TY - JOUR A1 - Suffa, Philipp A1 - Kemmler, Samuel A1 - Koestler, Harald A1 - Ruede, Ulrich T1 - Large-scale simulations of fully resolved complex moving geometries with partially saturated cells N2 - We employ the Partially Saturated Cells Method to model the interaction between the fluid flow and solid moving objects as an extension to the conventional lattice Boltzmann method. We introduce an efficient and accurate method for mapping complex moving geometries onto uniform Cartesian grids suitable for massively parallel processing. A validation of the physical accuracy of the solid–fluid coupling and the proposed mapping of complex geometries is presented. The implementation is integrated into the code generation pipeline of the waLBerla framework so that highly optimized kernels for Central Processing Unit (CPU) and Graphical Processing Unit (GPU) architectures become available. We study the node-level performance of the automatically generated solver routines. 71% of the theoretical peak performance can be achieved on CPU nodes and 86% on GPU accelerated nodes. Only a moderate overhead is observed for the processing of the solid–fluid coupling when compared to the fluids simulations without moving objects. Finally, a counter-rotating open rotor is presented as a prototype industrial scenario, resulting in a mesh size involving up to 4.3 × 109 fluid grid cells. For this scenario, excellent parallel efficiency is reported in a strong scaling study on up to 32 768 CPU cores on the LUMI-C supercomputer and on up to 1024 NVIDIA A100 GPUs on the JUWELS Booster system. KW - Computational fluid dynamics KW - Lattice Boltzmann methods KW - Fluid coupling KW - Turbulent flows KW - Supercomputer PY - 2025 DO - https://doi.org/10.1063/5.0268021 SN - 1070-6631 VL - 37 IS - 5 SP - 1 EP - 13 PB - AIP Publishing AN - OPUS4-63188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Straub, D. A1 - Schneider, Ronald A1 - Bismut, E. A1 - Kim, H.-J. T1 - Reliability analysis of deteriorating structural systems N2 - Reliability analysis of deteriorating structural systems requires the solution of time-variant reliability problems. In the general case, both the capacity of and the loads on the structure vary with time. This analysis can be approached by approximation through a series of time-invariant reliability problems, which is a potentially effective strategy for cases where direct solutions of the time-variant reliability problem are challenging, e.g. for structural systems with many elements or arbitrary load processes. In this contribution, we thoroughly Review the formulation of the equivalent time-invariant reliability problems and extend this approximation to structures for which inspection and monitoring data is available. Thereafter, we present methods for efficiently evaluating the reliability over time. In particular, we propose the combination of sampling-based methods with a FORM (first-order reliability method) approximation of the series system reliability problem that arises in the computation of the lifetime reliability. The framework and algorithms are demonstrated on a set of numerical examples, which include the computation of the reliability conditional on inspection data. KW - Monitoring KW - Reliability KW - Deterioration KW - Structural systems KW - Bayesian analysis KW - Inspection PY - 2020 DO - https://doi.org/10.1016/j.strusafe.2019.101877 VL - 82 SP - Paper 101877, 1 PB - Elsevier Ltd. AN - OPUS4-48952 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Wiehle, Philipp T1 - Closure of "Quantification of moisture content in earth block masonry under natural climatic conditions" N2 - In January 2025, the research paper “Quantification of moisture content in earth block masonry under natural climatic conditions” was published in Construction and Building Materials. The central theme was the moisture monitoring of a masonry wall made of unstabilised earth blocks over a period of around 18 months. The experimental results were compared to WUFI simulations, and the moisture transport in layered wall constructions was eventually studied in WUFI. Prof. Janssen discussed this publication in Construction and Building Materials. He raised concerns about the experiments and modelling of moisture transport. In this closure, the capillary adsorption coefficient was recalculated, and deviations from the initial value were quantified. Sensitivity analyses were conducted in WUFI to evaluate the influence of different water vapour resistances and water adsorption coefficients. The resulting moisture transport was then compared to material moisture profiles measured using 1H NMR relaxometry. Finally, the water adsorption behaviour of different earth materials is discussed in respect to material moisture and corresponding relative humidity. KW - Earth masonry KW - Moisture transport KW - Capillary water absorption KW - Embedded humidity sensors KW - NMR KW - WUFI KW - Material moisture KW - Water vapour diffusion resistance KW - Sustainable building materials PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-637569 DO - https://doi.org/10.1016/j.conbuildmat.2025.142552 SN - 0950-0618 VL - 491 SP - 1 EP - 6 PB - Elsevier Ltd. AN - OPUS4-63756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Patrick A1 - Schneider, Ronald A1 - Baeßler, Matthias A1 - Morgenthal, Guido ED - Cha, Young-Jin T1 - A Bayesian Probabilistic Framework for Building Models for Structural Health Monitoring of Structures Subject to Environmental Variability N2 - Managing aging engineering structures requires damage identification, capacity reassessment, and prediction of remaining service life. Data from structural health monitoring (SHM) systems can be utilized to detect and characterize potential damage. However, environmental and operational variations impair the identification of damages from SHM data. Motivated by this, we introduce a Bayesian probabilistic framework for building models and identifying damage in monitored structures subject to environmental variability. The novelty of our work lies (a) in explicitly considering the effect of environmental influences and potential structural damages in the modeling to enable more accurate damage identification and (b) in proposing a methodological workflow for model‐based structural health monitoring that leverages model class selection for model building and damage identification. The framework is applied to a progressively damaged reinforced concrete beam subject to temperature variations in a climate chamber. Based on deflections and inclinations measured during diagnostic load tests of the undamaged structure, the most appropriate modeling approach for describing the temperature‐dependent behavior of the undamaged beam is identified. In the damaged state, damage is characterized based on the identified model parameters. The location and extent of the identified damage are consistent with the cracks observed in the laboratory. A numerical study with synthetic data is used to validate the parameter identification. The known true parameters lie within the 90% highest density intervals of the posterior distributions of the model parameters, suggesting that this approach is reliable for parameter identification. Our results indicate that the proposed framework can answer the question of damage identification under environmental variations. These findings show a way forward in integrating SHM data into the management of infrastructures. KW - Verkehrsinfrastukturen KW - SHM KW - Model Updating KW - Environmental and Operational Variability KW - Damage Identification KW - Model Building PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605027 DO - https://doi.org/10.1155/2024/4204316 SN - 1545-2255 VL - 2024 IS - 1 SP - 1 EP - 23 PB - Wiley AN - OPUS4-60502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Patrick A1 - Schneider, Ronald A1 - Baeßler, Matthias A1 - Morgenthal, Guido T1 - Parallelized adaptive Bayesian updating with structural reliability methods for inference of large engineering models N2 - The reassessment of engineering structures, such as bridges, now increasingly involve the integration of models with realworld data. This integration aims to achieve accurate ‘as-is’ analysis within a digital twin framework. Bayesian model updating combines prior knowledge and data with models to enhance the modelling accuracy while consistently handling uncertainties. When updating large engineering models, numerical methods for Bayesian analysis present significant computational challenges due to the need for a substantial number of likelihood evaluations. The novelty of this contribution is to parallelize adaptive Bayesian Updating with Structural reliability methods combined with subset simulation (aBUS) to improve its computational efficiency. To demonstrate the efficiency and practical applicability of the proposed approach, we present a case study on the Maintalbrücke Gemünden, a large railway bridge. We leverage modal property data to update a linear-elastic dynamic structural model of the bridge. The parallelized aBUS approach significantly reduces computational time, making Bayesian updating of large engineering models feasible within reasonable timeframes. The improved efficiency allows for a wider implementation of Bayesian model updating in structural health monitoring and maintenance decision support systems. KW - Bayesian model updating KW - Bayesian updating with structural reliability methods KW - Structural health monitoring KW - Parallelization KW - Modal analysis KW - Railway bridge PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-633686 DO - https://doi.org/10.1177/13694332251346848 SN - 1369-4332 SN - 2048-4011 SP - 1 EP - 26 PB - Sage AN - OPUS4-63368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick A1 - Schneider, Ronald A1 - Baeßler, Matthias ED - Yokota, H. ED - Frangopol, D. M. T1 - Bayesian system identification of a reinforced concrete beam subject to temperature variations based on static response data N2 - Changes in the measured response of structural systems can be an indication of structural damages. However, such changes can also be caused by the effect of varying environmental conditions. To detect, localize and quantify changes or damages in structural systems subject to varying environmental conditions, physics-based models of the structural systems have to be applied which explicitly account for the influence of ambient conditions on the structural behavior. Data obtained from the structural systems should be used to calibrate the models and update predictions. Bayesian system identification is an effective framework for this task. In this paper, we apply this framework to learn the parameters of two competing structural models of a reinforced concrete beam subject to varying temperatures based on static response data. The models describe the behavior of the beam in the uncracked and cracked condition. The data is collected in a series of load tests in a climate chamber. Bayesian model class selection is then applied to infer the most plausible condition of the beam conditional on the available data. T2 - Tenth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2020) CY - Online meeting DA - 11.04.2021 KW - Structural systems KW - Bayesian system identification KW - Damage identification KW - Environmental effects KW - Structural health monitoring PY - 2021 DO - https://doi.org/10.1201/9780429279119-125 SP - 934 EP - 941 PB - CRC Press AN - OPUS4-52809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Simon, Patrick A1 - Baeßler, Matthias ED - Cunha, Álvaro ED - Caetano, Elsa T1 - On the reassessment of bridge superstructure vibrations for high-speed traffic N2 - The acceleration thresholds of bridge superstructures remain critical for designing and reassessing railway bridges on high-speed lines, with ballasted track systems historically limited to 3.5 m/s2 vertical accelerations due to destabilization risks. As part of the European InBridge4EU project, this study addresses methodological uncertainties in linking vertical bridge vibrations to lateral track creep—a key focus area for modernizing assessment protocols. A comparative analysis of two acceleration postprocessing methods (peak identification vs. fatigue-derived rainflow counting) as part of a recently proposed framework was conducted using an example bridge and train combination. Results demonstrate that rainflow counting yields more conservative creep estimates with the bulk of cumulative vibration-induced creep attributable to accelerations exceeding 3 m/s2. However, discretizing acceleration ranges into 1 m/s2 bins introduced significant errors compared to continuous cycle data, highlighting sensitivity to analysis parameters. These findings underscore the complexity of reconciling laboratory-derived harmonic vibration models with real-world bridge dynamics, where non-uniform acceleration patterns dominate. The research directly informs ongoing efforts to refine standardized criteria for ballasted track stability, particularly through the InBridge4EU project’s systematic re-evaluation of vibration limits and their engineering implications. By quantifying discrepancies between computational approaches, this work advances the development of robust protocols for predicting track degradation under high-speed operational loads. T2 - 11th International Conference on Experimental Vibration Analysis for Civil Enginering Structures (EVACES 2025) CY - Porto, Portugal DA - 02.07.2025 KW - Infrastructure KW - Railway bridges KW - Ballast destabilization KW - Acceleration limit KW - Ballasted track KW - Rainflow counting PY - 2025 SN - 978-3-031-96105-2 DO - https://doi.org/10.1007/978-3-031-96106-9_53 VL - 675 SP - 506 EP - 515 PB - Springer CY - Cham AN - OPUS4-64267 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Signorini, C. A1 - Bracklow, F. A1 - Hering, Marcus A1 - Butler, M. A1 - Leicht, L. A1 - Schubert, T. A1 - Beigh, M. A. B. A1 - Beckmann, B. A1 - Curbach, M. A1 - Mechtcherine, V. T1 - Ballistic limit and damage assessment of hybrid fibre-reinforced cementitious thin composite plates under impact loading N2 - Impact resistance of reinforced concrete (RC) structures can be significantly improved by strengthening RC members with thin composite layers featuring high damage tolerance. Indeed, to limit the well-known vulnerability of cement-based materials against impact loading, the synergistic effects of short fibres and continuous textile meshes as hybrid reinforcement has been proved to be highly beneficial. This paper addresses the characterisation of novel cement-based hybrid composites through accelerated drop-weight impact tests conducted on rectangular plates at different impact energies. Two distinct matrices are assessed, with particular interest in a newly developed limestone calcined clay cement (LC3)-based formulation. Important parameters quantifying energy dissipation capability, load bearing capacity and damage are cross-checked to compute the ballistic limit and estimate the safety-relevant characteristics of the different composites at hand. Although textiles alone can improve the damage tolerance of fine concrete to some extent, the crack-bridging attitude of short, well-dispersed fibres in hybrid composites imparts a certain ductility to the cement-based matrices, allowing a greater portion of the textile to be activated and significantly reducing the amount of matrix spalling under impact. KW - Impact loading KW - Cement-based composites KW - SHCC KW - TRC KW - Sustainable binders PY - 2023 DO - https://doi.org/10.1016/j.jobe.2023.108037 VL - 80 SP - 1 EP - 21 PB - Elsevier Ltd. AN - OPUS4-58793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, Ronald A1 - Simon, Patrick A1 - Hille, Falk A1 - Herrmann, Ralf A1 - Baeßler, Matthias T1 - Vibration-based system identification of a large steel box girder bridge N2 - The Bundesanstalt für Materialforschung und -prüfung (BAM) collaborates with TNO to develop a software framework for automated calibration of structural models based on monitoring data. The ultimate goal is to include such models in the asset management process of engineering structures. As a basis for developing the framework, a multi-span road bridge consisting of ten simply supported steel box girders was selected as a test case. Our group measured output-only vibration data from one box girder under ambient conditions. From the data, we determined eigenfrequencies and mode shapes. In parallel, we developed a preliminary structural model of the box girder for the purpose of predicting its modal properties. In this contribution, we provide an overview of the measurement campaign, the operational modal analysis, the structural modeling and qualitatively compare the identified with the predicted modes. As an outlook, we discuss the further steps in the calibration process and future applications of the calibrated model. T2 - XII International Conference on Structural Dynamics (EURODYN 2023) CY - Delft, The Netherlands DA - 02.07.2023 KW - Verkehrsinfrastukturen KW - SHM KW - Model updating KW - System identification KW - Operational modal analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605041 DO - https://doi.org/10.1088/1742-6596/2647/18/182039 SN - 1742-6596 VL - 2647 IS - 18 SP - 1 EP - 9 PB - IOP Publishing CY - Bristol AN - OPUS4-60504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schepers, Winfried A1 - Kulke, D. T1 - Cone penetration tests and dynamic soil properties N2 - ISO 14837-32:2015 and DIN EN 1998-1/NA:2021 as well as prEN 1997-2:2022 allow for us-ing correlations between the results of in-situ soil penetration tests and shear wave velocity (or shear modulus) to determine soil properties to be used in dynamic analyses. While the ISO and prEN standards even provide some recommendations on specific correlations to be used, the DIN standard does not. Due to the statistical nature of such correlations their general applica-bility has to be verified. We collected data sets from test sites from Germany as well as New Zealand at which cone penetration tests (CPT) as well as seismic site investigation methods were conducted. These sites comprise sandy soils as well as clayey soils, mixed soils as well as glacial soils. We compare the results of several correlations between CPT results and shear wave velocity. The accuracy of such correlations is assessed with respect to the accuracy of seismic in-situ tests. It turns out that for clean sands such correlations between CPT and Vs have a similar order of variability as seismic in-situ tests conducted at the same site. The higher the fines portion of the soil, the higher the variability of the statistical correlations, and conse-quently the less the general applicability. For glacial soils and other special soil types usage of statistical correlations to determine dynamic soil properties is not recommended. T2 - XII International Conference on Structural Dynamics CY - Delft, Netherlands DA - 02.07.2023 KW - Wave propagation KW - Soil properties KW - Dynamic excitation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604887 DO - https://doi.org/10.1088/1742-6596/2647/25/252005 VL - 2647 SP - 1 EP - 11 PB - IOP Publishing CY - Bristol AN - OPUS4-60488 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schepers, Winfried A1 - Brinkgreve, RBJ A1 - Appel, S. T1 - Recommendations on finite element modelling of non-seismic excitation in soil-structure interaction problems N2 - Nowadays geotechnical engineering firms have powerful software tools to extent their consult-ing business also into dynamic soil-structure interaction, which before has been restricted to a rather small community of specialized experts in this field, and they certainly do. This is par-ticularly true with respect to non-seismic sources, that is all kinds of human induced vibrations. Hence, there is a demand from clients as well as from contractors to have guidance on the re-quirements as well as the limits of numerical modelling of soil-structure interaction. From the literature as well as from relevant standards, recommendations for the numerical modelling of soil-structure interaction problems involving seismic actions are well known, e. g. ASCE/SEI 4-16. There are, however, some particularities when dealing with human-induced vibrations, which are absent in seismic analyses. For human-induced excitations very little specific guid-ance has been published in the past. A machine foundation on a homogeneous half space ex-cited by harmonic loads with excitation frequency between 4 Hz and 64 Hz has been ana-lysed by means of several commercially available software packages. Parametric studies have been performed to verify if recommendations for seismic soil-structure analyses are valid for non-seismic analyses as well. This paper provides details on the benchmark example and the most important conclusions from the undertaken parametric studies. T2 - XII International Conference on Structural Dynamics CY - Delft, Netherlands DA - 02.07.2023 KW - Numerische Analysen KW - Referenzbeispiel KW - Maschinenfundament KW - Wellenausbreitung PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604931 DO - https://doi.org/10.1088/1742-6596/2647/8/082014 SN - 1742-6596 VL - 2647 IS - 25 SP - 1 EP - 13 PB - IOP Publishing AN - OPUS4-60493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Savidis, S. A1 - Bergmann, M. A1 - Schepers, Winfried A1 - Fontara, I.-K. T1 - Wave propagation in inhomogeneous media via FE/PML method N2 - The Perfectly Matched Layer (PML) method is an efficient approach to imposing radiation conditions at the bounded region of interest in case of wave propagation in unbounded domains. This paper presents and validates 3D FE/PML numerical schemes based on two different PML formulations for homogeneous and inhomogeneous geological media exhibiting discrete or continuous inhomogeneity. In the equation of motion for the PML domain the applied stretching behavior is expressed either as complex material properties or as complex coordinates. Both PML formulations are implemented in the FEM and verified against analytical solutions. Three different types of material inhomogeneity are considered: layered half-space, continuously inhomogeneous half-space with linear velocity profile and continuously inhomogeneous half-space with nonlinear velocity profile. Sensitivity analyses are conducted, and the performance of the developed numerical schemes is investigated taking into account a broad variation of the PML parameters. Recommendations are given for the optimal values of the PML parameters for the case of homogeneous and inhomogeneous geological media. KW - Perfectly Matched Layer (PML) KW - Unbounded domain KW - Finite elements KW - Continuously inhomogeneous geological media PY - 2022 DO - https://doi.org/10.1002/gete.202100028 VL - 45 IS - 2 SP - 98 EP - 107 PB - Ernst & Sohn CY - Berlin AN - OPUS4-54969 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sadowski, A. A1 - Seidel, M. A1 - Al-Lawati, H. A1 - Azizi, E. A1 - Balscheit, Hagen A1 - Böhm, M. A1 - Chen, Lei A1 - van Dijk, I. A1 - Doerich-Stavridis, C. A1 - Kunle Fajuyitan, O. A1 - Filippidis, A. A1 - Winther Fischer, A. A1 - Fischer, C. A1 - Gerasimidis, S. A1 - Karampour, H. A1 - Kathirkamanathan, L. A1 - Subramanian, S. A1 - Topkaya, Cem A1 - Wagner, H. N. R. A1 - Wang, J. A1 - Wang, J. A1 - Kumar Yadav, K. A1 - Yun, X. A1 - Zhang, P. T1 - 8-MW wind turbine tower computational shell buckling benchmark - Part 1: An international ‘round-robin’ exercise N2 - An assessment of the elastic-plastic buckling limit state for multi-strake wind turbine support towers poses a particular challenge for the modern finite element analyst, who must competently navigate numerous modelling choices related to the tug-of-war between meshing and computational cost, the use of solvers that are robust to highly nonlinear behaviour, the potential for multiple near-simultaneously critical failure locations, the complex issue of imperfection sensitivity and finally the interpretation of the data into a safe and economic design. This paper reports on an international ‘round-robin’ exercise conducted in 2022 aiming to take stock of the computational shell buckling expertise around the world which attracted 29 submissions. Participants were asked to perform analyses of increasing complexity on a standardised benchmark of an 8-MW multi-strake steel wind turbine support tower segment, from a linear elastic stress analysis to a linear bifurcation analysis to a geometrically and materially nonlinear buckling analysis with imperfections. The results are a showcase of the significant shell buckling expertise now available in both industry and academia. This paper is the first of a pair. The second paper presents a detailed reference solution to the benchmark, including an illustration of the Eurocode-compliant calibration of two important imperfection forms. KW - Wind turbine tower KW - Computational KW - Shell buckling KW - Benchmark PY - 2023 DO - https://doi.org/10.1016/j.engfailanal.2023.107124 SN - 1350-6307 VL - 148 SP - 1 EP - 23 PB - Elsevier Science CY - Oxford AN - OPUS4-57019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ritz, Sebastian A1 - Loewe, Anna A1 - Bauer, Jan T1 - Specialties of HAZID-Study for Large Unmanned Underwater Vehicles N2 - This paper scopes the specialties of a hazard identification study for large and extra-large unmanned undersea vehicles (UUVs). A generic node/function structure is derived from different large and extra-large UUV designs, partially own vehicle designs from research projects, and partially from commercial vehicles. For each node, a short overview of its components and the proper function or operations is defined. A set of guide words is used to prompt a hazard discussion for each node, which identifies unwanted functions, resulting in potential hazards and unmitigated consequences. Related to the SafeMASS-Report from DNV, this work concentrates on selected topics of the bridge-related function on voyage, control & monitoring, and abnormal situations. For unmanned vehicles without any person on board, these three topics become more important for underwater vehicles with very limited connectivity or temporary disruptions of communication whereby an operator in a remote-control center could only be provided with rough vehicle or mission states. Therefore, vehicle control, whether in hard- or software, must handle most tasks belonging to the considered functions automatically or autonomously. Hence, the most appropriate reactions of the system to unwanted system behavior must be implemented. This HAZID study could, on the one hand, be used as background for such an implementation, and on the other hand, it is used to verify the implemented actions on the risks and hazards. T2 - OCEANS 2023 - Limerick CY - Limerick, Ireland DA - 05.06.2023 KW - Autonomous underwater vehicles KW - HAZID KW - Risk-based design KW - Safety KW - Cyber security PY - 2023 DO - https://doi.org/10.1109/OCEANSLimerick52467.2023.10244358 SP - 1 EP - 10 PB - IEEE AN - OPUS4-59099 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nerger, Deborah A1 - Hille, Falk A1 - Moosavi, Robabeh A1 - Grunwald, Marcel A1 - Redmer, Bernhard A1 - Kühn, T. A1 - Hering, M. A1 - Bracklow, F. T1 - Post-impact evaluation at RC plates with planar tomography and FEM N2 - Due to the wide range of applications, the easy production and the large field of use, reinforced concrete (RC) is a widespread building material. This variety of applications is reflected in a wide range of physical material properties. Not only therefor it still is a technical challenge to provide all necessary test conditions for experimentally reproducing dynamic effects under impact loading of RC structures. In this paper we present investigations on the thicknesses of RC plates under low and medium high velocity impact loading by a flat-tipped impactor. The planar tomography setup at BAM is used to visualize the impact damage and to characterize the damage features such as cracks, scabbing and spalling. Further, the comparison of tomography results with those of an applied numeric simulation analysis is used to verify the numeric models for future damage prognosis under impact loading. Using the results of both, the tomographic as well as the FE analysis, different damage features were investigated and compared regarding their validity. Crack damage plays a leading part and the significance of summarized crack values as well as their distribution is analyzed. The total damage value but also the determined damage distribution both provide an input for describing damage as a function of the impactor velocity and plate thickness. KW - Reinforced concrete structure KW - Post-impact evaluation KW - Damage characterization KW - Ansys Autodyn KW - Drucker-Prager KW - Planar tomography PY - 2020 DO - https://doi.org/10.1016/j.matpr.2020.05.671 SP - 1 EP - 10 PB - Elsevier AN - OPUS4-51115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, Alexander A1 - Dingel, Kristina A1 - Kottke, Daniel A1 - Degener, Sebastian A1 - Meier, David A1 - Sick, Bernhard A1 - Niendorf, Thomas T1 - Data selection strategies for minimizing measurement time in materials characterization N2 - Every new material needs to be assessed and qualified for an envisaged application. A steadily increasing number of new alloys, designed to address challenges in terms of reliability and sustainability, poses significant demands on well-known analysis methods in terms of their efficiency, e.g., in X-ray diffraction analysis. Particularly in laboratory measurements, where the intensities in diffraction experiments tend to be low, a possibility to adapt the exposure time to the prevailing boundary conditions, i.e., the investigated microstructure, is seen to be a very effective approach. The counting time is decisive for, e.g., complex texture, phase, and residual stress measurements. Traditionally, more measurement points and, thus, longer data collection times lead to more accurate information. Here, too short counting times result in poor signal-to-background ratios and dominant signal noise, respectively, rendering subsequent evaluation more difficult or even impossible. Then, it is necessary to repeat experiments with adjusted, usually significantly longer counting time. To prevent redundant measurements, it is state-of-the-art to always consider the entire measurement range, regardless of whether the investigated points are relevant and contribute to the subsequent materials characterization, respectively. Obviously, this kind of approach is extremely time-consuming and, eventually, not efficient. The present study highlights that specific selection strategies, taking into account the prevailing microstructure of the alloy in focus, can decrease counting times in X-ray energy dispersive diffraction experiments without any detrimental effect on data quality for the subsequent analysis. All relevant data, including the code, are carefully assessed and will be the basis for a widely adapted strategy enabling efficient measurements not only in lab environments but also in large-scale facilities. KW - Materials characterization KW - Machine learning KW - X-ray diffraction KW - Measurement optimization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630831 DO - https://doi.org/10.1038/s41598-025-96221-1 SN - 2045-2322 VL - 15 IS - 1 SP - 1 EP - 12 PB - Springer Science and Business Media LLC AN - OPUS4-63083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liehr, A. A1 - Wegener, T. A1 - Degener, Sebastian A1 - Bolender, A. A1 - Möller, N. A1 - Niendorf, T. T1 - Experimental Analysis of the Stability of Retained Austenite in a Low‐Alloy 42CrSi Steel after Different Quenching and Partitioning Heat Treatments N2 - Quenching and partitioning (Q&P) steels are characterized by an excellent combination of strength and ductility, opening up great potentials for advanced lightweight components. The Q&P treatment results in microstructures with a martensitic matrix being responsible for increased strength whereas interstitially enriched metastable retained austenite (RA) contributes to excellent ductility. Herein, a comprehensive experimental characterization of microstructure evolution and austenite stability is carried out on a 42CrSi steel being subjected to different Q&P treatments. The microstructure of both conditions is characterized by scanning electron microscopy as well as X‐ray diffraction (XRD) phase analysis. Besides macroscopic standard tensile tests, RA evolution under tensile loading is investigated by in situ XRD using synchrotron and laboratory methods. As a result of different quenching temperatures, the two conditions considered are characterized by different RA contents and morphologies, resulting in different strain hardening behaviors as well as strength and ductility values under tensile loading. In situ synchrotron measurements show differences in the transformation kinetics being rationalized by the different morphologies of the RA. Eventually, the evolution of the phase specific stresses can be explained by the well‐known Masing model. KW - Condensed Matter Physics KW - General Materials Science PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581618 DO - https://doi.org/10.1002/adem.202300380 SN - 1438-1656 VL - 25 IS - 17 SP - 1 EP - 16 PB - Wiley AN - OPUS4-58161 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liao, Chun-Man A1 - Niederleithinger, Ernst A1 - Bernauer, F A1 - Igel, H A1 - Hadziioannou, Céline T1 - Wave-Screening Methods for Prestress-Loss Assessment of a Large-Scale Post-Tensioned Concrete Bridge Model Under Outdoor Conditions N2 - This paper presents advancements in structural health monitoring (SHM) techniques, with a particular focus on wave-screening methods for assessing prestress loss in a large-scale prestressed concrete (PC) bridge model under outdoor conditions. The wave-screening process utilizes low-frequency wave propagation obtained from seismic interferometry of structural free vibrations and high-frequency wave propagation obtained through ultrasonic transducers embedded in the structure. An adjustable post-tensioning system was employed in a series of experiments to simulate prestress loss. By comparing bridge vibrations under varying post-tensioning forces, the study investigated prestress loss and examined temperature-related effects using the coda wave interferometry (CWI) method. Local structural alterations were analyzed through wave velocity variations, demonstrating sensitivity to bridge temperature changes. The findings indicate that wave-based methods are more effective than traditional modal analysis for damage detection, highlighting the dual impacts of prestress loss and temperature, as well as damage localization. This study underscores the need for long-term measurements to account for temperature fluctuations when analyzing vibration measurements to investigate changes in prestressing force in PC structures. KW - Coda wave interferometry KW - Damage detection KW - Prestress loss KW - Seismic interferometry KW - SHM KW - Temperature influence KW - Ultrasonics KW - Wave-screening PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-634244 UR - https://www.mdpi.com/2076-3417/15/11/6005 DO - https://doi.org/10.3390/app15116005 VL - 15 IS - 11 SP - 1 EP - 18 PB - MDPI AN - OPUS4-63424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Bernauer, F. A1 - Niederleithinger, Ernst A1 - Igel, H. A1 - Hadziioannou, C. T1 - Assessment of prestress loss in a large-scale concrete bridge model under outdoor condition N2 - Environmental conditions affect the accuracy of field measurements used to monitor civil structures. Previous studies have shown that measured dynamic responses often lack the sensitivity needed for effective localized damage detection. To address this issue, our study focuses on distinguishing environmental effects from damage related effects in measured data to enhance vibration-based damage identification methods. Experimentally, the problem of prestress loss in a prestressed concrete bridge model was examined. By adjusting the pre-stressing force in a large-scale concrete bridge model, cracking phenomena were observed. To demonstrate field monitoring of a large-scale prestressed structure, noise recording was performed and the measurement data was analyzed with operational modal analysis. Additionally, ultrasonic testing, known for its high sensitivity in damage localization, was used to cross-check the structural damage. Seismic and coda wave interferometry were also employed to estimate wave velocities, providing insights into the level of prestress loss and temperature sensitivity. Ultimately, these measurable wave properties help to overcome the uncertainties associated with traditional vibration-based damage detection methods. T2 - EVACES 2025 CY - Porto, Portugal DA - 02.07.2025 KW - Prestress Loss KW - NDT KW - Ambient Vibration KW - Ultrasonic Testing KW - Coda Wave Interferometry KW - Seismic Interferometry PY - 2025 SN - 978-3-031-96105-2 DO - https://doi.org/10.1007/978-3-031-96106-9_20 VL - 675 SP - 181 EP - 189 PB - Springer Nature CY - Cham AN - OPUS4-64212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liao, Chun-Man ED - Zhang, Jian T1 - Modal and Wave Propagation Analysis of Vibration Tests on a Laboratory Building Model Before and After Damage N2 - Weakened structural stiffness is often a consequence of building damage, particularly after severe events such as earthquakes, where compromised structural performance can pose significant risks. To prevent immediate structural failure, an early warning system is essential, which requires inspection of local components. This research aims to achieve that by exploring the wave propagation analysis method, specifically seismic interferometry. Previous studies have applied this method to building structures, treating them as homogeneous layers of grouped floors. By analyzing the wave travel time along the height of these layers, the fundamental period of the building was estimated. However, this approach did not account for local damage or the variability of structural components, similar to the limitations of vibration‐based damage detection methods, which mainly identify global changes. Thus, the goal of this paper is to improve structural health monitoring by examining the sensitivity of wave screening, bridging the gap between nondestructive testing and vibration‐based damage detection. A half‐scale, seven‐story building model, characterized by vertical stiffness irregularity and transverse plan asymmetry, was tested in a laboratory setting. Two vertical sensor arrays were placed near corner columns of different sizes, representing both strong and weak structural areas. These arrays recorded floor accelerations in three directions. The study confirmed the effectiveness of wave propagation analysis for detecting damage along the sensor arrays before and after the earthquake. A transmissibility damage indicator was used to correlate changes in wave velocity, providing a quantitative assessment of damage levels along the wave propagation path. KW - Damage location KW - Laboratory test KW - Soft story KW - Stifness irregular structure KW - Structural health monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624931 DO - https://doi.org/10.1155/stc/3453150 SN - 1545-2263 VL - 2025 IS - 1 SP - 1 EP - 17 PB - John Wiley & Sons Ltd. AN - OPUS4-62493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -