Evangelos Ntotsios

Evangelos Ntotsios
University of Southampton · Institute of Sound and Vibration Research (ISVR)

PhD, MSc MIOA

About

74
Publications
18,906
Reads
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1,159
Citations
Additional affiliations
May 2013 - present
University of Southampton
Position
  • Research Associate
October 2011 - April 2013
Loughborough University
Position
  • Research Associate
September 2007 - December 2008
University of Siegen
Position
  • Visiting Researcher
Education
September 1999 - June 2010
University of Thessaly
Field of study
  • Mechanical Engineering

Publications

Publications (74)
Article
A trench can act as a barrier to ground vibration and is a potential mitigation measure for low frequency vibration induced by surface railways. However, to be effective at very low frequencies the depth required becomes impractical. Nevertheless, for soil with a layered structure in the top few metres, if a trench can be arranged to cut through th...
Article
Full-text available
A bridge health monitoring system is presented based on vibration measurements collected from a network of acceleration sensors. Sophisticated structural identification methods, combining information from the sensor network with the theoretical information built into a finite element model for simulating bridge behavior, are incorporated into the s...
Article
Full-text available
The dynamic characteristics of two representative R/C bridges on Egnatia Odos motorway in Greece are estimated based on low amplitude ambient and earthquake-induced vibrations. The present work outlines the instrumentation details, algorithms for computing modal characteristics (modal frequencies, damping ratios and modeshapes), modal-based finite...
Article
Full-text available
A methodology is proposed for estimating damage accumulation due to fatigue in the entire body of a metallic structure using output-only vibration measurements from a sensor network installed at a limited number of structural locations. Available frequency domain stochastic fatigue methods based on Palmgren-Miner damage rule, S-N fatigue curves on...
Article
Full-text available
A case study on a small-scale laboratory vehicle frame is used to investigate the variability of the updated finite element (FE) models that arises from model and measurement errors and demonstrate the effect of this variability on response predictions. Conventional weighted modal residuals and recently introduced multi-objective identification met...
Article
Full-text available
Within the SILVARSTAR project, a user-friendly frequency-based hybrid prediction tool has been developed to assess the environmental impact of railway-induced vibration. This tool is integrated in existing noise mapping software. Following modern vibration standards and guidelines, the vibration velocity level in a building in each frequency band i...
Article
Full-text available
Within the SILVARSTAR project, a track-independent vehicle indicator (TVI) is proposed that can be used to identify railway vehicles which generate low ground-borne vibration and noise levels. The proposed TVI is based on applying a frequency weighting to the force density, which may be obtained at a site from the measured ground vibration velocity...
Chapter
Numerical models and vibro-acoustic measurements are used to assess the effect of reflections from the underside of a railway vehicle on the sound radiation from the rail. A 2D boundary element model is used in which the rail vibrates uniformly in either vertical or lateral directions; various different shapes of vehicle body are introduced into th...
Chapter
A finite element numerical model and a semi-analytical model are used to analyse the influence of buildings on ground vibration from underground railways. The insertion loss of a building with four types of foundations is examined using a 3D finite element model. Additionally, a semi-analytical model is built to analyse the vibration of the ground...
Chapter
A study is presented into the sensitivity of rolling noise to design changes in a two-stage baseplate rail fastening system. The focus is on the influence on the rolling noise of three parameters of the fastening system: the stiffnesses of the railpad and the baseplate pad and the thickness of the baseplate that determines its mass and sound radiat...
Chapter
One of the main objectives of the SILVARSTAR project is to develop a user-friendly frequency-based hybrid prediction tool to assess the environmental impact of railway induced vibration. This model is integrated in the noise mapping software IMMI. Following modern vibration standards and guidelines, the vibration velocity level in the building in e...
Article
Purpose The vibration of the rails is a significant source of railway rolling noise, often forming the dominant component of noise in the important frequency region between 400 and 2000 Hz. The purpose of the paper is to investigate the influence of the ground profile and the presence of the train body on the sound radiation from the rail. Design/...
Article
To improve the accuracy of railway induced ground vibration predictions, the influence of surrounding buildings should be considered. For this reason, a fast semi-analytical model is developed to investigate the vibration of the ground and the influence of a nearby building. The model contains two sub models: a finite element model which can simula...
Article
In previous in-situ measurements of metro trains it has been found that the velocity level on the track or tunnel wall may vary significantly between different train passages, even though the measuring section, the type of trains and the track and tunnel conditions are identical. An investigation is carried out into the sources of this variability,...
Conference Paper
To improve the accuracy of railway induced ground vibration predictions, the influence of surrounding buildings should be considered. For this reason, a fast semi-analytical model is developed to investigate the vibration of the ground and the influence of a nearby building. The model contains two sub models: a finite element model which can simula...
Conference Paper
p>A number of different track forms are studied from one tramway system including tracks in ballast, on slab, and embedded rail in grass. Measurements have been carried out of rail roughness, wheel roughness and track decay rate, which are used as input data for the noise prediction model TWINS. The rail vibration and exterior noise of trams in ope...
Chapter
The dynamic properties of the rail fastening system affect the damping of the rail and the degree of coupling between the rail and the foundation. It is well known that the rate of decay of vibration along the rail is closely linked to the noise performance of the track. For this reason, the track decay rate (TDR) is used as an important measurable...
Chapter
Full-text available
Railway crossings are an important source of localized ground vibration. Models are required for identifying ways to tackle unacceptable levels of vibration from existing as well as future railway lines. Yet, the use of a prediction model that directly allows for the non-Hertzian wheel-rail contact dynamics and also includes three dimensional calcu...
Article
Tramway noise can be significant even though the speeds are relatively low. The influence of track design on the rolling noise is studied through a systematic comparison of different tracks on a single network. These include a slab track with embedded sleeper blocks, a ballasted track and a track with embedded rails. Measurements have been taken of...
Conference Paper
When modelling the railway induced vibration in a building, three main aspects of the problem have to be considered: the vibration generation at the moving vehicle-track interaction points, the vibration propagation in the underlying infinite soil, and the vibration reception inside the building. This study proposes a computational modelling approa...
Article
Full-text available
The environmental impacts of noise and vibration are becoming increasingly important in the assessment of new and upgraded railway routes. Vibration from railways propagates through the ground to nearby buildings where it may cause annoyance as feelable vibration or as re-radiated noise. To tackle the adverse effects of ground-borne noise a range o...
Article
A novel computational modelling approach for prediction of environmental vibration is introduced. The model is formulated in both moving and fixed frames of reference, with a mixed frame of reference formulation introduced to couple the two frames of reference. The resulting system is able to model a vehicle travelling on an infinite railway track,...
Article
The prediction of the ground vibration transmitted from tunnels to neighbouring buildings is a vital step in the assessment of the ground-borne noise in buildings. In empirical models it is commonly assumed that the level of ground vibration reduces monotonically with the distance away from the tunnel alignment. In reality, a ‘shadow’ zone is obser...
Article
There is a great need to develop rail networks over long distances and within cities as more sustainable transport options. However, noise and vibration are seen as a negative environmental consequence. Compared with airborne noise, the related problem of ground vibration is much more complex. The properties of the ground vary significantly from on...
Article
With the development of non-ballasted track forms (often referred to as slab tracks) over the few last decades, it is important to understand their behaviour with respect to ground-borne vibration compared with the traditional ballasted tracks. This is important in deciding between the use of the two track forms. The present work aims to quantify t...
Article
Transport infrastructure produces many externalities. Increased accessibility and the resultant economic development are among the most notable positive ones. Accidents, air and noise pollution and other environmental issues, such as impacts on biodiversity, landscape and townscape, are the most important negative ones. In the case of railway infra...
Conference Paper
Railway crossings are an important source of localized ground vibration. Models are required for identifying ways to tackle unacceptable levels of vibration from existing as well as future railway lines. Yet, the use of a prediction model that directly allows for the non-Hertzian wheel-rail contact dynamics and also includes three dimensional calcu...
Conference Paper
Full-text available
The dynamic properties of the rail fastening system affect the damping of the rail and the degree of coupling between the rail and the foundation. It is well known that the rate of decay of vibration along the rail is closely linked to the noise performance of the track. For this reason, the track decay rate (TDR) is used as an important measurable...
Conference Paper
The noise and vibration from tramcars are studied, including rolling noise, ground vibration and roughness of both rail and wheel. The aim of the paper is to provide a comprehensive study of the sources of noise and vibration from tramways using theoretical models and field measurements. Means to reduce them will then be proposed based on the resul...
Article
Full-text available
When a train runs on soft ground it can approach or even exceed the speed of surface waves in the ground. Under such conditions the amplitudes of the track response increase considerably. Moreover, a resonance-like phenomenon can occur in which a clear oscillation trail can be observed behind the moving axle loads. An investigation is presented of...
Article
p>Transport infrastructure produces many externalities. Increased accessibility and the resultant economic development are among the most notable positive ones. Accidents, air and noise pollution, and other environmental issues, such as impacts on biodiversity, landscape and townscape, are the most important negative ones. In the case of railway in...
Conference Paper
Full-text available
In deciding between the use of ballasted track or slab track, an important issue is their noise and vibration performance, as slab track is usually considered to be noisier than ballasted track. The comparative performance of different track designs is assessed here in terms of both noise and vibration. The TWINS model is used to predict the rollin...
Article
This paper presents a methodology for studying ground vibration in which the railway track is modelled in the space-time domain using the finite element method (FEM) and, for faster computation, discretisation of the ground using either FEM or the boundary element method (BEM) is avoided by modelling it in the wavenumber-frequency domain. The railw...
Article
Full-text available
In predictions of ground-borne vibration from railways, it is generally assumed that the unevenness profile of the wheel and rail is fully correlated between the two rails and the two wheels of an axle. This leads to identical contact forces at the two rails and can allow further simplifications of the vehicle model, the track model and the track/g...
Article
Full-text available
A numerical model is presented for the ground-borne vibration produced by trains running in tunnels. The model makes use of the assumption that the geometry and material properties are invariant in the axial direction. It is based on the so-called two-and-a-half dimensional (2.5D) coupled Finite Element and Boundary Element methodology, in which a...
Article
Full-text available
Companies which manage railway networks have to cope continually with the problem of operating safety and maintenance intervention issues related to rail surface irregularities. A lot of experience has been gained in recent years in railway applications but the case of tramways is quite different; in this field there are no specific criteria to def...
Conference Paper
Full-text available
Companies which manage railway networks have to cope continually with the problem of operating safety and maintenance intervention issues related to rail surface irregularities. A lot of experience has been gained in recent years in railway applications but the case of tramways is quite different; in this field there are no specific criteria to def...
Article
A new state-space model is formulated for the dynamic analysis of sandwich beams that are made of two thin elastic layers continuously joined by a shear-type viscoelastic (VE) core. The model can accommodate different boundary conditions for each outer layer and accounts for the rate-dependent constitutive law of the core through additional state v...
Conference Paper
Full-text available
Within the context of railway ground-borne vibration, the dynamic pile-soil-pile interaction remains an area that has not been sufficiently investigated. Whilest a number of researchers have scrutinised the vibration response of piled-foundations, their approaches exhibit a compromise between computation time and solution accuracy. In this paper, t...
Conference Paper
Full-text available
This paper presents the influence of rail unevenness correlation on the predicted track and ground vibration. The study is based on an integrated railway model in the wavenumber-frequency domain with varying complexity describing the dynamic system of a ballasted track on layered elastic half-space. In order to investigate how ground vibration leve...
Conference Paper
Full-text available
In this paper, the dynamic pile-soil-pile interaction (PSPI) in a multi-layered half-space is investigated for the prediction of the response of piled foundations due to railway vibrations. Two methods of modelling piled foundations in a multi-layered half-space are presented. The first is an efficient semi-analytical model that calculates the Gree...
Conference Paper
Full-text available
This paper reports on recent developments in techniques for modelling ground vibration from railways. The modelling considers both surface and underground railways, and accounts for the main dynamic systems involved, i.e. tracks (both ballasted and slab), tunnels and multi-layered ground. Results are presented to illustrate the modelling capabiliti...
Conference Paper
Full-text available
Ground vibration and ground-borne noise from trains in tunnels are attracting increasing attention from researchers and engineers. They are important environmental issues related with the operation of underground networks in intensively-populated urban areas. An accurate prediction for this train-induced vibration can be very helpful in the impleme...
Conference Paper
Full-text available
The type of railpad model adopted in modelling the dynamic behaviour of a railway track influences the accuracy of prediction of the vibration of the track as well as the forces transmitted to the ground. The linear Kelvin-Voigt model is most widely used amongst authors. This model consists of a parallel arrangement of spring and viscous dashpot, r...
Conference Paper
Full-text available
In spite of the global financial crisis, considerable investments are being made in railway infrastructure in the UK and many countries around the world. Improvements in the quality and capacity of current services and the development of new railway infrastructure are needed to meet the increasing demand for transferring more people and goods in a...
Conference Paper
Full-text available
Ground-borne vibration from railways is generated at the wheel-rail interface due to the passage of individual wheels along tracks and due to irregularities of wheels and tracks. In this paper, two approaches are used to calculate the vibration Power Spectral Density (PSD) in the free field from a train moving on a surface railway track at a consta...
Conference Paper
Full-text available
Viscoelastic damping devices are effective in mitigating vibrations experienced by Civil Engineering structures subjected to natural actions, such as earthquakes, wind gusts or ocean waves. In this paper, an efficient computational framework for non-classically damped viscoelastic structures is proposed, allowing rheological information on nano-rei...
Conference Paper
Full-text available
A real-time online structural health monitoring system for the Metsovo bridge, the highest R/C bridge of the Egnatia Odos Motorway in Greece, is outlined and then used to develop high fidelity dynamic finite element models for the bridge-foundation-soil system. Operational modal analysis software is used to obtain the modal characteristics of the b...
Conference Paper
Full-text available
A Bayesian model class selection and updating framework is used for identifying the location and size of damage in a structure utilizing measured dynamic data. The framework consists of a two-level approach. At the first level the model classes chosen from a set of competing model classes are ranked and the best model class is selected. At the seco...
Thesis
Full-text available
This thesis concentrates on the development and validation of methods for identifying dynamic models of complex structures as well as predicting fatigue damage accumulation by exploiting measured vibration information. The identified models refer to mathematical modal models as well as linear finite element models of structures, while the applicati...
Conference Paper
Full-text available
A methodology is proposed for estimating damage accumulation due to fatigue in the entire body of a metallic structure using output-only vibration measurements from a sen-sor network installed at a limited number of structural locations. This method can also be seen as a tool for a life-time prognosis within SHM concepts. Available frequency domain...
Conference Paper
Full-text available
Available methods for structural model updating are employed to develop high fi-delity models of the Metsovo bridge using ambient vibration measurements. The Metsovo bridge, the highest bridge of the Egnatia Odos Motorway, is a two-branch balanced cantile-ver ravine bridge. It has a total length of 357m, a very long central span of 235m, and a heig...
Conference Paper
Full-text available
A multi-objective optimization framework is presented for updating finite element models of structures based on vibration measurements. The method results in multiple Pareto optimal structural models that are consistent with the measured data and the residuals used to measure the discrepancies between the measured and the finite element model predi...
Conference Paper
Full-text available
Methods for modal identification and structural model updating are employed to develop high fidelity finite element models of an experimental vehicle model using accelera- tion measurements. The identification of modal characteristics of the vehicle is based on ac- celeration time histories obtained from impulse hammer tests. An available modal ide...
Conference Paper
Full-text available
A Bayesian framework is presented for structural model selection and damage identification utilizing measured vibration data. The framework consists of a two-level ap- proach. At the first level the problem of estimating the free parameters of a model class given the measured data is addressed. At the second level the problem of selecting the best...
Thesis
Full-text available
This thesis addresses the problem of identifying the modal properties of structures using vibration measurements. Modal identification methodologies are proposed based on vibration measurements induced by artificial, ambient or earthquake loads applied on the structure. A modal model of the structure is identified using a weighted least-squares app...
Conference Paper
Full-text available
p>The instrumental rapid monitoring of the dynamic (ambient) response of a balanced cantilevered ravine bridge of Egnatia Motorway during its construction phases, when subjected to wind and other construction loads, was implemented. The aim is to verify the conformity both of the sequential construction phases and of the final completed structure o...
Conference Paper
Full-text available
p>Successful structural health monitoring and condition assessment depends to a large extent on the sensor and actuator networks place on the structure as well as the excitation characteristics. An optimal experimental design methodology deals with the issue of optimizing the sensor and actuator network, as well as the excitation characteristics, s...
Article
Full-text available
A multi-objective identification method for structural model updating based on modal residuals is presented. The method results in multiple Pareto optimal structural models that are consistent with the experimentally measured modal data and the modal residuals used to measure the discrepancies between the measured and model predicted modal characte...
Article
Full-text available
This work outlines the optimization algorithms involved in integrating system analysis and measured data collected from a network of sensors. The integration is required for structural health monitoring problems arising in structural dynamics and related to (1) model parameter estimation used for finite element model updating, (2) model-based damag...
Conference Paper
Full-text available
p>This work outlines the optimization algorithms involved in integrating system analysis and measured data collected from a network of sensors. The integration is required for structural health monitoring problems arising in structural dynamics and related to (1) model parameter estimation used for finite element model updating, (2) model-based dam...
Conference Paper
Full-text available
A multi-objective optimization framework based on modal data is presented for finite element model updating in structural dynamics. The framework results in multiple Pareto optimal structural models that are consistent with the measured data and the norms used for reconciling finite element models with data. Computationally efficient methods for es...
Conference Paper
Full-text available
A multi-objective optimization method is presented for estimating the parameters of finite element structural models based on modal residuals. The method results in multiple Pareto optimal structural models that are consistent with the measured modal data and the modal residuals used to measure the discrepancies between the measured modal values an...
Conference Paper
Full-text available
A multi-objective identification method for model updating based on modal residuals is proposed. The method results in multiple Pareto optimal structural models that are consistent with the measured modal data, the class of models used to represent the structure and the modal residuals used to judge the closeness between the measured and model pred...
Conference Paper
Full-text available
Theoretical and computational issues arising in the selection of the optimal sensor configuration in structural dynamics are addressed. The information entropy is introduced to measure the performance of a sensor configuration. Asymptotic estimates are used to rigorously justify that selections of optimal sensor configurations can be based solely o...

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