ABSTRACT
In the paper a detailed analysis of the dynamic response of a composite bridge to mining tremors typical for two main regions of mining activity in Poland (i.e. the Upper Silesian Coal Basin and the Legnica-Glogow Copper District) is presented. The representative time histories of accelerations registered in both regions were used as ground motion data in the calculation of the dynamic response of the structure. The frequency contents of both selected tremors were significantly different: the dominant frequency range of the mining tremor in the Upper Silesian Coal Basin consists of lower frequencies (1.5-3.5 Hz) than in the Legnica-Glogow Copper District (5-7.5 Hz). The ABAQUS software was used for the dynamic calculation. Firstly, natural frequencies of the structure were evaluated on both, experimental and numerical ways. The similarity of results allowed to validate the numerical model of the bridge. Then, for the assessment of the influence of dominant frequencies of the mining tremor on the dynamic response of the structure, full time history analyses were carried out. The comparison of the maximal stresses obtained for both shocks was presented. It proved that the dynamic response of the composite bridge strongly depended not only on the level of vibration amplitudes but on the dominant frequency range of the mining shock from the various mining region as well.
