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This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

This thesis presents a comprehensive modal analysis on an asphalt roller, focusing on optimizing excitation and measurement point selection for accurate characterization of the structure’s dynamic behavior. The thesis aims to find out how to select excitation points that ex-cite all mode shapes within a specific frequency range and to find out how to select measurement points that capture the dynamic behavior and mode shapes of the structure within the same frequency range. The method used is an action research method that includes four phases: planning, action, observation, and reflection. The planning phase involves numerical modal analysis, simulations, and selection of excitation and measurement points. The action phase includes experimental measurements preliminary tests, and the actual testing of the structure. The observation covers extracting modal parameters from measurement data and comparing results with simulation predictions. Reflection focuses on evaluating results and adapting the decision-making accordingly. The EODP method provides practical excitation points that successfully active modes consistent with the simulations. The minMAC GA approach identifies measurement points that capture the asphalt roller’s essential dynamic behavior, despite challenges with modal parameter extraction. Even though the mode shapes are not well separated due to the complexity of the structure, high-quality identification of mode shapes was achieved considering impact excitation which gives great insight into the asphalt roller’s dynamic properties. Overall, this research contributes to the understanding of modal analysis on complex mechanical structures, providing effective methods for excitation and measurement point selection. The findings in the study can inform the design and maintenance of similar structures in various engineering applications.

Les tubes à vortex sont des dispositifs mécaniques simples qui dilatent et séparent généralement le fluide en un courant à haute enthalpie et un courant à basse enthalpie. Leur simplicité réside dans leur conception qui ne comprend pas de pièces mobiles, ce qui limite l'entretien nécessaire sur une longue période de fonctionnement. Les études portant sur leur mise en œuvre dans les systèmes de réfrigération et de chauffage sont de plus en plus nombreuses et étendues, car elles représentent une potentielle solution de remplacement des vannes d'étranglement. Dans cette thèse, un modèle thermodynamique est développé pour prédire principalement les températures de sortie du tube à vortex pour des gaz réels en utilisant l'équation d'état du viriel et CoolProp. Le modèle est validé en utilisant trois fluides de travail : l'air, le R134a et le dioxyde de carbone, et comparé aux résultats d'un modèle de gaz idéal. Le modèle de gaz réel a montré une erreur maximale dans la prédiction de la température de seulement 3.9 %. Le modèle est ensuite utilisé pour effectuer une analyse paramétrique fonctionnant avec du dioxyde de carbone dans des conditions transcritiques, en étudiant la séparation des températures, la puissance et l'exergie. Ce modèle est ensuite étendu pour fonctionner dans le régime diphasique. Le modèle est validé par des expériences de tube à vortex fonctionnant avec du propane en régime diphasique. Le modèle présente une erreur maximale d'environ 5.95 % dans le cas d'un écoulement de propane diphasique. Ensuite, une autre étude paramétrique est menée pour étudier le fonctionnement du tube vortex avec du dioxyde de carbone diphasique. L'objectif principal de cette thèse est d'étudier la faisabilité de l'intégration d'un tube à vortex dans une pompe à chaleur (en particulier une pompe qui utilise du dioxyde de carbone comme réfrigérant). Par conséquent, le modèle développé est intégré dans un modèle de pompe à chaleur afin d'étudier plus en détail une telle combi, Vortex tubes are simple mechanical devices that generally expand and separate ŕuid into a high enthalpy stream and a low enthalpy one. Its simplicity lies within its design that does not include moving parts, limiting the maintenance required over a long range of operation. The studies implementing them within refrigeration and heating systems are increasing and widening since they represent a good potential substitution to throttling valves. In this thesis, a thermodynamic model is developed to mainly predict the exit temperatures of the vortex tube for real gases using the virial equation of state and CoolProp. The model is validated using three working ŕuids: air, R134a and carbon dioxide, and compared with the results of an ideal gas model. The real gas model showed a maximum error in terms of temperature prediction of only 3.9%. The model is then used to do a parametric analysis operating with carbon dioxide at transcritical conditions, studying the temperature separation, power and exergy. This model is then extended to operate within the two-phase regime. The model is validated with experiments of vortex tube operating with two-phase propane. Since the separated ŕow is expanded into two misty ŕows, the computation of the exit enthalpies is more precise. The model exhibited a maximum error of around 5.95% in the prediction of two-phase propane. Afterwards, another parametric study is conducted to study the operation of the vortex tube with two-phase carbon dioxide. The main objective of this thesis is to investigate the feasibility of integrating a vortex tube in a heat pump (especially one that is using carbon dioxide as a refrigerant). As a consequence, the model developed is integrated in a heat pump model to further study such a combination. The models of the other components are obtained through the commercial library TIL and the whole system is simulated using the software Dymola. Under certain operating conditions, the vortex tube integration

Green facade systems are gaining attention due to their potential for the urban environment, building aesthetics, and energy efficiency. This study compares different green facade systems and their surface weight, which is one of the critical parameters for performance and longevity. The research evaluates construction, installation, water consumption, and sustainable operation. Experimental measurements of surface weight examine changes depending on water consumption and performance.

This work is devoted to the analysis of the vibratory response of High-Speed (HS) multi-track railway bridges composed by simply-supported spans. In particular, it aims to investigate the influence of three geometrical aspects usually disregarded in numerical models used to evaluate the Serviceability Limit State of traffic safety in such structures: (i) the deck obliquity, (ii) the presence and correct execution of transverse diaphragms at the supports, and (iii) the number of successive simply-supported spans weakly coupled through the ballast track layer. The influence of these aspects is analysed from the correlation of a detailed numerical model and experimental measurements on an in-service High Speed (HS) multi-track railway bridge. From the reference model, a set of variants accounting for different levels of deck obliquity and diaphragm configurations are envisaged and the maximum transverse acceleration over the platform is determined under railway excitation. The analysis is extended to bridges with an increasing number of successive spans. Special attention is paid to the particular location of the maximum response and to the participation of modes different from the longitudinal bending one. Finally, a numerical–experimental comparison of the bridge response under two train passages is presented for the straight and oblique models, and the response adjustment along with the actual bridge performance are assessed.

This work is the result of a problem of premature development of rail corrugation found on a new metro line. As urgent solutions, a rail grinding was carried out and friction modifier started to be applied. Experimental corrugation measurements have been taken periodically in this line at 60 control points since 2018, and an extensive database has been collected since then. As a second stage, a computationally efficient new model has been developed to predict corrugation growth under different running conditions. The aim of this work has been to obtain feasible solutions to delay corrugation growth in metro type lines.

The COVID-19 pandemic highlighted the importance of indoor air quality (IAQ) and ventilation, which researchers have been warning about for years. During the pandemic, researchers studied several indicators using different approaches to assess IAQ and diverse ventilation systems in indoor spaces. To provide an overview of these indicators and approaches in the case of airborne transmission through aerosols, we conducted a literature review, which covered studies both from before and during the COVID-19 pandemic. We searched online databases for six concepts: aerosol dispersion, ventilation, air quality, schools or offices, indicators, and assessment approaches. The indicators found in the literature can be divided into three categories: dose-, building-, and occupant-related indicators. These indicators can be measured in real physical spaces, in a controlled laboratory, or modeled and analyzed using numerical approaches. Rather than organizing this paper according to these approaches, the assessment methods used are grouped according to the following themes they cover: aerosol dispersion, ventilation, infection risk, design parameters, and human behavior. The first finding of the review is that dose-related indicators are the predominant indicators used in the selected studies, whereas building- and occupant-related indicators are only used in specific studies. Moreover, for a better understanding of airborne transmission, there is a need for a more holistic definition of IAQ indicators. The second finding is that although different design assessment tools and setups are presented in the literature, an optimization tool for a room’s design parameters seems to be missing. Finally, to efficiently limit aerosol dispersion in indoor spaces, better coordination between different fields is needed., Urban Data Science, Environmental & Climate Design

This work is devoted to the analysis of the vibratory response of High-Speed (HS) multi-track railway bridges composed by simply-supported spans. In particular, it aims to investigate the influence of three geometrical aspects usually disregarded in numerical models used to evaluate the Serviceability Limit State of traffic safety in such structures: (i) the deck obliquity, (ii) the presence and correct execution of transverse diaphragms at the supports, and (iii) the number of successive simply-supported spans weakly coupled through the ballast track layer. The influence of these aspects is analysed from the correlation of a detailed numerical model and experimental measurements on an in-service High Speed (HS) multi-track railway bridge. From the reference model, a set of variants accounting for different levels of deck obliquity and diaphragm configurations are envisaged and the maximum transverse acceleration over the platform is determined under railway excitation. The analysis is extended to bridges with an increasing number of successive spans. Special attention is paid to the particular location of the maximum response and to the participation of modes different from the longitudinal bending one. Finally, a numerical–experimental comparison of the bridge response under two train passages is presented for the straight and oblique models, and the response adjustment along with the actual bridge performance are assessed.

Recently, large offshore wind power plants have been installed far from the shore, using long HVAC three-core armored cables to export power. Its high capacitance may contribute to the appearance of unwanted phenomena, such as overvoltages or resonances at low frequencies. To adequately assess these problems, detailed and reliable cable models are required to develop time-domain/frequency-domain analyses on this type of cables. This paper presents, for the first time in the literature, an assessment on the performance of 3D finite element method-based (3D-FEM) models for developing frequency-domain analyses on three-core armored cables, confronting simulation results with experimental measurements found in the literature for three real cables. To this aim, a simplified ultra-shortened 3D-FEM model is proposed to reduce the simulation time during frequency sweeps, through which relevant aspects never analyzed before with frequency-domain 3D-FEM simulations are addressed, such as total losses, induced sheath current, magnetic field around the power cable, positive and zero sequence harmonic impedances, as well as resonant frequencies. Also, a time-domain example derived from the frequency-domain analysis is provided. Remarkable results are obtained when comparing computed values and measurements, presenting the simplified ultra-shortened 3DFEM model as a valuable tool for the frequency-domain analysis of these cables.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

This contribution investigates the vertical coupling exerted by ballasted tracks on the vertical response of bridges composed either of (i) several successive simply-supported spans with weak coupling between them due to the continuous track; or (ii) adjacent single-track decks conforming a double-track bridge, in which interaction effects are induced due to the transverse continuity of the ballast layer. To this end, 2 D and 3 D track-bridge interaction Finite Element models are implemented, which consider a three-layer discrete and explicit idealization of the track. The 2 D track-bridge interaction model is used to perform sensitivity analyses on the track parameters, which have revealed that the ballast shear mechanisms along the track may significantly affect the train-induced vibrations under resonant conditions. Then, the influence of the ballast coupling on the response of twin adjacent decks is investigated with a 3 D track-bridge interaction model. To this end, this model is updated based on the results of an experimental campaign performed on a real bridge composed of two SS spans and two single track twin adjacent decks. The numerical-experimental comparison shows an evident dynamic vertical coupling between the bridge decks and reveals the importance of including the ballasted track in the modelling process of these structures.

This research is aimed at creating a generic design method for infiltration drywells on sandy soils by acquiring knowledge on the functioning of these wells. Infiltration drywells are vertical infiltration pipes that are installed above the groundwater table and through which stormwater is drained to the subsurface. Infiltration drywells can have a prominent place in urban water management since they mimic processes that occur under natural conditions. In urban areas the hydrological cycle is altered due to impermeable surfaces. Utilization of infiltration reduces the effects of the alteration on the hydrological cycle. Hereby, reducing the risk on urban flooding and surface water contamination. Furthermore, urban heat stress is reduced by enabling more drought resilient vegetation through groundwater replenishment. Especially considering that climate change will result in more extreme weather conditions, infiltration facilities can aid in creating more resilient urban areas. Until now, there are no design rules for these wells which hinders the implementation in urban areas that are fit for infiltration facilities. In this research a design method for sandy soils in the Netherlands is created and set forth. The theoretical and practical performance of infiltration drywells is analysed by conducting experiments with Hydrus 3-dimensional geohydrological model simulations, as well as in the field and laboratory. In the field falling head tests were performed with existing infiltration drywells to determine the functioning while soil samples were analysed in the laboratory to determine the hydraulic conductivity. The model simulations also exist of falling head tests and are compared to the experiments in practice. It was found that the most important parameters on functioning of infiltration drywells are the soil hydraulic conductivity and well dimensions. When comparing the simulated falling head tests to field tests and laboratory tests at the same location, Civil Engineering

The great expansion in offshore power plants is raising the concern regarding the cumulative effect of the electromagnetic field emissions caused by submarine power cables. In this sense, owners are required to predict these emissions during the permitting and consenting process of new power plants. This is a challenging task, especially in the case of HVAC three-core armored cables due to their complex geometry. Customarily, 2D approaches based on the finite element method (FEM) have been employed for evaluating the magnetic field emissions caused by these cables. However, inaccurate results are obtained since the phase conductors and armor twisting is omitted. This work develops, for the first time in the literature, an in-depth analysis of the magnetic field caused by this type of cable through an ultra-shortened 3D-FEM model, which is also faced to experimental measurements taken on an actual 132 kV, 800 mm2 three-core armored cable. Relevant conclusions are derived regarding the impact of the cable design on the magnetic field emissions, including material properties, as well as single and double-layer armors, presenting the proposed model not only as a valuable tool for predicting purposes, but also for optimizing cable design in terms of magnetic field emissions.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

This contribution investigates the vertical coupling exerted by ballasted tracks on the vertical response of bridges composed either of (i) several successive simply-supported spans with weak coupling between them due to the continuous track; or (ii) adjacent single-track decks conforming a double-track bridge, in which interaction effects are induced due to the transverse continuity of the ballast layer. To this end, 2 D and 3 D track-bridge interaction Finite Element models are implemented, which consider a three-layer discrete and explicit idealization of the track. The 2 D track-bridge interaction model is used to perform sensitivity analyses on the track parameters, which have revealed that the ballast shear mechanisms along the track may significantly affect the train-induced vibrations under resonant conditions. Then, the influence of the ballast coupling on the response of twin adjacent decks is investigated with a 3 D track-bridge interaction model. To this end, this model is updated based on the results of an experimental campaign performed on a real bridge composed of two SS spans and two single track twin adjacent decks. The numerical-experimental comparison shows an evident dynamic vertical coupling between the bridge decks and reveals the importance of including the ballasted track in the modelling process of these structures.

Single-track railway bridges are susceptible of experiencing high levels of vertical acceleration on the deck that may be dangerously accentuated at resonance. This is especially critical for short-to-medium span simply supported bridges. This problem can compromise the safety of the trains and increase the maintenance costs of the track. The main objective of this work is to investigate the influence of the ballasted track on the dynamic behaviour of these structures. The present contribution provides a detailed sensitivity analysis over a wide single-track bridge catalogue covering span lengths from 10 to 25 m and considering two common deck structural typologies: girder-deck and slab-deck bridges. The effect of the vertical stiffness of the neoprene bearings is also evaluated. A 2D Finite-Element track–bridge interaction model is implemented and used to analyse the effect of the track on the modal parameters, harmonic response and vertical acceleration of the bridges under train passages. Additionally, the weak coupling exerted by the track is studied for structures with an increasing number of consecutive spans. The results obtained reveal a notable influence of the mobilised ballast shear transfer mechanism on the dynamic response of the structures, especially for the shortest girder bridges. Finally, a track–bridge interaction model of an existing short girder bridge from a conventional railway line is updated and used to predict the experimental response measured under operating conditions. The adequacy of the numerical tool and influence of the ballast shear parameters on the dynamic response are shown.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

This contribution investigates the vertical coupling exerted by ballasted tracks on the vertical response of bridges composed either of (i) several successive simply-supported spans with weak coupling between them due to the continuous track; or (ii) adjacent single-track decks conforming a double-track bridge, in which interaction effects are induced due to the transverse continuity of the ballast layer. To this end, 2 D and 3 D track-bridge interaction Finite Element models are implemented, which consider a three-layer discrete and explicit idealization of the track. The 2 D track-bridge interaction model is used to perform sensitivity analyses on the track parameters, which have revealed that the ballast shear mechanisms along the track may significantly affect the train-induced vibrations under resonant conditions. Then, the influence of the ballast coupling on the response of twin adjacent decks is investigated with a 3 D track-bridge interaction model. To this end, this model is updated based on the results of an experimental campaign performed on a real bridge composed of two SS spans and two single track twin adjacent decks. The numerical-experimental comparison shows an evident dynamic vertical coupling between the bridge decks and reveals the importance of including the ballasted track in the modelling process of these structures.

Recently, large offshore wind power plants have been installed far from the shore, using long HVAC three-core armored cables to export power. Its high capacitance may contribute to the appearance of unwanted phenomena, such as overvoltages or resonances at low frequencies. To adequately assess these problems, detailed and reliable cable models are required to develop time-domain/frequency-domain analyses on this type of cables. This paper presents, for the first time in the literature, an assessment on the performance of 3D finite element method-based (3D-FEM) models for developing frequency-domain analyses on three-core armored cables, confronting simulation results with experimental measurements found in the literature for three real cables. To this aim, a simplified ultra-shortened 3D-FEM model is proposed to reduce the simulation time during frequency sweeps, through which relevant aspects never analyzed before with frequency-domain 3D-FEM simulations are addressed, such as total losses, induced sheath current, magnetic field around the power cable, positive and zero sequence harmonic impedances, as well as resonant frequencies. Also, a time-domain example derived from the frequency-domain analysis is provided. Remarkable results are obtained when comparing computed values and measurements, presenting the simplified ultra-shortened 3DFEM model as a valuable tool for the frequency-domain analysis of these cables.

The great expansion in offshore power plants is raising the concern regarding the cumulative effect of the electromagnetic field emissions caused by submarine power cables. In this sense, owners are required to predict these emissions during the permitting and consenting process of new power plants. This is a challenging task, especially in the case of HVAC three-core armored cables due to their complex geometry. Customarily, 2D approaches based on the finite element method (FEM) have been employed for evaluating the magnetic field emissions caused by these cables. However, inaccurate results are obtained since the phase conductors and armor twisting is omitted. This work develops, for the first time in the literature, an in-depth analysis of the magnetic field caused by this type of cable through an ultra-shortened 3D-FEM model, which is also faced to experimental measurements taken on an actual 132 kV, 800 mm2 three-core armored cable. Relevant conclusions are derived regarding the impact of the cable design on the magnetic field emissions, including material properties, as well as single and double-layer armors, presenting the proposed model not only as a valuable tool for predicting purposes, but also for optimizing cable design in terms of magnetic field emissions.

Recently, large offshore wind power plants have been installed far from the shore, using long HVAC three-core armored cables to export power. Its high capacitance may contribute to the appearance of unwanted phenomena, such as overvoltages or resonances at low frequencies. To adequately assess these problems, detailed and reliable cable models are required to develop time-domain/frequency-domain analyses on this type of cables. This paper presents, for the first time in the literature, an assessment on the performance of 3D finite element method-based (3D-FEM) models for developing frequency-domain analyses on three-core armored cables, confronting simulation results with experimental measurements found in the literature for three real cables. To this aim, a simplified ultra-shortened 3D-FEM model is proposed to reduce the simulation time during frequency sweeps, through which relevant aspects never analyzed before with frequency-domain 3D-FEM simulations are addressed, such as total losses, induced sheath current, magnetic field around the power cable, positive and zero sequence harmonic impedances, as well as resonant frequencies. Also, a time-domain example derived from the frequency-domain analysis is provided. Remarkable results are obtained when comparing computed values and measurements, presenting the simplified ultra-shortened 3DFEM model as a valuable tool for the frequency-domain analysis of these cables.

The great expansion in offshore power plants is raising the concern regarding the cumulative effect of the electromagnetic field emissions caused by submarine power cables. In this sense, owners are required to predict these emissions during the permitting and consenting process of new power plants. This is a challenging task, especially in the case of HVAC three-core armored cables due to their complex geometry. Customarily, 2D approaches based on the finite element method (FEM) have been employed for evaluating the magnetic field emissions caused by these cables. However, inaccurate results are obtained since the phase conductors and armor twisting is omitted. This work develops, for the first time in the literature, an in-depth analysis of the magnetic field caused by this type of cable through an ultra-shortened 3D-FEM model, which is also faced to experimental measurements taken on an actual 132 kV, 800 mm2 three-core armored cable. Relevant conclusions are derived regarding the impact of the cable design on the magnetic field emissions, including material properties, as well as single and double-layer armors, presenting the proposed model not only as a valuable tool for predicting purposes, but also for optimizing cable design in terms of magnetic field emissions.

Single-track railway bridges are susceptible of experiencing high levels of vertical acceleration on the deck that may be dangerously accentuated at resonance. This is especially critical for short-to-medium span simply supported bridges. This problem can compromise the safety of the trains and increase the maintenance costs of the track. The main objective of this work is to investigate the influence of the ballasted track on the dynamic behaviour of these structures. The present contribution provides a detailed sensitivity analysis over a wide single-track bridge catalogue covering span lengths from 10 to 25 m and considering two common deck structural typologies: girder-deck and slab-deck bridges. The effect of the vertical stiffness of the neoprene bearings is also evaluated. A 2D Finite-Element track–bridge interaction model is implemented and used to analyse the effect of the track on the modal parameters, harmonic response and vertical acceleration of the bridges under train passages. Additionally, the weak coupling exerted by the track is studied for structures with an increasing number of consecutive spans. The results obtained reveal a notable influence of the mobilised ballast shear transfer mechanism on the dynamic response of the structures, especially for the shortest girder bridges. Finally, a track–bridge interaction model of an existing short girder bridge from a conventional railway line is updated and used to predict the experimental response measured under operating conditions. The adequacy of the numerical tool and influence of the ballast shear parameters on the dynamic response are shown.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

Single-track railway bridges are susceptible of experiencing high levels of vertical acceleration on the deck that may be dangerously accentuated at resonance. This is especially critical for short-to-medium span simply supported bridges. This problem can compromise the safety of the trains and increase the maintenance costs of the track. The main objective of this work is to investigate the influence of the ballasted track on the dynamic behaviour of these structures. The present contribution provides a detailed sensitivity analysis over a wide single-track bridge catalogue covering span lengths from 10 to 25 m and considering two common deck structural typologies: girder-deck and slab-deck bridges. The effect of the vertical stiffness of the neoprene bearings is also evaluated. A 2D Finite-Element track–bridge interaction model is implemented and used to analyse the effect of the track on the modal parameters, harmonic response and vertical acceleration of the bridges under train passages. Additionally, the weak coupling exerted by the track is studied for structures with an increasing number of consecutive spans. The results obtained reveal a notable influence of the mobilised ballast shear transfer mechanism on the dynamic response of the structures, especially for the shortest girder bridges. Finally, a track–bridge interaction model of an existing short girder bridge from a conventional railway line is updated and used to predict the experimental response measured under operating conditions. The adequacy of the numerical tool and influence of the ballast shear parameters on the dynamic response are shown.

This contribution investigates the vertical coupling exerted by ballasted tracks on the vertical response of bridges composed either of (i) several successive simply-supported spans with weak coupling between them due to the continuous track; or (ii) adjacent single-track decks conforming a double-track bridge, in which interaction effects are induced due to the transverse continuity of the ballast layer. To this end, 2 D and 3 D track-bridge interaction Finite Element models are implemented, which consider a three-layer discrete and explicit idealization of the track. The 2 D track-bridge interaction model is used to perform sensitivity analyses on the track parameters, which have revealed that the ballast shear mechanisms along the track may significantly affect the train-induced vibrations under resonant conditions. Then, the influence of the ballast coupling on the response of twin adjacent decks is investigated with a 3 D track-bridge interaction model. To this end, this model is updated based on the results of an experimental campaign performed on a real bridge composed of two SS spans and two single track twin adjacent decks. The numerical-experimental comparison shows an evident dynamic vertical coupling between the bridge decks and reveals the importance of including the ballasted track in the modelling process of these structures.

This research is aimed at creating a generic design method for infiltration drywells on sandy soils by acquiring knowledge on the functioning of these wells. Infiltration drywells are vertical infiltration pipes that are installed above the groundwater table and through which stormwater is drained to the subsurface. Infiltration drywells can have a prominent place in urban water management since they mimic processes that occur under natural conditions. In urban areas the hydrological cycle is altered due to impermeable surfaces. Utilization of infiltration reduces the effects of the alteration on the hydrological cycle. Hereby, reducing the risk on urban flooding and surface water contamination. Furthermore, urban heat stress is reduced by enabling more drought resilient vegetation through groundwater replenishment. Especially considering that climate change will result in more extreme weather conditions, infiltration facilities can aid in creating more resilient urban areas. Until now, there are no design rules for these wells which hinders the implementation in urban areas that are fit for infiltration facilities. In this research a design method for sandy soils in the Netherlands is created and set forth. The theoretical and practical performance of infiltration drywells is analysed by conducting experiments with Hydrus 3-dimensional geohydrological model simulations, as well as in the field and laboratory. In the field falling head tests were performed with existing infiltration drywells to determine the functioning while soil samples were analysed in the laboratory to determine the hydraulic conductivity. The model simulations also exist of falling head tests and are compared to the experiments in practice. It was found that the most important parameters on functioning of infiltration drywells are the soil hydraulic conductivity and well dimensions. When comparing the simulated falling head tests to field tests and laboratory tests at the same location, Civil Engineering

The great expansion in offshore power plants is raising the concern regarding the cumulative effect of the electromagnetic field emissions caused by submarine power cables. In this sense, owners are required to predict these emissions during the permitting and consenting process of new power plants. This is a challenging task, especially in the case of HVAC three-core armored cables due to their complex geometry. Customarily, 2D approaches based on the finite element method (FEM) have been employed for evaluating the magnetic field emissions caused by these cables. However, inaccurate results are obtained since the phase conductors and armor twisting is omitted. This work develops, for the first time in the literature, an in-depth analysis of the magnetic field caused by this type of cable through an ultra-shortened 3D-FEM model, which is also faced to experimental measurements taken on an actual 132 kV, 800 mm2 three-core armored cable. Relevant conclusions are derived regarding the impact of the cable design on the magnetic field emissions, including material properties, as well as single and double-layer armors, presenting the proposed model not only as a valuable tool for predicting purposes, but also for optimizing cable design in terms of magnetic field emissions.

Due to recent advances, the numerical analysis of submarine three-core armored cables can nowadays be developed through the finite element method (FEM) in a small slice of the cable. This strongly reduces the computational burden and simulation time. However, the performance of this ultra-shortened 3D-FEM model is still to be fully assessed with experimental measurements. This paper focuses on this validation for an extensive variety of situations through the experimental measurements available in the specialized literature for up to 10 actual cables. In particular, it deals not only with relevant calculations at power frequency, like the series resistance and inductive reactance or the induced sheath current, but also with other aspects never analyzed before through 3D-FEM simulations, such as the zero sequence impedance, the magnetic field distribution around the power cable, as well as side effects due to the nonlinear properties of the armor wires. All this considering different armoring and sheath bonding configurations. Results show a very good agreement between measured and computed values, presenting the ultra-shortened 3D-FEM model as a suitable tool for the analysis and design of three-core armored cables, and opening the possibility to reduce the need of extensive experimental tests in the design stage of new cables.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This paper is devoted to track-bridge interaction phenomena in railway bridges of short simply-supported (SS) spans composed by ballasted tracks. These structures may experience high vertical acceleration levels under operating conditions. In particular, the coupling effect exerted by the ballast track shared by structural parts that are theoretically independent, such as consecutive simply-supported spans or twin adjacent single-track decks, is investigated. Experimental evidence shows that in these cases there may be an important vibration transmission from the loaded to the unloaded track, and that the interlocked ballast granules couple some of the lowest modes of vibration to an important extent. To this end a detailed three-dimensional (3D) Finite Element (FE) model of an existing bridge is implemented where the ballast in weakly connected regions is simulated as transversely isotropic material, in order to represent in a simplified manner the degraded state due to the relative motion between the disconnected structural parts. First, the bridge numerical model is updated from the ambient vibration response of the structure previously measured by the authors. Second, a sensitivity analysis is performed on the properties of the degraded ballast and their effect on the first five modes of vibration of the bridge is discussed. Finally, the response of the bridge under operating conditions is computed numerically, compared with the response measured experimentally in the time and frequency domains and conclusions are extracted regarding the model adequacy.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This paper is devoted to track-bridge interaction phenomena in railway bridges of short simply-supported (SS) spans composed by ballasted tracks. These structures may experience high vertical acceleration levels under operating conditions. In particular, the coupling effect exerted by the ballast track shared by structural parts that are theoretically independent, such as consecutive simply-supported spans or twin adjacent single-track decks, is investigated. Experimental evidence shows that in these cases there may be an important vibration transmission from the loaded to the unloaded track, and that the interlocked ballast granules couple some of the lowest modes of vibration to an important extent. To this end a detailed three-dimensional (3D) Finite Element (FE) model of an existing bridge is implemented where the ballast in weakly connected regions is simulated as transversely isotropic material, in order to represent in a simplified manner the degraded state due to the relative motion between the disconnected structural parts. First, the bridge numerical model is updated from the ambient vibration response of the structure previously measured by the authors. Second, a sensitivity analysis is performed on the properties of the degraded ballast and their effect on the first five modes of vibration of the bridge is discussed. Finally, the response of the bridge under operating conditions is computed numerically, compared with the response measured experimentally in the time and frequency domains and conclusions are extracted regarding the model adequacy.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This paper is devoted to track-bridge interaction phenomena in railway bridges of short simply-supported (SS) spans composed by ballasted tracks. These structures may experience high vertical acceleration levels under operating conditions. In particular, the coupling effect exerted by the ballast track shared by structural parts that are theoretically independent, such as consecutive simply-supported spans or twin adjacent single-track decks, is investigated. Experimental evidence shows that in these cases there may be an important vibration transmission from the loaded to the unloaded track, and that the interlocked ballast granules couple some of the lowest modes of vibration to an important extent. To this end a detailed three-dimensional (3D) Finite Element (FE) model of an existing bridge is implemented where the ballast in weakly connected regions is simulated as transversely isotropic material, in order to represent in a simplified manner the degraded state due to the relative motion between the disconnected structural parts. First, the bridge numerical model is updated from the ambient vibration response of the structure previously measured by the authors. Second, a sensitivity analysis is performed on the properties of the degraded ballast and their effect on the first five modes of vibration of the bridge is discussed. Finally, the response of the bridge under operating conditions is computed numerically, compared with the response measured experimentally in the time and frequency domains and conclusions are extracted regarding the model adequacy.

Systémy zelených stěn a fasád jsou moderním prvkem pozemních staveb. Pro zajištění správného návrhu a funkčnosti těchto systémů v průběhu jejich životního cyklu je nezbytný popis jejich vlastností. Jednou ze základních vlastností fasádních a obkladových prvků je plošná hmotnost. Ta závisí na zvoleném systému provedení vegetační stěny či fasády, zvoleném množství a druhovém zastoupení vegetace a v neposlední řadě na okolních podmínkách místa instalace. Vzhledem k tomu, že se jedná o živé prvky, je nutné konstatovat, že tato vlastnost nelze vyjádřit jednou hodnotou, ale hmotnostním rozsahem. Z důvodu velké odlišnosti těchto systémů od standardních obkladových či fasádních prvků jsou pro zjištění plošné hmotnosti standardní metody zkoušení nepoužitelné. Tento příspěvek popisuje možnou metodiku pro stanovení plošné hmotnosti systémů vegetačních fasád a jejich změn v čase., Green wall and facade systems are a modern element of building construction. To ensure the correct design and functionality of these systems during their life cycle, it is necessary to describe their properties. One of the basic properties of facade and cladding elements is the basis weight. It depends on the chosen system of vegetation wall or facade, the chosen amount, and species representation of vegetation and, last but not least on the surrounding conditions of the installation site. Given that these are living elements, it must be stated that this property cannot be expressed in a single value, but in a mass range. Due to the great difference between these systems and standard cladding or façade elements, standard testing methods are not applicable for determining the basis weight. This paper describes a possible methodology for determining the basis weight of vegetation facade systems and their changes over time.

The running safety and passenger comfort levels in a vehicle are tightly related to the technical state of the suspension elements. The technical state of the suspension depends of the service life time as its components become old and wear out. In this paper, a study on the dynamic behaviour of a railway vehicle is established in relation to the damping elements in one of its suspension stages. An experimental measurement model is developed, obtaining a set of useful signals for the identification of the dynamic parameters of the vehicle and developing a test through the application of the operational modal analysis technique, using least-squares complex exponential method as a basis to validate the numerical model of the multi-body system. Then, the study focuses on developing numerical simulations for the identification of the technical state of the dampers by the registration of dynamic variables under commercial service conditions and on estimating the state of the suspension elements. © 2012 Taylor & Francis.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

Systémy zelených stěn a fasád jsou moderním prvkem pozemních staveb. Pro zajištění správného návrhu a funkčnosti těchto systémů v průběhu jejich životního cyklu je nezbytný popis jejich vlastností. Jednou ze základních vlastností fasádních a obkladových prvků je plošná hmotnost. Ta závisí na zvoleném systému provedení vegetační stěny či fasády, zvoleném množství a druhovém zastoupení vegetace a v neposlední řadě na okolních podmínkách místa instalace. Vzhledem k tomu, že se jedná o živé prvky, je nutné konstatovat, že tato vlastnost nelze vyjádřit jednou hodnotou, ale hmotnostním rozsahem. Z důvodu velké odlišnosti těchto systémů od standardních obkladových či fasádních prvků jsou pro zjištění plošné hmotnosti standardní metody zkoušení nepoužitelné. Tento příspěvek popisuje možnou metodiku pro stanovení plošné hmotnosti systémů vegetačních fasád a jejich změn v čase., Green wall and facade systems are a modern element of building construction. To ensure the correct design and functionality of these systems during their life cycle, it is necessary to describe their properties. One of the basic properties of facade and cladding elements is the basis weight. It depends on the chosen system of vegetation wall or facade, the chosen amount, and species representation of vegetation and, last but not least on the surrounding conditions of the installation site. Given that these are living elements, it must be stated that this property cannot be expressed in a single value, but in a mass range. Due to the great difference between these systems and standard cladding or façade elements, standard testing methods are not applicable for determining the basis weight. This paper describes a possible methodology for determining the basis weight of vegetation facade systems and their changes over time.

The aim of the paper is to investigate the transient regime of hot water boiler numerically and experimentally. In the regime of starting up, as the most critical one, measurements were done on the boiler critical element. The operating characteristics as well as safe and reliable operation conditions of hot water boilers are limited by thermal stresses that occur in their structure. The greatest thermal stresses occur in transient operating regimes such as starting-up, changing operation mode or sudden shutdown, resulting in uneven heating or cooling of boiler elements. Large temperature gradients cause high thermal stresses that are especially critical in elements with thick walls. As thermal stresses may limit the heating and cooling rates of temperature changes, boiler structure is exposed to variable temperature and stress field. The largest absolute value of thermal stresses occurs at the inner surface, where direct measurements are not possible to take, since the inner surface is in direct contact with hot water under high pressure. This was the reason to measure the temperature of boiler structure inside the boiler, on tube plate, as one of the critical part of the boiler. In this paper the experimental results of temperature measurement of tube plate were presented, during the regime of starting-up. Numerical model done by FEM was verified by experimental results. The performed analysis showed that the tube plate of the first reversing chamber, the boiler element with the thickest wall, is exposed to the highest thermal stresses. This part of the boiler is exposed to temperatures t>500 ℃ and it is exposed to creep. In conditions of creep, continuous accumulation of plastic deformations occurs at a rate that depends on the level of stress, temperature and material characteristics.

The detachment of a product from a suction cup gripper is a challenge that emerged in recent years in the high-speed case packing of packaged food. In this industry suction cups are used to temporarily attach a product to a case packing robot. The detachment of products from the suction cup gripper threatens throughput. In, some cases, the industry notes robots to operate at only 40 picks per minute. This is 30 % of their maximum throughput. This study aims to gain a better understanding of the dynamic grasping strength of suction cups. This was done by reviewing the state-of-the-art from industry and state-of-the-practice from literature. It was found that suction cups are the best overall gripper class, and that actuation time poses the main limiting factor for other grippers to perform well in this industry. Secondly, a six-axis force moment sensor that passes airflow for gripper actuation and without limiting the pull-out load measurement performance was designed, fabricated, and validated. With the current sensor technology, the vacuum hose must be placed over the sensor, leading to the generation of parasitic loads. Passing the airflow through the senor structure is essential to eliminate loads otherwise induced by the stiff vacuum hose. The sensor was designed using strain gauges and a Maltese cross sensor structure. Finite Element Modeling and optimization using sequential quadratic programming was used to determine the dimensions of the sensor. The sensor validation showed a maximum measurement error of 8% in the z direction. Lastly, with the validated sensor, the dynamic grasping strength of compliant and stiff suction cups was measured using motion paths and products that are typically seen in the packaged food industry. For both the stiff and compliant suction cups, the moment around the axis perpendicular to the plane of motion showed to be a leading factor in detachment of a product from a suction cup gripper. The failure of stiff suct, FlexCRAFT, Mechanical Engineering | Mechatronic System Design (MSD)

This work is devoted to the experimental evaluation of the dynamic response of railway bridges with common typologies in short-to-medium span lengths. An extensive experimental campaign is performed in several railway bridges belonging to the High-Speed (HS) and conventional Spanish railway network. The main objectives are to (i) characterise the structures main features affecting their dynamic behaviour, (ii) determine the soil properties at the structures respective locations; and (iii) analyse the bridge dynamic responses under different operating conditions. All the bridges are composed by simply-supported (S-S) spans except the last one which is a continuous beam bridge. The structures present different steel, concrete and steel–concrete composite typologies. Five bridges have been experimentally investigated. The five bridges are nowadays at full operation. The study includes the identification of the bridges modal parameters and dynamic soil properties at the sites, a discussion on the identified structural damping in all the bridges, the measurement of the vibration levels induced by railway traffic under operational conditions in the first four bridges, and under construction operation machinery in the fifth case, and a final analysis on the differences found in the structural behaviour of the different typologies for similar traffic. This paper summarizes a vast experimental campaign. The data is available and may be useful to other researchers in order to estimate the response in similar cases and to validate numerical models.

This paper is devoted to track-bridge interaction phenomena in railway bridges of short simply-supported (SS) spans composed by ballasted tracks. These structures may experience high vertical acceleration levels under operating conditions. In particular, the coupling effect exerted by the ballast track shared by structural parts that are theoretically independent, such as consecutive simply-supported spans or twin adjacent single-track decks, is investigated. Experimental evidence shows that in these cases there may be an important vibration transmission from the loaded to the unloaded track, and that the interlocked ballast granules couple some of the lowest modes of vibration to an important extent. To this end a detailed three-dimensional (3D) Finite Element (FE) model of an existing bridge is implemented where the ballast in weakly connected regions is simulated as transversely isotropic material, in order to represent in a simplified manner the degraded state due to the relative motion between the disconnected structural parts. First, the bridge numerical model is updated from the ambient vibration response of the structure previously measured by the authors. Second, a sensitivity analysis is performed on the properties of the degraded ballast and their effect on the first five modes of vibration of the bridge is discussed. Finally, the response of the bridge under operating conditions is computed numerically, compared with the response measured experimentally in the time and frequency domains and conclusions are extracted regarding the model adequacy.

This paper is devoted to track-bridge interaction phenomena in railway bridges of short simply-supported (SS) spans composed by ballasted tracks. These structures may experience high vertical acceleration levels under operating conditions. In particular, the coupling effect exerted by the ballast track shared by structural parts that are theoretically independent, such as consecutive simply-supported spans or twin adjacent single-track decks, is investigated. Experimental evidence shows that in these cases there may be an important vibration transmission from the loaded to the unloaded track, and that the interlocked ballast granules couple some of the lowest modes of vibration to an important extent. To this end a detailed three-dimensional (3D) Finite Element (FE) model of an existing bridge is implemented where the ballast in weakly connected regions is simulated as transversely isotropic material, in order to represent in a simplified manner the degraded state due to the relative motion between the disconnected structural parts. First, the bridge numerical model is updated from the ambient vibration response of the structure previously measured by the authors. Second, a sensitivity analysis is performed on the properties of the degraded ballast and their effect on the first five modes of vibration of the bridge is discussed. Finally, the response of the bridge under operating conditions is computed numerically, compared with the response measured experimentally in the time and frequency domains and conclusions are extracted regarding the model adequacy.