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Wind-induced fatigue is a major issue for the design of slender high-rise structures. However, there are still few studies focused on this topic, resulting in a lack of practical design procedures for this type of structures. This paper aims to fill this gap by presenting a complete and practical methodology for the wind-induced fatigue life assessment of high-rise towers and its application to a 120 m cable-stayed steel tower composed by a modular lattice. The wind actions were considered as the sum of the quasi-static component according to international codes and a numerically generated, trough an ergodic stochastic process, turbulent component which is based on the Kaimal wind spectrum. Real wind measurements were also taken for a period of 15 months on a nearby MET station which, when compared with the normative scenario, proved to be much less conservative and were not used for the safety analysis. The wind velocities were used as inputs for a nonlinear dynamic analysis from which stress time histories were derived for 10 potentially critical structural details. The damage in each detail was computed through the application of the Rainflow counting algorithm and Palmgren-Miner’s damage accumulation law, indicating the connection region between the modules as the critical detail with respect to fatigue damage., This work was financially supported by Base Funding - UIDB/04708/ 2020 and Programmatic Funding - UIDP/04708/2020 of the CONSTRUCT - Instituto de I&D em Estruturas e Construçoes ˜ – funded by national funds through the FCT/MCTES (PIDDAC).

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 t...

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 ...

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 Chi...

A study regarding the safety against crosswinds of a high-speed train running over a railway bridge belonging to the future high-speed railway network in Russia is presented. The dynamic analyses a...

This paper presents the numerical simulation of a model with one bolt connecting two or three plates using the finite element method. This unitary model with one bolt is validated by comparing its results with those obtained in the literature for three different types of applied load: tension, shear, and a combination of both. The results are also compared with the American and Brazilian design codes. The unitary model includes all necessary considerations: contacts between the plates and the nut, head and shank of the bolt; contact between the plates, as well as the friction between them; and pre-load on the bolt. Moreover, it responds properly to forces parallel and perpendicular to the contact surface between the plates including prying action effects and slip. These calibrated models can be then introduced on a model that represents a full connection through a relatively simple process using ANSYS APDL language, thus allowing the study of any bolted connection type.

Purpose The purpose of this paper is to evaluate the fatigue process through the dynamic analysis of the global structural model and local static sub-modelling in a critical detail using the hot-spot stress approach. The detail was studied in three different positions at the “Alcácer do Sal” access viaduct, and the methodologies from the IIW and Eurocode EN 1993-1-9 were compared. Design/methodology/approach In this study, the fatigue life process based on the hot-spot stress approach was evaluated using a global dynamic analysis and a local sub-modelling based on a static analysis of welded connections in the “Alcácer do Sal” railway structure, Portugal, taking into consideration the recommendations from IIW and Eurocode EN 1993-1-9. The hot-spot stresses were calculated through the static analysis of the sub-model of the welded connection for each vibration mode with the aim to obtain the temporal stresses using the modal coordinates and modal stresses of the extrapolation points. The Ansys® and Matlab® softwares were used for the numerical analysis and the hot-spot stress calculations, respectively. Findings The proposed methodology/approach to obtain fatigue assessment is based on the modal analysis of the global structural model and local static sub-modelling. The modal analysis was used to extract the boundary conditions to be used in the local model to determine the temporal stresses of the extrapolation points. Based on the modal superposition method, the stresses as function of time were obtained for fatigue life evaluation of a critical detail by the hot-spot stress approach. The detail was studied in three different positions. Originality/value In the present study, a global-local fatigue methodology based on dynamic analysis of the global structural model and local static sub-modelling of the critical detail using the hot-spot stress approach is proposed. Herein, the modal analysis of the global structural model supported by the modal superposition method was used to obtain the matrix of modal coordinates. The static analysis of the local sub-model for each mode from the modal analysis of global structural model was done to estimate the hot-spot stresses. The fatigue damage calculation was based on S-N curve of the critical detail and rainflow method. The IIW recommendation proved to be more conservative compared to the proposed rules in the Eurocode EN 1993-1-9. The global-local modelling based on dynamic analysis is an important and effective tool for fatigue evaluation in welded joints.

This paper presents a case study on the behaviour of precast reinforced columns with non-conventional cross-section. An experimental program was developed to verify the serviceability and ultimate limit states of these columns, loaded with eccentric compression forces. In addition, results obtained through a theoretical model based on the Brazilian standard ABNT NBR 6118:2014 and a Finite Element numerical model using ANSYS software were presented. Analysis of the results showed that the proposed models satisfactorily predicted column behaviour. However, the ultimate strength of the column could not be determined due to limitations in the formulation of the theoretical model. The numerical model presented good agreement with the experimental results, both in serviceability and in ultimate limit state

The First International Symposium on Risk Analysis and Safety of Complex Structures and Components (IRAS 2019) was organised in-teamed with the ESIS/TC12 Technical Committee on Risk Analysis and Safety of Large Structures and Components, which took place between 1-2 July 2019 at the Faculty of Engineering of the University of Porto (FEUP), in the City of Porto, located at seaside in the northwest region of Portugal. The guest editors of the IRAS 2019 deeply acknowledges all members of the International Scientific Committee, Thematic Sessions Organizers, Keynote Speakers and authors that contributed to the success of this event, that gathered more than 126 participants presenting more than 168 papers and posters. Sponsors are also fully acknowledged for their important contributions. The ESIS/TC12 2019 winners of the Robert Moskovic Award, Award of Merit TC12, and ESIS/TC12 Young Scientist Award were announced during the conference. Additionally, the guest editors (conference chairs) sincerely thank the tireless efforts of the Organizing Committee members as well as students and other FEUP and Construction Institute staff involved in the organization. Finally, the guest editors are pleased to inform that the second edition of the IRAS event will be organised by Prof. Aleksandar Sedmak (University of Belgrade, Serbia) which will take place in Belgrade in Serbia in the year 2021.

A railway bridge over the Paraopeba River was built in Moeda, Minas Gerais, Brazil; however, the railway line for which it was intended was deactivated and, to reuse it as a road bridge, a ...

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 on a turbulent wind model, to both the bridge and the vehicle, it is possible to evaluate the wheel-rail contact forces and, consequently, the running safety criteria, namely the Nadal, Prud’homme and unloading indexes. A case study is presented in this paper, which consists of a high-speed (HS) train running over the new Volga River railway bridge belonging to the future Russian HS network. The critical wind speeds for which the train’s safety can be jeopardize are identified for a vast range of running speeds. At the end, the results obtained with the stochastic turbulent model are compared with those obtained using the discrete gust model proposed by the European Norms. A comparative critical analysis between the realistic turbulent wind model and the simplified discrete gust model is carried out.

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, the natural frequencies and mode shapes. This article describes the experimental calibration of 3D FE numerical models of railway vehicles, one for passenger and one for freight, based on modal parameters. The BBN vehicle is a tourist class vehicle that belongs to Alfa Pendular train and the vehicle Kbs is a freight railway wagon for transport of timber, both operating in the Portuguese railway network. The 3D FE numerical model of the vehicles consider the flexibility of the carbody/base floor and includes the suspensions and axles. The dynamic tests of the vehicles allowed the determination of the frequencies and modal configurations of several vibration modes involving rigid body and structural movements. The calibration was successfully performed through an iterative method based on a genetic algorithm, which demonstrated the stability of a significant number of numerical parameters estimates, and above all, a very good agreement between experimental and numerical modal parameters.

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 composite patch (CFRP and adhesive) will experience degradation during fatigue cyclic loading. In this regard, a new approach that takes into account the fatigue cyclic degradation of the composite patch is proposed in this paper by introducing in the fatigue damage accumulation model of the metallic element, a cycle-dependent stiffness degradation parameter of the composite patch. The stiffness degradation parameter is obtained using a fatigue stiffness degradation model calibrated from experimental fatigue data of CFRP adhesively bonded double strap joints. Experimental data available in the literature of central hole aluminium plates bonded with CFRP are utilized for validation of the approach.

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 ...

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 the UAV-structure based on target tracking, and second, subtracting movement of the UAV based on the data derived from an embedded Inertial Measuring Unit (IMU). Computer-vision processing tools based on heuristic features were developed for target tracking, while an efficient numerical integration strategy was implemented for processing IMU data. A successful integration process requires a baseline correction of the records through the application of high-pass filters and a rigorous control of distortion errors. The validation of the proposed methodology was based on exploratory dynamic tests performed in the laboratory and in the field. The laboratory test involved measuring the displacements of a moving target, positioned over a seismic table using a Linear Variable Differential Transformer (LVDT), a DC accelerometer and the UAV video system in a stationary position. An excellent agreement was achieved for the three estimated displacements, both in the time and frequency domains. In particular, the comparison between the video and the LVDT displacement records showed a peak value error of 0.096 mm and a Root Mean Square (RMS) error of 3.1%. The field test consisted of measuring the displacements of a target fixed to a massive Reinforced Concrete (RC) wall based on the UAV video system in motion. Under these circumstances, the target does not experience any movement, and therefore, the virtual displacement of the target estimated by the video is due exclusively to the self-movements of the UAV. The comparison between the video and the IMU displacement records shows a good agreement, with a peak value error of 1.47 mm (15.5% relative error) and a RMS error of 9.3%. The results of this study are a step forward in estimating the absolute displacements of a vibrating structure based on camera-based measurement from UAVs, specifically with the support of IMU systems for the elimination of measurement inaccuracies as a result of the UAV motion.

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 in the presence of winds. By computing the wheel-rail contact forces, the derailment risk is evaluated based on the unloading criterion, as suggested by the European Norm EN 14067–6 (2016), for several scenarios with different train and wind speeds. The wind is simulated with a stochastic model that allows the generation of turbulent wind time-histories based on power spectral density functions. The reference vehicle adopted in this work corresponds to the European InterCity Express 3 (ICE-3) train, whose original properties were parameterized in order to evaluate their influence in the vehicle's stability. The parametric study focused on several properties of the vehicle, namely the carbody mass, height of the gravity centre, aerodynamic coefficients, and stiffness and damping of the suspensions. Apart from the suspensions' properties, which prove to have a negligible influence in the vehicle's stability, the remaining parameters have a significant impact in the running safety against crosswinds.

This paper presents an analytical model to predict the mode I fatigue crack growth of steel Central Cracked Tensile (CCT) specimens repaired with Carbon Fiber Reinforced Polymer (CFRP) bonded on the two sides of the plate. A review of the behaviors observed in past experimental tests is provided. The CFRP-steel stiffness ratio, as well as the level of the initial crack length and the location of the CFRP patch, influence the performance of the CFRP crack repair. A total of 69 experimental and 7 numerical results of CFRP repaired specimens were collected from the literature and a database is created. Seventy percent of the data (Experimental only) were used for the development of the model and thirty percent for verification. The fatigue crack propagation of each pair of unrepaired and repaired experimental specimens was calibrated for the development of the model. The effect of the CFRP on the fatigue crack propagation is represented by a SIF reduction factor, β . An analytical law based on nonlinear regression analysis is proposed to evaluate β which depends on the CFRP-steel ratio, level of damage of the steel plate, and patch location. The model is fairly validated with experimental and numerical results. A parametric study is conducted for further verification, the model shows reasonable trends.

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 consists of a continuous nine-span steel–concrete composite bridge belonging to the French HS railway line TGV Nord, and on the German HS train ICE3 composed by eight independent cars. Firstly, the analysis is carried out considering the flexibility of the viaduct through train–bridge interaction (TBI) coupling system, where the running safety is analyzed according to Nadal, Prud'homme and Unload criteria. The results are then compared with those obtained using a rigid structure, which allowed to draw important conclusions regarding the effects of the viaduct’s vibrations. From the results it was possible to conclude that the criteria have shown a good agreement with the limits laid down in the European norms. In addition, it was also possible to assume that the viaduct flexibility did not influence the results with respect to the derailment risk. Thus, for this particular case study, the train running safety assessment could be carried out using a simpler rigid structure model, which considerably reduces the degrees of freedom and the problem complexity without losing accuracy.

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 in the Lisbon Metro. The dynamic response of the system has been evaluated using two distinct methodologies, namely a moving loads model and a vehicle–bridge interaction model. To achieve this goal, finite element (FE) models from both the bridge and the vehicle have been developed and a comprehensive study has been carried to evaluate the influence of distinct factors in the dynamic response of the bridge–train system, namely the methodology used to assess the dynamic response, the location of the response reference point in the deck, the train speed and the vehicle configuration (single or double vehicle). Moreover, both the traffic safety, passenger comfort and pedestrian comfort have also been evaluated using normative criteria based on acceleration responses. The results shown that the normative limits related to traffic safety and passenger comfort were never exceeded in any condition analyzed in the study. However, the pedestrian comfort was jeopardized when the train speed exceeded 20[Formula: see text]km/h.

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 advanced dynamic analysis in order to achieve more realistic results. Therefore, a methodology to numerically evaluate the IM in bridges is described. The methodology is based on a vehicle-bridge interaction model that can take into account any configuration of pavement irregularities. A case study consisting of two modular steel bridges is presented. In order to reach a comprehensive characterization of the IM factors, a probabilistic analysis is conducted, taking into consideration the stochastic generation of random irregularity profiles based on pavement roughness and experimentally measured manufacturing imperfections, as well as a wide range of vehicle speeds. The results obtained in this study demonstrate the advantages of performing a probabilistic numerical evaluation of the IM factor in comparison to the use of pre-defined factors proposed by design codes. The consideration of IM factors based on probabilistic assessments can lead to relevant material savings in the design of steel modular bridges.

