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Schlagworte
- Ground vibration (38)
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- Mitigation (9)
- Track-soil interaction (9)
- Train passage (9)
- Vehicle-track interaction (9)
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- Wavenumber integrals (4)
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- Wind energy tower (3)
- ground vibration (3)
- mitigation (3)
- railway track (3)
- 2-span bridge (2)
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- Axle-sequence spectrum (2)
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- Bauteile (2)
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- Boundary element method (2)
- Bridge resonance (2)
- Brücken (2)
- Displacements (2)
- Dynamic testing (2)
- Environmental vibrations (2)
- Evaluation (2)
- Finite element models (2)
- Floating slab track (2)
- Foundations (2)
- Freight train (2)
- Ground vibration measurements (2)
- Hammer tests (2)
- High-speed train (2)
- High-speed trains (2)
- Irregular ballast (2)
- Modalanalyse (2)
- Office tower (2)
- Passenger train (2)
- Plate-soil interaction (2)
- Rail roughness (2)
- Railway measurement campaign (2)
- Railway tracks (2)
- Railway tunnel (2)
- Railway vibration (2)
- Railways (2)
- Rayleigh wave (2)
- Resonance (2)
- Scattered axle impulses (2)
- Soil properties (2)
- Soil-structure interaction (2)
- Soil-wall-floor model (2)
- Static axle loads (2)
- Surface line (2)
- Surface-tunnel reduction (2)
- Track damage monitoring (2)
- Train excitation (2)
- Under-ballast plate (2)
- Varying track stiffness (2)
- Vehicle–track interaction (2)
- Vibration measurement (2)
- Vibration reduction (2)
- Wave excitation (2)
- Wavenumber method (2)
- floor vibration (2)
- modal analysis (2)
- track-soil interaction (2)
- undersleeper (2)
- wave analysis (2)
- 1-D insertion loss (1)
- Amplitude-charge weight laws (1)
- Amplitude-distance law (1)
- Assessment (1)
- Axle loads (1)
- Axle pulses (1)
- Axle-load spectra (1)
- Axle-sequence (1)
- Ballast mat (1)
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- Combined finite-element boundary-element method (1)
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- Dynamic axle loads (1)
- Dynamic loads (1)
- Dynamic pile and pile group stiffness (1)
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- Elastic track elements (1)
- Emission (1)
- Experimental verification (1)
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- Explosion-induced ground vibrations (1)
- FEBEM and simplified methods (1)
- Fequency domain (1)
- Filter effect of the soil (1)
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- Finite-element boudnary-element method (1)
- Finite-element method (1)
- Flexibility (1)
- Flexible car body (1)
- Flexible plate (1)
- Flexible wheelset (1)
- Floor amplification (1)
- Floor resonance (1)
- Floors (1)
- Footbridge (1)
- Foundation reduction (1)
- Frequency response function (1)
- Frequency-specific attenuation (1)
- Frequency-wavenumber method (1)
- Geometric trackbed irregularities (1)
- Geometric vehicle and track irregularities (1)
- High-Rise Building (1)
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- Inertial Interaction (1)
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- Measured railway vibrations (1)
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- Monitoring (1)
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- Multi-beam method (1)
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- Non-synoptic wind event (1)
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- Pile Foundation (1)
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- Pile-soil interaction (1)
- Prediction of explosion induced ground and building vibration (1)
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- Predictions (1)
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- Quasi-static response; (1)
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- Rail pad (1)
- Railbridge (1)
- Railway forces (1)
- Railway induced ground vibration (1)
- Railway induced vibration (1)
- Railway track vibration (1)
- Railway trafiic (1)
- Random dynamics and vibrations (1)
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- Reduction (1)
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- Sleeper passage (1)
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- Soil forces (1)
- Soil transfer function (1)
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- Soil-pile interaction (1)
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- Track and vehicle irregularities (1)
- Track beam (1)
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- Track damage quantification (1)
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- Track filter (1)
- Track filtering (1)
- Track irregularities (1)
- Track-soil and vehicle-track resonances (1)
- Train configuration (1)
- Train induced ground vibration (1)
- Train-induced vibration (1)
- Tran speed (1)
- Transfer fuction (1)
- Transfer function (1)
- Trench (1)
- Tunnel (1)
- Tunnel line (1)
- Tunnel track (1)
- Tunnel vibration (1)
- Tunnel-pile transfer (1)
- Tunnel-to-surface reduction (1)
- Turnout (1)
- Under sleeper pad (1)
- Under sleeper pads (1)
- Under-sleeper pads (1)
- Varying soil stiffness (1)
- Varying stiffness (1)
- Vibration (1)
- Vibration excitation (1)
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- Wave attenuation (1)
- Wave propagation (1)
- Wave theory of attenuation (1)
- Wave velocity (1)
- Wave-number integrals (1)
- Wavenumber domain (1)
- Waves (1)
- Wheel out-of-roundness (1)
- Wheelset (1)
- Wheelset accelerations (1)
- Wide sleeper (1)
- layered soil (1)
- sleeper pads (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (59)
- 7.2 Ingenieurbau (59)
Eingeladener Vortrag
- nein (46)
Mitigation measures of railway induced vibration have been demonstrated at the emission, transmission and immission part. It must be carefully observed that the correct masses and stiffnesses are used.
Typical mistakes have been shown,
- 1D models for vehicle-track interaction,
- impedance instead of stiffness for the infill material of a trench,
- rigid buildings or neglecting the soil-building interaction.
The dominant mid-frequency part of the ground vibration is due to the irregular soil.
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.
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.
The dynamic behaviour of slab and ballast tracks has been investigated by measurements and calculations. Hammer impacts and train passages have been analysed. Measurements have been performed by geophones (velocity transducers) which have been time-integrated to displacements. The calculations are done in frequency-wavenumber domain for multi-beam-on-continuous soil models. The characteristics of the different tracks and track elements have been established in theory and experiment. The frequency-dependent compliances (displacement transfer functions) show clear rail-on-rail-pad resonances or highly damped track-soil resonances. Compared to the rail and sleeper, the track plate has much lower amplitudes. The slab track has usually the highest rail amplitudes due to soft rail pads. The train passage yields track displacements which are a superposition of the axle loads from the two neighbouring axles of a bogie and from the two bogies of two neighbouring carriages. This global behaviour is characteristic for the track plate of the slab track whereas the rails of the slab and the ballast track behave more local with only one bogie of influence. The measurements agree very well with the theory of the continuous soil in case of the six measured slab tracks and acceptably well for the six measured ballast tracks. The measurements allow to find appropriate model parameters and to check the models, for example the Winkler model of the soil has been found less appropriate as it reacts more locally.
Many measurements of train induced ground vibrations show high amplitudes for a certain mid-frequency range. This ground vibration component cannot be well explained by dynamic loads of the train. Many characteristics indicate that the axle impulses, which are scattered by an irregular soil, are the excitation. This new understanding of railway-induced ground vibration is verified by numerical analysis. The response of the regular homogeneous and irregular inhomogeneous soils has been calculated by the finite-element method in frequency domain. A specific superposition of the impulse responses has been invented including time shift, axle sequence, track filter and hanning filter. The superposition 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 of which the stiffness varies randomly in space, the superposition yields a mid-frequency ground vibration component from the scattering of the axle impulses. The existence and the importance of this component can thus be demonstrated by the calculations. Some rules of the influence of distance, train speed, soil stiffness, strength and width of the stiffness variation have been derived from the calculations. Many measurements show the unique explanation of the mid-frequency ground vibration component by the scattered axle impulses.
Train passages induce forces on the track, train-induced vibrations propagate through the soil and excite neighbouring buildings. The emission, which is the first part of the prediction of vibrations near railway lines, is presented by focusing on the dynamic axle loads. The calculation of the axle loads is based on the vehicle-track-soil interaction. This interaction calculus utilises the dynamic stiffness of the vehicle (the inertia of the wheelset) and the dynamic stiffness of the track-soil system. Based on various time consuming finite-element boundary-element calculations, an approximate track-soil model has been established. The vehicle-track-soil analysis yields several transfer functions between the various geometric or stiffness irregularities and the axle loads of the train. Geometric irregularities of the vehicle (the wheels) and the track (rail surface and track alignment) are the simplest components. Geometric irregularities of the subsoil (trackbed irregularities) have to be transferred to effective irregularities at rail level. The bending stiffness of the track is filtering out the short-wavelength contribution. Stiffness irregularities occur due to random variations in the ballast or the subsoil, which must also be transferred to effective track irregularities, and due to the discrete rail support on sleepers. All necessary transfer functions for the prediction of axle-load spectra are presented as general formula and as specific graphs for differing vehicle and track parameters. The prediction method is applied to a ballast track and a slab track and compared with corresponding axle-box measurements. Moreover, ground vibration measurements at numerous sites are exploited for the axle-load spectra and the validation of the prediction method. All theoretical and experimental results confirm that the dynamic axle-load spectra have an approximate value of 1 kN per third of octave and increase with train speed, track stiffness and around the vehicle-track resonance.
The dynamic compliance of different railway tracks on different layered soils have been calculated using a combined finite-element and boundary-element method:
conventional track on homogeneous soil with different stiffness,
extreme normal and inverse layering of the soil,
plates in and on top of the soil (slab track on various soils),
conventional track with elastic rail pads.
The damage detection and repair control have become important tasks for ballast and slab tracks. Measurements which compare the damaged and the repaired status of the same track section at different times, or which compare a damaged and an intact track section at the same time, have been successfully performed at some sites in Germany. The loss of contact between the sleeper and the track plate, between the track plate and the base plate, and between the base plate and the base layer have been analysed. The soil properties of each site have been measured and have been used to establish realistic track-soil models. Theoretical results of the wavenumber domain and the finite-element boundary element method have been compared with the experimental results. The observed experimental and theoretical results, changes in the time histories of displacements and velocities due to train passages and in the transfer functions (receptances) due to hammer impacts, are encouraging that these measurements can be used to detect track damage.
Offshore wind energy towers are dynamically loaded by waves and wind. Pile foundations provide stiffness and damping and should be properly calculated. A combined finite-element boundary-element method for the dynamic interaction of flexible structures and the soil has been developed. The flexible structures such as single piles or complete wind energy towers are modeled by the finite element method whereas the homogeneous or layered soil is modeled by the boundary element method which uses the Green’s functions for interior loads in the layered half-space to establish the dynamic stiffness matrix of the soil. Soils with a stiffness that is continuously increasing with depth can be modeled as multi-layer soils with step-wise increasing stiffness. The effects of different parameters such as the stiffness of the soil, the axial and bending stiffness of the pile, and the radius of the cylindrical contact area will be analysed for the different components of excitation (vertical, horizontal, rotation and coupling). The results can be determined as specific power laws which are different for the different load cases and for the different soil models (Winkler support, homogeneous continuum, continuum with increasing stiffness). The dynamic effect of radiation damping will be analysed by the frequency-dependent compliance functions. A clear layering of the soil can cause noticeable changes in the dynamic compliances as reductions of the stiffness and the damping in certain frequency ranges (below and around layer resonance frequencies). The distribution of the displacements along the pile help to explain the observed laws. An example of an offshore wind energy tower has been modeled and calculated for wind, wave and weight loads. The resonances of the tower are usually limited by the radiation damping which is strongest for a soft soil.