This paper is a review of the effect of vehicle characteristics on ground- and track borne-vibrations from railways. It combines traditional theory with modern thinking and uses a range of numerical analysis and experimental results to provide a broad analysis of the subject area. First, the effect of different train types on vibration propagation is investigated. Then, despite not being the focus of this work, numerical approaches to vibration propagation modelling within the track and soil are briefly touched upon. Next an in-depth discussion is presented related to the evolution of numerical models, with analysis of the suitability of various modelling approaches for analysing vehicle effects. The differences between quasi-static and dynamic characteristics are also discussed with insights into defects such as wheel/rail irregularities. Additionally, as an appendix, a modest database of train types are presented along with detailed information related to their physical attributes. It is hoped that this information may provide assistance to future researchers attempting to simulate railway vehicle vibrations. It is concluded that train type and the contact conditions at the wheel/rail interface can be influential in the generation of vibration. Therefore, where possible, when using numerical approach, the vehicle should be modelled in detail. Additionally, it was found that there are a wide variety of modelling approaches capable of simulating train types effects. If non-linear behaviour needs to be included in the model, then time domain simulations are preferable, however if the system can be assumed linear then frequency domain simulations are suitable due to their reduced computational demand.

https://www.tandfonline.com/doi/pdf/10.1080/23248378.2014.897791

Railway-induced ground vibrations – a review of vehicle effects

An innovative phosphate-based consolidant for limestone. Part 1: Effectiveness and compatibility in comparison with ethyl silicate

Railway local irregularities are a growing source of ground-borne vibration and can cause negative environmental impacts, particularly in urban areas. Therefore, this paper analyses the effect of railway track singular defects (discontinuities) on ground vibration generation and propagation. A vehicle/track/soil numerical railway model is presented, capable of accurately predicting vibration levels. The prediction model is composed of a multibody vehicle model, a flexible track model and a finite/infinite element soil model. Firstly, analysis is undertaken to assess the ability of wheel/rail contact models to accurately simulate the force generation at the wheel/rail contact, in the presence of a singular defect. It is found that, although linear contact models are sufficient for modelling ground vibration on smooth tracks, when singular defects are present higher accuracy wheel/rail models are required. Furthermore, it is found that the variation in wheel/rail force during the singular defect contact depends on the track flexibility, and thus requires a fully coupled vehicle/track/foundation model. Next, a parametric study of ground vibrations generated by singular rail and wheel defects is undertaken. Six shapes of discontinuity are modelled, representing various defect types such as transition zones, switches, crossings, rail joints and wheel flats. The vehicle is modelled as an AM96 train set and it is found that ground vibration levels are highly sensitive to defect height, length and shape.

Railway ground vibrations induced by wheel and rail singular defects

Dynamic interaction of suspension-type monorail vehicle and bridge: Numerical simulation and experiment

The environmental effects of ground-borne vibrations generated due to localised railway defects is a growing concern in urban areas. Frequency domain modelling approaches are well suited for predicting vibration levels on standard railway lines due to track periodicity. However, when considering individual, non-periodic, localised defects (e.g. a rail joint), frequency domain modelling becomes challenging. Therefore in this study, a previously validated, time domain, three-dimensional ground vibration prediction model is modified to analyse such defects. A range of different local (discontinuous) rail and wheel irregularity are mathematically modelled, including: rail joints, switches, crossings and wheel flats. Each is investigated using a sensitivity analysis, where defect size and vehicle speed is varied. To quantify the effect on railroad ground-borne vibration levels, a variety of exposure–response relationships are analysed, including: peak particle velocity, maximum weighted time-averaged velocity and weighted decibel velocity. It is shown that local irregularities cause a significant increase in vibration in comparison to a smooth track, and that the vibrations can propagate to greater distances from the line. Furthermore, the results show that step-down joints generate the highest levels of vibration, whereas wheel flats generate much lower levels. It is also found that defect size influences vibration levels, and larger defects cause greater vibration. Lastly, it is shown that for different defect types, train speed effects are complex, and may cause either an increase or decrease in vibration levels.

/pdf/the-effect-of-railway-local-irregularities-on-ground-3g1dq3azts.pdf

The effect of railway local irregularities on ground vibration

Composition and compatibility requirements of mineral repair mortars for stone – A review

This paper is concerned with the problem of ground vibrations induced by railway traffic and its modelling through a decoupled approach, using only the finite element modelling for evaluating the ground waves propagation. The vehicle/track dynamics is calculated separately. An important modelling aspect is undoubtedly the track/soil interaction, which can play an important role in the generation of seismic waves. To avoid excessive computational resources, a coupled lumped mass model (CLM model) of the soil has been recently developed and is considered in this study. The influence of ballast and soil stiffnesses is presented, in order to confirm the range of validity of the CLM model. Combined with a discrete two layer model of the track, it offers the possibility of working with a simple compound track/soil model. A comprehensive analysis is provided to show the benefit of the finite element model with the proper radiation conditions at infinity, for analysing the structural response of a building located in the vicinity of the track. Focusing on typical results based on the tram of Brussels, the effects of track/soil and soil/structure coupling are investigated. Modal analyses of the vehicle and the building are presented in order to understand the effects of seismic wave amplification, especially when the source contains frequencies close to the natural frequencies of the building.

/pdf/prediction-of-ground-vibrations-induced-by-urban-railway-5fc0p9w5sr.pdf

Prediction of Ground Vibrations Induced by Urban Railway Traffic: An Analysis of the Coupling Assumptions Between Vehicle, Track, Soil, and Buildings

A well-known, light, and almost reversiblere furbishment solution for existing timber floors is the use of a top timber flange connected to the joists to build up a “new” composite. This article pr...

Refurbishment of existing timber floors with screwed CLT panels

Widely used for light frame structures or for heavy laminated wood structures, dowel-type fasteners are the most commonly used kind of connectors in timber construction. The purpose of this work is to develop a tool for the semi-rigid analysis and design of such joints. Firstly, interests and approaches described in literature for the semi-rigid modeling of timber plane frames are summarized. Secondly, for a better understanding of the problem, the main characteristics of wood used as a structural material are presented. Finally, a method for an efficient study of joints built with dowel-type fasteners is proposed and developed. This method consists of the introduction of a specific finite element called “Finite Semi-Rigid Element (FSRE)” between the ends of the jointed members. This joint element consists of two nodes, each with three degrees of freedom. These nodes will be tied with common beamelements during the FE analysis. The stiffness of the FSRE is computed from the geometry of the joints and embe...

Development of a Specific Finite Element for Timber Joint Modeling

Despite the fact that, from the mechanical point of view, there is no ageing issues of timber elements when they are properly used, many old timber structures require important interventions because of changes in uses (which modifies the regulating rules for example), of material decay (misuse of timber) or possibly of a faulty design or construction. In particular, timber floors in old structures often present large deflections and most the time had been designed for a maximum load much lower than the one prescribed by contemporary rules. After an introduction about timber floors and a short review about the reinforcement technics that exist, the present paper presents a new proposal for their reinforcement. The solution developed in the present paper uses a Cross Laminated Timber (CLT) panel screwed over the existing floor, keeping a small gap between the panel and the existing joists. In this way, the new “composite” floor presents higher stiffness and the gap is used for horizontal line runs. For the design of such a “composite floor”, modified Johanssen’s equations (including the gap between the CLT panel and the joists) are proposed and their application on a case study is presented.

/pdf/proposal-of-a-clt-reinforcement-of-old-timber-floors-20igqbaw3r.pdf

Laurent Van Parys

Papers

Composition and compatibility requirements of mineral repair mortars for stone – A review

Prediction of Ground Vibrations Induced by Urban Railway Traffic: An Analysis of the Coupling Assumptions Between Vehicle, Track, Soil, and Buildings

Refurbishment of existing timber floors with screwed CLT panels

Development of a Specific Finite Element for Timber Joint Modeling

Proposal of a CLT Reinforcement of Old Timber Floors