O.B. Oleynikov1, I.N. Dubovik2

1,2 PJSC “Radiofizika” (Moscow, Russia)

1,2 Moscow Aviation Institute (National Research University) (Moscow, Russia)

1 captain_oleg@mail.ru; 2 dubovig@mail.ru

In recent years, the frequency of earthquakes has increased significantly even in those parts of the world where they occur quite rarely, which forces in addition to strength and stiffness also assess the seismic resistance of stationary antenna structures, the process of which is a rather complex task due to the uncertainty of setting the seismic load itself. This load is inseparable from dynamic properties of the structure and, in fact, is not the impact of the earthquake as such but the result of its interaction with the structure. The antenna is influenced by oscillatory movements of the earth’s surface, which are transmitted to the base of its mounting in the form of kinematic excitation, which leads to the appearance of inertial seismic forces in the structure. The main problem is how to obtain the seismic impact spectrum and generate a plot of peak responses in the form of amplitude acceleration values in a certain frequency range to determine the response of the antenna structure without resorting to expensive vibration-impact tests or in the absence of the necessary equipment.

In the Simcenter Femap software package, a methods was considered for calculating the response spectrum based on the spectral theory of M. Biot, where the peak values of the responses of a certain set of test oscillators (pendulums) with different natural frequencies, measured experimentally and obtained as a result of base movements during an earthquake forma spectrum accelerations or spectrum of seismic load influence. In this case the maximum responses of the oscillators were determined by a given accelerogram in the form of a plot of the amplitudes of vibrations of the earth’s surface depending on time. Because the conversion of external seismic accelerogram data from the time domain to the frequency domain to obtain the response spectrum cannot be performed using Fast Fourier Transform (FFT) algorithms. Therefore, first of all spectral analysis was carried out using the finite element method (FEM) to form a spectrum of external seismic influence, which was then applied to the calculation model of the antenna structure to calculate its seismic resistance. The maximum dynamic response of the calculation model of a stationary antenna to the resulting seismic impact spectrum was assessed in the form of the largest values of stresses and displacements corresponding to resonant vibration modes in a given frequency region.  

Oleynikov O.B., Dubovik I.N. Spectral analysis of seismic resistance of stationary antenna structures. Radiotekhnika. 2024. V. 88.
№ 4. P. 46−55. DOI: https://doi.org/10.18127/j00338486-202404-04 (In Russian)

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