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  • 1.
    Andersson, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines2017Report (Other academic)
    Abstract [en]

    This report contains a comprehensive parametric study on the coupled dynamic train–track–bridge interaction (TTBI) system for non-ballasted railway bridges. The existing design limits in Eurocode EN 1990 A2 regarding vertical deck acceleration and vertical deck displacement is compared with the wheel–rail forces and car body acceleration from simulations.

    The simulations are based on a 2D TTBI model with linear Hertzian contact that allows for loss of contact. The model has been verified against both other numerical simulations as well as experiments, all with good agreement. The parametric study consists of a large number of theoretical bridges, all optimized to reach the limit of either vertical deck acceleration or vertical deck displacement. The study comprises both single- and double track bridges.

    The track irregularities are found to be of paramount importance. Two different levels are therefore studied; “higher track quality” corresponding to a well-maintained track for high-speed railways and “lower track quality” corresponding to the Alert Limit in EN 13848-5. The final conclusions are based on the “lower track quality” in order not to underestimate the risk of running safety and passenger comfort. Simulations with the bridge excluded show that the additional contribution from the bridge is low, especially for the lower track quality.

    The existing limit for vertical deck acceleration is set to 5 m/s2 in EN 1990 A2 and is based on a very simple assumption of the gravity acceleration reduced by a factor 2. The results in this report show that this likely is a too conservative measure of the running safety. Based on the wheel–rail forces from the simulations, the resulting wheel unloading factor and duration of contact loss does not reach critical values before the deck acceleration is beyond 30 m/s2.

    In EN 1990 A2, a vertical car body acceleration of 1 m/s2 is stipulated as “very good level of comfort” and is indirectly limited by the vertical deck displacement. Good agreement is generally found in the simulations between deck displacement and expected car body acceleration. In the simulations, the limit for car body acceleration is always exceeded before the running safety is compromised.

  • 2.
    Andersson, Andreas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train-Track-Bridge Interaction for non-ballasted Railway Bridges on High-Speed Lines2018In: Railways 2018, 2018Conference paper (Other academic)
    Abstract [en]

    This paper presents the result from a parametric study of the dynamic response of railway bridges during train passage. A 2D coupled train-track-bridge interaction (TTBI) model is used to calculate the response from both the bridge and the vehicle.

    To assure traffic safety and riding comfort, Eurocode EN 1990/A2 gives a set of design limits for railway bridges on high-speed lines. The vertical bridge deck acceleration and displacement are often of main interest. For bridges with non-ballasted tracks the vertical deck acceleration is limited to 5 m/s2, simply obtained as the gravity divided by a safety factor 2, under the assumption that loss of wheel-rail contact will occur at 1g. The vertical bridge deck displacement is an implicit measure to assure riding comfort, based on a limited set of simulations carried out in the 1980ies and 1990ies.

    The main aim of this paper is to study the relation between the vertical bridge deck acceleration and the risk of derailment as well as the relation between the vertical deck displacement to the riding comfort. The risk of derailment is estimated both as a wheel-unloading factor based on the filtered wheel-rail contact forces or as the duration of contact loss based on the unfiltered wheel-rail contact forces.

    A large set of theoretical bridges are studied, all optimised to reach the design limits according to EN 1990/A2 for either vertical bridge deck acceleration or displacement. The results show that there is no risk of derailment until the deck acceleration exceeds 30 m/s2. Based on the present parametric study, it appears that the current limit for vertical deck acceleration of non-ballasted railway bridges is very conservative but that the limits for vertical deck displacement is in the correct order of magnitude. It is further concluded that the magnitude of rail irregularities is of great importance, often causing larger dynamic response in the vehicle than due to the vibration of the bridge.

  • 3.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train–Bridge Interaction: Literature Review and Parameter Screening2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    New railway lines are continuously being constructed and existing lines are upgraded. Hence, there is a need for research directed towards efficient design of the supporting structures. Increasingly advanced calculation methods can be motivated, especially in projects where huge savings can be obtained from verifying that existing structures can safely support increased axle loads and higher speeds.

    This thesis treats the dynamic response of bridges under freight and passenger train loads. The main focus is the idealisation of the train load and its implications for the evaluation of the vertical bridge deck acceleration. To ensure the running safety of train traffic at high speeds the European design codes set a limit on the vertical bridge deck acceleration. By considering the train–bridge interaction, that is, to model the train as rigid bodies on suspension units instead of constant moving forces, a reduction in bridge response can be obtained. The amount of reduction in bridge deck acceleration is typically between 5 and 20% for bridges with a span up to 30 m. The reduction can be higher for certain train–bridge systems and can be important also for bridge spans over 30 m. This thesis aims at clarifying for which system parameter combinations the effect of train–bridge interaction is important.

    To this end, a thorough literature survey has been performed on studies in train–track–bridge dynamics. The governing parameters in 2D train–bridge systems have been further studied through a parameter screening procedure. The two-level factorial methodology was applied to study the effect of parameter variations as well as the joint effect from simultaneous changes in several parameters. The effect of the choice of load model was thus set in relation to the effect of other parameter variations.

    The results show that resonance can arise from freight train traffic within realistic speed ranges (< 150 km/h). At these resonance peaks, the reduction in bridge response from a train–bridge interaction model can be considerable.

    From the screening of key parameters it can furthermore be concluded that the amount of reduction obtained with a train–bridge interaction model depends on several system parameters, both for freight and passenger train loads. In line with the European design code’s guidelines for dynamic assessment of bridges under passenger trains an additional amount of damping can be introduced as a simplified way of taking into account the reduction from train–bridge interaction. The amount of additional damping is today given as function of solely the bridge span length, which is a rough simplification. The work presented in this thesis supports the need for a refined definition of the additional damping.

  • 4.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train–Track–Bridge Interaction for the Analysis of Railway Bridges and Train Running Safety2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, train–track–bridge interaction (TTBI) models are used to study the dynamic response of railway bridges. A TTBI model considers the dynamics of the train in addition to that of the track–bridge system. The TTBI model enables the assessment of train running safety and passenger comfort. In the bridge design stage, a moving force model is instead typically used for the train load. The main aim of this thesis is to use results from TTBI models to assess the validity of some of the Eurocode design criteria for dynamic analysis of bridges.

    A 2D rigid contact TTBI model was implemented in ABAQUS (Paper II) and in MATLAB (Paper III). In Paper V, the model was further developed to account for wheel–rail contact loss. The models were applied to study various aspects of the TTBI system, including track irregularities. The 2D analysis is motivated by the assumption that the vertical bridge vibration, which is of main interest, is primarily dependent on the vertical vehicle response and vertical wheel–rail force.

    The reduction in bridge response from train–bridge interaction was studied in Papers I–II with additional results in Part A of the thesis. Eurocode EN 1991-2 accounts for this reduction by an additional damping Δζ. The results show that Δζ is non-conservative for many train–bridge systems since the effect of train–bridge interaction varies with various train–bridge relations. Hence, the use of Δζ is not appropriate in the bridge design stage.

    Eurocode EN 1990-A2 specifies a deck acceleration criterion for the running safety at bridges. The limit for non-ballasted bridges (5 m/s2) is related to the assumed loss of contact between the wheel and the rail at the gravitational acceleration 1 g. This assumption is studied in Paper V based on running safety indices from the wheel–rail force for bridges at the design limit for acceleration and deflection. The conclusion is that the EN 1990-A2 deck acceleration limit for non-ballasted bridges is overly conservative and that there is a potential in improving the design criterion.

  • 5.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Train running safety on non-ballasted bridgesManuscript (preprint) (Other academic)
    Abstract [en]

    The train running safety on non-ballasted bridges is studied based on safety indices from the vertical wheel–rail forces. A 2D train–track–bridge interaction model that allows for wheel–rail contact loss is adopted for a comprehensive parametric study on high-speed passenger trains. The relation between bridge response and vehicle response is studied for more than 200 theoretical bridges in 1–3 spans. The bridge's inuence on running safety and passenger comfort is differentiated from the influence of the track irregularities. The Eurocode bridge deck acceleration limit for non-ballasted bridges is 5 m/s2 based on the assumed derailment risk at 1g from wheel–rail contact loss. This study shows that the running safety indices are not compromised for bridge accelerations up to 30 m/s2. Thus, accelerations at 1g do not in itself lead to contact loss and there is potential to enhance the Eurocode safety limits for non-ballasted bridges.

  • 6.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Swedish Transport Adm Trafikverket, Solna, Sweden..
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train running safety on non-ballasted bridges2019In: International Journal of Rail transportation, ISSN 2324-8378, E-ISSN 2324-8386, Vol. 7, no 1, p. 1-22Article in journal (Refereed)
    Abstract [en]

    The train running safety on non-ballasted bridges is studied based on safety indices from the vertical wheel-rail forces. A 2D train- track-bridge interaction model that allows for wheel-rail contact loss is adopted for a comprehensive parametric study on high-speed passenger trains. The relation between bridge response and vehicle response is studied for more than 200 theoretical bridges in 1-3 spans. The bridge's influence on running safety and passenger comfort is differentiated from the influence of the track irregularities. The Eurocode bridge deck acceleration limit for non-ballasted bridges is 5 m/s(2) based on the assumed derailment risk at 1 g from wheel-rail contact loss. This study shows that the running safety indices are not compromised for bridge accelerations up to 30 m/s(2). Thus, accelerations at 1 g do not in itself lead to contact loss and there is potential to enhance the Eurocode safety limits for non-ballasted bridges.

  • 7.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Modelling Alternatives in the Dynamic Interaction of Freight Trains and Bridges2014In: Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance, 2014Conference paper (Refereed)
    Abstract [en]

    This paper focuses on studying the dynamic response of bridges under passing freight trains. To increase transport efficiency, infrastructure mangers are asked to allow for higher freight train speeds and higher axle loads. However, little work has been done on the influence of increased freight train speeds on bridges. In this paper a two-level factorial experiment was used to identify the most important factors in train-bridge interaction systems comprising the Swedish Steel Arrow freight train passing over simply supported beam bridges. Thereby, the effect of a simple 2D multibody model as opposed to moving forces was set in relation to variations in other key system parameters. Preceding the factorial experiment, four train models were compared to determine a relevant vehicle idealisation. Through the factorial design, effects of single parameters, as well as joint effects from simultaneous changes in several parameters, were evaluated. The type of load model was found to have a large effect, reducing the bridge deck response at resonance considerably for the four studied bridges of span 6, 12, 24 and 36 m. For the relatively light 24 and 36 m span bridges, clear resonance peaks from heavy freight train passages in the speed interval 50-150 km/h were much reduced.

  • 8.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train–bridge interaction: a review and discussion of key model parameters2014In: International Journal of Rail Transportation, ISSN 2324-8386, Vol. 2, no 3, p. 147-186Article in journal (Refereed)
    Abstract [en]

    Research in the field of train–bridge interaction is reviewed, with a particular focus on the vertical dynamic response of the bridge. The most influential system parameters are identified and discussed, providing a basis from which to establish an appropriate degree of complexity in train and track modelling. A two-level factorial experiment is presented. This is used to highlight the relative influence of train–bridge interaction in the train–bridge model, compared with variations in other key parameters. We distinguish those parameter combinations in the train–bridge system that lead to a significant reduction in bridge response due to the train–bridge interaction. The present survey fills an important gap in our existing knowledge by synthesising conclusions from the vast literature on train–bridge interaction. Moreover, the knowledge is related to the European design code’s guidelines for dynamic bridge analysis. The conclusions are summarised to give a rough guidance on modelling choices for train–bridge interaction systems.

  • 9.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Pacoste, Costin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. ELU Konsult AB, Sweden.
    Statistical screening of modelling alternatives in train-bridge interaction systems2014In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 59, p. 693-701Article in journal (Refereed)
    Abstract [en]

    The effect of parameter variations in railway bridges subjected to train loads has been evaluated within the framework of a two-level factorial experiment. Especially, the influence of train-bridge interaction in comparison to other parameter variations is highlighted. Variations in the system parameters were introduced, corresponding to modelling alternatives considering reasonable uncertainties in a bridge design model. The dynamic effect from a passenger train set has been evaluated at, and away from, resonance in beam bridges of span lengths 6, 12, 24 and 36. m. By means of the two-level factorial design, effects from changes in a single parameter, as well as joint effects from simultaneous changes in several parameters, may be evaluated. The effect of including train-bridge interaction through a simple vehicle model as opposed to moving forces was found most distinct at resonance. The effect of the choice of load model was furthermore shown largest for the bridges of span length 24 and 36. m, where it was found more influential or comparable to the effect of other system parameter uncertainties. The high influence of the load model may well be attributed to the fact that the natural frequencies of the 24 and 36. m bridges are close to the vertical frequency of the primary suspension system of the train. The reduction of response obtained with the train-bridge interaction model are discussed in relation to bridge frequency rather than span length, and compared to the Additional Damping Method given in the European design code.

  • 10.
    Arvidsson, Therese
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Zangeneh, Abbas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Cantero, Daniel
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Influence of Sleeper Passing Frequency on Short Span Bridges: Validation against Measured Results2017Conference paper (Refereed)
    Abstract [en]

    The railway track, being discretely supported at each sleeper, has a varying stiffness. The periodic loading from the wheels passing the sleepers at a certain speed introduces the sleeper passing frequency. This excitation of the track is a well-known source of vibration for track embankments. However, the interaction between the sleeper passing frequency and the railway bridge vibration is not well studied. In this paper, a 2D finite element model is calibrated against measured frequency response functions from a short span portal frame bridge. The track is modelled with the rail as a beam resting on discrete spring–dashpots at each sleeper location. In replicating the measured signals from train passages, the train load is typically idealized as moving forces. For the case study bridge, the resulting bridge deck acceleration amplitudes from such a moving force analysis were significantly lower compared to the measured signal. It is shown that if the wheel mass is introduced in the model, and thus the sleeper passing frequency, the model provides results in good agreement with measured data. Thus, it is demonstrated that the bridge deck vibration can be greatly amplified if the sleeper passing frequency matches a bridge frequency. A sensitivity analysis shows that the effect of the sleeper passing frequency is sensitive to track stiffness and bridge frequency.

  • 11.
    Cantero, Daniel
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges. Roughan & O’Donovan Innovative Solutions, Dublin, Ireland.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    O'Brien, Eugene
    Karoumi, Raid
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Train–track–bridge modelling and review of parameters2016In: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980, Vol. 12, no 9, p. 1051-1064Article in journal (Refereed)
    Abstract [en]

    This study gathers all necessary information to construct a model to calculate the coupled dynamic response of train–track–bridge systems. Each component of the model is presented in detail together with a review of possible sources for the parameter values, including a collection of vehicle models, a variety of track configurations and general railway bridge properties. Descriptions of the most important track irregularity representations are also included. The presented model is implemented in MATLAB and validated against a commercially available finite element package for a range of speeds, paying particular attention to a resonant speed. Finally, the potential of the described model is illustrated with two numerical studies that address interesting aspects of train and bridge dynamic responses. In particular, the effect of the presence of a vehicle on the bridge’s fundamental frequency is studied, as well as the influence of the wavelength of the rail irregularities on the dynamic effects of the bridge and the vehicle.

  • 12.
    Johansson, Christoffer
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Arvidsson, Therese
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Martino, Davide
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Solat Yavari, Majid
    ELU-Konsult AB.
    Andersson, Andreas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Pacoste, Costin
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Raid, Karoumi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Höghastighetsprojekt - Bro: Inventering av järnvägsbroar för ökad hastighet på befintliga banor2011Report (Other academic)
    Abstract [en]

    The following report comprises extensive dynamic analyses of railway bridges, with the aim of presenting an initial estimate on the feasibility to allow future high-speed trains on existing bridges. The lines studied are the West main line between Stockholm and Gothenburg, the South main line between Stockholm and Malmö and the West coast line between Gothenburg and Malmö. This comprises more than 1000 bridges.

    Detailed studied of all bridges is beyond the scope of the present study. Instead, a combination of detailed studies and probability-based methods has been chosen. The analyses have been limited to beam- and slab bridges and portal frame bridges, constituting about 90 % of the total included bridge stock. The requirements for the dynamic analyses follow Eurocode EN-1990 and EN-1991-2 and are mainly related to the vertical acceleration of the bridge deck, limited to 3.5 m/s2. The aim of the study is to investigate allowable speeds up to250 km/h.

    Based on extensive parametric analyses, a number of factors have been identified as decisive for the dynamic bridge behaviour. Many of these parameters are difficult to properly estimate and often influence the structural response in a non-regular manner. Extensive Monte-Carlo simulations have been performed based on simplified 2D-models. The results show that about 70 % of the beam- and slab bridges and about 50 % of the portal frame bridges are expected to exceed the design criterions stated by the Eurocode. Even if the allowable speed would be decreased to150 km/h, 15 % of the beam- and slab bridges and 30 % of the portal frame bridges are expected to exceed the criterions. Expected probabilities for each bridge are presented in Appendix F, to be used for further investment cost estimates.

    The presented results are a consequence of the strict criterions stated by the Eurocode, also valid for design of new bridges. Other conditions regarding e.g. train load model or frequency range for evaluation of accelerations will be critical for the results. One of the main remaining questions is the dynamic behaviour of short span bridges appertaining high natural frequencies. The dynamic response from such bridges often constitutes of transient loading rather than resonance. According to the previous Swedish bridge design code BV-Bro, the frequency range was limited to 30 Hz. In Eurocode the frequency range is limited to the third mode of vibration for each studied structural member. This often results in significantly higher frequency ranges, especially for short span bridges. The validity of these criterions must be investigated further.

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