TY - JOUR A1 - Auersch, Lutz T1 - Reduction in Train-Induced Vibrations—Calculations of Different Railway Lines and Mitigation Measures in the Transmission Path N2 - The reduction in train-induced ground vibrations by different railway lines and by mitigation measures in the propagation path was analysed in a unified approach by two-dimensional finite element calculations. In general, there was no reduction at low frequencies, and the reduction be-came stronger with increasing frequencies. A maximum reduction of 0.1 at high frequencies was established with an open trench. Reductions between 0.7 and 0.2 have been found for the other sit-uations, filled trenches, walls, plates, and blocks, as well as for railway lines on dams, in cuts and in a tunnel. Bridges can produce amplifications due to their resonance frequencies, but also strong reductions due to massive bridge piers. The influence of some parameters has been analysed, such as the bridge span, the inclination of the dam and the cut, the stiffness of the soil, and the tunnel structure. The dynamic track stiffnesses of a surface, bridge, and tunnel track have been calculated using the 3D finite-element boundary-element method for comparison with corresponding meas-urements. KW - Train-induced vibration KW - Mitigation KW - Trench KW - Obstacles KW - Tunnel KW - Bridge KW - Finite element KW - Boundary element PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579573 DO - https://doi.org/10.3390/app13116706 VL - 13 IS - 11 SP - 1 EP - 19 PB - MDPI CY - Basel AN - OPUS4-57957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schneider, Ronald T1 - Von der Datenerfassung bis zur Entscheidungsfindung: Jede Brücken-Überwachung bedarf einer Gesamtmethodik N2 - Brücken müssen laufend überwacht werden, damit die Unsicherheiten hinsichtlich ihres Zustands, ihrer Beanspruchung und ihrer Leistungsfähigkeit verringert werden können. Diese Aufgabe soll künftig mit digitalen Methoden erleichtert werden. Im folgenden Beitrag werden deshalb die digitale Bauwerksmodellierung und die Entscheidungsfindung beleuchtet. Dazu wird gezeigt, wie Zustandsdiagnosen und -prognosen digital ermöglicht werden und wie durch diagnostische und prognostische Modelle eine wissenschaftliche Basis für risikobasierte Entscheidungen über Erhaltungsmaßnahmen und für den Übergang vom reaktiven zum vorausschauenden Brückenmanagement gebildet werden kann. Dabei wird klar: Jede Brücken-Überwachung bedarf einer Gesamtmethodik, ihre wichtigsten Elemente sind: Datenerfassung, Datenmanagement, Datenanalyse, Bauwerksmodellierung, Bauwerksbewertung und die letztendlichen Entscheidungen über notwendige Erhaltungsmaßnahmen. KW - Prädiktive Instandhaltung KW - Brücken KW - Erhaltungsmanagement KW - Digitale Zwillinge PY - 2023 IS - 62 SP - 76 EP - 83 AN - OPUS4-57811 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Stolpe, Heiko A1 - Wiehle, Philipp T1 - Moisture diffusion affected by the Knudsen effect in temporal changing pore networks N2 - Almost all building materials in civil engineering have an open porosity and interact with or are affected by the environmental conditions. Structures might suffer from effects such as moisture adsorption, carbonation, corrosion, penetration of salt ions and chemical substances, etc. In the hygroscopic range, these processes are mostly driven by diffusion. Due to the confinement of small pores (less than1 µm), the Knudsen effect reduces the molecular diffusion. This reduction can become more significant in case of temporal changing pore systems because of physisorption of water vapor, carbonation, or chemisorption. In this study, unstabilised earth blocks and earth masonry are investigated. In a first step, the pore size distribution of the blocks is measured and sorption isotherms are recorded in experiments. Besides the ordinary physisorption, the involved clay minerals undergo swelling or shrinking due to chemisorption. The following two effects must be considered: first, the reduction of the available pore space by the adsorbed water layer. For this, the Hillerborg sorption theory is used, which is a combination of the well-known Brunauer-Emmett-Teller sorption theory and the Kelvin equation. This allows the computation of adsorbed water layers even in curved pore geometries. Second, the variation of the initial pore size distribution due to chemisorption needs to be modelled. Based on these two models, the effective diffusion coefficient can be predicted. For validation, arrays of relative humidity sensors were embedded into a free-standing earth masonry wall. This monitoring was carried out over more than a year to have a broad variety of environmental conditions and was located in Berlin, Germany. The prediction of the effective diffusion coefficient can also be transferred to other processes and allows the investigation of materials having temporarily changing pore systems. Examples are the carbonation of cementitious materials, alkali silica reaction, calcium leaching of long-lasting structures, etc. These effects are prominent in the meso-pore range and might significantly alter the effective diffusion coefficient. KW - Earth material KW - Material moisture KW - Physisoprtion KW - Chemisorption PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-583811 DO - https://doi.org/10.1016/j.matpr.2023.09.034 SN - 2214-7853 SP - 1 EP - 8 PB - Elsevier Ltd. CY - Amsterdam, Niederlande AN - OPUS4-58381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hering, Marcus A1 - Sievers, Jürgen A1 - Curbach, Manfred A1 - Beckmann, Birgit T1 - An Approach to Predicting the Ballistic Limit of Thin Textile-Reinforced Concrete Plates Based on Experimental Results N2 - In this article, a partial selection of experiments on enhancing the impact resistance of structural components with non-metallic, textile-reinforced concrete is discussed. The focus is on the experimental investigations in which the impact resistance of thin, textile-reinforced concrete plates is characterized. The article discusses the materials, fabrics and test setup used. For the experimental work, a drop tower from the Otto Mohr Laboratory, which belongs to the Technische Universtät Dresden, was used. Furthermore, the experimental results are presented and evaluated using different methods. Based on the collected data, a suitable approach to determining the perforation velocity of an impactor through the investigated thin, textile-reinforced concrete plates is shown. KW - Building and Construction KW - Civil and Structural Engineering PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586692 DO - https://doi.org/10.3390/buildings13092234 VL - 13 IS - 9 SP - 1 EP - 14 PB - MDPI AN - OPUS4-58669 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - The dynamic train-track interaction on a bridge and in a tunnel compared with the simultaneous vehicle, track, and ground vibration measurements at a surface line N2 - The vehicle–track interaction generates forces and consequently vibrations in the environment. The interaction has been analysed by the simultaneous measurements of vehicle, track and ground vibrations during test runs with varied train speeds. The special effects of the passage over a bridge and through a tunnel are studied and compared with the measurements on a conventional ballasted surface line. The maximum amplitudes, narrow band and one-third octave band spectra are presented for the axle-box accelerations and for the track, bridge and ground vibrations. The different frequencies and frequency bands are related to wheel out-of-roundness, track alignment errors, the sleeper passage and the wheelset–track resonance. An axle impulse component has been observed at the track, at the near-field soil and as a scattered version in the far field. Specific results can be found for the bridge track, where clearly speed-dependent bridge resonances occur due to the axle sequence of the train, and for the tunnel track where soft rail pads are responsible for a strong amplification around the wheelset–track resonance. On the other hand, the axle impulses are strongly reduced by the tunnel track, and the scattered axle impulse component is not as relevant as for the surface track. As a consequence, a strong mid-frequency amplitude reduction of the tunnel compared to the surface line has been measured for low and high train speeds by the Federal Institute of Material Research and Testing (BAM) and by other institutes. KW - Vehicle–track interaction KW - Ground vibration KW - Tunnel-to-surface reduction KW - Bridge resonance KW - Axle sequence PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-585139 DO - https://doi.org/10.3390/app131910992 VL - 13 IS - 19 SP - 1 EP - 23 PB - MDPI CY - Basel, Schweiz AN - OPUS4-58513 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brinkmann, M. A1 - Wiehle, Philipp T1 - Correlation between relative humidity and the strength and deformation characteristics of unstabilised earth masonry N2 - The mechanical properties of unstabilised earthen building materials are distinctively influenced by changes in material moisture content. However, this moisture-dependency often remains unconsidered in the calculation of the load-bearing capacity of earth constructions. This paper aims to derive a convenient way to sufficiently consider the impact of different material moisture contents on the mechanical properties of unstabilised earth masonry. Therefore, the influence of relative humidity and temperature on the strength and deformation characteristics of unstabilised earth blocks, earth mortar and earth masonry is evaluated by conducting compression tests under various climate conditions. The results show that the compressive strength and the modulus of elasticity are linearly correlated with the relative humidity, whereas changes in temperature at constant relative humidity have no significant influence. To account the distinct moisture-dependency, a general applicable modification factor for unstabilised earthen materials is provided, which enables the adjustment of the compressive strength and the modulus of elasticity in dependency of arbitrary hygroscopic material moisture contents. KW - Earth masonry KW - Earth blocks KW - Relative humidity KW - Modulus of elasticity KW - Moisture KW - Compressive strength KW - Stress–strain-relation PY - 2023 DO - https://doi.org/10.1016/j.conbuildmat.2022.130048 SN - 0950-0618 VL - 366 IS - 22 SP - 1 EP - 11 PB - Elsevier BV AN - OPUS4-56732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Benseghier, Z. A1 - Luu, L.-H. A1 - Cuéllar, Pablo A1 - Bonelli, S. A1 - Philippe, P. T1 - On the erosion of cohesive granular soils by a submerged jet: a numerical approach N2 - This paper presents an erosion interpretation of cohesive granular materials stressed by an impinging jet based on the results of a micromechanical simulation model. The numerical techniques are briefly described, relying on a two-dimensional Lattice Boltzmann Method coupled with a Discrete Element Methods including a simple model of solid intergranular cohesion. These are then used to perform a parametric study of a planar jet in the laminar regime impinging the surface of granular samples with different degrees of cohesive strength. The results show the pertinence of using a generalized form of the Shields criterion for the quantification of the erosion threshold, which is valid for cohesionless samples, through empirical calibration, and also for cohesive ones. Furthermore, the scouring kinetics are analysed here from the perspective of a selfsimilar expansion of the eroded crater leading to the identification of a characteristic erosion time and the quantification of the classical erosion coefficient. However, the presented results also challenge the postulate of a local erosion law including erodibility parameters as intrinsic material properties. The paper then reviews the main limitations of the simulation and current interpretation models, and discusses the potential causes for the observed discrepancies, questioning the pertinence of using time-averaged macroscopic relations to correctly describe soil erosion. The paper concludes addressing this question with a complementary study of the presented simulations re-assessed at the particle-scale. The resulting local critical shear stress of single grains reveals a very wide dispersion of the data but nevertheless appears to confirm the general macroscopic trend derived for the cohesionless samples, while the introduction of cohesion implies a significant but systematic quantitative deviation between the microscopic and macroscopic estimates. Nevertheless, the micro data still shows consistently that the critical shear stress does actually vary approximately in linear proportion of the adhesive force. KW - Soil erosion KW - Granular cohesion KW - Lattice Boltzmann Method KW - Discrete Element Method KW - Impinging jet PY - 2023 DO - https://doi.org/10.1007/s10035-022-01289-5 VL - 25 IS - 8 SP - 1 EP - 20 PB - Springer AN - OPUS4-56525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Titscher, Thomas A1 - van Dijk, T. A1 - Kadoke, Daniel A1 - Robens-Radermacher, Annika A1 - Herrmann, Ralf A1 - Unger, Jörg F. T1 - Bayesian model calibration and damage detection for a digital twin of a bridge demonstrator N2 - Using digital twins for decision making is a very promising concept which combines simulation models with corresponding experimental sensor data in order to support maintenance decisions or to investigate the reliability. The quality of the prognosis strongly depends on both the data quality and the quality of the digital twin. The latter comprises both the modeling assumptions as well as the correct parameters of these models. This article discusses the challenges when applying this concept to realmeasurement data for a demonstrator bridge in the lab, including the data management, the iterative development of the simulation model as well as the identification/updating procedure using Bayesian inference with a potentially large number of parameters. The investigated scenarios include both the iterative identification of the structural model parameters as well as scenarios related to a damage identification. In addition, the article aims at providing all models and data in a reproducibleway such that other researcher can use this setup to validate their methodologies. KW - Damage detection KW - Finite element analysis KW - Load identification KW - Model updating KW - Estimation KW - System identification KW - Variational Bayesian statistics PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574496 DO - https://doi.org/10.1002/eng2.12669 SN - 2577-8196 SP - 1 EP - 27 PB - Wiley CY - Hoboken, NJ AN - OPUS4-57449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -