bluuebunny/crossref_metadata_2025 huggingface dataset:
Sedimenty spodního badenu na lokalitě Zaječí hora
Authors: Nehyba Slavomir , Brzobohatý Rostislav , Diviš Karel , Gregorová Růžena , Tomanová Petrová Pavla
Published: January 2023

Lower Badenian deposits were newly exposed at Zaječí hora Hill (Brno city). Sedimentological and paleontological study of the succession recognised two facies associations. The lower one was formed by the lower Badenian clastic deposits known locally as “Brno sands”. The upper one is formed by the lower Badenian offshore clays known as “tegel”. The Neogene beds were covered by Quaternary loess loam. Lower Badenian succession is interpreted as progradation of the Gilbert-type delta foreset into relatively deep basin followed by the flooding of the area by the open sea. The position of the locality close to a steep basin margin was prone to reflect role of local factors influencing the depositional processes and conditions.
Chemické složení amfibolů v polétavém prachu z vybraných lokalit Brněnska
Authors: Buriánek David , Svatuška Jiří
Published: January 2023

This study aimed to characterise the morphological and chemical properties of amphiboles from airborne dust samples collected from three localities in Brno and its surroundings. We analysed approximately 3 g of airborne dust particles from each sample. The mineralogical and morphological characteristics of the dust particles were examined by polarised-light microscopy and electron microprobe analysis. All studied airborne dust inorganic particles with length ≥ 5 μm show a ratio ≤ 3 : 1 or diameter of > 3 μm and therefore do not be potentially dangerous to human health. We compared the chemical analyses of airborne needle-like dust particles (tremolite-actinolite, magnesiohornblende, pargasite; Si = 6.32–7.90 apfu; Mg/(Mg+Fe2+) = 0.34–0.84) with existing chemical composition amphiboles from possible source areas. The amphibole in airborne dust from the locality in the centre of the Brno town is completely dominated by actinolite and magnesiohornblende (Si = 6.48–7.56 apfu; Mg/(Mg+Fe2+) = 0.50–0.80) derived from basic and ultrabasic rocks of the Central Basic Belt of the Brno Massif. The granitoids of the Brno massif can be also a significant source of dust particles. Anthropogenic activity can explain a substantial proportion of amphibole from a relatively small body of amphibolites near Želešice (quarry in the Central Basic Belt of the Brno Massif) because these rocks are widely used as sanding material in the entire Brno agglomeration. The second locality of Rosice (west of Brno) is dominated by amphiboles (Si = 6.51–7.90 apfu; Mg/(Mg+Fe2+) = 0.55–0.84) from the west and northwest metamorphic units (Moravian and Moldanubicum). However, amphiboles from the rocks of the Brno massif are also presented. Amphiboles in the airborne dust from the Rajhradice (locality situated S from Brno) predominantly originated from the rocks of the Central Basic Belt of the Brno Massif (Si = 6.85–7.63 apfu; Mg/(Mg+Fe2+) = 0.50–0.78). Calcareous microfossils suggest that an essential component of the dust is also the material transported from the southeast, where dominated sediments of the Carpathian Flysch units and their foreland. Our results validate amphiboles as valuable minerals for identifying source areas from which dust has been derived and confirm dominant wind flows in the SE and NW directions.
Towards a Good Urban Climate – 12 Rules for Strategic and Spatial Interventions
Authors:   Co-founding partner of sa_partners, Switzerland, Kovári-Binggeli Dunja
Published: January 2023

Global climate change results in an increasing number of extreme events such as heavy precipitation and droughts, prolonged heat and the associated formation of heat islands in cities around the world. Cities and municipalities are however vulnerable to such extreme conditions and rapid changes and need to develop innovating ways of coping with these challenges. In this paper, we argue that a good urban climate is a stepping stone to a livable environment for healthy communities and that the promotion of climate-adapted developments can lead to significantly more robust and resilient cities and communities. By producing a practice-oriented know-how and illustrating our points with three concrete urban design and planning projects, we not only point out the relevance of integrating urban climate considerations into urban design and planning projects, but also take a step forward in bridging climate research with urban planning and design practices.
Employing vision-based sensing for long-term monitoring
Authors:   Imetrum, Kassotakis Nicko ,   Imetrum, Burn Nicholas ,   University of Exeter, Fenney Lee ,   University of Exeter, PILLAI Ajit ,   University of Exeter, Johanning Lars
Published: January 2023

Despite the crucial role of structural health monitoring (SHM), traditional contact-based sensors are costly and lacking automation. Vision-based sensors have recently emerged as a potential substitute, due to their non-contact nature and low cost. However, investigations lack validating their long-term performance. This study assesses vision-based sensing for robust and efficient long-term displacement monitoring. Additionally, the suitability of various machine learning (ML) algorithms in automatically extracting information from the generated data are examined. A first experiment examines the capability to monitor ambiently excited structures over long periods. The parameters assessed are: a) noise and drift (e.g., related to environmental changes such as temperature, humidity, and lighting); and b) obtainable displacement resolution related to ambient excitation. Then, a second experiment examines the capability to monitor dynamically excited structures over long periods (via the employment of an artificial excitation, e.g., an eccentrically loaded mass motor). Here, the following parameters assessed are the: a) frequency bandwidth range; b) frequency resolution; c) displacement resolution related to dynamic excitation; and d) maximum number monitored points for given computational resources. Finally, for processing the generated data, the following ML algorithms are examined: a) Artificial Neural Networks (ANNs); b) support vector machines (SVMs); c) decision trees; and d) Convolutional Neural Networks (CNNs). Concerning long-term monitoring, the paper found that non-contact sensing had comparable accuracy with traditional contact-based sensors. About the ML models, the CNNs were found to be advantageous. Whilst this study was carried out on a small-scale structure, the potential of vision-based sensing for long-term monitoring of full-scale structures was highlighted.
The positive effect on compliance, security, and efficiency by the use of state-of-the-art NDT management software
Authors:   AAP-NDT GmbH, HANSEN Achim ,   AAP-NDT GmbH, Thielen Andreas ,   Dürr NDT GmbH Co.KG, Ruzek Oliver ,   Dürr NDT GmbH Co.KG, Moschtak Andreas ,   Dürr NDT GmbH Co.KG, Roth Adrian
Published: January 2023

The Digitalization and the associated networking of systems is progressing continuously in the NDT industry. In terms of workflow management, however, a combination of several tools such as Excel spreadsheets, Word documents, a wide variety of software and even paper documents are still often used. There is therefore enormous potential for improvement through digitalization. Recent NDT workflow management systems are the key, efficiently integrating all NDT test methods and associated processes into a single system. All information is available centrally and digitally for every stakeholder involved. This guarantees compliance and enables comprehensive transparency and control of the entire NDT workflow and real-time status overview of all inspections. Inspection personnel can be managed, as well as customers, equipment, test objects, inspection procedures and standards. All processes and test results are and will remain traceable at all times. This paper describes the application of such management software and it discusses the significant increases in compliance, security, and efficiency along the basic NDT workflow.
NDT assessment of a thick-walled reinforced concrete mock-up of NPP concrete structures
Authors:   Aalto University, Al-neshawy Fahim ,   VTT Technical Research Centre of Finland, Ferreira Miguel ,   Aalto University, Puttonen Jari
Published: January 2023

Different materials within the Nuclear Power Plants (NPP) concrete structure can undergo ageing process which causes defects in the materials and can lose, partially or totally, their designed function. The typical defects include corrosion of reinforcement steel, delamination, cracks, malfunction of post-tensioning or steel composite systems etc. The testing methods to detect the defects of concrete structures are (i) destructive examinations and (ii) non-destructive testing (NDT).
The challenges for assessing the performance of the NPP concrete structures using (NDT) methods include (i) the limited access time (only during the annual overhauls) and (ii) the accuracy and reliability of the available NDT testing devices.
To overcome these challenges, a mock-up wall representing a section of the concrete containment of the NPP was built. Simulated defects and errors were embedded inside the wall such as dimensional errors, honeycombing, delamination, and voids in the post-tensioned grouted tendon ducts.
Different NDT techniques and combinations were used for assessing the simulated defects of the mock-up wall. These techniques included basic NDT methods as rebound hammer, ultrasonic pulse velocity (UPV) and concrete cover meter and advanced NDT as Ground Penetrating Radar (GPR) and ultrasonic pulse echo (MIRA and MONOLITH).
The results of basic NDT techniques as concrete cover meter, rebound hammer and UPV presented the basic characteristic properties of the concrete mock-up wall as concrete cover depth, compressive strength, and quality of concrete. The use of advanced NDT as GPR and MIRA and MONOLITH enabled us to detect and locate the embedded defect and the construction faults inside the mock-up wall.
We conclude that the construction of the with simulated defects offers the possibility to investigate accuracy and reliably of the available NDT methods and increases the field experts’ skills providing also an important and very much needed educational platform for future NDE experts.
Numerical investigation of near and far field ultrasound transducer radiation characteristics in concrete
Authors:   Helmut-Schmidt-University, Dethof Fabian ,   Fraunhofer-Institute for Non-Destructive Testing (IZFP), Rabe Ute ,   Helmut-Schmidt-University, Kessler Sylvia
Published: January 2023

Concrete is the most frequently used material in civil engineering. Therefore, it also plays an im-portant role for nondestructive testing methods like ultrasonic testing. In the past Dry Point Contact transducers have proven to be very efficient transmitters and receivers for ultrasonic testing of concrete. The individual element consists of a spring-loaded ceramic tip, driven by a piezoelectric bimorph and oscillating either normally or laterally with respect to the component surface. In order to predict the resulting sound fields quantitatively, appropriate modeling is required. Analytic formulas for the wave fields derived from elastic wave theory are available, however, they usually only cover bulk waves (body waves) in the far field and discrepancies between calculated and measured di-rectivity patterns are reported in the literature. We therefore conduct numerical simulations using the staggered-grid finite difference code EFIT to investigate radiation patterns of US transducers cover-ing surface and bulk waves in the near and the far field. The simulations are performed in a strongly heterogeneous, two-phased medium representing the material parameters and the mesostructure of concrete. With this model, the effects of damping as well as scattering at pores and aggregates on radiation characteristics shall be investigated in future. In order to validate EFIT results, measure-ments were conducted on a concrete specimen with an embedded tube as a test feature. As will be shown, a good agreement between measurements and simulations was found. During the evaluation of the simulation and measurement results focus was put on surface waves because a significant part of the wave field’s energy goes into the surface modes. Ultimately, these studies might be used for US transducer sensitivity analysis as well as for US testing reliability assessments in the future.
Detect Surface Cracks Using Explainable Neural Networks
Authors:   The MathWorks, Bolliger Christine ,   The MathWorks, Lenzi Vasco
Published: January 2023

This presentation explores an end-to-end AI workflow by implementing and validating an explainable single-class classification algorithm. The neural network accurately detects cracks in images of concrete, while returning a heatmap of anomalies.
A semi-supervised one-class learning approach is taken, meaning that the network is trained on data consisting only of examples of images without anomalies. Despite training only on samples of normal scenes, the model learns how to distinguish anomalies. One-class learning offers many advantages for anomaly detection problems such as:
1. Representations of anomalies can be scarce
2. Anomalies can represent expensive or catastrophic outcomes
3. There can be many kinds of anomalies, and these can change over the lifetime of the model. Describing what "good" looks like is often more feasible than providing data that represents all possible anomalies in real world settings
A crucial part of detection is for a human observer to be able to understand why a trained network classifies images as anomalies. Explainable classification supplements the class prediction with information that justifies how the neural network reached its decision.
The presentation further explores how to deploy the algorithm onto a portable device, so that the classification could happen, in real-time, on-prem.
Prediction of Chloride Induced Corrosion Using Dynamic Bayesian Updating and Monitoring Data
Authors:   Socotec Monitoring, Bayane Imane ,   Ecole Polytechnique -CNRS/IN2P3, Ronco Dominique ,   Socotec Monitoring, Magnaval Gauthier
Published: January 2023

Corrosion of steel rebars represents the main cause of deterioration of reinforced concrete (RC). Corrosion of steel rebars occurs with the break of the passivation protective layer on the surface of rebars due to carbonation or chloride contamination of concrete cover. Estimating the risk of corrosion initiation in time can provide reliable information to protect rebars and plan maintenance of RC structures. This paper presents a framework for a probabilistic modelling of corrosion initiation in RC structures induced by chloride contamination. The approach is based on a dynamic Bayesian network updated over time using corrosion monitoring data. The dependencies between variables are represented in a directed graph and joint probability density functions are computed using Fick’s law and Monte Carlo sampling. The approach is illustrated with the CorroVolta® sensor, an embedded corrosion sensor designed and manufactured at Socotec Monitoring. Results prove the feasibility of using the dynamic Bayesian approach for corrosion monitoring of RC structures and would support a reliable decision basis for reinforced-concrete bridges and wind-turbine foundations.
Detailed investigation of capillary active insulation materials by 1H nuclear magnetic resonance (NMR) and thermogravimetric drying
Authors:   BAM Federal Institute for Materials Research and Testing, Munsch Sarah ,   BAM Federal Institute for Materials Research and Testing, Bintz Thilo ,   Dresden University of Technology (TU Dresden), Heyn Rüdiger ,   Dresden University of Technology (TU Dresden), Hirsch Hauke ,   Dresden University of Technology (TU Dresden), Grunewald John ,   Technische Universität (TU) Berlin, Kruschwitz Sabine
Published: January 2023

Capillary active interior insulation materials are an important and innovative approach to minimize energy losses of historical buildings. In an experimental setup, we investigate the development of moisture profiles under realistic boundary conditions to determine the liquid moisture conductivity for two different interior insulation materials. The moisture profiles were determined by destructive sample cutting with subsequent thermogravimetric drying as well as directly measured by the non-destructive method NMR, which has a higher spatial resolution and even enables repetitive measurements during the course of the experiments. We observed that the moisture profiles obtained from both methods showed good agreement, when compared at the low spatial resolution of sample cutting. This raises confidence in the method of simple mechanical sample cutting.
In the next step, the liquid moisture conductivity was calculated using an inverse modelling approach based on both measured moisture profiles separately. Then, we compared the pore-size distributions of the investigated samples based on NMR T2-relaxation-time distributions, mercury intrusion porosimetry and indirect determination from pressure plate and sorption isotherm measurements. Moreover, the measured T2-relaxation-time distributions across the sample depth may give further insight into the saturation degree of the different pore sizes.
Construction and validation of a novel phased array borehole probe for ultrasonic investigations at sealing structures in radioactive repositories
Authors:   BAM Federal Institute for Materials Research and Testing, Prabhakara Prathik ,   BAM Federal Institute for Materials Research and Testing, Mielentz Frank ,   BAM Federal Institute for Materials Research and Testing, Stolpe Heiko ,   BAM Federal Institute for Materials Research and Testing, Behrens Matthias ,   BAM Federal Institute for Materials Research and Testing, Lay Vera ,   BAM Federal Institute for Materials Research and Testing, Niederleithinger Ernst
Published: January 2023

A new type of ultrasonic borehole probe is developed for the quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The goal is to examine the sealing structures made of salt concrete for possible cracks, delamination, and embedded objects. A prototype probe uses 12 individual dry point contact (DPC) horizontal shear wave transducers separated by equidistant transmitter/receiver arrays, each made up of six individual transducers. It is operated with a commercially available portable ultrasonic flaw detector used in the civil engineering industry. To increase the generated sound pressure of the borehole probe, the number of transducers in the novel probe is increased to 32. In addition, timed excitation of each probe is used to direct a focused sound beam to a specific angle and distance based on calculated time delays. Hence, the sensitive test volume is limited, and the signal-to-noise ratio of the received signals is improved. This paper presents the validation of the newly developed phased array borehole probe by beam computation in CIVA software and experimental investigations on a semi-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction techniques, an optimised radiation pattern of the probe is expected to improve the signal quality and thus increase the reliability of the imaging results. This is of great importance for the construction of safe sealing structures needed for the disposal of radioactive or toxic waste.
Ultrasonic quality assurance for underground salt shotcrete sealing structures in Teutschenthal mine, Germany
Authors:   BAM Federal Institute for Materials Research and Testing, Lay Vera ,   BAM Federal Institute for Materials Research and Testing, Effner Ute ,   BAM Federal Institute for Materials Research and Testing, Niederleithinger Ernst ,   TU Bergakademie Freiberg, Arendt Jennifer ,   TU Bergakademie Freiberg, Kudla Wolfram
Published: January 2023

Underground sealing structures are necessary to seal radioactive or toxic waste in underground repositories. Particularly developed MgO concrete is used in the mine in Teutschenthal and applied at a large-scale test with the aim to provide concrete with low permeabilities. The test structures (up to 10 m long) were created with the help of a shotcrete procedure. Besides destructive tests, non-destructive ultrasonic measurements are used for quality assurance to monitor potential anomalies such as cracks, concrete inhomogeneities, and delamination. We show results of ultrasonic measurements with a multi-transducer system used at the front site of the concrete structure. Images are obtained by synthetic aperture focusing techniques. Concreting sections are not systematically imaged so that a successful concreting is assumed as also indicated by observed low permeabilities. Several reflectors up to a depth of 1.2 m are identified and interpreted as potential damages in the concrete. Phase analysis of prominent reflectors reveal a negative impedance contrast thus indicating air filled voids, cracks or delamination. Boreholes through some of the identified reflectors are used to verify the results from ultrasonic measurements. Additionally, an experiment with incorporated defects is undertaken to analyse the reliability of the applied methods. Overall, the conducted tests show the great potential of ultrasonic measurements to detect critical anomalies. Despite challenges at small-scale structures (cm-order), large-scale anomalies can be identified. Implementing ultrasonic monitoring during and after the construction of concrete sealing structures is recommended as a tool for quality assurance.
Full-Field Modal Property Extraction from Motion Video Measurement: Considering Out-of-Plane Motions
Authors:   National Taiwan University (NTU), Chang Chia Ming ,   National Taiwan University (NTU), Chou Jau-Yu
Published: January 2023

Aging problems and potential damage of structures will increase the risks of structural collapse in the upcoming extreme loading events (i.e., earthquakes, hurricanes). Thus, structural health monitoring (SHM) is an essential technique to determine structural soundness through in-situ measurements. However, a successful SHM system requires a dense array of sensors that may be challenging in real-world applications. Alternatively, the structural response can be acquired through motion videos. This measurement method not only overcomes the disadvantages of the conventional SHM systems but also gives the opportunity to investigate more detailed dynamic behavior. In this study, a full-field modal property extraction method based on motion videos is proposed, in particular for out-of-plane motions. The measurements are first padded to reduce the distortion effect caused by the image pyramid. The responses are then compressed and decomposed into sub-bands using an image pyramid decomposition. The modal properties are subsequently extracted using the OMA approach known as frequency-domain stochastic subspace identification. The advantages and limitations of the proposed approach are illustrated numerically using a physics-based graphics model of a continuous beam. Subsequently, experimental validation is conducted for a 3-story model building using the Intel RealSenseTM D415 depth camera. Modal properties are shown to be determined quickly, with high accuracy and noise robustness.
Neutral Temperature Estimation of Continuous Welded Rails using Group Velocity of Ultrasonic Waves
Authors:   Sejong University, Kang Myung Soo ,   Sejong University, Azad Ali ,   Sejong University, An Yun-Kyu
Published: January 2023

This study proposes a neutral temperature estimation technique of continuous welded rails using group velocity of ultrasonic waves. In case of boundary-confined metallic structures, especially civil infrastructures exposed to harsh environmental conditions such as continuous welded rail, thermal stress is one of the critical control factors to avoid structural breakage and buckling. It has been known that the ultrasonic wave propagation is sensitive to target structure’s stress variation, so that the neutral temperature can be determined based on the propagation characteristics of stress-dependent ultrasonic wave. To numerically investigate the stress-dependent ultrasonic wave behavior, a 3D rail model with 1 mm mesh size was constructed using actual material property and dimensions of KR60 rail. Here, the two boundary conditions, i.e., Fix-Free and Fix-Fix boundary conditions, applied to the 3D model so that neutral temperature is extracted. The simulation results showed that the group velocity of ultrasonic waves was consistently decreased on the Fix-Free boundary condition according to temperature increase. Similarly, the group velocity on the Fix-Fix boundary condition was also decreased, but the decrement of group velocity was less than the Fix-Free boundary one due to thermal stress. Based on the observation, the stress-dependent group velocity trends can be estimated using the difference between the Fix-Free and Fix-Fix boundary resultants. Finally, the neutral temperature can be estimated by picking up the cross point of two group velocity trend graphs.
Damage detection in tensegrity under varying temperature using interacting Particle-Ensemble Kalman Filter
Authors:   Indian Institute of Technology Mandi (iitmandi), Aswal Neha ,   Indian Institute of Technology Mandi (iitmandi), Sen Subhamoy ,   Institut national de recherche en informatique et en automatique (INRIA), Mevel Laurent
Published: January 2023

Tensegrities are structural mechanisms, with dedicated compression (struts/bars) and tension members (cables). The compression members float inside the network of tension members. Tensegrities are characterized by the presence of at least one infinitesimal mechanism, which is stabilized by the pre-stress present in the members, to ensure the equilibrium of the structure. Under external load, tensegrity may change its form by altering its member pre-stress, thereby affecting its global stiffness even in the absence of damage. Moreover, tensegrities can have different stiffness properties under the same structural configuration in the absence of any damage or external load, if the pre-stress levels of the members are different. However, the change in dynamic characteristics of tensegrities is not limited to the aforementioned causes only and is also affected by ambient uncertainties. A variation in temperature may alter the dynamic characteristics of a tensegrity by influencing its material (Young’s modulus, etc.) and structural (boundary conditions, structural dimensions, etc.) properties. This can potentially lead to a false impression of tensegrity damage/health.
Meanwhile, the prolonged usage of tensegrity may lead to loss of pre-stress in the cables, buckling of the bars, corrosion, and damage of the members, etc. Thus affecting the structural stiffness which leads to change in the measured dynamic properties of the tensegrity. To account for this actual damage in the tensegrity, all the mentioned major challenges that could lead to a false alarm need to be dealt with. The present study develops a vibration-based time-domain approach for tensegrity health monitoring in the presence of uncertainties due to ambient force, measurement noise, and varying temperature. An interacting filtering technique has been used, where the state variables are estimated by the Ensemble Kalman filter that resides inside the Particle filter which computes the health parameters.
Photothermal determination of thermal properties of concrete - a method evaluation
Authors:   BAM Federal Institute for Materials Research and Testing, Krankenhagen Rainer ,   BAM Federal Institute for Materials Research and Testing, Zirker Stefan
Published: January 2023

The evaluation of thermal properties is probably an underrated tool for the onsite health monitoring of concrete structures. While the influence of water content on the thermal behaviour is obviously, a specific correlation with microcrack-density or carbonization state can be suspected. For further investigations, a robust measurement method is needed to characterize the thermal behaviour of concrete – under lab conditions as well as onsite. The photothermal approach offers a possibility to realize a real onsite measurement. Here, the surface to be investigated is heated shortly by a laser pulse and the cooling down is contactless recorded by an infrared camera or pyrometer. The obtained temperature transient allows the calculation of the thermal effusivity of the heated material. Especially this parameter - the thermal effusivity - is very sensitive to characteristic material modifications because it is the simple product of density, thermal conductivity and specific heat capacity. This contribution presents the application of the photothermal approach on three different concrete types. The obtained results were compared with those of a commercial device for laboratory investigations. Both agreed well within the estimated uncertainty ranges and therefore demonstrate the applicability of the photothermal method for this kind of investigations. First results of a concrete sample with different water contents support the potential of this method for the characterization of concrete in general.
Infrastar Training School on Fatigue and Reliability Analysis of Structures - Training for Assessment of Risk
Authors:   Université Gustave Eiffel, Abraham Odile ,   BAM Federal Institute for Materials Research and Testing, Niederleithinger Ernst ,   Université Gustave Eiffel, SCHMIDT Franziska ,   Aalborg University, Sørensen John Dalsgaard ,   Lund University, THONS Sebastian ,   Université Gustave Eiffel, Chapeleau Xavier ,   Insavalor, Ferria Hakim
Published: January 2023

The Infrastar training school (https://trainingschool.infrastar.eu/) provides lectures and hands-on training to Master and PhD students, early-stage researchers, young professionals on all aspects of asset management of civil infrastructures with respect to fatigue of materials.
It is organized yearly since 2019 and up to 20 profiles are selected to attend the 3,5-day training.
A team of 7 teachers provides multi-disciplinary and intersectoral basic concepts in three core fields, ranging from the design to the dismantling of the structures (bridges and wind turbines):
    1. Monitoring and auscultation.
    2. Structural and action models.
    3. Reliability, risk and decision analyses.
Each year, a recognized expert is invited to deliver a keynote to raise interest in a specific aspect of one of the fields covered. The presentation is recorded and published on the training school website.
A participant who successfully has taken part in the Infrastar training school are able to understand:
    1. How to smarten the structures and its benefits.
    2. How to model structural and material behaviours under loading.
    3. How to develop, perform and assess structural risks and the value of structural information.
Coda Wave Interferometry for Monitoring Bridges with Embedded Ultrasonic Transducers – Lessons Learned at the Gänstorbrücke Bridge Ulm, Germany
Authors:   BAM Federal Institute for Materials Research and Testing, Epple Niklas ,   BAM Federal Institute for Materials Research and Testing, Niederleithinger Ernst ,   BAM Federal Institute for Materials Research and Testing, Fontoura Barroso Daniel
Published: January 2023

Ultrasonic Coda Wave interferometry has the potential to detect minute changes in scattering materials like concrete. By permanently installing ultrasonic transducers in concrete, DFG Research unit CoDA aims to develop methods for concrete damage assessment in Germany's ageing infrastructure. To test the methods developed in simulations and laboratory experiments on a large scale, we have implemented several ultrasonic transducers, both embedded and externally attached at the Gänstorbrücke Ulm, one of Germany's most monitored road bridges. Since fall 2020 we are monitoring parts of the centre of the Bridge, as well as an abutment, and compare the results to the commercial monitoring system. All data is recorded with a self-made data collection device, the so-called W-Box, and analyzed with different coda wave-based algorithms to detect signal and volumetric velocity changes for several transducer combinations. The long-term measurements show that the influence of temperature changes on strains and therefore ultrasound velocity changes calculated with coda waves can be monitored. Maps of velocity change show that parts of the bridge react differently to environmental heating or cooling which indicates material property differences comparing those areas. The capabilities and limitations of the coda wave-based monitoring system are tested in a controlled experiment. Static loading using a truck with varying load at several positions allows the calibration of the system to improve the detectability of possibly damaging loads and changes induced by this loading versus the influence of the environment.
Laser-induced breakdown spectroscopy - a tool for the chemical investigation of concrete infrastructure
Authors:   BAM Federal Institute for Materials Research and Testing, Wilsch Gerd ,   BAM Federal Institute for Materials Research and Testing, Völker Tobias ,   BAM Federal Institute for Materials Research and Testing, Klewe Tim ,   BAM Federal Institute for Materials Research and Testing, Kruschwitz Sabine
Published: January 2023

LIBS is a complementary method to XRF and can detect all elements without the need for vacuum conditions. Automated systems are already commercially available capable of scanning surfaces with a resolution of up to 0.1 mm within a few minutes. In addition to possible applications in R&D, LIBS is also used for practical applications in building materials laboratories and even on-site.
In view of ageing infrastructure facilities, a reliable assessment of the condition of concrete structures is of increasing interest. For concrete structures, the ingress of potential harmful ions is affecting the serviceability and eventually structural performance. Pitting corrosion induced by penetrating chlorides is the dominant deterioration mechanism. Condition assessment based on frequently performed chloride profiling can be useful to identify the extent and evolution of chloride ingress. This could prove to be more economical than extensive repairs, especially for important infrastructure facilities.
Currently the most common procedure for determining the chloride content is wet chemical analysis with standard resolution of 10 mm. The heterogeneity is not considered. LIBS is an economical alternative for determining the chloride content at depth intervals of 1 mm or less. It provides 2D distributions of multiple elements and can locate spots with higher concentrations. The results are directly correlated to the mass of binder and can also be performed on-site with a mobile LIBS-System.
The application of a LIBS-system is presented. Calibration is required for quantitative analysis. Concrete cores were drilled, sliced and analyzed to determine the 2D-distribution of harmful elements. By comparing the chloride ingress and the carbonation, the interaction of both processes can be visualized in a measurement that takes less than 10 minutes for a 50 mm x 100 mm drill core.
A leaflet on the use of LIBS for the chloride ingress assessment has been completed.
Automated and Standardized Nondestructive Evaluation of Bridge Decks Using "insight" System
Authors:   Infratek Solutions Inc., Rezvani Amir ,   Infratek Solutions Inc., Moon Franklin ,   Infratek Solutions Inc., Zain Syed ,   Infratek Solutions Inc., Meng Xiao ,   Infratek Solutions Inc., Hasan Syed Ali ,   Infratek Solutions Inc., Maher Ebi ,   Infratek Solutions Inc., Marrero Andrew
Published: January 2023

A common form of deterioration in reinforced concrete bridge decks is corrosion induced deck delamination that is invisible during visual inspection. Current evaluation techniques rely on visual, chain drag and manual NDE technics. Due to inefficient data collection, processing, analysis and interpretation, these manual evaluation techniques cannot provide a thorough evaluation of the structure’s condition. The presented study focuses on a novel NDE solution called “insight” which has brought artificial intelligence, robotic automation, autonomous driving and many more advanced technologies to nondestructive evaluation of bridge decks and other concrete structures. By doing so, comprehensive NDE projects can take place with higher speeds and spatial resolution, in more cost-effective and efficient manners resulting in more widespread and affordable projects.
The Infratek insight solution consists of two platforms, the High Definition (HD) and the High Speed (HS). For the HD platform, results include delamination maps from Impact Echo (IE), attenuation (depth corrected amplitude) and cover depth maps from Ground-Coupled Ground Penetrating Radar (GPR), modulus distribution maps from Ultrasonic Surface Waves (USW), and resistivity maps from Electrical Resistivity (ER). ER and GPR are used to assess the corrosion potential throughout the bridge deck. IE is the primary delamination evaluation tool, while USW enables evaluation of concrete degradation through a modulus measurement. For the HS platform, results include delamination maps from automated high-speed sounding and infrared thermography (IR), attenuation (depth corrected) amplitude and cover depth maps from air-coupled GPR, crack mapped bridge deck image from cameras coupled with machine learning crack mapping technics, surface profiles from laser profilers and additional beneficial information from 360 imaging, and LiDAR. Furthermore, the results are analyzed in a holistic approach using all the collected NDE data. Maps and data-driven recommendations are portrayed in an interactive web portal with options to generate standard inspection and other custom reports.
Delamination Detection in Concrete Plates using a Laser Ablation Impact Echo Technique
Authors:   Technical University of Munich (TUM), Scherr Johannes ,   RED Bernard GmbH, Dallinger Sonja ,   Soundtec GmbH, Püschel Dirk ,   BERNARD Gruppe ZT GmbH, Mazur Jost ,   Technical University of Munich (TUM), Grosse Christian U.
Published: January 2023

This study investigates the detection of delaminations in concrete plates using non-contact laser ablation instead of the conventional hammer excitation. Tests were performed on two specimens of which one had an artificial delamination. 5 mm to 15 mm diameter steel tip hammers were used as a reference source and compared to a 7 ns pulsed 1064 nm Nd:YAG laser with 150 mJ pulse energy. Signals were recorded by surface- mounted accelerometers and in air by microphones and a laser Doppler vibrometer. Frequencies up to 150 kHz are excited with a broad frequency spectrum and little energy compared to the narrower frequency spectra of the hammers. The characteristic thickness resonance frequency of the intact plates can be accurately detected by the hammer excitation. The laser can excite low frequency flexural vibration modes over a shallow delamination at 3 cm depth, but does not excite the thickness resonance frequency. The low frequency flexural vibrations are verified by numerical natural frequency analysis.
Estimation of Depth Direction of Crack by measuring the Residual Magnetic Vector Flux Density around Grains
Authors:   Chosun University, Berkache Azouaou ,   Chosun University, Lee Jinyi ,   Chosun University, Dubin Wang
Published: January 2023

We suggests an algorithm to estimate the depth direction of fatigue cracks. This algorithm uses the distribution of residual magnetic vector flux density (RMVFD) on the specimen. Magnetic domains are the region with a magnetic moment in the same direction. A grain has several magnetic domains. Domain wall is the boundary of the magnetic domain. Magnetic energy stabilized when no external magnetic field applied. That is, the sum of the total magnetic moments is close to zero. It is because that the magnetic flux densities are canceling each other at both ends of the domain wall. The domain wall moves when an external magnetic field applied. As a result, the magnetic domain, which has the same direction with the external magnetic field, enlarged. This phenomenon is magnetization. The domain wall stops moving when it meets with factors that limit the domain wall movement (FLWM). Here FLWM are dislocations, defects, and crystal boundaries. The magnetic energy is unstable at the end of FLWM in the magnetic hysteresis phenomenon. Other end of FLWM has to have the opposite direction of RMVFD to stabilize the magnetic energy. Thus, there are opposite direction of RMVFD each other around crack or grain boundaries. Three dimensional RMVFD (3-RMVFD) can indicates crack existence and depth direction of crack. To verify this theorem, we prepared fatigue crack specimens with different depth direction. The three dimensional shapes of grains reconstructs at the crack. The RMVFD measured by scanning a 3-axis magnetic sensor. And the 3-RMVFD indicated in each grains around crack. The depth directions of crack and grains could estimated by using the 3-RMVFD.
Quantification of the effect of pump wave amplitude on crack breathing for the Nonlinear Coda Wave Interferometry
Authors:   Université Gustave Eiffel, Qu Shilin ,   University of Nantes, Hilloulin Benoît ,   Université Gustave Eiffel, Chupin Olivier ,   Université Gustave Eiffel, Piau Jean-Michel ,   Université Gustave Eiffel, Abraham Odile ,   Université du Maine, Tournat Vincent
Published: January 2023

In civil engineering, an emerging ultrasonic approach based on Code Wave Interferometry (CWI), called Nonlinear Coda Wave Interferometry (NCWI) has been developed to detect microcracks in cementitious materials that cannot be detectedby conventional ultrasonic methods. NCWI uses a high amplitude low frequency (LF) nonlinear pump wave to generate a nonlinear clapping effect at microcracks that can be detected by a high frequency (HF) probe wave.

The imaging of cracks inside heterougeneous materials using NCWI requires the inversion technique, which is constitued by model space and data space, in which conatains model parameters and data parameters respectively. In the frame of inversion with NCWI, the model parameter used is the scatetring cross section of a crack sigmaD, and the experimental parameter is the decorrelation coefficient Kd. Knowing that sigmaD depends on the pump wave amplitude. Therefore, in order to introduce NCWI in inversion, the relationship between the pump wave and sigmaD is needed, which is the goal of this study.

The dynamic pump wave generates clapping effect at crack tips, the probe wave frequencies are higher than the pump waves’ by an order of magnitude, hence the effect of pump wave on the coda wave is rather averaged. Previous study showed that this clapping effect is equivalent to a single crack length change dL, dL can be related to an equivalent static stress sigma0 which produces the same dL in quasi-static regime, which is equivalent to the dynamic pump wave. Therefore, a relation can be established between sigma0 and sigmaD. This introduces NCWI into the inverison. Then, the theoretical estimation of Kd can be achieved by the simulation of NCWI using 2D Spectral Element Method (SEM2D), combining with the relationship between sigma0 and sigmaD, which can be used later on in the inversion for the crack imaging.
Evaluation Of Post Tensioned Bridges’ Tendon Ducts By NDT And Minor Invasive Measures
Authors:   Ramboll Finland Oy, Rapaport Guy
Published: January 2023

This presentation introduces the author’s accumulated long experience in applying state of the art NDT methods for post tensioned bridges’ grout injection evaluation together with minor invasive investigations for validating NDT results and for evaluation of prestressing system condition including duct’s grout injection and prestressing steel corrosion.

The injection grout (cementitious based grout) has a crucial role in protecting the prestressing steel against corrosion caused by different environmental stresses. Corrosion of prestressing steel may cause dangerous fracture mechanisms such as hydrogen embrittlement and stress corrosion cracking. In addition, the injection grout has the important role of intermediating the prestressing forces from the prestressing steel to the concrete structure. Therefore, successful grout injection is critical for the correct structural functionality of a post tensioned bridge.

The introduced NDT methods (ultrasound tomography and Impact-Echo), used together with invasive investigations, have already been successfully applied by the author in over 110 inspections of post tensioned bridges in the past 12 years, mostly in Finland. In situ evaluation of NDT testing results pinpoint the logical locations for invasive investigations. These include opening of tendon ducts and evaluation of the steel duct, injection grout and condition of the prestressing steel (ocular corrosion evaluation).

There are thousands of aging post-tensioned bridges, frequently on critical transportation routes, built mostly in the 1960s-1970s. Occasionally the prestressing was applied in a faulty manner due to various reasons. In some cases, when stress from the environment is added to faulty construction, the consequences may be severe and possibly affect the safe usage of bridges. Faults and damages in prestressing systems are hidden from the eyes. Therefore the severity of the situation is unknown and it may result in extreme cases even in sudden collapse of bridges - as witnessed in the 2018 catastrophic collapse of the Morandi Bridge in Genoa Italy where apparently, according to publications, a post tensioned main structural part failed.

Significant part of the aged post tensioned bridges have already reached renovation time. Therefore, their condition should be assessed. Bridge condition evaluation usually involves “traditional” inspection techniques which do not provide information on the internal prestressing system even though it has a crucial role in the bridge load carrying capacity. The abovementioned NDT methods combined with invasive investigations enable this critical evaluation task.

In addition, those abovementioned NDT methods are suitable as quality assurance measures in newly constructed post tensioned bridges for ensuring long service life of bridges since day one.
Non-Destructive Evaluation of Hydraulic Conditions in Service Pipeline using Elastic Wave Method
Authors:   Obayashi Road Corporation, Kitanohara Tomohiro ,   Obayashi Road Corporation, Homma Jun ,   Niigata University, Suzuki Tetsuya
Published: January 2023

For the effective evaluation of hydraulic conditions of pipeline system, it is necessary to evaluate not only steady flow parameters but also unsteady flow conditions. In this study, quantitative evaluation of stress concentration in model pipeline is going to be performed, applying 3D image analysis and fracture mechanics. The characteristics of stress conditions in model pipeline are correlated with un-steady flow. Using image analysis method, a relationship different inner water pressure conditions and detected fracture mechanics parameters are correlated. By NDT monitoring in service pipeline based on these results, the stress-strain characteristics is successfully detected by 3D image analysis.