Rui Calçada

• University of Porto

The assessment of running safety of railway bridges is conditioned by the Eurocode EN 1990 A2 by limiting vertical deck acceleration. On ballastless track bridges, this value is 5 m/s2. The background for this value is not clear, and it is believed that it originates in the application of an arbitrary safety factor of 2 on accelerations around 1 g...

High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations. For the design of these structures, the European norm EN 1991-2 introduces the high-speed load model (HSLM)—a set of point loads intended to include the effects of existing high-speed trains. Yet, the evolution of current trains and...

Knowledge of the structural health of components with greater failure criticality can help increase the longevity of railway vehiclesby allowing increasing the spacing between inspections. This article presents an experiment to determine the typical stress spectrumobserved in parabolic leaf springs of railway freight wagons. The stress spectrum gen...

This article is focused on a state-of-the-art on the most recent computer vision methodologies for railway bridge inspection, including the procedures for integrating the valuable data into decision-making systems. Railway bridges are a critical component of the infrastructure, but they are susceptible to material and structural degradation, as wel...

Over the years, the rail industry has demonstrated its potential to combat climate change and reduce its carbon footprint. Due to its enormous potential, EU countries have invested in the development of new solutions for the freight and passenger rail sector. However, the lack of innovation and scientific knowledge in the Portuguese railway sector...

Railway infrastructures play a pivotal role in developing the national transportation system. Recently, the strategy of the railway engineer has been significantly shifted; along with the development of new assets, they tend to pay increasing attention to the operation and management of existing railway assets. In this regard, this paper proposes a...

An enhancement in the wheel–rail contact model used in a nonlinear vehicle–structure interaction (VSI) methodology for railway applications is presented, in which the detection of the contact points between wheel and rail in the concave region of the thread–flange transition is implemented in a simplified way. After presenting the enhanced formulat...

Structural damping is an important characteristic in railway bridges, which affects the performance of the structure, especially for bridges with train speeds higher than 200 km/h. The accurate evaluation of damping must be performed properly to correctly assess the structural performance of the bridge under dynamic loading conditions. The present...

The long term performance of the railway tracks is a relevant topic and a major concern of the railway Infrastructure Managers due to the technical and economical aspects related to the degradation of the track. Thus, there are several factors that have a significant influence on the short and long term performance of the ballasted and ballastless...

Mode pairing is a crucial step for the stability of any model-updating strategy based on experimental modal parameters. Automatically establishing a stable and assertive correspondence between numerical and experimental modes, in many cases, proves to be a very challenging task, especially in situations where complex mode shapes are present. This a...

This article describes the validation of a 3D dynamic interaction model of the train–track–bridge system on a bowstring-arch railway bridge based on experimental tests. The train, track, and bridge subsystems were modeled on the basis of large-scale and highly complex finite elements models previously calibrated on the basis of experimental modal p...

Nowadays, monitoring the condition of railway infrastructure has become necessary and led railway companies to take advantage of artificial intelligence (AI) technologies to improve safety and reduce operating costs. This paper aims to present an unsupervised methodology to detect railway wheel flats. The automatic damage detection algorithm is bas...

O dimensionamento de pontes ferroviárias com via não-balastrada sujeitas a ações dinâmicas é atualmente condicionado por um critério que limita a aceleração vertical nos tabuleiros. No Eurocódigo 1-Parte 2 este valor é estabelecido como 5 m/s 2 , o que sugere a aplicação de um coeficiente de segurança de 2 ao valor de 10 m/s 2 que poderia causar a...

This article presents the validation of a non-linear FE numerical model of a multi-span stone arch railway bridge based on experimental tests and under in-service freight trains. Static loading tests allow evaluating the bridge response in terms of vertical displacements in the arches, opening/closure deformations on specific block joints of the ar...

This paper presents an integrated fatigue analysis methodology for existing metallic railway bridges, progressively implementing global to local fatigue assessment methods, each requiring a different level of calculation detail. The former are adopted mainly for screening the fatigue-critical connections using nominal stress-based SN curves, which...

This article describes the experimental and numerical evaluation of the dynamic behaviour of Cascalheira bridge located on the Northern Line of the Portuguese railway network. The bridge has a short span formed by two filler-beam half-decks each one accommodating a railway track. The study includes the development of a finite element numerical mode...

In a recent research paper, Alencar et al. [1] demonstrated that the Master S‐N curve method (ASME) is also applicable for the fatigue analysis of welded bridge details. Thus, in this paper a methodology based on the Master S‐N curve for the fatigue analysis of welded railway bridges subjected to the railway traffic is proposed. A finite element mo...

The main goal of this paper is to present an unsupervised methodology to identify railway wheel flats. This automatic damage identification algorithm is based on the acceleration evaluated on the rails for the passage of traffic loads and deals with the application of a two-step procedure. The first step aims to build a confidence boundary using ba...

Railways are increasingly an essential part of a greener future. In Europe, the Shift2Rail programme has promoted research projects related to rail infrastructure, including the enhancement of building codes. Concerning the EN 1990-Annex A2, this study discusses its limit for vertical deck acceleration on ballasted track railway bridges and the par...

Bridges are typically large structures whose numerical modelling is focused on the global scale, mainly due to computational constraints. Using such models, the evaluation of fatigue phenomena is not possible based on local mechanical quantities, with the difference between the dimension of the structure and the local nature of the damage being a m...

The numerical assessment of the building's dynamic response due to railway traffic usually requires advanced numerical models. However, from an engineering perspective, simple and efficient methodologies are desirable. Thus, a hybrid approach is formulated, combining numerical/experimental results and post-processing techniques. The underlying conc...

Wheel defects can induce damage to the railway tracks, increasing considerable maintenance costs for both railway administrations and rolling stock operators. This paper aims to develop an unsupervised early damage detection methodology, capable of automatically distinguishing a defective wheel from a healthy one, with respect to the small flat siz...

The fatigue analysis of large structures is highly limited by a multiscale problem between the global responses of structural systems and the localised nature of fatigue damage. Currently, S-N curves are used to overcome such an issue using nominal stresses, but overly conservative safety margins may be assumed when investigating existing metallic...

The main goal of this paper is to present an unsupervised methodology to identify railway wheel flats. This automatic damage identification algorithm is based on the acceleration evaluated on the rails for the passage of traffic loads and deals with the application of a two-step procedure. The first step aims to build a confidence boundary using ba...

This book chapter aims at detecting damage in railway bridges based on traffic-induced dynamic responses. To achieve this objective, an unsupervised automatic data-driven SHM strategy is presented, consisting of a hybrid combination of multivariate statistical techniques. Damage-sensitive features of train-induced responses are extracted and allow...

The development of efficient weigh-in-motion and wheel defect detection methods with high accuracy estimation procedures from track measurements is one of the major subjects that draw the attention of both the railway industry and scientific researchers. This information triggers a warning in the administration system when a train is overloaded or...

Deep-learning techniques have been applied to inspect cracks in RC structures. Capitalizing on that experience a technique is proposed for automated detection of exposed rebars. The results obtained are promising, confirming the adaptability of CNN based methodologies for structural inspection.

Several methods have been employed in scientific research to detect train wheel flat in recent decades [1, 2]. However, reported literature on automatic early wheel flat detection has been limited so far. In most proposed wheel flat detection techniques, there is no indication of automatically distinguishing a defective wheel from a healthy one. Mo...

In recent years deep-learning techniques have been developed and applied to inspect cracks in RC structures. The accuracy of these techniques leads to believe that they may also be applied to the identification of other pathologies. This article proposes a technique for automated detection of exposed steel rebars. The tools developed rely on convol...

This article describes the experimental and numerical evaluation of the dynamic behaviour of the Cascalheira bridge, located on the Northern Line of the Portuguese railway network. The bridge has a short span formed by two filler-beam half-decks, each one accommodating a railway track. The study includes the development of a finite element numerica...

Passenger riding comfort is a major concern in railways, particularly in high-speed (HS) networks due its strict requirements. Both the track and vehicle conditions may influence the comfort experienced by the passengers, but other external factors may also do it. Among these factors, the effects caused by crosswinds stand out due to the high level...

This paper presents an advanced submodelling methodology for local stress analysis of complex details of existing metallic railway bridges. The fatigue assessment of connections of large structures based on local methods leads inherently to a multiscale problem that can only be solved by adopting efficient numerical procedures. Aiming to overcome s...

A R T I C L E I N F O Keywords: Train running safety Train-track-bridge interaction High-speed railway bridges Wind loads Bridge lateral flexibility Track condition A B S T R A C T This paper studies the influence of different factors related to the structure-track-vehicle coupling system in the train's stability against crosswinds, namely the brid...

This paper exploits unsupervised data-driven structural health monitoring (SHM) in order to propose a continuous online procedure for damage detection based on train-induced dynamic bridge responses, taking advantage of the large-magnitude loading for enhancing sensitivity to small-scale structural changes. While such large responses induced by tra...

This paper focuses on the stochastic response of railway embankments considering the uncertainties in soil cohesion and friction angle. The non-sampling stochastic method concerning generalised polynomial chaos (gPC) expansion was employed for the dynamic numerical simulation. The uncertain parameters, including soil cohesion and friction angle, we...

The simulation of the dynamic behavior of the train-track system is strongly dependent on the accuracy of the numerical models of the train and track subsystems. The use of calibrated numerical models of the railway vehicles, based on experimental data, enhances their ability to correctly reproduce the dynamic responses of the train under operation...

Railway track transition zones are characterised by an abrupt change in track support stiffness, which increases dynamic wheel loads and leads to the acceleration of differential settlement and track degradation. The performance of transition zones is a concern for railway Infrastructure Managers due to the increased maintenance operations and cost...

Short-span railway bridges subjected to high-speed traffic are structures where dynamic effects are mandatory. Additionally, the variability associated with materials and geometric characteristics introduces uncertainty to the safety assessment of railway traffic. This work discusses the current norm’s limit for vertical deck acceleration regarding...

A receptance test was performed in a ballasted track section with three sleepers after cyclic loading tests. This physical model is installed in the laboratory of Heriot-Watt University. The ballasted track is resting on a compacted substructure that is characterized by a frost protection layer (FPL), subgrade and geosynthetic-reinforced soils (GRS...

The Portuguese railway sector has suffered a significant shortage of resources, generating many issues associated with the maintenance of the rolling stock affecting its operational ability. Many of these problems are caused by the fatigue phenomenon in leaf springs of freight wagons. Thus, the study of fatigue becomes an important role in the stru...

In practice, fatigue properties such as stress life and strain life are often fit from a relatively small amount of data, making accurate statistical analysis a challenge. Using a strain energy based damage model to predict strain-life and stress-life curves from individual specimens (Huffman in Int J Fatigue 88:197–204, 2016 [1]), a set of curves...

Railway has proved to be a sustainable transportation alternative. This potential has caused a huge investment in the sector in recent years. However, in the freight sector, leaf spring suspensions have been suffering failures due to fatigue, causing derailments and serious losses. This work intends to provide resources to predict future structural...

Prediction and mitigation of ground-borne vibrations are one of the largest environmental challenges for railway exploitation in urban areas. The expansion and improvement of the railway network demands put new challenges on technical community, namely in the assess the environmental impact of the exploitation of railway infrastructures in the surr...

At present, in modern railway systems, train or rolling stocks are powered by electricity through the overhead wire or the third rail on the ground. Overhead line equipment (OHLE) is the component for the electric train which supplies electric power to the train. OHLE is, for one or two tracks, normally supported by cantilever masts, while a portal...

Typically, bridge structural systems are affected by random loads that can cause significant damage. One challenging problem in this field is the high-stress amplitude associated with distortion-induced fatigue. In this study, the hot-spot method and the master S-N curve method were validated for the evaluation of fatigue resistance induced by dist...

This article presents an efficient methodology for the calibration of a numerical model of a Sgnss freight railway wagon based on experimental modal parameters, namely natural frequencies and mode shapes. Dynamic tests were performed for two distinct static loading configurations, tare weight and current operational overload, under demanding test c...

Progressive updating strategies are commonly used for the calibration of numerical models such as those of a track-bridge system. These strategies involve, first, updating the track model based on dedicated dynamic tests, and second, the calibration of the bridge model based on ambient vibration tests considering the updated track parameters. This...

A novel practical three-dimensional (3D) wheel-rail interaction (WRI) element is developed to simulate the interaction between a fast-moving wheel node and nodes of the rail. Different from most previous methods of wheel-rail contact in multibody dynamics, the wheel-rail relationship in this paper is simulated by the WRI element. The WRI element is...

This chapter addresses unsupervised damage detection in railway bridges by presenting a novel AI-based SHM strategy using traffic-induced dynamic responses. To achieve this goal a hybrid combination of wavelets, PCA, and cluster analysis is implemented. Damage-sensitive features from train-induced dynamic responses are extracted and allow taking ad...

In Europe, a large number of old riveted metallic bridges approach the end of their fatigue life. Past research has shown that the application of CFRP can be very efficient in delaying the crack growth rate of deficient structural elements with existing crack. However, little attention is given to the fatigue resistance of non‐damaged metallic memb...

This paper presents a new approach to estimate the fatigue life of metallic details retrofitted with bonded CFRP patch. Existing phenomenological and analytical methods to predict the fatigue life of metallic structural details retrofitted with bonded CFRP patch do not consider the cyclic degradation of the composite patch. As for all materials the...

The Master S-N curve method enables the use of computationally efficient coarse FE models without overlooking accuracy in fatigue life estimates of welded structures. However, the use of the method in daily design practice of engineering offices faces the barrier of a largely available finite element post-processor. This paper intends to fill the g...

The aim of the present study consists of evaluating the influence of the most relevant geometric, mechanical and aerodynamic vehicle properties in the risk of derailment caused by crosswinds. To achieve this objective, a vehicle-structure interaction model is used to carry out non-linear dynamic analyses to assess the train-track coupling behaviour...

Train running safety is a major concern among railway engineers, since a derailment may cause significant personal and material damages. This problem becomes more important if the derailment occurs on bridges, especially at high ¬¬speeds, where the consequences may be even worse. The sudden development of high speed (HS) railway networks that occur...

The assessment of vibrations induced by railway traffic is a complex issue that demands numerical tools for prediction of its generation and propagation along the track-ground-building system. For that purpose, this paper presents a 2.5D FEM-MFS model for modelling the track-ground system, where the Finite Element Method (FEM) is used to model the...

The verification of the Master S-N curve approach using an equivalent structural stress parameter, has been carried out for welded joints with different geometries, thickness and loading modes, mainly representative of pressure vessels and piping components. The application of the Master S-N curve to a new field requires the reassessment of the rel...

Wheel defects on railway vehicles are documented as a critical source of damage to railway infrastructure. Recently, the condition monitoring of railway infrastructure has become particularly important and has led the railway companies to apply artificial intelligence (AI) techniques to evaluate the railway wheel condition in operation, by monitori...

The dynamic analysis of the vehicle-bridge system is a complex interaction problem which typically involves the development of advanced finite element (FE) models of the vehicles, track and bridge subsystems and their interfaces. The experimental calibration of the FE models of these subsystems is usually performed based on modal parameters, namely...

This article presents a methodology for assessing the train running safety on bridges subjected to strong crosswinds. The methodology is based on an in-house numerical tool called VSI - Vehicle-Structure Interaction Analysis, which computes the dynamic response of the coupled system formed by the train and the bridge. By imposing the wind load, bas...

This article presents an efficient methodology for the calibration and validation of a numerical model of a freight wagon based on a dynamic test under real operation conditions. The dynamic test takes place during a regular journey of the train and involved the installation of on-board accelerometers and LVDTs, whose number and location was condit...

In this paper, the performance of different railway structures – ballasted and two types of slab tracks (Rheda system and a ballastless track only constituted by the concrete slab) – is evaluated in terms of stresses and permanent deformations through the selection of some important parameters: wavelength of the unevenness profile, train’s speed, s...

The gradual deterioration of train wheels can increase the risk of failure and lead to a higher rate of track deterioration, resulting in less reliable railway systems with higher maintenance costs. Early detection of potential wheel damages allows railway infrastructure managers to control railway operators, leading to lower infrastructure mainten...

This article describes an innovative methodology for estimating in-plane horizontal displacements of Civil Engineering structures based on video systems integrated on Unmanned Aerial Vehicles (UAVs). As the structure and the UAV are both in motion, estimating absolute structural displacements involves, first, assessing the relative displacements of...

[Read and share here: https://rdcu.be/ceTSc] This paper presents a progressive numerical model validation of a bowstring-arch railway bridge based on the analysis of experimental data from different structural response measurements, namely, static deformations under environmental actions, modal vibrations, and transient dynamic responses under tra...

[Read and share here: https://authors.elsevier.com/a/1cqCTW4G4TdI2] This paper aims at detecting damage in railway bridges based on traffic-induced dynamic responses. To achieve this goal, an unsupervised automatic data-driven methodology is proposed, consisting of a combination of time series analysis methods and multivariate statistical techniqu...

This paper addresses the evaluation of the running safety of high-speed (HS) train moving over a continuous viaduct with different track conditions, ranging from very well-maintained to the worst condition possible according to the European recommendations, referred to as the safety limit. The case study focuses on the "La Scarpe" viaduct, which co...

Ballast and slab railway track structures are constructed from different materials, thus requiring different maintenance strategies. Therefore, this paper compares the settlement performance of both structures using laboratory experiments, and calibrates numerical models based upon the results. Firstly, a comparison of the short and long-term behav...

The present work focuses on the evaluation of the dynamic behavior of a centenary steel arch bridge, located in Portugal, under light railway traffic loads. This works aims to assess the dynamic behavior of the bridge subjected to an alternative type of railway vehicle, more specifically, a typical underground vehicle that is currently in service i...

This paper presents a cost-effective Bridge Weigh-in-Motion (B-WIM) system for the identification of train loads using fiber-optic technology. The system is capable of estimating the train’s speed, geometry and static axle loads, using the algorithm proposed by Moses. This algorithm involves the resolution of an inverse identification problem where...

This paper describes the development of a new inverse analysis approach to derive the fracture mode I parameters of fibre reinforced concrete (FRC) by using the experimental data obtained from three-point notched beam bending tests (3PNBBT) and round panel tests supported on three points (RPT-3PS). The approach is based on a global fitting strategy...

This paper describes statistical methodologies for removing the influence of operational effects from the dynamic responses of a telecommunications tower. The characterization of the dynamic responses of the structure, over a period of 3 months, was based on a continuous monitoring system that included accelerometers, anemometers and a meteorologic...

This article presents a methodology for assessing the train running safety on bridges subjected to strong crosswinds. The methodology is based on an in-house numerical tool called VSI-Vehicle-Structure Interaction Analysis, which computes the dynamic response of the coupled system formed by the train and the bridge. By imposing the wind load, based...

Structural integrity and failure analysis of metallic materials and structures: part I This special issue represents a set of contributions in the field of structural integrity and failure analysis of metallic materials and structures. The experts in this field have to be encouraged to enhance their knowledge over a vast set of topics, such as fati...

This article describes the simulation of the Korean high-speed train passing over a single-track viaduct and the influence of track isolated defects on the dynamic behaviour of the system. The model of the viaduct is validated and calibrated using a finite element model updating technique, and a three-dimensional (3D) model is used to account for t...

The use of numerical tools to predict and analyze the dynamic response of buildings exposed to railway traffic is essential to face the continuous challenges motivated by the increasing demand for transportation infrastructures in urban context. Given the complexity of the entire system involved, their experimental validation is an essential step....

The identification of structural damages based on numerical model updating has been of increasing interest in several areas of engineering, and basically consists on an optimization process relying on the minimization of the residuals between the measured and estimated numerical responses. Most of the existing studies using this methodology are app...

Due to the increasing demand for safer and faster rail transport, train wheelsets operating under high axle loads require more careful and reliable inspections and maintenance. During service, the train wheelsets are constantly operating under harsh conditions such as fatigue, thermal variation and impact. The wheel defects can induce damage to rai...

Due to the increasing demand for safer and faster rail transport, train wheelsets operating under high axle loads require more careful and reliable inspections and maintenance. During service, the train wheelsets are constantly operating under harsh conditions such as fatigue, thermal variation and impact. The wheel defects can induce damage to rai...

Offshore structures are mainly associated with the oil and gas industry given that globally, nearly one-third of the oil and gas extracted worldwide comes from offshore sources. This situation is likely to continue to rise over the coming decades because of abundant deposits of oil and gas still present in the oceans and society's dependency on hyd...

A reliable evaluation of dynamic amplification effects is crucial in bridge design in order to achieve safer and economical solutions. In engineering practice, these effects are commonly taken into account through dynamic load allowance factors (IM) specified by the codes. However, some codes allow the calculation of these IM factors through more a...

A R T I C L E I N F O Keywords: Turbulent wind model Discrete gust wind model Train running safety Vehicle-structure interaction High-speed railways Bridges Wind design codes A B S T R A C T This article presents a study on the train stability against crosswinds simulated with different wind models. The work focuses on the evaluation of derailment...

This article describes an innovative methodology for remote inspection of reinforced concrete (RC) structures using Unmanned Aerial Vehicles (UAVs) and based on advanced digital image processing. The use of specific heuristic feature-extraction methods, developed in MATLAB©, allows the automatic identification of various types of RC pathologies, pa...

The assessment of structural integrity via numerical model updating has been drawing attention in several areas of engineering over the last years. Basically, it consists in an optimization process based on the minimization of the residuals between measured and estimated numerical responses. In such methodologies, several factors influence the succ...

This paper presents the results of long-term monitoring of the track–bridge interaction on a 100-m-long net-arch bridge with the MW steering bar system. Monitoring track–bridge interaction phenomena is a specific type of structural health monitoring (SHM). The paper begins with a thorough description of the configuration of the track and the bridge...

In this paper, a numerical study regarding the influence of the wind speed and orientation on the train running safety against crosswinds is presented. The wind profiles are defined through the Chinese Hat Model taking into account multiple combinations of vehicle speed, wind speed and wind orientation, resulting in 180 dynamic analyses solved usin...

Geomaterials exhibit elastoplastic behaviour during dynamic and repeated loading conditions. These loads are induced by the passage of a train or vehicle which then generates recoverable (resilient) deformation and/or permanent (plastic) deformation. Modelling this behaviour is still a challenge for geotechnical engineers as it implies the understa...

In Europe, a large number of old riveted metallic bridges approach the end of their fatigue life. Past research has shown that the application of CFRP can be very efficient in delaying the crack growth rate of deficient structural elements with existing crack. However, little attention is given to the fatigue resistance of non-damaged metallic memb...

This paper addresses the dynamic behavior of the La Scarpe viaduct, which consists of a continuous nine-span steel-concrete composite bridge belonging to the French HSR line TGV Nord. The main objective of the paper is to compare the responses of the existing viaduct with an alternative solution using a double composite action deck with a lower con...

The present paper presents a methodology for evaluating the possibility of derailment of trains running over bridges subjected to crosswinds. The dynamic model consists of a train–bridge interaction coupling system that takes into account the contact interface between wheel and rail from which the contact forces arise. These contact forces are the...

The ballasted and ballastless tracks present substantial differences in terms of the structural configuration and mechanical behaviour. In order to better understand the foundation performance, numerical analysis of the two types of railway track was carried out, computing the stress paths induced by the passage of trains. In this analysis, the eff...