Analysis of oscillator damping under real seismic impact

Introduction. This paper presents the processing and investigation of real seismic data in order to study the impact spectra and response of the oscillator at various damping levels. The aim. Determination of the maximum, practically significant damping percentages using an informative, simple technique based on the amplitudes of the reaction spectra. Materials and methods. Accelerograms were processed using Microsoft Excel and SeismoSignal software from SeismoSoft. Results. A spectrum (impact spectrum) was constructed for each direction, and the total spectrum was calculated using the «Square Root of the Sum of Squares (SRSS)» method. The response spectrum of a system with one degree of freedom (oscillator) was compared with the impact spectrum. The total response spectra were calculated using three methods, and based on the analysis, the most acceptable one was identified. To analyze the damping properties, a family of spectral curves with different damping percentages was constructed for each axis. The maximum damping percentages, which are of practical importance, were determined using a developed technique based on the analysis of the maximum amplitudes of the response spectra. Conclusions. It follows from the obtained results: the maximum values of the spectral power densities of impacts and reactions are different for periods in all three directions; the maximum damping percentages are different for each of the directions.