TY - CONF A1 - Auersch, Lutz T1 - Effects of a varying track and soil stiffness on ground vibrations near railway lines N2 - Usually, geometric irregularities are considered as the main cause of ground vibrations from trains. A varying stiffness of the track, the track support and the soil can also generate ground vibrations. The regular stiffness variation of the track on and between the sleepers results in a deterministic dynamic axle load. The random stiffness variation of the track support yields also dynamic axle loads. The dynamic axle loads are generated by the varying wheel displacements under the static axle load by the acceleration of the unsprung mass of the rail vehicle. The random stiffness variation has a second effect. The pulses from the passage of the static axle loads are superposed regularly to the quasi-static response, but also irregularly to yield a “scattered” part of the axle pulses. The same holds for a random variation of the soil stiffness. All these effects of stiffness variations have been calculated by wavenumber-domain multi-beam track models, a random finite-element soil model and the superposition of axle impulses in a stochastic simulation. The results are confronted with many measurements at different sites. It is concluded that the stiffness variation of the track and the soil generate an important ground vibration component near railway lines. T2 - Railways 2022 CY - Montpellier, France DA - 22.08.2022 KW - Ground vibration KW - Railways KW - Varying track stiffness KW - Varying soil stiffness PY - 2022 AN - OPUS4-56036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Railway-induced ground and building vibrations – Analysis in frequency-wavenumber domain and fast prediction with approximate models N2 - A simple and fast prediction scheme is presented for train-induced ground and building vibrations. For the emission, finite-element boundary-element or multiple-beam-on-continuous-soil models of the track have been analysed and approximated by faster track-on-Winkler-soil models. The vehicle-track interaction due to irregularities yields the excitation forces. For the transmission of waves in the soil, the wavenumber integral of the compliance of layered soils has been evaluated. The calculation time is reduced for the prediction by using the solution of a homogeneous half-space with a frequency-dependent wave velocity (the dispersion) of the soil. For the immision, many 2 and 3-dimenisonal finite-element building models have been investigated, and a good approximation has been established by a 1-dimensional soil-wall-floor model. In addition, the axle sequence of the train, the quasi-static and the “scattered” response of the soil, and the wave propagation from a tunnel to a pile foundation of a building have been included. T2 - ISMA-Conference CY - Leuven, Belgium DA - 12.09.2022 KW - Ground vibration KW - Building vibration KW - Railways KW - Simple and fast prediction PY - 2022 AN - OPUS4-56038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Challenges of vibration prediction – realistic irregularities, the scattering of axle pulses, and the tunnel-surface reduction N2 - A prediction software has been developed by BAM. The following topics have still be solved. A realistic irregularity spectrum can be derived from axle-box measurements. It agrees wel with the spectrum used for the high-speed 2 project in the United Kingdom. In addition, the scattering of axle pulses should be included. This mid-frequency component can also be found in the HS2 procedure. Finally, the reduction in case of a tunnel line compared to a surface line should be included. Some measurement results of BAM, HS2 and other institutes show a certain mid-frequency reduction. This is due to the load distribution of the tunnel which yields softer axle pulses and the scattered axle impulses are reduced. T2 - ISO/TC 108/SC 2/WG 8 Working group Ground-borne noise and vibration from rail systems CY - London, UK DA - 21.11.2022 KW - Ground vibration KW - Railway trafiic KW - Prediction KW - Irregularities KW - Axle pulses KW - Tunnel line KW - Surface line PY - 2022 AN - OPUS4-56738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Characteristic Frequencies of Train-Induced Bridge, Track, Ground and Building Vibrations – Excitation and Mitigation N2 - The characteristic frequencies of train-induced vibrations are discussed in theory and experiment following the propagation of vibrations from the source to the receiver: 1. Out-of-roundness frequencies of the wheels, 2. sleeper-passage frequency, 3. the vehicle-track eigenfrequency, 4. band frequency of the impulses of the passing static axle loads, 5. car-length frequency and multiples, 6. axle-distance frequencies with two characteristic zeros, 7. bridge eigenfrequencies, 8. the cut-on frequency due to the layering, and 9. the cut-off frequency due to the material damping of the soil, 10. the building-soil eigenfrequency, 11. as a rigid building or flexible wall/column mode, 12. floor eigenfrequencies, 13. acoustic room resonances, 14. the „resonance“ frequency or cut-off frequency of a base isolation. Coincidences of some of these characteristic frequencies or frequency ranges can be typically problematic and mitigation measures at the track or at the building can be necessary. The bridge response to the passing static loads is deter¬mined by the axle-sequence spectrum, the eigenfrequency (transfer function) of the bridge, and the modal force or mode shape spectrum. The ground vibration has typically high frequencies for a stiff soil and low frequencies for a soft soil. The high amplitudes between the zeros of the axle-sequence spectrum are often measured in the ground vibrations, and they can be mitigated by soft support elements or a higher bending stiffness of the track. T2 - EVACES 2025 CY - Porto, Portugal DA - 02.07.2025 KW - Train-induced vibration KW - Axle-sequence spectrum KW - Vehicle-track eigenfrequency KW - Axle impulses PY - 2025 AN - OPUS4-63654 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Erschütterungsprognose mit KI? Schnelle Ersatzmodelle und physikbasiertes maschinelles Lernen in der Bauwerk-Boden-Dynamik N2 - Erschütterungsprognosen können mit sehr detaillierten Modellen durchgeführt werden. Dies ist sowohl bei der Erstellung des Modells (zum Beispiel für ein Finite-Element-Modell für Boden und Bauwerk), als auch bei der Berechnung zeitaufwändig, von einigen Minuten für die Wellenausbreitung in geschichteten Böden mit Wellenzahlintegralen bis zu mehreren Stunden für Randelementlösungen für die korrekte Bauwerk-Boden-Wechselwirkung. Hier sind einfache und schnelle Ersatzmodelle von Vorteil, die die Ergebnisse der detaillierten Berechnungen gut wiedergeben. Diese Ersatzmodelle können vollständig auf physikalischen Überlegungen beruhen (white-box Modelle) oder mit Hilfe von maschinellem Lernen aus einer Vielzahl von detaillierten Rechenergebnissen erzeugt werden (black-box Modelle). Erfahrungen mit black-box Modellen zeigen, dass es sinnvoll ist das maschinelle Lernen mit physikalischen Informationen anzureichern (grey-box Modelle). Es werden Anwendungsmöglichkeiten für physikbasiertes maschinelles Lernen im Bereich von Bahnerschütterungen aufgezeigt, die Erschütterungsemission durch die Fahrzeug-Fahrweg-Wechselwirkung, die Wellenausbreitung im Boden, die Erschütterungsimmission in Gebäude, Gleisschäden und das Monitoring von Eisenbahnbrücken. T2 - VDI-Tagung Baudynamik CY - Würzburg, Germany DA - 02.04.2025 KW - Bahnerschütterungen KW - Emissionsmodell KW - Immissionsmodell KW - Transmissionsmodell KW - Tunnelausbreitung KW - Gleisüberwachung PY - 2025 AN - OPUS4-62889 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Frequency-wavenumber method for the wave propagation through the soil and the soil-structure interaction of railway tracks and building foundations near railway lines N2 - In soil-structure interaction, the soil and the (flexible) structures are modelled as elastic continua. The partial differential equations of elasticity can be transformed to algebraic equations in frequency-wavenumber domain where they can be solved by matrix methods. The results for the soil and a structure can be coupled in frequency-wavenumber domain, and the solution in space domain is obtained by an infinite wavenumber integral (the back-transformation). This method has several applications for the prediction of the emission, transmission and immission of railway-induced vibrations. The wave propagation in homogeneous or layered soils is calculated for surface and tunnel lines by a single wavenumber integration (transmission). The response of ballast or slab tracks (for the emission problem) and the foundation stiffness (for the immission problem) need an additional integration across the track or foundation width. In wavenumber domain, tracks and foundations of infinite length are analysed. Finite structures can be calculated by finite element models where the soil is calculated by the boundary element method. The Green’s functions for the boundary element method are calculated by a wavenumber integration as for the transmission problem. Some example results for all these tasks will be shown. The immission into buildings will be analysed in detail, and the effect of stiff slab foundations and (basement) walls on the incoming wavefield is quantified in a parameter study. The transfer function (the amplitude ratio) structure to free field usually starts with 1 at 0 Hz and decreases continuously with frequency. The reduction is due to the structural stiffness against wave deformation which turns to be higher than the stiffness of the soil, for example above the structure-soil coincidence frequency of the slab foundation. The reduction is better for a high structural stiffness and for a low soil stiffness. Walls are stiffer than plates for the relevant frequency range, but even walls and especially low basement walls are not infinitely rigid and can follow the wave deformation to a certain extent. These basic rules from frequency-wavenumber analysis can well be used for real building projects near railway lines where stiff foundations can be an alternative reduction method to the commonly used base isolation by elastic elements. T2 - COMPDYN 2025 CY - Rhodos, Greece DA - 15.06.2025 KW - Frequency-wavenumber method KW - Wave propagation KW - Soil-structure interaction KW - Building foundations KW - Mitigation measures PY - 2025 AN - OPUS4-63468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Prediction of ground vibrations from rail tunnels finite element, boundary element and wavenumber calculations N2 - The prediction of ground and building vibrations has been established for surface lines and has now been extended to tunnel lines. The wave propagation in homogeneous or layered soils (the transmission) is calculated by an integration in wavenumber domain. The wave amplitudes at different distances and for different frequencies will be analysed for the following situations. 1. The horizontal propagation from a surface point to a surface point constitutes the basic rules. 2. The horizontal propagation from a source point at depth to a receiver point at depth which is related to a building with a deep basement or on a pile foundation. 3. The propagation from depth to the surface, which is the normal case for free-field measurements, has some different characteristics, for example a weaker attenuation with the horizontal distance from the source, which can be approximated by the full-space solution and the reflection rules for incident waves. The emission from a tunnel structure has been calculated by a finite-element model of the tunnel combined with a boundary-element model of the soil giving the reduction compared to a point-load excitation. The immission has been analysed by finite-element models of tunnel-soil-building systems for examples of research and consultancy work. Measurement results from a high-speed and a metro line confirm some of the established rules. T2 - Recent Advance in Structural Dynamics (RASD) CY - Southampton, UK DA - 01.07.2024 KW - Ground vibration KW - Building vibration KW - Railway tunnel KW - Wavenumber method KW - Finite element method KW - Boundary element method PY - 2024 AN - OPUS4-61230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Die Einfügedämmung bei Schienenfahrwegen Definition, Messung und Berechnung N2 - Die Definition und Beschreibung der Einfügedämmung im Normentwurf DIN 45673-4 ist noch nicht richtig. Es wird die Beschreibung aus DIN 45673-3 herangezogen, die für Messungen gilt. Für die drei Rechenverfahren gibt es jeweils eine passende Beschreibung. Mit diesen Vorlagen ist eine vernünftige Definition der Einfügungsdämmung zu finden. Es bedarf einer Abgrenzung gegenüber anderen (falschen) Möglichkeiten. Des Weiteren ist der Anhang 2 erweitert und der Parametersatz im Anhang 1 auf das Wesentliche reduziert worden. T2 - Norm-Arbeitsausschuss Schwingungsminderung in der Umgebung von Verkehrswegen CY - Online meeting DA - 14.12.2022 KW - Einfügungsdämmung KW - Schienenfahrwege KW - Kraft auf den Boden KW - Erschütterungen im Fernfeld PY - 2022 AN - OPUS4-56601 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Prognoseverfahren für Bahnerschütterungen – DIN 45672-3, VDI 3837, HighSpeed2 und die Fahrzeug-Fahrweg-Boden Wechselwirkung N2 - Die VDI Richtlinie 3837 enthält detaillierte Angaben zur Erschütterungsemission. Die DIN 45672-3 enthält nur den Tunnel- oder einen Bodenmesspunkt als Ausgangspunkt der Prognose. Die Erschütterungsanregung durch die Fahrzeug-Fahrweg-Wechselwirkung wird beschrieben. Die ERgebnisse der BAM stimmen sehr gut mit dem Prognosekonzept von Highspeed 2 überein. Dies wird an den Punkten 1. Störgrößen, 2. Achsimpulse, 3. Tunnelstrecken aufgezeigt. T2 - Norm-Arbeitsausschuss Schwingungsminderung in der Umgebung von Verkehrswegen CY - Frankfurt/M., Germany DA - 08.02.2023 KW - Normung KW - Bahnerschütterungen KW - Emission KW - Fahrzeug-Fahrweg-Boden-Wechselwirkung KW - Störgrößen KW - Achsimpulse KW - Tunnelstrecke PY - 2023 AN - OPUS4-56978 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Modal analysis of road and rail bridges for damage detection and resonance prediction N2 - In the 1980s, the Federal Institute of Material Research and Testing started with modal analysis measurements of some bridges before and after repair. For one of the bridges, a structural health monitoring was installed 1994 which is still working up to now. It has been modified and extended several times. The monitoring was extended from the critical span to three neighbouring spans. A modal analysis of the whole bridge with seven spans have been done three times, twice together with EMPA of Switzerland. Additional calibration measurements have been done and additional evaluation procedures have been implemented for the monitoring of the steadily increasing loads from the road traffic. Additional sensors were installed such as strain gauges, crack-width, and temperature sensors. The strong influence of the temperature on the natural frequencies has been studied over the years. Later, a temperature compensation has been established and a weak aging trend has been found in the monitoring data. Now, the bridge will be demolished and replaced by a new bridge. Some results of this long-term monitoring will be shown and possible damages (changes of the pre-stress or the support structure) will be discussed. A second application of modal analysis will be demonstrated: the prediction of the resonances due to passing trains. The response of a bridge to passing trains can be calculated in frequency domain as the multiplication of three spectra, the axle sequence spectrum of the train, the transfer function of the bridge, and the modal force spectrum of a single passing load. A resonance occurs if a maximum of the train spectrum coincides with the maximum of the bridge spectrum. The amplitude at this resonance is strongly influenced by the modal force spectrum which is identical to the frequency or wavenumber spectrum of the corresponding mode shape. Therefore, modal analysis from calculation, impact measurements, wind and train measurements are necessary for the prediction of the resonance occurrence and amplification. Examples of mode shape spectra for single or multi-span bridges with simply supported or continuous spans will be shown, and some relations between mode shapes and resonance amplifications will be concluded. T2 - 11th International Operational Modal Analysis Conference (IOMAC) CY - Rennes, France DA - 20.05.2025 KW - Bridge monitoring KW - Multi-span bridges KW - Damage detection KW - Resonance PY - 2025 AN - OPUS4-63472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -