TY - CONF A1 - Auersch, Lutz T1 - A mid-frequency component of train-induced ground vibration due to scattered axle impulses and the irregularities of the soil and ballast N2 - The passage of the train is dominated by the impulses of the static axle loads. The response of the regular homogeneous and irregular soils has been calculated by the finite-element method in frequency domain. The superposition of the impulse responses yields the quasi-static component of the ground vibration which is restricted to very low frequencies and to the close near-field of the track. In case of an irregular soil or ballast of which the stiffness varies randomly in space, a mid-frequency ground vibration component is generated by the scattering of the axle impulses. Measurements will be shown which prove the existence of the mid-frequency ground vibration component and the unique explanation by the scattered axle impulses: many international measurements with a raised mid-frequency component, axle-box measurements with a too low mid-frequency dynamic load, amplitude-speed dependencies which are incompatible with irregularity-induced dynamic loads, and ground vibration reductions due to stiff track elements. T2 - International Conference on Noise and Vibration Engineering (ISMA/USD) CY - Online meeting DA - 07.09.2020 KW - Ground vibration KW - Railway KW - Irregular soil KW - Irregular ballast KW - Axle impulses PY - 2020 SP - 2611 EP - 2625 PB - KULeuven CY - Leuven AN - OPUS4-51210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir A1 - Rohrmann, R. T1 - Natural frequencies and modes of poles, beams, floors, road and rail bridges N2 - In the last three decades, the vibrations of many floors and bridges have been measured. The contribution shows some evaluation methods, experimental results and some modelling and theoretical results. Simple evaluation methods have been developed for single and coupled floors. Two coupled beams have been measured in good agreement with the theory. A more complex coupling model has been found for a large wooden floor in a castle consisting of six floor bays which correlates well with the measurements. Damaged and intact poles have been tested by their natural frequencies and damping values, and a fair correlation between the degree of damage and the shift of the frequency. Road bridges have been analysed in detail and some examples are presented. Railway bridges and trains are studied for resonant excitation. The risk of resonance can be estimated in frequency domain by using axle-sequence spectra of the train and the natural frequencies of the bridge. A measurement example shows the amplification, but even stronger the cancellation of the subsequent axle responses. Several high-speed trains and freight trains have been analysed for their potential resonance amplification. T2 - International Conference on Noise and Vibration Engineering (ISMA/USD 2020) CY - Online meeting DA - 07.09.2020 KW - Modalanalyse KW - Bauwerke KW - Bauteile KW - Brücken KW - Achsfolgespektren PY - 2020 SP - 1573 EP - 1585 PB - KULeuven CY - Leuven AN - OPUS4-51211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Ziemens, Susanne T1 - The response of different buildings to free-field excitation – a study using detailed finite element models N2 - A study on building vibrations has been performed by finite element calculations. Family houses, multi-storey residential buildings, office buildings and office towers have been modelled in detail. The frequency-dependent response due to a free-field excitation has been evaluated for walls, columns and floors. The ratio of building amplitudes to free-field amplitudes starts with uB/u0 = 1 at zero frequency and is usually lower than 1 at 50 Hz, the end of the frequency range considered here. In between, amplifications occur due to several reasons. There are „soil resonances“ where the whole building is vibrating on the compliant soil, “column resonances” where the upper storeys are vibrating on the compliant columns, and the “floor resonances” where the floors are vibrating excited by their supports. Results are presented for all building types, but a special focus is set on office buildings. A parameter study shows the influence of the stiffness of the soil, the number of storeys, and the width of the building. It has been found that the “soil resonance” is strongly modified by the low-frequency floor resonances for the normal office building. The main resonance of a twenty-storey office tower is determined equally by the “soil mode” and the “column mode”. It is an important observation for these office buildings that the resonances can differ for different parts of the building such as the centre, the edge, the corner, and the core of the building. This leads to non-uniform vibration modes across the building, which look like another type of “floor resonance” and which have been observed in several real building projects. Experimental results will be shown which can confirm the calculated phenomena. T2 - EURODYN 2020 XI International Conference on Structural Dynamics CY - Online meeting DA - 13.11.2020 KW - Building vibration KW - Office building KW - Residential building KW - Soil-building resonance KW - Floor resonance KW - Column/wall resonance PY - 2020 SN - 978-618-85072-2-7 SP - 4560 EP - 4576 CY - Athen AN - OPUS4-51678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Zur Prognose von Erschütterungen aus Bahntunneln N2 - Zur Erschütterungsausbreitung an oberirdischen Bahnlinien gibt es gute Übereinstimmungen zwischen Messungen und der Theorie geschichteter Böden. Bei der Interpretation der Ergebnisse spielt die Rayleigh-Welle eine große Rolle. Je nach Frequenz und Wellenlänge hat die Rayleigh-Welle eine bestimmte Eindringtiefe und erreicht damit mehr oder weniger steife Bodenschichten. Damit bekommt man eine frequenzabhängige Bodensteifigkeit für die Erschütterungsprognose. Für die Wellenausbreitung in der Tiefe statt an der Bodenoberfläche müssen eigene Gesetzmäßigkeiten gefunden werden. Es werden die Punktlastlösungen im Frequenz-Wellenzahlbereich und durch Integration über die Wellenzahlen berechnet. Man erhält die Wellenfelder, die Terzspektren für verschiedene Entfernungen und Frequenzen. Es wird die Tiefenlage und das Bodenmodell (homogen, geschichtet und kontinuierlich zunehmende Steifigkeit) variiert. Die Rayleigh-Welle verliert ihre Bedeutung und stattdessen kann die Vollraumlösung zur Interpretation und Prognose verwendet werden. Es werden die Halbraumlösung mit und ohne Rayleigh-Welle und die Vollraumlösung in der Tiefe diskutiert und verglichen. Neben der Wellenausbreitung (der Transmission) werden auch Effekte der Erschütterungsanregung (der Emission) und der Übertragung in Gebäude (der Immission) mit Hilfe der Finite-Element-Randelement-Methode berechnet. Die Verteilung der dynamischen Achslast durch die Tunnelsohle ergibt eine Minderung gegenüber der Punktlastanregung. Bei der Immission hat man keine Freifeldanregung wie an der Bodenoberfläche. Man muss entweder neben der Wellenamplitude (Verschiebung oder Schwinggeschwindigkeit) in der Tiefe auch die Spannung der ankommenden Welle berücksichtigen, oder man muss die Freifeldamplituden nach Bodenaushub berechnen. Die Rechenergebnisse deuten darauf hin, dass man als Freifeldanregung die zweifache Vollraumlösung ansetzen kann. T2 - Wiener Dynamik Tage 2021 CY - Vienna, Austria DA - 22.7.2021 KW - Erschütterungsausbreitung KW - Tunnel KW - Halbraum KW - Vollraum PY - 2021 SP - 1 EP - 11 PB - Steinhauser Consulting Engineers (STCE) CY - Wien AN - OPUS4-53253 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - Carletti, E. ED - Crocker, M. ED - Pawelczyk, M. ED - Tuma, J. T1 - Dynamic measurements during drop tests on stiff foundations N2 - Measurements at the foundation, the surrounding soil and nearby buildings have been done during several drop tests of different containers on different foundations. The first measurements have been done on a big foundation where it should be guaranteed that the foundation is rigid and the container is tested properly. It was controlled that the foundation does not absorb more than 2 percent of the energy of the container. Most of the drop energy is lost in shock absorbers. Later on, a smaller drop test facility has been built on the ground but inside an existing building. It had to be controlled by prediction and measurements that the drop test will not damage the building. Tests from different heights on soft, medium, and stiff targets have been done to find out rules which allow to identify acceptable and unacceptable drop tests. Later on, the biggest drop test facility has been built for masses up to 200 t. It was necessary for the design of the foundation to estimate the forces which occur during the drop tests. On the other hand, the acceptable tests should be selected and controlled by measurements where the impact duration is important. Different sensors, accelerometers, accelerometers with mechanical filters, geophones (velocity transducers), strain gauges, and pressure cells have been applied for these tasks. The signals have been transformed to displacements which proved to be best suited for the interpretation of the impact mechanism. Modell calculations have been used to check and understand the dynamic measurements. The simplest law is the conservation of the momentum which is a good approximation if the impact is short. If the soil under the foundation has an influence on the deceleration of the container, the maximum foundation velocity is lower than the simple estimation. The amplitudes of the foundation could also be estimated from the ground vibrations and their amplitude-distance law. T2 - 27th International Congress on Sound and Vibration (ICSV27) CY - Online meeting DA - 11.07.2021 KW - Drop test KW - Vibration measurement KW - Container loading KW - Foundation load PY - 2021 SN - 978-83-7880-799-5 SN - 2329-3675 SP - 1 EP - 8 PB - Silesian University Press CY - Gliwice, Poland AN - OPUS4-53255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Aspekte der Erschütterungsprognose bei Bahnlinien: Quasi-Statik und Achsfolge, unregelmäßiger Schotter und Boden, Wellenausbreitung bei Tunneln und Besonderheiten bei Bürogebäuden N2 - Erschütterungen, die durch Eisenbahnverkehr erzeugt werden, breiten sich durch den Erdboden aus und regen benachbarte Gebäude zu Schwingungen an. Es wurde ein Prognoseverfahren für Bahnerschütterungen ent-wickelt, das mit einfachen Modellen schnell Ergebnisse liefert. Dies sind physikalische Modelle, zum Beispiel 1-dimensionale Modelle mit Übertragungsmatrizen für die Fahrzeug-Fahrweg-Boden-Wechselwirkung und für die Gebäude-Boden Wechselwirkung. Damit werden die komplexen Verhältnisse bei der Emission (dem Zusammen¬wirken von Fahrzeug und Fahrweg), bei der Transmission durch den homogenen oder geschichteten Boden und bei der Immission in Gebäuden näherungsweise erfasst. In (Auersch, 2020) wird gezeigt, dass diese einfachen Prognosemodelle die Ergebnisse von detaillierten Modellen wie der Finite-Element-Randelement-Methode für das Gleis, die Wellenzahlintegrale für den Boden und 3-dimensionale Finite-Element-Modelle für das Gebäude gut wiedergeben können. Dies entspricht auch der Absicht, die Prognosemodelle aus den Ergebnissen der Detailmodelle abzuleiten. Die drei Prognoseteile werden getrennt berechnet, aber es werden physikalisch sinn¬volle Schnittstellen verwendet. Für die Emission und Transmission sind es die auf den Untergrund wirkenden Erregerkräfte von Fahrzeug und Fahrweg, für die Transmission und Immission sind es die Freifeldamplituden des Bodens. T2 - 17. D-A-CH Tagung Erdbebeningenieurwesen und Baudynamik CY - Online meeting DA - 16.09.2021 KW - Erschütterungen KW - Emission KW - Transmission KW - Immission PY - 2021 SP - 17 EP - 18 PB - ETH Zürich CY - Zürich AN - OPUS4-53313 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Prediction of building noise and vibration – 3D finite element and 1D wave propagation models N2 - Construction work or traffic excite nearby buildings, and the perceptible or audible vibration can be a nuisance for the inhabitants. The transfer of the vibration from the free field to the building has been calculated by the finite element method for many models in consultancy and research work. The analysis for all storeys of certain building points such as walls, columns and floors unveiled some rules, some typical modes, and some wavetype responses. A simplified building-soil model has been created, which includes well these effects of building-soil resonance, wall/column resonance, floor resonances, and the high-frequency reduction. The model consists of one wall for a wall-type apartment building or a column for each specific part (mid, side or corner) of a column-type office building. The building response in the high-frequency (acoustic) region is calculated as mean values over all storeys and over wider frequency bands, by wave-type asymptotes of an infinitely tall building, and by the soil to wall ratio of impedances. The secondary noise is predicted by Transfer values between the building vibration (center of floors, walls at a room corner) and the sound pressure. T2 - Euronoise 2021 CY - Online meeting DA - 25.10.2021 KW - Building vibration KW - Finite element models KW - Soil-wall-floor model KW - Apartment building KW - Office tower PY - 2021 SN - 978-989-53387-0-2 SP - 1792 EP - 1801 AN - OPUS4-53702 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Wellenausbreitung und Pfähle im inhomogenen Boden – Gesetzmäßigkeiten für die Gründung von Windenergieanlagen und für die Prognose von Bahnerschütterungen aus Tunneln N2 - Es wird eine gekoppelte Finite-Element-Randelementmethode zur Berechnung von Pfahlgrün-dungen in inhomogenen (geschichteten) Böden vorgestellt. Sie beruht auf den Greenschen Funktionen (Punktlastlösungen) für inhomogene Böden. Diese Lösungen können auch für die Wellenausbreitung in der Tiefe, zum Beispiel von einem Bahntunnel zu einem eingebetteten Gebäude, dem Kellergeschoss benutzt werden. Die Punktlastlösungen in der Tiefe werden mit der Halbraumlösung an der Bodenoberfläche und mit der Vollraumlösung verglichen und Gesetzmäßigkeiten für geschichtete Böden abgeleitet. Zu den Pfahlgründungen werden die Horizontalnachgiebigkeiten von Pfählen in geschichteten Böden dargestellt. Für den homogenen und den kontinuierlich steifer werdenden Boden werden Potenzgesetze für den Boden- und Pfahleinfluss aufgestellt. Der Vergleich mit dem Winkler-Modell der rein lokalen Bodenreaktion zeigt, dass die Winkler-Bettung in allen Fällen einen zu kleinen Bodeneinfluss ergibt. T2 - 7. VDI-Fachtagung Baudynamik CY - Würzburg, Germany DA - 27.04.2022 KW - Wellenausbreitung in der Tiefe KW - Nachgiebigkeiten KW - Windenergieanlagen PY - 2022 SN - 978-1-18-092379-6 SN - 0083-5560 VL - 2379 SP - 697 EP - 706 PB - VDI-Verlag CY - Düsseldorf AN - OPUS4-54768 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Wave propagation from hammer, vibrator and railway excitation – theoretical and measured attenuation in space and frequency domain N2 - The attenuation of wave amplitudes is ruled by the planar, cylindrical or spherical geometry of the wave front (the geometric or power-law attenuation) but also by the damping of the soil (an exponential attenuation). Several low- and high-frequency filter effects are derived for the layering and the damping of the soil, for the moving static and the distributed train loads and for a homogeneous or randomly heterogeneous soil. Measurements of hammer- and train-induced vibrations at five sites have been analysed for these attenuation and filter effects. The measured attenuation with distance can be discribed by generalised power laws and some reasons will be discussed. The theoretical filter effects can well be found in the measurements. T2 - Wave Mechanics and Vibrations Conference CY - Lisbon, Potugal DA - 04.07.2022 KW - Hammer impact KW - Train passage KW - Layered soil KW - Attenuation KW - Filter effects KW - Randomly heterogeneous soil KW - Scattering PY - 2023 SN - 978-3-031-15757-8 DO - https://doi.org/10.1007/978-3-031-15758-5_35 SP - 352 EP - 359 PB - Springer Nature CY - Cham, Schweiz AN - OPUS4-56034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Railway vibration – fast physics-based models for the prediction of ground vibration and the identification of track damage N2 - The following applications of machine learning will be discussed: 1. The prediction of the wave propagation from a railway line (completely physics based for surface lines, physics-based machine learning for tunnel lines) 2. The track behaviour for the emission of train-induced ground vibration (physics based for homogeneous soil, machine learning for layered soil) 3. Track damage detection and quantification from frequency response functions and moving load responses 4. Bridge damage detection and localisation from modal analysis and moving load 5. The use of axle-box acceleration for the identification of track/sub-soil condition and bridge resonances. The prediction of railway vibration usually needs time-consuming finite element, boundary element and wavenumber domain calculations. For a user-friendly prediction software however, fast calculations are needed. Several time-consuming detailed calculations have been used to develop simpler and fast models for the surface railway lines. The more challenging prediction from tunnel lines will be attacked by purely mathematical and by physics-informed machine learning. The dynamic stiffnesses of isolated or un-isolated railway tracks from detailed calculations with a continuous soil have been approximated with the simpler Winkler soil. The vehicle-track resonance (P2 resonance) rules the effect of the mitigation measures, and it can also be used for the on-board monitoring of the track and sub-soil condition. For the identification of track damage such as gaps between sleepers, track slabs and layers, detailed models with a continuous soil have been updated to get the best fit to the measured frequency response functions from hammer tests and the deformation pattern from the moving load response. Whereas the track damage can be locally identified, this is more difficult for bridges where the modal analysis gives mainly global information. The influence lines of the inclination for statically passing vehicles (locomotive, truck, compaction roller) have been used to localise bridge damage (stiffness variations). The on-board monitoring of rail bridges needs special conditions (regular trains with special speeds) to excite and measure the bridge resonance. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 10.06.2024 KW - Vibration prediction KW - Track damage detection KW - Human and machine learning KW - Wave propagation KW - Surface line KW - Tunnel KW - Bridge resonance PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612462 DO - https://doi.org/10.58286/29865 SN - 1435-4934 SP - 1 EP - 9 PB - NDT.net CY - Kirchwald AN - OPUS4-61246 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Maack, Jürgen A1 - Eidenmüller, Moritz A1 - Auersch, Lutz T1 - Prognose von Erschütterungs- und Sekundärschall- Immissionen an Bahnlinien unter Verwendung von FEM Gebäudemodellen N2 - Die Errichtung von Wohngebäuden an Bahnstrecken erfordert Betrachtungen zur Begrenzung der Erschütterungs- und Sekundärschallimmissionen. Hierzu werden spektrale Prognoseverfahren ausgehend von Freifeldmessungen eingesetzt. Im rechnerischen Modell werden die Teilaspekte der Körperschallübertragung mit Hilfe von spektralen Übertragungsfunktionen beschrieben. Kenntnis über die Zusammenhänge dieser spektralen Übertragungsfunktionen erhält man im Wechselspiel von: - Messergebnissen von Körperschall- und Luftschallmessungen für einzelne Übertragungssysteme - Modellberechnungen mit der Finite-Elemente-Methode, Parameterstudien, Abgleich mit Messergebnissen - Modellberechnung mit der Finite-Elemente-Methode zur Wechselwirkung des schwimmenden Estrichs mit dem Gebäude T2 - VDI-Tagung Baudynamik CY - Würzburg, Germany DA - 02.04.2025 KW - Bahnerschütterungen KW - Gebäudemodelle KW - Schwimmender Estrich KW - Sekundärschall PY - 2025 SN - 978-3-18-092447-2 SN - 0083-5560 VL - 2447 SP - 301 EP - 314 PB - VDI-Verlag CY - Düsseldorf AN - OPUS4-62887 LA - deu 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 SN - 978-3-18-092447-2 SN - 0083-5560 VL - 2447 SP - 53 EP - 64 PB - VDI-Verlag CY - Düsseldorf AN - OPUS4-62886 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - Papadrakakis, Manolis 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 SP - 1 EP - 15 PB - NTUA CY - Athen AN - OPUS4-63470 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 2022 CY - Leuven, Belgium DA - 12.09.2022 KW - Ground vibration KW - Simple prediction KW - Vehicle-track interaction KW - Layered soil KW - Soil-building interaction KW - Soil-wall-floor model KW - Propagation from a tunnel KW - Tunnel-pile transfer PY - 2022 SP - 1 EP - 13 PB - KU Leuven CY - Leuven AN - OPUS4-56603 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir A1 - Rohrmann, R. T1 - Measurement and evaluation tools for ground and building vibrations from industrial pro-cesses, construction work, traffic and other sources N2 - Vibration measurements have many causes and many technical and natural sources. Problems can sometimes be solved by short-term measurements, but in many cases, a long-term measurement is necessary. In long-term measurements of days, weeks, months and even years, it is easy to collect a huge quantity of raw data, but at the end, the post-processing of these data can be exhausting (for example one-year vibration data of a wind energy tower). A software has been developed which con-sists of measuring and evaluation routines where the measuring routines can operate different meas-uring systems and different measuring cards. The main advantage of this software is the fact that the interesting evaluations can be integrated in the measuring process so that the characteristics of the vibration can be extracted without storing all the raw data. Only important time segments are stored, for example train passages. The overall concept of the software and the main evaluation routines will be described in some details. Examples of our measurement experience will illustrate the capabilities of the software. 1) Surveying construction work in nearby sensitive buildings (for example an old wind tunnel), including a stable alarm system and meaningful vibration limits. 2) Prediction of train-induced vibration for a planned building to prevent annoyance and to improve the building design. 3) Modal analysis and long term measurements of several single- or multi-span, concrete or steel bridges 4) Modal and wave analysis of coupled floors in a historical building (“Neues Palais” at Potsdam). 5) Soil properties of various measurement sites (different routines to evaluate the dispersion). Moreover, from many projects, amplitudes, frequencies, and attenuation laws have been collected and analysed for the different sources such as vibratory or impact pile driving and ground compaction, demolition work with different machines, blasting in quarries and in tunnel works, bomb and mine clearing. T2 - 28th International Congress on Sound and Vibration CY - Online meeting DA - 24.07.2022 KW - Ground vibration KW - Building vibration KW - Measurement KW - Evaluation KW - Modes KW - Waves PY - 2022 SP - 1 EP - 8 AN - OPUS4-56602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 which are generated by the acceleration of the unsprung mass (from the varying wheel displacements under the static axle load). 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 - International Conference Railways 2022 CY - Montpellier, France DA - 22.08.2022 KW - Ground vibration KW - Axle loads KW - Irregularities KW - Varying stiffness PY - 2022 SP - 1 EP - 11 AN - OPUS4-56605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir T1 - System and damage identification for cars, floors and roofs, bridges, tracks and foundations by modal analyses, frequency response functions and moving-load responses N2 - The following objects have been analysed by frequency response functions and moving load responses. A simple modal analysis which is based on the transformed and weighted system equations has been tested for an automotive test car and for many floors in many buildings to get some rules for their natural frequency and damping. Moreover, six neighboured equal, weakly coupled, wooden floors in a castle have been measured by ambient and hammer excitation, and a special method to extract the different mode shapes of the closely spaced natural frequencies has been developed and tested. Different foundations, for which the soil-structure interaction is generally important, have been measured and compared with finite-element boundary-element models of varying soil properties. Similarly by FEBEM calculations, damages in railway tracks have been identified from flexibility functions (frequency response functions) and from the moving-load responses to normal train operation. Rail and foot bridges have been measured during train passages and by quasi-static tests with moving vehicles. The repeatability of the inclinometer measurements has been checked for different passages, passage directions, and measurement campaigns at a six-span foot bridge. Two rail bridges at the Hanover-Würzburg high-speed line have been measured and evaluated for integrity and for the train- and speed-dependent bridge resonances. The relation between the multi-axle and the single-axle excitation can be solved in frequency domain by the axle-sequence spectrum of the vehicle or the whole train. The single axle response has been used to identify track and bridge damages in laboratory and in situ. T2 - 10th International Operational Modal Analysis Conference (IOMAC 2024) CY - Naples, Italy DA - 21.05.2024 KW - Weakly coupled floors KW - Bridge passage KW - Track damage KW - Foundation-soil interaction KW - Flexibility function KW - Moving load response PY - 2024 SN - 978-3-031-61420-0 DO - https://doi.org/10.1007/978-3-031-61421-7_19 SN - 2366-2557 SP - 187 EP - 195 PB - Springer Nature Switzerland AG CY - Cham, Schweiz AN - OPUS4-61248 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Vibrations of multi-span structures like floors, rail and road bridges N2 - Resonances of rail bridges due to the passage of trains have been mainly investigated for sin-gle-span bridges. When multi-span bridges are to be considered, it is of interest if stronger resonance amplifications must be taken into account. Measurements of several multi-span structures have been evaluated for natural frequencies and mode shapes. An integral rail bridge with three different spans shows a separated local resonance of the longest main span and clearly higher natural frequencies of the shorter side spans. A two-span continuous beam on the test area of the Federal Institute of Material Research and Testing showed a regular pattern of natural frequencies where always a pair of frequencies is found with a certain fre-quency ratio. The corresponding mode shapes are the out-of-phase and in-phase combinations of the first, second, third … bending mode. A seven-span road bridge has been monitored for one of the almost equally long spans. Similar mode shapes have been observed for different, clearly separated natural frequencies. Three modal analyses measurement campaigns have been performed on the whole bridge. The combined mode shapes of the seven spans have been clearly identified where different combinations of spans are dominating in the different mode shapes. Equal weakly coupled spans have been analysed for a large wooden floor in a castle. A cluster of natural frequencies has been observed and a special method to extract the mode shapes has been developed and tested. The consequences of multi-span bridges for rail traffic will be discussed. If n simply supported bridge spans have no coupling, n equal modes with amplitude A/n exist and their superposition would yield the same resonance as for a single bridge. Real simply supported bridges have always a weak coupling due to the track or the common piers. Therefore, the natural frequencies differ a little and they cannot be in reso-nance at the same time for the same train passage so that the resonance amplification cannot be as strong as for the single bridge. This rule holds also for the average amplitude of the time history of the bridge passage which is an adequate quantity to judge for the bridge behaviour. The maximum amplitude of the time histories of different bridge points are quite random and could exceed the values of a single bridge. The meaning of such criteria is questioned and fre-quency domain analyses are suggested for a clearer bridge analysis and understanding. T2 - DinEst 2024 Third Conference on Structural Dynamics CY - Seville, Spain DA - 12.09.2024 KW - Rail bridge PY - 2024 SP - 41 EP - 59 PB - Escuela Tecnica Superior de Ingenieria CY - Sevilla AN - OPUS4-61238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Die Minderung von Bahnerschütterungen – Messergebnisse aus Österreich, Deutschland und der Schweiz N2 - Die Minderung von Bahnerschütterungen neben Eisenbahnstrecken ist an vielen Stellen gemessen worden. Dabei ist neben der hochfrequenten Wirkung von elastischen Gleiselementen wie Schienenlager, Schwellensohlen und Unterschottermatten auch oft eine tieffrequente Minderung beobachtet worden. Diese tieffrequente Minderung wird interpretiert und mit der weiteren Lastverteilung der statischen Last erklärt. T2 - 3. Wiener Dynamik Tage CY - Vienna, Austria DA - 25.07.2024 KW - Bahnerschütterungen KW - Minderung KW - Messungen KW - Schwellensohlen KW - Unterschottermatten KW - Gleistrog PY - 2024 SP - 1 EP - 13 AN - OPUS4-61244 LA - deu 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. Figure T2 - Int. Conf. RASD, Recent Advance in Structural Dynamics CY - Southampton, GB DA - 01.07.2024 KW - Ground vibration KW - Tunnel line KW - Wave propagation KW - Wavenumber method KW - Building vibration KW - Thin layer method PY - 2024 SP - 1 EP - 12 CY - Southampton AN - OPUS4-61266 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Conreaux, Laurence A1 - Said, Samir A1 - Müller, Roger T1 - The excitation, propagation, and mitigation of train-induced ground vibrations from the axle impulses on the track N2 - Train-induced vibrations in soft ground usually have a strong low-frequency component. This component has a characteristic spectrum which is related to the axle sequence and the speed of the train. Its attenuation with distance is weaker than the attenuation for higher frequencies, and it always dominates the far-field ground vibration. Narrow-band frequency analyses clearly show that this ground vibration component is due to the static axle loads. Axle box vibrations have a different characteristic where the first out-of-roundness of the wheels is the only remarkable low-frequency component. Therefore, the dynamic axle loads from wheel and track irregularities are not the reason for the strong ground vibration component. The moving static axle loads generate the quasi-static response of the soil at very low frequencies and at very near distances. A part of the original impulse spectrum is scattered when it propagates through an inhomogeneous ballast and soil with a randomly varying stiffness. The axle impulses are smoother for a higher bending stiffness or a lower support stiffness (under sleeper pads, under ballast mats) of the track. This mitigation of the ground vibration will be demonstrated by measurements at three sites in Switzerland as well as the characteristic of the soil and axle-box vibrations. T2 - Sixth International Conference on Railway Technology: Research, Development and Maintenance CY - Prague, Czech Republic DA - 01.09.2024 KW - Soil and vehicle measurements KW - Train passages KW - Ground vibration KW - Excitation mechanisms KW - Mitigation KW - Under sleeper pads KW - Under ballast mat PY - 2024 DO - https://doi.org/10.4203/ccc.7.13.2 SN - 2753-3239 VL - 7 SP - 1 EP - 13 PB - Civil-Comp Press CY - Edinburgh, United Kingdom AN - OPUS4-61240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Frequenz- und bodenabhängige Prognose und Minderung von Bahnerschütterungen N2 - Die Prognose und Minderung von Bahnerschütterungen haben eine lange Tradition in der Bundesanstalt für Materialforschung und -prüfung. Im Jahr 2006 wurde eine Prognose-Software fertiggestellt, die viele Forschungs- und Messergebnisse zusammenfasst. Sie umfasst die Teilbereiche Emission (die Anregung durch die Fahrzeug-Fahrweg-Untergrund-Wechselwirkung), die Transmission (die Ausbreitung durch den Boden) und die Immission (die Übertragung vom Freifeld in ein Gebäude). Die Prognose geschieht in allen Teilen mit einfachen Formeln, die veröffentlicht sind und zur Anwendung für Jedermann zur Verfügung stehen. Es werden Beispiele zur Emission und zur Transmission gezeigt. Im Bereich Transmissionsprognose werden zu den Anregungskräften (aus dem Emissionsteil) die Bodenerschütterungen als Schwinggeschwindigkeitsterzspektren berechnet. Das Ergebnis hängt stark von der Bodensteifigkeit, -dämpfung und -schichtung ab. Dies wurde später mit einer Messkampagne in der Schweiz an 10 Messorten bestätigt. Die Berechnung erfolgt näherungsweise für einen geschichteten Boden mit einer frequenzabhängigen Wellengeschwindigkeit (Dispersion) oder einem tiefenabhängigen Wellengeschwindigkeitsprofil. Die Anregungskräfte werden im Prognosebereich Emission mit einem 2-dimensionalen Gleismodell berechnet. 1-dimensionale Modelle liefern meist falsche Ergebnisse und 3-dimensionale Modelle (zum Beispiel mit der kombinierten Finite-Element-Randelement-Methode) sind für eine Erschütterungs¬prognose sicherlich zu aufwändig. Das 2-dimensionale Modell wurde an 3-dimensionale Ergebnisse so angepasst, dass die Ergebnisse für viele Gleise und Böden annähernd zutreffen. Auch Minderungs¬maßnahmen am Gleis können mit diesem Modell sehr gut berechnet werden. Die Prognoseverfahren wurden in den folgenden Jahren weiter verfeinert. Es wurde die quasi-statische Anregung durch die bewegten statischen Zuglasten mit einer Näherungsformel ergänzt, so dass auch das tieffrequente Nahfeld realistisch erfasst werden kann. Mit der Berücksichtigung der Achsfolge (insbesondere zwischen den Achsen im Drehgestell) ergeben sich zwei typische Minima in den Erschütterungsspektren, die oft auch in den Messungen beobachtet werden. Der Amplitudenanteil zwischen diesen beiden Minima ist oft stärker angehoben, so dass hier eine zusätzliche Erschütterungsanregung vermutet wird. Dieser Anteil kann rein empirisch prognostiziert werden, so wie das in den englischen Prognosen (zuletzt für das Highspeed2-Projekt) enthalten ist. Die Begründung dieses Anteils ist allerdings nicht die Achsfolge, sondern die Zerstreuung der statischen Achslastimpulse durch einen unregelmäßigen Gleisuntergrund und Boden. Die messtechnische Ermittlung eines Minderungseffektes ist komplizierter als allgemein angenommen. Es reicht nicht aus, jeweils an einem Messpunkt in der Nähe eines Gleises mit und ohne Minderungsmaßnahme die Erschütterungen zu messen und aus dem Verhältnis der Amplituden (beziehungsweise aus der Differenz der Pegel) „die Einfügedämmung“ zu ermitteln. Es wird an Beispielen gezeigt, wie man hier sinnvoller vorgehen kann. 1. Zunächst ist es wichtig, nicht nur die Einfügedämmung sondern auch die Originalspektren mit und ohne Minderung zu dokumentieren und zu veröffentlichen, damit man kontrollieren kann, ob wesentliche Amplituden und Frequenzbereiche reduziert sind oder ob es sich um eher zufällige Minderungen oder Verstärkungen handelt. (Beispiel Unterschottermatte/Raron, Müller/SBB) 2. Der Messpunkt sollte nicht im Nahbereich des Gleises liegen, da ansonsten eine zu günstige, falsche Einfügedämmung bestimmt wird. (Beispiel Tunnel/ Leipzig/Breitsamter) 3. Um Zufälligkeiten zu vermeiden, sollte man an mehr als einem Punkt messen. (Beispiel Unterschotterplatte/Altheim/Auersch) 4. Man sollte eigentlich immer auch die Bodenkennwerte (Steifigkeit, Dämpfung, Amplituden-abnahme, Übertagungsfunktion) messen. Selbst bei nahegelegene Messquerschnitten kann man Überraschungen erleben. (Beispiel erste ICE-Messungen/bei Würzburg/Auersch) 5. Bei verschiedenen Bodenkennwerten kann man eine Korrektur durchführen. (Beispiel Gleis-tröge/Mistler) Am besten bestimmt man ein äquivalentes Kraftspektrum zu jedem Messort und jedem Messzug (Beispiel Feste Fahrbahn/Gardelegen/Auersch) 6. Prinzipiell gibt es nicht die Einfügedämmung einer Maßnahme. Die Einfügedämmung ist immer boden- und referenzsystemabhängig. Die „beste“ Einfügungsdämmung erhält man mit einem steifen Untergrund (Beispiel Unterschottermatte/Tunnel/München Gasteig/Wettschureck) Das heißt aber nicht, dass die Maßnahme durch einen künstlich versteiften Untergrund besser wird (Beispiel Unterschottermatten/RRT2006/Auersch) Es werden Messbeispiele gezeigt, die alle neben einer hochfrequenten dynamischen Minderung auch eine mittelfrequente quasi-statische Minderung aufweisen. Dabei wird der mittelfrequente Zerstreuanteil der statischen Achslastimpulse durch die breitere Lastverteilung und damit die Impulsdehnung der Achslastimpulse reduziert. Diese Impulsdehnung lässt sich mit dem 2-dimensionalen Gleismodell berechnen. Die Minderungswirkung hängt aber wiederum vom Referenzsystem und dessen unregelmäßiger Steifigkeitsverteilung ab. Je unregelmäßiger der Boden und Gleisuntergrund des Referenzsystems, desto stärker ist die Minderungswirkung. T2 - 24. Symposium für Baudynamik und Erschütterungsmessungen CY - Dübendorf, Sitzerland DA - 09.06.2023 KW - Bahnerschütterungen KW - Erschütterungsprognose KW - Erschütterungsminderung KW - Elastische Gleiselemente KW - Gleiströge KW - Zerstreute Achsimpulse PY - 2023 SP - 1 EP - 32 PB - Ziegler Consultants CY - Zürich AN - OPUS4-57953 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Soil-foundation-structure problems related to train induced vibrations - the kinematic interaction of tunnel excited pile foundations and the inertial interaction of high rise buildings N2 - The soil-foundation-structure interaction is always important when building vibrations due to train passages have to be considered. The frequency range for train vibrations is up to 100 Hz. Normally, soft surface soils are crucial so that the wavelength can be much smaller than the foundation dimensions. Three topics are of interest for the prediction and the under-standing of building vibrations. 1. The „kinematic interaction“ or the „added foundation ef-fect“, which is calculated either by the combined boundary-element finite-element method or by the wavenumber domain method, results in a reduction of the free-field vibration. The stiff-ness of the foundation resists the wave deformation, plates and walls for horizontally propa-gating waves or piles for vertically incident waves. 2. The „inertial interaction“ or the „added building effect“ yields an amplification around the vertical building resonance, which may be a rigid mode on the compliant soil or a flexible mode for high-rise buildings, and a reduction at higher frequencies. This has been analysed by detailed finite element models of apartment and office buildings. 3. Base isolation is a method to further reduce building vibrations. It is important to know the soil-foundation impedance for the possible reduction, as well as the correct building impedance. A high-rise building cannot be considered as a rigid mass model. It has a frequency-dependent behaviour with longitudinal waves travelling from the founda-tion to the top of the building which include the effect of floor vibrations. Experiences from building projects in Vienna, Frankfort and Berlin will give some additional results for the ex-citation from tunnel lines, the kinematic response of pile foundations, and the inertial re-sponse of the flexible multi-storey buildings. T2 - COMPDYN 2023 CY - Athen, Greece DA - 12.06.2023 KW - Kinematic Interaction KW - Inertial Interaction KW - Surface Foundation KW - Pile Foundation KW - High-Rise Building PY - 2023 SP - 1 EP - 14 PB - NTUA CY - Athens AN - OPUS4-57959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Some resonance effects of non-typical trains and railway bridges investigated by a frequency-domain method N2 - The resonances of railway bridges have often been analysed for short bridges under periodical high-speed trains, for simply supported one-span bridges, for the fundamental bridge mode, and by time-domain analyses. Many time-consuming calculations have been performed to establish simplified rules for standards. In this contribution, the passage of different (existing, new and hypothetic) trains over different bridges will be analysed in frequency domain by using three separated spectra with the purpose to get a better physical insight in the phenomena. At first, the excitation spectrum of the modal forces is built by the mode shape and the passage time of the train over the bridge. The second spectrum is the frequency response function of the bridge which include the modal frequency, damping and mass. The third part is the spectrum of the axle sequence of an arbitrary train which is not limited to periodical or specific (conventional, articulated, regular or standard) trains and which does not include any bridge parameters. The final solution in frequency domain is obtained as the product of these three complex, strongly varying spectra for the dominating bridge mode or in general as the sum of these products over all relevant bridge modes. The time domain solution is obtained via the inverse Fourier transform, and the resulting time histories have been successfully compared with some measurement results. The method is applied to the vertical and torsional modes of a mid-long 1-span bridge on elastomeric bearings under standard train speeds, and to a long multi-span integral bridge under long periodical freight trains. Different resonance and cancellation effects have been found for systematically varied train speeds according to the axle sequence of the whole train which is dominated by the two locomotives in that case. To be more specific, the first torsional mode of the mid-span bridge is excited for a train speed of 100 km/h whereas the second bending mode is excited for a train speed of 160 km/h. In both cases, the other mode is suppressed by the minima of the axle-distance spectra. In addition, the case of the German high-speed train ICE4 and the very high-speed hyperloop case will be discussed briefly. In general, it is shown that resonance effects are also worth to be studied for freight and passenger trains with lower speeds. T2 - XII International Conference on Structural Dynamics CY - Delft, The Netherlands DA - 03.07.2023 KW - Railway bridge KW - Transfer function KW - Modal force spectrum KW - Axle-sequence spectrum KW - Freight train KW - Passenger train KW - High-speed train KW - 2-span bridge KW - Long-span bridge PY - 2023 SP - 1 EP - 10 PB - TU Delft CY - Delft AN - OPUS4-57961 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Train-induced ground vibrations - the emission and transmission from tunnel and surface lines N2 - Train-induced ground vibrations are quite different for tunnel and surface lines. The excitation of the track and ground vibration by the vehicle-track-soil interaction maybe influenced by the stiffer track support of the tunnel invert. The excited waves are propagating on a different path compared to the surface line. The wave propagation in the interior of the soil is calculated by a wavenumber integral in a similar way as the propagation along the surface and a general reduction of < 0.5 has been found. An additional reduction has been found because of the missing Rayleigh wave. The different excitation of tunnel lines is analysed theoretically by the combined finite-element boundary-element method and some results about the influencing tunnel and soil parameters will be shown. Measurements have been made at the Mühlberg-Tunnel in Germany. The vibrations of the train, the track and the soil have been measured simultaneously at the tunnel and a nearby surface line. Spectra will be shown for different train speeds between 60 and 160 km/h. A clear reduction effect for the tunnel line compared to the surface line has been observed in a specific (train-speed-dependent) frequency range. This agrees well with the observations of other research institutes. The mid-frequency tunnel-surface reduction seems to be a consequence of the stiffer track structure which leads to a wider distribution of the axle loads. Therefore, the axle impulses due to the train passage are longer and have a lower frequency content. This will have an effect on the ground vibrations at some distance which are present in case of an irregular transmission path through a ballast and soil with varying stiffness. A similar reduction effect can also be found for other track forms where the axle impulses are distributed on a longer track segment, for example slab tracks, tracks with under ballast plates, under ballast mats or under sleeper pads. T2 - 29th International Congress on Sound and Vibration CY - Prague, Czech Republic DA - 09.07.2023 KW - Ground vibration KW - Railway tunnel KW - Layered soil KW - Surface-tunnel reduction KW - Measurements PY - 2023 SP - 1 EP - 8 PB - IIAV CY - Auburn, USA AN - OPUS4-57962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Impacts Between Different Drop Masses and Different Targets in Different Scales N2 - The Federal Institute of Material Research and Testing has performed many impact tests from very small laboratory tests to very big “free-field” tests with heavy containers on stiff foundations. The first measurements have been done on a big foundation where it should be guaranteed that the foundation is rigid and the container is tested properly. Later on, a smaller drop test facility has been built on the ground inside an existing building. It had to be controlled by prediction and measurements that the drop test will not damage the building. Tests from different heights on soft, medium, and stiff targets have been done to find out rules which allow to identify acceptable and unacceptable drop tests. Later on, the biggest drop test facility has been built for masses up to 200 t. It was necessary for the design of the foundation to estimate the forces which oc-cur during the drop tests. In addititon, the acceptable tests should be selected and controlled by measurements where the impact duration is important. Dif-ferent sensors, accelerometers, accelerometers with mechanical filters, geo-phones (velocity transducers), strain gauges, and pressure cells have been ap-plied for these tasks. Signal transformations and model calculations have been used to check and understand the dynamic measurements. The simplest law is the conservation of the momentum which is a good approximation if the impact is short. If the soil under the foundation has an influence on the deceleration of the container, the maximum foundation velocity is lower than the simple esti-mation. T2 - Experimental Vibration Analysis for Civil Engineering Structures (EVACES 2023) CY - Milano, Italy DA - 30.08.2023 KW - Drop test KW - Vibration measurements KW - Container loading KW - Foundation load PY - 2023 SN - 978-3-031-39116-3 DO - https://doi.org/10.1007/978-3-031-39117-0_60 SN - 2366-2557 SP - 592 EP - 602 PB - Springer Nature Switzerland CY - Cham, Schweiz AN - OPUS4-58503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir A1 - Rohrmann, Rolf ED - Döhler, Michael 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 SP - 39 EP - 46 PB - INRIA CY - Rennes AN - OPUS4-63473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Song, Jiaojiao T1 - Analysis of intact and damaged (floating) slab tracks by finite-element boundary-element models and by measurements N2 - The damage detection and repair control have become important tasks for slab tracks. Different intact and damaged slab tracks have been investigated theoretically and experimentally for train passages and hammer impacts. The following damages have been considered: The loss of contact between the sleeper and the track slab, between the track slab and the base slab, and between the base slab and the base layer. At first, a slab track with a gap between the track slab and the base layer has been calculated by the combined finite-element boundary-element method which correctly incorporates the behaviour of the infinite soil. The basic results are the track displacements of the rail, the track slab, and the base layer along the track which are caused by a single axle load. These solutions are properly superposed for to get the complete train load. The influence of track and soil parameters and of the track damage has been analysed. For the intact track, the compliance of the soil is dominant whereas the track bending stiffness becomes more important for the damaged track. By comparing the calculated results with the measurements, the length of the gap could be quantified. A slab track with a loose sleeper (without contact to the supporting track slab) was analysed by the transfer function between the displacements and the hammer force (receptance functions) where a resonance appeared in case of the damage. Differences between the different track elements confirmed the detection of the damage. A floating slab track with a thin rubber layer has been investigated for a possible gap between the base slab and the base layer. The behaviour of the intact track has been calculated by a wavenumber-domain method, and the same behaviour has been found in the measurements at several track sections, indicating that there is no damage. Finally, a floating slab track with steel springs and viscous fluid dampers has been measured in the Tongji laboratory. The modes of the floating track slab and the transfer function with corresponding resonances have been calculated and successfully compared with results from wheelset drop tests. T2 - Third International Conference on Rail Transportation (ICRT2024) CY - Shanghai, China DA - 07.08.2024 KW - Railway track KW - Damage KW - Vibration measurement KW - Finite element method KW - Boundary element method KW - Frequency response function KW - Moving load response KW - Floating slab track PY - 2025 SN - 978-0-7844-8594-1 SP - 591 EP - 600 AN - OPUS4-61267 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 - Vehicle excitation KW - Track response KW - Bridge resonance KW - Ground vibration KW - Soil-building transfer KW - Floor resonance KW - Axle-sequence spectrum KW - Vehicle-track eigenfrequency KW - Axle impulses PY - 2025 SN - 978-3-031-96113-7 DO - https://doi.org/10.1007/978-3-031-96106-9_77 VL - 2025 SP - 1 EP - 8 PB - Springer CY - Cham, Schweiz AN - OPUS4-63655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz T1 - Reduction of ground-induced building vibrations by kinematic and inertial soil-structure interac-tion and by base isolation N2 - Many buildings on the soil have been measured and the transfer function freefield-to-building is ana-lysed. In general, an amplification at low frequencies, an amplification for the floor resonances, and a reduction for higher frequencies can be observed. Most of the measurement examples show a flexible behaviour along the height of the buildings. The prediction of building vibration consists typically of three steps. At first, the dynamic stiffness of the foundation and secondly the kinematic soil-structure interaction has to be calculated for example by the combined finite-element boundary-element meth-od. The stiffness of the foundation reduces the incoming waves (the kinematic interaction). Finally, the inertial interaction of the building with the foundation soil is calculated by the conventional finite ele-ment method where the dynamic foundation stiffness from the first step is added at the bottom of the building. The building on the compliant soil has a fundamental vertical resonance usually below 10 Hz. A parametrical variation clearly shows the influence of the elasticity of the building on this reso-nance frequency and amplitude. Moreover for column-type office buildings, the low-frequency floor resonances can further reduce this fundamental frequency. A 1-dimensional model has been estab-lished which can well approximate the behaviour of the 3-dimensional building models. It is used to demonstrate the effect of a base isolation with soft elements at the foundation. A rigid building model clearly over-estimates the isolation effect, which is smaller for a model with flexible walls, columns and floors. An even simpler model of an infinitely high building is suggested for the mitigation effect, and the resonance frequency of the rigid building should be replaced by a better performance indica-tor, which is based on the impedance ratio of the isolation and the wall and which can be also ex-pressed as a characteristic frequency. T2 - 30th International Congress on Sound and Vibration CY - Amsterdam, Netherlands DA - 08.07.2024 KW - Building vibrations KW - Base isolation KW - Foundation stiffness KW - Kinematic soil-structure interaction KW - Transfer functions of flexible buildings PY - 2024 SN - 978-90-90-39058-1 SN - 2329-3675 SP - 1 EP - 8 AN - OPUS4-61245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -