Keywords: microtremor, railway traffic effects on structures, prediction dynamic half space response models, in situ tests, spectral analysis.

The free-field dynamic response at the distance (from the railway track) and dynamic response of building structures are described. In the numerical model (NM) the soils are modelled as a viscoelastic halfspace [1]. This model is used both for evaluation of the track-soil interaction forces as well as for prediction of the ground-borne vibrations. The numerical results in the frequency domain free-field response are presented using the response spectra of the viscoelastic soil medium [2]. Finally this output response (e.g. acceleration) spectrum at a distance are applied as the input spectra for building structure dynamic response calculation arising from railway traffic using the relevant computational building structure model.

The numerical model which calculates the expected ground-borne vibration level arising from the railway traffic can be divided in two steps. The first step determines the dynamic track-soil interaction forces using a detailed train model and the dynamic behaviour of the layered spring-damper system and the through-soil coupling of the sleepers are accounted for the soil model. The calculation of the ground-borne vibration level at the distance in the second step is based on the viscous-elastics soil model.

The analytical-experimental model proposes the test and the theory data combination to calculate the level of ground vibration. In this process the acceleration spectra measured at the nearest ground point to the track for the individual case study is used as an input signal. The frequency response function (transfer function) of the ground in this approach can be derived using the experimental impulse seismic method (ISM) or cross-hole test data, from which elastic and attenuation parameters of the ground can be obtained, too. The output response acceleration spectrum at the distance arising from the input accelerations spectrum can be derived [3].

For calculation of the expected structure dynamic response for example in the frequency domain the response spectrum at a distance is used to obtain the expected structure dynamic response arising from the train.

1

J. Bencat, "Microtremor due to Traffic", Research report A-4-92/b, UTC Zilina, SK, 1992.

2

J. Bencat, "Studies of the TEN-T railway traffic effects on IBM Data Centrum - ST building in Bratislava", Report 16/SvF/2009, UTC SvF Zilina, 2009.

3

J.S. Bendat, A.G. Piersol, "Engineering Applications of Correlation and Spectral Analysis", Wiley & Sons, New York, 1993.

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