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 the local deformations of the slab accurately. The direct method, an efficient vehicle-structure interaction algorithm previously developed by the authors, is used to solve the dynamic problem. It proved to be significantly more efficient than the widely used finite element software ANSYS® when solving large and complex problems. The computational time has been reduced by more than ten times. The results obtained show that the shape of the isolated defects and the local deformations of the slab strongly influence the dynamic behaviour of the system. Neither is taken into account in the current standards, and hence further research is necessary.

A linear-elastic Fracture Mechanics approach is used to estimate the fatigue life of riveted connections present in railroad bridge built-up steel girders under variable amplitude loading. Special care has been taken to analyze the effect of thermal clamping stresses on fatigue life. The analysis is developed using the variable amplitude stresses generated due to a traversing heavy axle train on a simply supported girder. Stress intensity factors for quarter elliptical corner crack emanating from a through-thickness (rivet) hole under remote tension were used. Thermal clamping stress, typically generated during the installation process, was quantified through a finite element simulation. Superposition principle was utilized to account for localized clamping stress present on the base material along with remote tension. Fatigue life estimations calculated using a linear-elastic Fracture Mechanics approach with and without considering clamping stress are compared. Finally, crack growth proved to be different under the effect of localized clamping stresses when compared to a crack growth emanating from a hole with no clamping stress.

This article presents a study on the train stability against crosswinds simulated with different wind models. The work focuses on the evaluation of derailment indexes, which are dependent on the wheel-rail contact forces obtained through dynamic analyses performed with a vehicle-structure interaction methodology. The results obtained using the normative European Committee for Standardization (CEN) Discrete Gust model are compared with those obtained with a turbulent wind model based on stochastically generated wind fields. The calculations are performed considering several heights above the terrain to simulate the behaviour of a train running over a bridge deck located at different elevations. The CEN Discrete Gust model proved to be inaccurate and increasingly conservative, in relation to the Turbulent Wind model, as the height above the ground increases, since the former is based on a fixed turbulence intensity corresponding to the ground level, while the latter considers the correct turbulence intensity dependent on the deck elevation. Based on these results, the present article describes an alternative discrete gust approach that takes into consideration the variable turbulence intensity and terrain category in order to improve its applicability in the evaluation of the train running safety on bridges with decks located at different heights.

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, particularly, biological colonies, efflorescences, cracks and exposed steel rebars. The developed inspection methodology is applied to the Monte da Virgem telecommunications tower, which has a total height of 177 m and is the highest structure of this kind in Portugal. The results demonstrate the efficiency and robustness of the methodology in: i) its ability to accurately locate and characterize the existing pathologies, ii) visualizing the full extent of pathologies in 3D photogrammetric reconstitutions of the structure, and iii) integrating the identified pathologies into a Building Information Modeling (BIM) model. The regular use of the proposed methodology over time will allow accurate monitoring of the evolution of pathologies to assess the condition of the structure. Additionally, the integration of the inspection results into BIM digital models will help infrastructure managers to decide on the implementation of the most adequate facility management strategies in order to optimize the scheduling of maintenance, rehabilitation and retrofitting interventions.

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 inputs for the safety criteria that are later used to evaluate derailment. The wind fluctuating component is accurately considered through a stochastic process that generates correlated wind velocity fields, which are later converted into wind loads that are applied to both the bridge and the train. Before evaluating the running safety, the dynamic response of the train–bridge system is assessed to understand the influence of the train speed and wind velocity on it. Then, the running safety is analyzed based on three criteria, namely the Nadal, Prud’homme and unloading indexes, being the influence of the bridge lateral flexibility in the derailment risk also discussed. Finally, the results obtained with the stochastic wind model are compared with those obtained with a simplified discrete gust model proposed by the European normative. The maximum wind velocities, obtained through the stochastic and simplified formulations, for which no derailment criteria allowance is exceeded are computed and a comparative critical analysis between the models is presented.

This article presents an accurate, efficient and stable algorithm to analyze the nonlinear vertical\ud vehicle-structure interaction. The governing equilibrium equations of the vehicle and structure are\ud complemented with additional constraint equations that relate the displacements of the vehicle with the\ud corresponding displacements of the structure. These equations form a single system, with displacements\ud and contact forces as unknowns, that is solved using an optimized block factorization algorithm. Due to\ud the nonlinear nature of contact, an incremental formulation based on the Newton method is adopted. The\ud vehicles, track and structure are modeled using finite elements to take into account all the significant\ud deformations. The numerical example presented clearly demonstrates the accuracy and computational\ud efficiency of the proposed method.