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 - Rücker, Werner A1 - Auersch, Lutz T1 - A user-friendly prediction tool for railway induced ground vibrations: Emission - transmission - immission T2 - 9th IWRN - International Workshop on Railway Noise CY - Munich, Germany DA - 2007-09-04 PY - 2007 SP - S.4.2, 1 EP - 6 PB - International Workshop on Railway Noise CY - München AN - OPUS4-18592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - Cunha, A. ED - Caetano, E. ED - Ribeiro, P. ED - Müller, G. T1 - Amplification and reduction phenomena of soil-building interaction by finite-element boundary-element calculations and simplified methods N2 - Vibration of normal apartment, office and production buildings, which are excited by technically induced ground vibrations are considered. Many wavelengths of the Rayleigh waves of the soil fit into the foundation dimensions. The related high discretization effort can nowadays be realized with detailed soil-structure interaction method. The combined finite-element boundary-element method is used here as a detatiled method. Simplified method can be used with less computation time, but these methods must be calibrated by exact results. One simplification is to extent the structure to infinity and to solve the problem by wavenumber domain methods. Another simplification is the use of a Winkler soil instead of the continuous soil. Usually, the Winkler parameters are not only soil parameters but depend also on the rigid or flexible foundation structure. Substructure methods use commercial FEM software for the building part. The contribution will show some detailed and some simplified results on large structural elements such as foundation plates, walls, storey plates on columns as well as results on complete buildings. The reduction of the ground vibration by stiff elements and the amplification due to floor or building resonances are discussed which are the most important phenomena of the soil-building interaction. T2 - EURODYN 2014 - 9th International conference on structural dynamics CY - Porto, Portugal DA - 30.06.2014 KW - Soil-building interaction KW - Foundation reduction KW - Floor amplification KW - FEBEM and simplified methods PY - 2014 SN - 978-972-752-165-4 SN - 2311-9020 SP - 591 EP - 597 AN - OPUS4-31163 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 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 - Dynamic Soil-Structure Interaction of Rigid and Flexible Foundations T2 - 5th International Conference on Soil Dynamics and Earthquake Engineering CY - Karlsruhe, Germany DA - 1991-09-23 PY - 1991 VL - 5 SP - 467 EP - 478 CY - Berlin AN - OPUS4-11569 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Said, Samir T1 - Dynamic testing of tracks and track sites before and after construction, after damage and after repair N2 - The Federal Institute of Material Research and Testing (BAM) has collected some experience with the testing of damaged, repaired and newly constructed railway tracks. The experimental methods are hammer testing of the track at different positions, hammer testing of the soil, measurement of train passages, and in all cases, measurements with geophones at different positions. The measured signals are evaluated for wave velocities (dispersion of the soil or the track-soil system), for transfer functions (transfer admittances of the soil, compliances of the track in amplitude and phase), and one-third octave band spectra of the track response to hammer and train excitation. These methods are applied at different stages of the track construction. Before track construction, wave velocities and transfer functions of the sub-soil can indicate problems with soft soils. After track construction, a check of the acceptable state of the track can be done by comparison of many excitation positions and track sites. After a track damage (a lose sleeper or a lose plate of a slab track) and after its repair, the sensitivity of the different measurement quantities to different track errors and the achieved improvement of the repair can be determined. The contribution shows examples of all these track situations. T2 - First International Conference on Rail Transportation CY - Chengdu, China DA - 10.7.2017 KW - Track damage KW - Dynamic testing KW - Hammer tests KW - Train passages PY - 2017 SP - 1 EP - 9 PB - Southwest Jiaotong University CY - Chengdu, China AN - OPUS4-42090 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 - Said, Samir A1 - Auersch, Lutz T1 - Environmental vibration due to normal and extreme excitation: railway traffic, explosions and heavy mass drop tests T2 - ISEV 2007, 3rd International Symposium on Environmental Vibrations: Prediction, Monitoring, Mitigation and Evaluation CY - Taipei, Taiwan DA - 2007-11-28 PY - 2007 SP - 1 EP - 6 AN - OPUS4-18408 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -