Filtern
Erscheinungsjahr
Dokumenttyp
- Beitrag zu einem Tagungsband (66) (entfernen)
Schlagworte
- Ground vibration (11)
- Finite-element boundary-element method (4)
- Layered soil (4)
- Railway track (4)
- Bahnerschütterungen (3)
- Building vibration (3)
- Hammer impact (3)
- Slab track (3)
- Track-soil interaction (3)
- Vibration measurements (3)
- Container loading (2)
- Drop test (2)
- Field tests (2)
- Foundation load (2)
- Layered soils (2)
- Measurement (2)
- Mitigation (2)
- Soil properties (2)
- Soil-building interaction (2)
- Soil-wall-floor model (2)
- Train passage (2)
- Train speed (2)
- Train-induced ground vibration (2)
- Vehicle-track interaction (2)
- Vehicle-track-soil interaction (2)
- 1-D insertion loss (1)
- 2-span bridge (1)
- Achsfolgespektren (1)
- Amplitude-charge weight laws (1)
- Amplitude-distance laws (1)
- Apartment building (1)
- Assessment (1)
- Attenuation (1)
- Axle impulses (1)
- Axle loads (1)
- Axle sequence (1)
- Axle-sequence spectrum (1)
- Ballast track (1)
- Ballast tracks (1)
- Bauteile (1)
- Bauwerke (1)
- Bodendynamik (1)
- Bodeneigenschaften (1)
- Bodenübertragungsfunktion (1)
- Boundary element method (1)
- Bridge resonance (1)
- Bridge track (1)
- Brücken (1)
- Column/wall resonance (1)
- Continuously inhomogeneous soils (1)
- Damping (1)
- Dispersion (1)
- Dispersionsmessung (1)
- Displacements (1)
- Dynamic testing (1)
- Eisenbahnschwingungen (1)
- Elastische Gebäudelagerung (1)
- Elastische Gleiselemente (1)
- Emission (1)
- Erschütterungen (1)
- Erschütterungsausbreitung (1)
- Erschütterungsminderung (1)
- Erschütterungsprognose (1)
- Erschütterungsursachen (1)
- Evaluation (1)
- Excitation forces (1)
- Explicit Green´s functions (1)
- Explosion-induced ground vibrations (1)
- FEBEM and simplified methods (1)
- Filter effects (1)
- Finite element method (1)
- Finite element models (1)
- Floating slab track (1)
- Floor amplification (1)
- Floor resonance (1)
- Force transfer (1)
- Foundation reduction (1)
- Freight train (1)
- Frequenzbereiche (1)
- Gleiströge (1)
- Ground vibration measurements (1)
- Halbraum (1)
- Hammer tests (1)
- High-Rise Building (1)
- High-speed train (1)
- Immission (1)
- Inertial Interaction (1)
- Irregular ballast (1)
- Irregular soil (1)
- Irregularities (1)
- Kinematic Interaction (1)
- Laboratory tests (1)
- Long-span bridge (1)
- MASW (1)
- Measurements (1)
- Mitigation measures (1)
- Modal force spectrum (1)
- Modalanalyse (1)
- Modes (1)
- Nachgiebigkeiten (1)
- Office building (1)
- Office tower (1)
- Passenger train (1)
- Pile Foundation (1)
- Pile bending stiffness (1)
- Pile foundation (1)
- Plate-soil interaction (1)
- Prediction of explosion induced ground and building vibration (1)
- Prognoseverfahren (1)
- Propagation from a tunnel (1)
- Radiation damping (1)
- Railway (1)
- Railway bridge (1)
- Railway induced ground vibration (1)
- Railway tracks (1)
- Railway tunnel (1)
- Railway vibration (1)
- Randomly heterogeneous soil (1)
- Rechenmodelle (1)
- Residential building (1)
- SASW (1)
- SPAC (1)
- Scattering (1)
- Simple prediction (1)
- Soil stiffness (1)
- Soil-building resonance (1)
- Surface Foundation (1)
- Surface line (1)
- Surface-tunnel reduction (1)
- Track compliance (1)
- Track damage (1)
- Track damage monitoring (1)
- Track irregularities (1)
- Track vibration (1)
- Train passages (1)
- Transfer function (1)
- Transmission (1)
- Tunnel (1)
- Tunnel track (1)
- Tunnel vibration (1)
- Tunnel-pile transfer (1)
- Under sleeper pads (1)
- Under-ballast plate (1)
- Varying stiffness (1)
- Verkehrserschütterungen (1)
- Vibration measurement (1)
- Vibration reduction (1)
- Vollraum (1)
- Wave excitation (1)
- Wave velocity (1)
- Wavenumber integrals (1)
- Waves (1)
- Wellenausbreitung in der Tiefe (1)
- Wellengeschwindigkeit (1)
- Wind energy tower (1)
- Windenergieanlagen (1)
- Zerstreute Achsimpulse (1)
- Zuggeschwindigkeit (1)
- floor vibration (1)
- ground vibration (1)
- mitigation (1)
- modal analysis (1)
- railway track (1)
- track-soil interaction (1)
- undersleeper (1)
- wave analysis (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (24)
- 7.2 Ingenieurbau (24)
Explosion-induced ground vibrations have been measured at several places. Results about the wave propagation are shown in this contribution. The particle velocities of the soil have been measured at up to 1000 m distance from the explosion and are presented as time records (seismograms) and one-third octave band spectra (transfer functions). The results are compared with the results of hammer impacts. The seismograms clearly show different wave types, compressional waves of the air, the water and the soil, and the Rayleigh wave. The hammer impacts yield good results up to 100 m and incorporate higher frequencies at about 50 Hz, whereas the explosion results in a ground vibration with frequencies around 10 Hz and a longer range of influence. Explosion and hammer excitations are evaluated for the wave velocities of the soil by using the wavenumber and the spatial auto-correlation method. The attenuation of the ground vibration amplitudes A with distance r can well be presented by a power law A ~ r -q. This type of amplitude-distance law and the corresponding power q > 1 are substantiated in the contribution. The influence of the charge weight W is evaluated as an additional power law A ~ W -p for each measuring site. The power is found quite similarly around q 0.6 as all sites have a medium soft soil such as sand and clay. The obtained amplitude-charge-distance law can be used to predict the explosion-induced ground and building vibrations at other sites.
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.
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.
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.
A variety of isolation measures exists to reduce the vibration in the neighbourhood of railway lines. They can be roughly classified as elastic or stiffening systems. There are the following elastic elements, rail pads or resilient fixation systems between rail and sleeper, under sleeper pads or sleeper shoes under the sleepers, and ballast mats under the ballast. Stiffening systems (plates) are used as slab tracks, floating slab tracks, or mass-spring systems. In the EU project “Railway induced vibration abatement solutions (RIVAS)”, elastic under sleeper pads have been investigated. The dynamic behaviour of the track and the surrounding soil has been calculated by the combined finite-element boundary-element method in a systematic parameter study. It has been shown that the mitigation effect can be improved by soft under sleeper pads or by heavy sleepers. Consequently, such track elements (soft under sleeper pads and heavy sleepers) have been thoroughly investigated in laboratory tests to establish the static and dynamic parameters as well as their serviceability. Finally, field tests at and near railway tracks with and without under sleeper pads have been performed. To determine the reduction effect of the isolated track, the ground vibrations excited by trains or artificial sources have been measured. The soil properties at the different sites have also been measured so that the comparison of the isolated and un-isolated track can take into account possible differences of the soil parameters. The contribution shows how the different (numerical, laboratory and field) methods and results can be combined to achieve an improved mitigation solution with soft under sleeper pads and heavy sleepers for ballasted and slab tracks.
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 with slab tracks and ballast tracks and compared with the theoretical behaviour of intact and damaged tracks. The loss of contact between the sleeper and the plate, between the plate and the base layer, and some problems with soft or weakened soil have been analysed. The observed results, changes in the time histories of displacements and velocities due to train passages and in the transfer functions (compliances) due to hammer impacts, are encouraging that these measurements can be used to detect track damage. In addition, calculations with the combined finite-element boundary-element method have been used to confirm the conclusions about intact or damaged railway tracks.
Die Grundidee einer Schwingungsminderung ist es eine tiefe Eigenfrequenz der Struktur zu erreichen, so dass höhere Frequenzen abgemindert werden. Das gilt für die Minderung an der Quelle, zum Beispiel einem Eisenbahngleis, und für die Minderung am Empfänger, dem Gebäude. Die Eigenfrequenz ermittelt man aus dem Verhältnis der Auflagersteifigkeit und der Masse. Wie ist die Masse bei einem Gebäude zu wählen? Und wie ist die Untergrundsteifigkeit zu berücksichtigen? Als Referenzsituation ohne Minderungsmaßnahme? Der Beitrag bringt Rechenergebnisse zu abgefederten Gebäuden mit einfachen und komplexen (FE-) Modellen, Mess- und Rechenergebnisse zur Schwingungsübertragung von unabgefederten Gebäuden. Es wird der Einfluss der Abstimmfrequenz, der Bodensteifigkeit und der „starren“ Gebäudemasse untersucht. Die komplexen Gebäudemodelle erlauben, neben der Berechnung einer elastischen Gebäudelagerung, auch die Variation von Gebäudeparametern zur Reduktion der Deckenschwingungen. Den Ergebnissen bei der Erschütterungs-übertragung in Gebäude werden zwei ähnliche Beispiele zur elastischen Maschinenlagerung und zur elastischen Gleislagerung gegenübergestellt.
An drei Straßenbrücken unterschiedlicher Länge und Bauart wurden vor Inbetriebnahme ambiente Schwingungsmessungen mit bis zu 350 Messpunkten durchgeführt, um auch höhere Eigenformen detaillierter zu ermitteln. An einer Eisenbahnbrücke der Strecke Hannover-Würzburg wurden bei Testzugfahrten mit definierten Geschwindigkeiten verschiedene Resonanzanregungen beobachtet. Dies wird mit dem Achsfolgespektrum des ganzen Zuges erklärt, wobei eher spezifische Frequenzauslöschungen als Resonanzanregungen maßgeblich sind.
Measured train passages and hammer impacts in combination with track-soil calculation have been successfully used for the detection of damaged slab tracks. This approach is now extended to intact slab and ballast tracks. The vibrations of many tracks have been measured at several levels from rail, sleeper, track plate, base plate, base layer to the subsoil by velocity or acceleration sensors. The time histories have to be integrated once or twice to get the displacements. The displacement signals include an arbitrary time-dependent shift which must be eliminated or respected in the interpretation. On the other hand, the calculation of slab and ballast tracks have been done in frequency-wavenumber domain. The displacements along the track and the frequency-dependent compliance transfer functions can be calculated. The latter can be compared with the results of the hammer impacts on the track. The deformation of the track can be transformed to time histories for a whole train and compared to the measured train passages. Many slab (and ballast) tracks have been measured at different sites. The displacements of the tracks are presented, and the following parameters have been analysed in the measurement results: slab track vs. ballast track, different types of slab tracks, damaged slab tracks, different trains, switches at different measuring points, an elastic layer, the mortar layer, different soils at different places. The soil should have the dominant influence on the track-plate displacements. Slab and ballast track yield also big differences in maximum displacement and width of deformation. Some of the preceding aspects will be analysed in comparison of measurement and theory.