Response spectra at elevations of station dam equipment installation

The object of the study is a concrete station dam of a run-of-river hydroelectric power plant (HPP). A review of publications on the methods of calculating the dynamic responses of structures is presented. The calculation studies were carried out using the finite element method. The initial data for the calculation are the physical characteristics of the concrete material, steel and rock foundation, the geometric parameters of the dam obtained as a result of engineering surveys and strength calculations of the structure. To determine the natural frequencies and vibration modes of the station dam, eight dynamic calculations of the structure and foundation system were performed for eight design nodes at the equipment installation marks. An analysis is presented describing the dam vibrations and response spectra at the equipment installation marks of the station dam. The issues of strength and stability of the station dam are not included in this study, but were taken into account when determining the geometric dimensions of the structure. To calculate the response spectra at the structure marks, a finite element model of the “structure-foundation” station dam of the Nizhne-Bureyskaya HPP was built. The construction of the calculation model was based on the geometric and physical parameters of the station dam and foundation. The accelerogram is selected in accordance with the design period of the station dam of the Nizhne-Bureyskaya HPP, which is 0.23 sec. It corresponds to the first form of oscillations with a frequency of 4.43 Hz. Using the calculated accelerogram, eight dynamic calculations of the “structure-foundation” system were performed for eight calculated nodes at the elevations of the HPP equipment installation. The solution of the equations of motion with decomposition by the initial oscillation forms was performed for each of the eight calculated nodes. The calculated nodes were determined based on the condition of the location of the HPP equipment on them.