TY - JOUR A1 - Niederleithinger, Ernst A1 - Wang, Xin A1 - Mierschke, Vivien A1 - Bertschat, Anja Sophie T1 - Concepts from seismic interferometry transferred to sonic and ultrasonic concrete inspection and monitoring N2 - Seismic interferometry (SI) deals either with the sensible detection of changes in the subsurface or with the reconstruction of virtual signals between two receivers by crosscorrelation of signals from diffuse sources. These concepts can be applied in NDT in civil engineering for various purposes, e. g. to detect changes in bridges. Here it is demonstrated using data from a reference structure on our test site. Practical applications can be expected in the very near future. T2 - 12th European Conference on Non-Destructive Testing (ECNDT 2018) CY - Gothenburg, Sweden DA - 11.6.2018 KW - Ultrasound KW - Concrete KW - Monitoring KW - Coda KW - Interferometry PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-468465 UR - http://www.ndt.net/?id=22760 SN - 1435-4934 VL - 23 IS - 8 SP - 1 EP - 2 PB - NDT.net CY - Kirchwald AN - OPUS4-46846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Clauß, F. A1 - Epple, Niklas A1 - Ahrens, M. A. A1 - Niederleithinger, Ernst A1 - Mark, P. T1 - Comparison of Experimentally Determined Two-Dimensional Strain Fields and Mapped Ultrasonic Data Processed by Coda Wave Interferometry N2 - Due to the high sensitivity of coda waves to the smallest structural alterations such as strain, humidity or temperature changes, ultrasonic waves are a valid means to examine entire structures employing networks of ultrasonic transducers. In order to substantiate this ex ante assessment, the viability of measuring ultrasonic waves as a valid point of reference and inference for structural changes is to be further scrutinized in this work. In order to investigate the influence of mechanical strain on ultrasonic signals, a four-point bending test was carried out on a reinforced concrete beam at Ruhr University Bochum. Thus, measurements collected from a network of selected transducer pairings arranged across the central, shear-free segment of the test specimen, were correlated to their respective strain fields. Detected ultrasonic signals were evaluated employing Coda Wave Interferometry. Such analysis comprised the initial non-cracked state as well as later stages with incremental crack depth and quantity. It was to ascertain that the test specimen can in fact be qualitatively compartmentalized into areas of compression and tension identified via Relative Velocity Changes presented in Attribute Maps. However, since results did not entail a zero crossing, i.e., neither positive nor negative values were to be calculated, only relative changes in this work displayed staggered over the height of the object under test, are discussed. Under the given methodological premises, additional information is currently required to make quantitative assertions regarding this correlation of ultrasonic and strain results. This holds true for the comparability of the ultrasonic and strain results for both non-cracked and even the cracked state. KW - Digital image correlation KW - Fiber optic sensors KW - Coda Wave Interferometry KW - Ultrasound KW - Concrete PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510501 DO - https://doi.org/10.3390/s20144023 SN - 1424-8220 VL - 20 IS - 14 SP - Paper 4023, 1 PB - MDPI CY - Basel AN - OPUS4-51050 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Xin A1 - Chakraborty, J. A1 - Bassil, A. A1 - Niederleithinger, Ernst T1 - Detection of Multiple Cracks in Four-Point Bending Tests Using the Coda Wave Interferometry Method N2 - The enlargement of the cracks outside the permitted dimension is one of the main causes for the reduction of service life of Reinforced Concrete (RC) structures. Cracks can develop due to many causes such as dynamic or static load. When tensile stress exceeds the tensile strength of RC, cracks appear. Traditional techniques have limitations in early stage damage detection and localisation, especially on large-scale structures. The ultrasonic Coda Wave Interferometry (CWI) method using diffuse waves is one of the most promising methods to detect subtle changes in heterogeneous materials, such as concrete. In this paper, the assessment of the CWI method applied for multiple cracks opening detection on two specimens based on four-point bending test is presented. Both beams were monitored using a limited number of embedded Ultrasonic (US) transducers as well as other transducers and techniques (e.g., Digital Image Correlation (DIC), LVDT sensors, strain gauges, and Fiber Optics Sensor (FOS)). Results show that strain change and crack formation are successfully and efficiently detected by CWI method even earlier than by the other techniques. The CWI technique using embedded US transducers is undoubtedly a feasible, efficient, and promising method for long-term monitoring on real infrastructure. KW - Coda wave interferometry KW - Reinforced concrete KW - Cracks KW - SHM KW - Damage detection PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-506666 DO - https://doi.org/10.3390/s20071986 VL - 20 IS - 7 SP - 1 EP - 17 PB - MDPI CY - Basel AN - OPUS4-50666 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Gardner, S. A1 - Kind, Thomas A1 - Kaiser, R. A1 - Grunwald, Marcel A1 - Yang, G. A1 - Redmer, Bernhard A1 - Waske, Anja A1 - Mielentz, Frank A1 - Effner, Ute A1 - Köpp, Christian A1 - Clarkson, A. A1 - Thompson, F. A1 - Ryan, M. A1 - Mahon, D. T1 - Muon Tomography of the Interior of a Reinforced Concrete Block: First Experimental Proof of Concept N2 - Quality assurance and condition assessment of concrete structures is an important topic world-wide due to the aging infrastructure and increasing traffic demands. Common topics include, but are not limited to, localisation of rebar or tendon ducts, geometrical irregularities, cracks, voids, honeycombing or other flaws. Non-destructive techniques such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened up new fields of application, such as the investigation of freight containers. Muon imaging also has the potential to fill some of the gaps currently existing in concrete NDT. As a first step towards practical use and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. The data acquisition takes more time and signals contain more noise, but the images allowed to detect the same important features that are visible in conventional high energy X-ray tomography. In our experiment, we have shown that muon imaging has potential for concrete inspection. The next steps include the development of mobile detectors and optimising acquisition and imaging parameters. KW - Concrete KW - Muon KW - Radar KW - Ultrasound KW - X-ray PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529974 DO - https://doi.org/10.1007/s10921-021-00797-3 VL - 40 IS - 3 SP - 1 EP - 14 PB - Springer Nature AN - OPUS4-52997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wang, Xin A1 - Niederleithinger, Ernst A1 - Hindersmann, Iris T1 - The installation of embedded ultrasonic transducers inside a bridge to monitor temperature and load influence using coda wave interferometry technique N2 - This article presents a unique method of installing a special type of embedded ultrasonic transducers inside a 36-m-long section of an old bridge in Germany. A small-scale load test was carried out by a 16 ton truck to study the temperature and load influence on the bridge, as well as the performance of the embedded transducers. Ultrasonic coda wave interferometry technique, which has high sensitivity in detecting subtle changes in a heterogeneous medium, was used for the data evaluation and interpretation. The separation of two main influence factors (load effect and temperature variation) is studied, and future applications of wave velocity variation rate Φ for structural health condition estimation are discussed. As a preliminary research stage, the installation method and the performance of the ultrasonic transducer are recognized. Load- and temperature-induced weak wave velocity variations are successfully detected with a high resolution of 10−4%. The feasibility of the whole system for long-term structural health monitoring is considered, and further research is planned. KW - Ultrasound KW - Bridge KW - Monitoring KW - coda wave interferometry KW - embedded PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527978 DO - https://doi.org/10.1177/14759217211014430 SN - 1475-9217 VL - 21 IS - 3 SP - 913 EP - 927 PB - SAGE AN - OPUS4-52797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Arndt, R.W. A1 - Grosse, C.U, A1 - Maehner, D. A1 - Niederleithinger, Ernst A1 - Taffe, A. A1 - Algernon, D. A1 - Berger, J. A1 - Kessler, S. A1 - Krueger, M. A1 - Kruschwitz, Sabine A1 - Ufermann-Wallmeier, D. A1 - Walther, A. T1 - Non-destructive testing in civil engineering: A memorandum for teaching at German-speaking universities N2 - This contribution summarizes actual developments and draft fundamental teaching topics in the field of nondestructive testing in civil engineering (NDT-CE). It is based on the first memorandum on teaching and research in the field of NDT-CE at German speaking universities and provides an overview of the academic education and highlights possible focuses, especially in teaching but also takes into account noteworthy developments and topics in research in the field of NDT-CE. Suggestions are given for the development and advancement of the teaching curricula in regards to a comprehensive and sound professional education of students in civil engineering and adjacent disciplines. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Curriculum KW - NDT-CE KW - University KW - Competencies PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563269 UR - https://www.ndt.net/article/ndtce2022/paper/61547_manuscript.pdf SP - 1 EP - 10 PB - NDT.net AN - OPUS4-56326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epple, Niklas A1 - Niederleithinger, Ernst A1 - Fontoura Barroso, Daniel T1 - Coda Wave Interferometry for Monitoring Bridges with Embedded Ultrasonic Transducers – Lessons Learned at the Gänstorbrücke Bridge Ulm, Germany N2 - 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 aging infrastructure. To test the methods developed in simulations and laboratory experiments on a large scale, we have implemented several ultrasonic transducers at the Gänstorbrücke Ulm, one of Germany's most monitored road bridges. Since fall 2020 we are monitoring parts of the center 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. 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. The capabilities and limitations of the coda wave-based monitoring system are tested in a controlled experiment. Static loading using a truck with varying loads at several positions allows the calibration of the system to improve the detectability of possibly damaging loads and changes induced by this loading. A map of velocity change analyzing data from this load experiment shows that the influence of load on the material and strain distribution can be detected with array measurements. T2 - NDT-CE 2022 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Zurich, Switzerland DA - 16.08.2022 KW - Coda Wave Interferometry KW - Ultrasound KW - Embedded sensors KW - Bridge Monitoring KW - Load Experiment PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-564531 SP - 1 EP - 8 AN - OPUS4-56453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rabe, U. A1 - Pudovikov, S. A1 - Herrmann, H.-G. A1 - Wiggenhauser, H. A1 - Prabhakara, Prathik A1 - Niederleithinger, Ernst T1 - Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound N2 - The retroreflective corner echo is used, for example, in ultrasonic non-destructive testing of metals to find fatigue cracks in tubes or shafts. If the much weaker crack tip signal is additionally detected, the crack length can also be determined. A corner reflection occurs in cases of surface breaking cracks with predominantly perpendicular orientation to the surface. The intensity of the corner reflection depends on the angle of incidence and on the ultrasonic wave mode used. For the reliable detection of vertical surface breaking cracks in metals, transversal waves are commonly used, which propagate at an angle of 37° to 53° to the inspection surface. As shown in this contribution, the wide spread low frequency ultrasonic arrays with dry point contact sources available for ultrasonic testing of concrete also allow to receive corner echoes. These devices generate transversal waves in concrete structures with a large divergence of the sound field. A series of experiments was carried out with such dry point contact arrays on concrete specimens with artificial test defects and controlled induced cracks of different depths. The ultrasonic time-of-flight signals were recorded, exported and reconstructed utilising the SAFT (Synthetic Aperture Focusing Technique) algorithm. The SAFT reconstruction parameters were adjusted to visualize the corner echo indication. As will be shown, with this targeted processing, the reproducible detection of surface breaking cracks in concrete is possible. The retroreflective corner echo can thus be exploited in civil engineering for non-destructive inspection of concrete. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Concrete KW - Crack depth KW - Ultrasound KW - SAFT PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563365 UR - https://www.ndt.net/article/ndtce2022/paper/27256_manuscript.pdf IS - 27256 SP - 1 EP - 4 PB - NDT.net AN - OPUS4-56336 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, U. A1 - Pudovikov, S. A1 - Herrmann, H.-G. A1 - Wiggenhauser, H. A1 - Prabhakara, Prathik A1 - Niederleithinger, Ernst T1 - Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound N2 - The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the surface as, for example, corrosion cracks in metal pipes or shafts. This echo is formed by two planes, the surface of the crack and the surface which the crack breaks. It can also be classified as a half-skip method, since a reflection of the pulse occurs on the backwall before the reflection at the defect takes place. In combination with the diffraction from the crack tip, the corner echo also allows crack sizing. As shown in this paper, the corner reflection can be used in civil engineering for nondestructive inspection of concrete. Commercially available low frequency ultrasonic arrays with dry point contact sources generate SH transversal waves with sufficient divergence of the sound field in order to detect corner reflections. Ultrasonic line-scans and area-scans were acquired with a linear array on flat concrete specimens, and the data were reconstructed by the Synthetic aperture focusing technique. If the angles and the area of reconstruction are chosen accordingly, the corner echo reflection can be distinguished from other ultrasonic information. The corner echo can thus be used as a method for deciding whether a crack is a partial-depth crack or a full-depth crack and thus for obtaining a statement about crack depth. This paper presents corresponding experimental results obtained on concrete specimens with artificial test defects and cracks induced under controlled conditions. KW - Ultrasound KW - Crack depth KW - Concrete KW - Corner echo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574631 DO - https://doi.org/10.1007/s10921-023-00956-8 SN - 0195-9298 VL - 42 IS - 2 SP - 1 EP - 19 PB - Springer Nature AN - OPUS4-57463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maack, Stefan A1 - Küttenbaum, Stefan A1 - Bühling, Benjamin A1 - Borchardt-Giers, Kerstin A1 - Aßmann, Norman A1 - Niederleithinger, Ernst T1 - Low frequency ultrasonic pulse-echo datasets for object detection and thickness measurement in concrete specimens as testing tasks in civil engineering N2 - The dataset contains raw data gathered with the ultrasonic pulse-echo method on concrete specimens. The surfaces of the measuring objects were automatically scanned point by point. Pulse-echo measurements were performed at each of these measuring points. The test specimens represent two typical testing tasks in construction industry: the detection of objects and the determination of dimensions to describe the geometry of components. By automating the measurement process, the different test scenarios are examined with a high repeatability, precision and measuring point density. Longitu- dinal and transversal waves were used and the geometrical aperture of the testing system was varied. The low-frequency probes operate in a range of up to approximately 150 kHz. In addition to the specification of the geometrical dimensions of the individual probes, the directivity pattern and the sound field characteristics are provided. The raw data are stored in a universally readable format. The length of each time signal (A-scan) is two milliseconds and the sampling rate is two mega-samples per second. The provided data can be used for comparative studies in signal analysis, imag- ing and interpretation as well as for evaluation pur- poses in different, practically relevant testing scenarios. KW - Validation KW - Puls-echo method KW - Ultrasonic KW - Non-destructive testing KW - SAFT KW - Reconstruction algorithm PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-575185 DO - https://doi.org/10.1016/j.dib.2023.109233 SN - 2352-3409 VL - 48 SP - 1 EP - 16 PB - Elsevier Inc. AN - OPUS4-57518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Maack, Stefan A1 - Buske, Stefan T1 - Application of iterative elastic SH reverse time migration to synthetic ultrasonic echo data N2 - The ultrasonic echo technique is widely used in non-destructive testing (NDT) of concrete objects for thickness measurements, geometry determinations and localization of built-in components. To improve ultrasonic imaging of complex concrete structures, we transferred a seismic imaging technique, the Reverse Time Migration (RTM), to NDT in civil engineering. RTM, in contrast to the conventionally used synthetic aperture focusing technique (SAFT) algorithms, considers all wavefield types and thus, can handle complex wave propagations in any direction with no limit on velocity variations and reflector dip. In this paper, we focused on the development, application and evaluation of a two-dimensional elastic RTM algorithm considering horizontally polarized shear (SH) waves only. We applied the elastic SH RTM routine to synthetic ultrasonic echo SH-wave data generated with a concrete model incorporating several steps and circular cavities. As these features can often be found in real-world NDT use cases, their imaging is extremely important. By using elastic SH RTM, we were able to clearly reproduce almost all reflectors inside the concrete model including the vertical step edges and the cross sections of the cavities.We were also capable to show that more features could be mapped compared to SAFT, and that imaging of complex reflectors could be sharpened compared to elastic P-SV (compressional-vertically polarized shear) RTM. Our promising results illustrate that elastic SH RTM has the potential to significantly enhance the reconstruction of challenging concrete structures, representing an important step forward for precise, high-quality ultrasonic NDT in civil engineering. KW - Ultrasonic echo technique KW - Concrete structures KW - Elastic reverse time migration KW - Synthetic aperture focusing technique KW - Horizontally polarized shear waves PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-591716 DO - https://doi.org/10.1007/s10921-023-01010-3 SN - 1573-4862 VL - 43 SP - 1 EP - 16 PB - Springer Science and Business Media CY - Dordrecht AN - OPUS4-59171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Timofeev, Juri A1 - Azari, H. A1 - Satyanarayana, R. T1 - Controlled Creating of Delaminations in Concrete for Nondestructive Testing N2 - Locating and sizing delaminations is a common inspection task in the maintenance and quality control of construction and rehabilitation. Their detection is an important area of application of nondestructive testing in civil engineering (NDT-CE). To improve this application, NDT test systems and test solutions must be compared, for which specimens containing well-defined delaminations are needed to serve as a reference. Currently, there are no widely accepted procedures available for creating such flaws locally and reproducibly. This study presents procedures for creating artificial delaminations repeatably and as close as possible to natural delaminations. To produce the discontinuities only substances were used which can occur in concrete components and do not affect the application of NDT-CE methods. Ultrasonic pulse-echo (UPE) was used to test the flaws in the specimens. The delaminations were created by applying expansive mortar in prepared through holes. Three specimens with two delaminations each were built and tested using UPE. KW - Concrete KW - Reference KW - Delamination KW - Test specimen KW - Non-destructive testing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595201 DO - https://doi.org/10.1007/s10921-023-01044-7 SN - 0195-9298 VL - 43 IS - 1 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, T. A1 - Niederleithinger, Ernst T1 - Combining Passive and Active Ultrasonic Stress Wave Monitoring Techniques: Opportunities for Condition Evaluation of Concrete Structures N2 - Concrete structures are invaluable assets to a society and managing them efficiently and effectively can be supported by information gathered through structural health monitoring (SHM). In this paper, a combined approach based on passive, i.e., acoustic emission (AE), and active, i.e., ultrasonic stress wave (USW) monitoring techniques for application to concrete structures is proposed and evaluated. While AE and USW are based on the same underlying physics, i.e., wave motion in solids, they differ fundamentally with respect to the nature of the source. For the former, external stimuli such as mechanical loads or temperature cause the rapid release of energy from initially unknown locations. As a result, AE events are unique and cannot be repeated. For the latter, a known source at a known location is employed at a specified time. This approach is thus controlled and repeatable. It is argued that a combination of these two techniques has the potential to provide a more comprehensive picture of ongoing fracture processes, damage progression, as well as slowly occurring aging and degradation mechanisms. This combined approach does thus promise new opportunities to support condition assessment of concrete structures. After providing an overview and comparison of the two techniques, results, and observations from a full-scale laboratory experiment and an in-service bridge monitoring study are discussed to demonstrate the promise of the proposed combined monitoring approach. Finally, suggestions for further work are presented. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Ultrasound KW - Acoustic emission KW - Concrete structures KW - Monitoring PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563242 UR - https://www.ndt.net/article/ndtce2022/paper/61607_manuscript.pdf SP - 1 EP - 11 PB - NDT.net AN - OPUS4-56324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Feistkorn, S. A1 - Algernon, D. A1 - Arndt, R. A1 - Ebell, Gino A1 - Friese, M. A1 - Grosse, C. U. A1 - Holstein, R. A1 - Niederleithinger, Ernst A1 - Schickert, M. A1 - Schulze, S. A1 - Taffe, A. A1 - Walther, A. A1 - Wolf, J. A1 - Zoega, A. A1 - Zwanzig, M. T1 - Introduction to DIN 4871: Qualification of NDT Personnel in Civil Engineering (NDT-CE) N2 - Recently, non-destructive testing in civil engineering (NDT-CE), in particular of concrete components, has successfully mastered the leap from research to practice. Several methods have been established for field inspections to determine the concrete cover of reinforcement or to estimate the compressive strength as well as other parameters related to the concrete material. In addition, the application of nondestructive testing is indispensable, if information about the inner structure - such as the location of rebars and tendon ducts or the damage-related condition assessment to detect grouting defects, honeycombs, delamination, or corrosion - is required. Besides the selection of a suitable NDT method and an appropriate inspection system, the reliability of the results depends largely on the person who applies the non-destructive inspection technique and evaluates the inspection results. To ensure a high quality of non-destructive concrete evaluation as well as to keep the uncertainty caused by the inspection personnel to a minimum, structured, consistent and regulated theoretical as well as practical training of inspection personnel is essential. To close this gap, the subcommittee of education (UA-A) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP) has been reactivated in 2018 to establish uniform training standards for nondestructive concrete inspections in the long term. The subcommittee consists of scientists, practitioners, authorities, and clients. So far, the national standard DIN 4871 “Non-destructive testing - Qualification and Certification of NDT personnel in Civil Engineering (NDT-CE)” was developed and is currently under review. This standard considers the civil-industry-specifics, for example, that standards for NDT of concrete, as well as related product standards with a few exceptions, still do not exist at the moment. Within this presentation, the concept, the connection to ISO 9712 and other standards as well as an overview of the developed German standard DIN 4871 will be presented. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Non-destrucive testing KW - Civil engineering PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-555250 UR - https://www.ndt.net/article/ndtce2022/paper/66594_manuscript.pdf VL - 2022/09 SP - 1 EP - 12 PB - NDT.net CY - Bad Breisig AN - OPUS4-55525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Guangliang, Y. A1 - Mahon, D. A1 - Gardner, S. T1 - Muon tomography applied to assessment of concrete structures: First experiments and simulations. N2 - Non-destructive techniques for reinforced or prestressed concrete inspection such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened new fields of application. As a first step towards practical application in civil engineering and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. In a second step, we have performed simulations to assess the potential for a set of important testing problems such as grouting defects in tendon ducts. The next steps include the development of mobile detectors and optimizing acquisition and imaging parameters. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Muon tomography KW - Concrete KW - Inspection KW - Simulation PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563224 UR - https://www.ndt.net/article/ndtce2022/paper/60943_manuscript.pdf SP - 1 EP - 8 PB - NDT.net AN - OPUS4-56322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Buske, B. T1 - Application of Elastic Reverse Time Migration to Ultrasonic Echo Data in Civil Engineering N2 - To improve ultrasonic imaging of concrete structures, we transferred a seismic migration technique, the Reverse Time Migration (RTM), to non-destructive testing. A 2D elastic RTM algorithm was tested on synthetic ultrasonic echo data. Compared to the typically used synthetic aperture focusing technique (SAFT) as well as our acoustic RTM algorithm, the presented elastic RTM results show an enhancement in imaging vertical reflectors and complex features inside the 2D numerical concrete model. T2 - The International Symposium on Nondestructive Testing in Civil Engineering CY - Zurich, Switzerland DA - 16.08.2022 KW - Ultrasonic Echo Technique KW - Reverse Time Migration KW - Synthetic Aperture Focusing Technique PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-561147 UR - https://www.ndt.net/article/ndtce2022/paper/60699_manuscript.pdf SP - 1 EP - 6 AN - OPUS4-56114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Abraham, O. A1 - Niederleithinger, Ernst A1 - Schmidt, F. A1 - Sörensen, J.D. A1 - Thöns, S. A1 - Chapeleau, X. A1 - Ferria, H. T1 - Infrastar Training School on Fatigue and Reliability Analysis of Structures - Training for Assessment of Risk N2 - The Infrastar training school provides lectures and hands-on training to Master and PhD students, early-stage researchers and (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 insight in 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 lecture to raise interest in a specific aspect of one of the fields covered. The presentation is recorded and published on the training school website. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Doctoral School KW - Multidisciplinary KW - Fatigue KW - Reliability PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-563253 UR - https://www.ndt.net/article/ndtce2022/paper/61021_manuscript.pdf SP - 1 EP - 3 PB - NDT.net AN - OPUS4-56325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Maack, Stefan A1 - Buske, Stefan T1 - Correction: Application of iterative elastic SH reverse time migration to synthetic ultrasonic echo data N2 - This is a corrigendum to the original article "Application of iterative elastic SH reverse time migration to synthetic ultrasonic echo data" that was published in the "Journal of nondestructive evaluation" (2014, DOI: 10.1007/s10921-023-01010-3). PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599597 DO - https://doi.org/10.1007/s10921-024-01052-1 SN - 1573-4862 VL - 43 IS - 1 SP - 1 EP - 3 PB - Springer Science and Business Media CY - Dordrecht AN - OPUS4-59959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Maack, Stefan T1 - Low-frequency ultrasound data (pulse-echo technique) with shear horizontal and longitudinal waves on a reference polyamide specimen “BAM-Pk218” N2 - This dataset contains raw data observed with ultrasound measurements on a polyamide reference specimen at Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin. The internal specimen identifier is „Pk218“. The measurements were conducted using the pulse-echo method. KW - Nondestructive testing KW - Ultrasound KW - Pulse-echo technique KW - Validation KW - Reference material KW - Reconstruction algorithm PY - 2022 DO - https://doi.org/10.7910/DVN/KVN7CY PB - Harvard College CY - Cambridge, MA, USA AN - OPUS4-54959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Niederleithinger, Ernst T1 - Optimierung und Erweiterung der Parallel-Seismik-Methode zur Bestimmung der Länge von Fundamentpfählen N2 - Das Parallel-Seismik-Verfahren dient vor allem der nachträglichen Langenmessung von Fundamentpfählen oder ähnlichen Elementen zur Gründung von Bauwerken. Eine solche Messung wird beispielsweise notwendig, wenn ein Gebäude verstärkt, erhöht oder anders als bisher genutzt werden soll, aber keine Unterlagen mehr über die Fundamente vorhanden sind. Das Messprinzip des schon seit einigen Jahrzehnten bekannten Verfahrens ist relativ einfach: Auf dem Pfahlkopf wird meist durch Hammerschlag eine Stoßwelle erzeugt, die durch den Pfahl nach unten lauft. Dabei wird Energie in den Boden abgegeben. Die abgestrahlten Wellen werden von Sensoren in einem parallel zum Pfahl hergestellten Bohrloch registriert. Aus den Laufzeiten lassen sich die materialspezifischen Wellengeschwindigkeiten im Pfahl und im Boden sowie die Pfahllange ermitteln. Bisher wurde meist ein sehr einfaches Verfahren zur Datenauswertung verwendet, das die Lange der Pfahle systematisch überschätzt. In der vorliegenden Dissertation wurden die mathematisch-physikalischen Grundlagen beleuchtet und durch Computersimulation die Wellenausbreitung in Pfahl und Boden genau untersucht. Weitere Simulationen klarten den Einfluss verschiedener Mess- und Strukturparameter, beispielsweise den Einfluss von Bodenschichtung oder Fehlstellen im Pfahl. So konnte geklärt werden, in welchen Fällen mit dem Parallel-Seismik-Verfahren gute Ergebnisse erzielt werden können (z. B. bei Fundamenten in Sand oder Ton) und wo es an seine Grenzen stößt (z. B. bei Gründung im Fels). Auf Basis dieser Ergebnisse entstand ein neuer mathematischer Formalismus zur Auswertung der Laufzeiten. In Verbindung mit einem Verfahren zur Dateninversion, d. h. der automatischen Anpassung der Unbekannten in den Gleichungen an die Messergebnisse, lassen sich sehr viel genauere Werte für die Pfahllange ermitteln als mit allen bisher publizierten Verfahren. Zudem kann man nun auch mit relativ großen Abstanden zwischen Bohrloch und Pfahl (2 - 3 m) arbeiten. Die Methode wurde an simulierten Daten ausführlich getestet. Die Messmethode und das neue Auswerteverfahren wurden in einer Reihe praktischer Anwendungen getestet – und dies fast immer erfolgreich. Nur in einem Fall komplizierter Fundamentgeometrie bei gleichzeitig sehr hoher Anforderung an die Genauigkeit war schon nach Simulationen klar, dass hier ein Einsatz nicht sinnvoll ist. Dafür zeigte es sich, dass auch die Lange von Pfahlwanden und Spundwanden ermittelt werden kann. Die Parallel-Seismik-Methode funktioniert als einziges verfugbares Verfahren zur Fundamentlangenermittlung zugleich in den meisten Bodenarten sowie an metallischen und nichtmetallischen Fundamenten und kommt ohne Kalibrierung aus. Sie ist nun sehr viel breiter einsetzbar und liefert sehr viel genauere Ergebnisse. Die Simulationen zeigten noch Potential für Erweiterungen, zum Beispiel durch den Einsatz spezieller Sensoren, die zusätzliche Wellentypen empfangen und unterscheiden können. N2 - The Parallel Seismic (PS) method is used for determination of the unknown or undocumented depth/length of foundations, mostly piles. PS is an established but rather not commonly used geophysical technique, which has been developed several decades ago. Currently, this method is standardized in France and included in the FHWA method catalog. The principle behind PS is quite simple: an impulse is generated on top of the pile by a hammer stroke, generating elastic waves (mainly compressional) traveling downward through the pile. Due to the high impedance contrast between pile and soil, the main part of the energy remains in the pile, but some is transmitted as guided waves into the surrounding soil. After reaching the pile toe, transmitted/diffracted waves of nearly spherical front are generated. These waves are recorded by sensors (hydrophones or geophones) in a nearby borehole. From the first arrival times registered at the sensors, the apparent wave velocity is calculated, which is different above the pile toe (pile velocity) and below (soil velocity). In the conventional data analysis, the pile length is estimated based on the intersection of the two travel time branches, leading to a systematic overestimation of the length of the pile. This thesis provides a systematic treatise of the mathematical and physical foundations of wave propagation in piles and soil. Extensive numerical simulations and parametric studies have been carried out to investigate the nature of the wave-field and influence of measurement and structural parameters. The results revealed the range of applicability of Parallel Seismic, but also some limitations, e. g. in the case of rock socketed foundations or piles containing flaws. A new formalism for data interpretation was developed based on the simulation results, which takes into account the soil layers and the borehole inclination. This novel data interpretation scheme was used in combination with different data inversion methods. A comparison of the results showed that the commonly used Levenberg-Marquardt type least squares approach gives sufficiently accurate estimations in most common scenarios. The VFSA (very fast simulated annealing) method offers some advantages (e. g. avoiding local minima under certain conditions) but is much more time consuming. The new interpretation method was successfully validated using several sets of simulated data. It proved to be not only more accurate than all other available methods, but also to extend the maximum allowable pileborehole distance to 2 – 3 m. Besides the numerical study, several field investigations have been carried out for the purpose of this study and also in the framework of real world projects. The foundation types included secant pile walls and sheet piles. The method performed successfully in all cases but one: a highly accurate determination of the connection of a T-shaped footing. In this particular case, the inapplicability of the method was concluded after some preliminary simulations, thus avoiding unnecessary costs to the client. Performing simulations prior to the actual testing is recommended in dealing with all non-standard cases. Today, Parallel Seismic is the only method applicable on metallic and non metallic foundations which can be used without calibration. It has the largest range of all borehole methods. T3 - BAM Dissertationsreihe - 70 KW - Parallel-Seismik KW - Fundament KW - Inversion KW - Bohrpfahl KW - Längenbestimmung PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-883 SN - 978-3-9813853-5-9 SN - 1613-4249 VL - 70 SP - 1 EP - 221 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-88 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -