data-driven) fault detection methods, such as artificial neural network, and Bayesian belief network–based structural health monitoring methods. A comparative study, which aims to discuss and compare the performance of the reviewed types of structural health monitoring methods, is then presented by analysing a short-span steel structure of a railway bridge. Opportunities and future challenges of the fault detection methods of railway bridges are highlighted. [ABSTRACT FROM AUTHOR]

The paper is aimed at investigating the longitudinal vibration and vibration reduction of a cable-stayed bridge under vehicular loads with emphasis on the longitudinal resonance. To investigate the phenomenon of longitudinal resonant vibration, the equivalent longitudinal excitation for the bridge deck due to moving vertical loads is approximately expressed as longitudinal loads with a sine-wave form. A formula for estimating the longitudinal resonant speed of the cable-stayed bridge is developed. A long-span cable-stayed railway bridge is considered in the case study to calculate the longitudinal response of the bridge under moving loads at different speeds. The numerical results indicate that the longitudinal resonance for the cable-stayed bridge occurs when the speeds of the moving loads approach the resonant speed predicted by the analytical formula. A fluid viscous damper (FVD) is employed to reduce the longitudinal vibration of the bridge under moving loads. The results show that the longitudinal resonant responses of the cable-stayed bridge can be effectively mitigated by the FVD adopted. [ABSTRACT FROM AUTHOR]

Short-span portal frame bridges are predominant in Swedish railway lines. Although it is well known that the dynamic response of these partially-buried rigid structures is governed by the surrounding soil, the effect of the soil is usually neglected in the train-induced vibration analysis due to the expensive computational costs. This paper focuses on studying the effect of the surrounding soil conditions on the dynamic response of portal frame railway bridges. The study aims to validate the accuracy of simplified numerical models in evaluating the dynamic stiffness and modal properties of the bridge–soil system. To achieve this aim, a model updating method was used for FE model calibration of a full–scale portal frame bridge using measured frequency response functions. Both measured and computed responses identify the substantial contribution of the surrounding soil on the global damping of the system and highlight the importance of the soil–structure interaction on the dynamic response of these structures. [ABSTRACT FROM AUTHOR]

In this contribution the authors include results and conclusions from an experimental and numerical analysis of a railway bridge belonging to the Madrid-Sevilla High-Speed railway line in Spain. This structure is monitored due to its short length and typology, which make it susceptible to experience high transverse vibration levels. During the in-situ tests the soil properties at the site were obtained. Also, the response of the structure under the circulation of railway convoys was measured at several points of the deck and at the abutments. From the experimental measurements the modal parameters of the bridge are identified. Finally the experimental results are compared to those provided by a finite element numerical model in the time and frequency domains. Conclusions are extracted regarding the structure performance and the adequacy of the numerical model implemented. [ABSTRACT FROM AUTHOR]

Structural damping in high-speed railway bridges is a key parameter that affects significantly the performance of the structure in terms of fatigue life and comfort of the passengers and hence has a significant impact on the design procedures. For these reasons its accurate assessment is a paramount task to be performed and hence the results of an experimental campaign carried out on a prestressed concrete (four box-girder) beam bridge of the new Italian high-speed network are presented in this work. A total amount of fifteen accelerometers were used to ensure redundancy of measurements. Both a time domain technique and a Frequency-Domain Decomposition (FDD) technique are used to analyse the vibration signals and extract the modal frequencies, shapes and damping ratio of the first mode of the structure. The results are compared with the design provisions, and with other expectation provided by the technical literature. The paper from one hand provides a contribution in the framework of the damping evaluation of high-speed railway bridges, and from the other hand would furnish a first assessment of those damping sources that are not usually accounted for in the modelling process. [ABSTRACT FROM AUTHOR]

Skew bridges are common in highways and railway lines when non perpendicular crossings are encountered. The structural effect of skewness is an additional torsion on the bridge deck which may have a considerable effect, making its analysis and design more complex In this paper, the dynamic vibration of skew bridges due to railway traffic including the vehicle-bridge interaction is analysed and studied. An analytical model following 3D beam theory is first developed. Following, a simplified 2D model is also considered which includes only vertical beam bending. Both models are applied to a short skew real bridge from the Spanish railway network. The dynamic responses of the bridge obtained from both models are compared with the results obtained by a 3D FE model. A parametric study for a large number of bridges is performed with the simplified model in order to investigate the influence of various parameters as skew angle, span length and torsion stiffness. [ABSTRACT FROM AUTHOR]

One of the significant parameters in design as well as fatigue assessment of railway bridges is the dynamic factor. The dynamic factor, also called dynamic amplification factor (DAF), must be applied to the static load model in order to take account of dynamic magnification of stresses and vibration effects in the bridge. The dynamic factor which actually enhances the static load effects depends on many parameters that are difficult to take into account with reasonable accuracy. The maximum bridge-span, train speed, self-weight, expansion joints if any is placed in bridge, the type of bridge supports and finally soil–structure interaction are among these parameters. This paper studies the variations of the analytical and experimental observations on steel railway bridge dynamics. For this purpose the measured stresses due to passing a locomotive through a historical steel railway bridge in Germany are compared with the calculated stresses contemplating the dynamic factor proposed by EN1991-2 [1] applied to the static load model of the same locomotive. [ABSTRACT FROM AUTHOR]

The lateral vibration of railway bridges induced by moving trains has traditionally been solved through numerical integration. Although it provides practical prediction, the numerical approach does not explicitly reveal the underlying driving mechanism of the train- bridge interaction. In this paper, a closed-form solution is derived for the lateral vibration of a simply supported bridge subjected to hunting forces from running wheel sets. Through complex Fourier expansion, this solution leads to the formulation of three influential factors with explicit physical meanings, namely, the effective unit moving load on the bridge, the arrangement of all moving wheel sets, and the frequency response function of the bridge. On the basis of these factors, a simplified formula to estimate the maximum vibration of the bridge is proposed. The closed-form solution and the simplified formula are validated through comparison with results from numerical integration. The resonance conditions of the bridge due to moving hunting forces are derived using the simplified estimation. [ABSTRACT FROM AUTHOR]

In this article, the use of external damping systems for vibration mitigation of railway bridge dynamics is studied. For a presented case study bridge, the performance of different tuned mass damper systems (TMDs) is studied. During train passage, the change in dynamic characteristics of the bridge may produce a significant detune to a passive TMD. Therefore, routines for a variable stiffness TMD using incremental frequency estimates are developed. Based on numerical simulations, the cumulative fatigue damage is calculated for different damper systems. Due to resonant behavior, the results are found to highly depend on the train speed. Based on an assumed probability density function for the train speed, fragility curves are produced to express the probability of fatigue failure as a function of the number of train passages. [ABSTRACT FROM AUTHOR]

This study describes the calibration and experimental validation of the dynamic model of a railway viaduct with precast deck. Global modal parameters of the structure and local modal parameters of the upper slab of the deck are identified based on a dynamic test. The calibration of the numerical model is done using a genetic algorithm that allows obtaining optimal values of 11 parameters of the numerical model. The inclusion of local modal parameters proved to be crucial, as various parameters of the numerical model do not have significant influence on global modal parameters. Mode pairing between numerical and experimental vibration modes is performed using a recent technique based on modal strain energy. The experimental validation of the calibrated numerical model is done by the comparison between numerical responses and experimental responses obtained in a dynamic test under railway traffic. This dynamic test shows the existence of a nonlinear behaviour of the viaduct's supports. There is an excellent correlation between numerical and experimental responses for different train speeds with the adjustment of the longitudinal supports stiffness of the calibrated model. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Bridge damage location and extent are detectable using ANN with vibration responses. [•] General reliability of damage detection mainly depends on the step of location. [•] Damage near the middle span is easier to be detected than that near the support. [•] The reliability of detection is sensitive to noise, train speed and axle load. [•] Impact of noise is alleviated when resonance occurs with certain train properties. [Copyright &y& Elsevier]

Abstract: In this work models with nonlinear wheel–rail contact forces are considered for analysing the dynamic interaction between high speed trains and bridges, in order to study dynamic effects both in the bridge and in the vehicles resulting from the coupling. Nonlinear contact models may be necessary for evaluating the stability and the safety of running traffic in situations such as vehicle overturn when the train is crossing a bridge under strong lateral winds or when an earthquake occurs. For studying the coupled dynamic response of trains and bridges, models of multibody dynamics are used for vehicles and the finite element method for structures. Special relevance is given here to the consideration of contact interaction forces between railway vehicles and the track. Four different interaction models are compared in this work: (1) a model where the vehicle wheelset is considered to be rigidly coupled to the track; (2) a staggered uncoupled method in which vehicle and structure are analysed separately; (3) a linear contact model in which lateral relative displacements between rails and train wheels are allowed, assuming biconic wheel and rail profiles and linear Kalker theory for tangential contact; (4) a nonlinear model in which realistic wheel and rail profiles, Hertz''s nonlinear theory for normal contact and Kalker''s nonlinear theory for tangential contact are used. The different models are applied and compared to experimental measurements for a test case of a high-speed train in China. [Copyright &y& Elsevier]

The interaction between railway vehicle and bridge is dynamic and nonlinear in nature. This paper aims to develop a computer-aided numerical method for analyzing coupled railway vehicle-bridge systems of nonlinear features. The finite element method is used to establish not only a bridge model (bridge subsystem) but also flexible vehicle models (vehicle subsystem). The connections between the two subsystems are considered through wheel-rail contact models with and without wheel jumps. All the nonlinear forces and concentrated damping forces in the two subsystems and the nonlinear contact forces at their interface are treated as pseudo forces to facilitate nonlinear analysis. The mode superposition method is then applied to the two subsystems, and both non-iterative and iterative computation schemes are utilized to find the best solution. The convergence of iterative computation schemes is investigated with and without wheel jumps. The explicit integration scheme is found to possess higher convergence than other schemes. The applicability and accuracy of the proposed numerical method are finally illustrated through numerical examples and comparisons with previous work. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, the dynamic performance of a certain kind of existing bridge under the action of high-speed railway traffic is addressed. Short-to-medium-span simply supported structures are susceptible to experiencing harmful transverse vibrations under resonant conditions, leading to excessive levels of vertical acceleration, the subsequent premature deconsolidation and degradation of the ballast layer, passenger discomfort and high maintenance costs of the corresponding lines. This dynamic problem, which can require the reduction of the design velocity or the temporary interruption of the railway service to undertake corrective actions, has been reported in Europe, China and Japan during the last decades (European Rail Research Institute (2000) , Duan (1995) , Ishibashi (2004) ). In particular, single-track simply supported short bridges appear to be quite critical structures in this regard. In what follows, the authors present an evaluation of the dynamic performance of three real bridges on the Spanish railway network, located in double-track branches but composed of structurally independent decks. The objective of the investigation is to compare their performance with that of hypothetical modified double-track versions of the original decks. An orthotropic plate finite element model, whose properties are updated from experimental tests performed on the bridges in the past, is used to predict the structural dynamic responses in the time domain. Finally, the predominant effect of the increase in the mass of the bridges over the increase in the eccentricity of the tracks, the reduction in the natural frequency experienced by the torsion mode, and the relevance of three-dimensional modal contributions is proven, leading to remarkable reductions of the maximum acceleration levels in the multiple-track modified structures. [Copyright &y& Elsevier]

This paper describes Twim, a toolbox written in the MATLAB computer language. Twim is designed for monitoring bridge behaviour during train passages as well as for performing Bridge Weigh-In-Motion of railway traffic, both in real-time and offline. The algorithms calculate the static bogie loads and bogie distances, as well as the speed and acceleration of the train. Twim also includes visualization functions, automatic identification of known locomotives and an auto-calibration that uses locomotives with known bogie loads. The algorithms used place specific requirements on both the bridge type and the instrumentation of the bridge. These requirements are explained in the paper. The instrumentation of several bridges is described, and some of the interesting results gained through this instrumentation are presented. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the in situ dynamic measurements and the experimental validation of the numerical model for the prediction of high-speed train-induced vibration. The Sesia viaduct is considered, which is a composite railway bridge consisted by seven spans. The responses of the bridge are measured both under ambient vibration and under the excitation of Italian ETR500Y high-speed trains. From the modal analysis of the ambient vibration data, two types of mode shapes are identified by operational modal analysis. Based on the dynamic behavior of the adjacent spans, the modes of the bridge can be distinguished as symmetrical and anti-symmetrical patterns, which indicates that although each span is statically decoupled, the ballast and the rails realize a connection between the adjacent spans of the bridge. To predict the bridge response due to the passage of high-speed trains, two numerical models are considered. First, a train–bridge interaction model for a vehicle system with 15 degrees of freedom is implemented. Second, the train is modeled as a series of moving load. The numerical simulation is validated by comparing the predicted accelerations and strains with measured results, Both models give a good correspondence between the predicted and the measured response. This study provides a better understanding of the structural behavior of a composite railway bridge under the excitation of high-speed trains. [Copyright &y& Elsevier]

To study the problems associated with vibration control of train-bridge-track systems a mathematical model with the capability of representing supplementary vibrational control devices is proposed. The train system is assumed as rigid bodies supported on double-deck suspension mechanism with semi-active features. The bridge system is modeled using the modal approach. Vibration control for bridge responses is provided by tuned mass dampers. A non-classical incremental Eigen analysis is proposed to trace the system characteristics across the time. In an example, the capability of the proposed model in investigating the vibration control prospects of a bridge-train system is shown. The results indicate the effectiveness of active suspension mechanism in reducing train's body movements, particularly the pitching angle and the vertical accelerations. Accordingly, the results also verify the potential of TMD devices in reducing the bridge responses at resonance motions. [ABSTRACT FROM AUTHOR]